Composite laminates made from carbon fibers and epoxy resin (CFRP) have been obtained and used as a strengthening of concrete in the form of cylinders. The laminates were made with the use of high-modulus and high-strength carbon fibers. Different types of laminates (1D, 2D) of different thickness were wrapped and glued to the surface of concrete cylinders. The studies were focused on the compressive strength improvement of the cylinders. Compressive strengths and axial strains of unconfined and CRFP-confined concrete cylinders were compared. Compressive strength of concrete cylinders was considerably improved by wrapping the cylinders with the high-strength carbon laminates in the hoop direction.

The mechanism of two-dimensional specific cutting resistance and steady excavating force for weak rock mass have been analysed by means of the failure criterion of rock materials. As a result, the specific cutting resistance could be estimated by Eqs. (11),(12) from the unconfined compressive strength, radial compressive strength, assuming that the shear failure develops on the whole linear slippage line on which the normal stress distributes to the power of 0.30 and the steady excavating force could be estimated by Eqs. (28) from the unconfined and radial compressive strength, assuming that the shear failure develops on the logarithmic spiral and linear line on which the normal stress distributes to the power of 1.79. The steady cutting force could be expressed by the function of specific cutting resistance, depth of excavation and rake angle of the blade. Described items are as follows: Weak rock specimens. Specific cutting resistance. Stationary excavation force. Simulation analysis. 10 refs., 12 figs., 3 tabs.

Enormous amounts of oyster shell waste have been illegally disposed of at oyster farm sites along the southern coast of Korea. In this study to evaluate the possibility of recycling this waste for use as a construction material, the mechanical characteristics of pulverized oyster shell were investigated in terms of its potential utilization as a substitute for the aggregates used in mortar. The unconfined compressive strengths of various soil mortar specimens, with varying blending ratios of cement, water and oyster shell, were evaluated by performing unconfined compression tests, and the results were compared with the strengths of normal cement mortar made with sand. In addition, the effect of organic chemicals on the hardening of concrete was evaluated by preparing ethyl-benzene-mixed mortar specimens. The long-term strength improvement resulting from the addition of fly ash was also examined by performing unconfined compression tests on specimens with fly-ash content. There was no significant reduction in the compressive strength of the mortars containing small oyster shell particles instead of sand. From these test data, the possible application of oyster shells in construction materials could be verified, and the change in the strength parameters according to the presence of organic compounds was also evaluated. PMID:15253499

In general, the effect of shallow soil stabilization is examined by the unconfined compressive strength of soil mixed with stabilizer in laboratory. Therefore, the in-situ strength of ground stabilized has not been conformed to be satisfied the criteria. In this paper, the author proposes a new evaluating method of shallow soil stabilization, i.e. the impact value of repulsion power of rammer fell down. The relation between the impact value and K value was examined for it , and it was found that the impact value was proportional to K-value. The author applied the impact value and the K-value to a quality control of ground in a factory. The other items used for the quality control are the unconfined compressive strength and a color identification test by phenolphthalein. 10 refs., 12 figs., 1 tab.

Unconfined compression tests and suction measurements were carried out in the present work on sandy specimens with distinct Class F fly ash amounts, lime contents, porosities and curing periods to assess key parameters controlling strength of fly ash-lime amended soil. A special effort has been allocated in order to develop a dosage methodology for fly ash-lime improved soils based in a rational criterion, as it exists in the concrete technology where the water/cement ratio plays a fundamental role in the assessment of the target strength. The results show that the unconfined compressive strength (UCS) increased linearly with the amount of lime for soil-fly ash-lime mixtures at all curing time periods studied. A power function fits better the relation UCS-porosity for soil-fly ash-lime mixtures. The bigger the amount of fly ash and the curing time, the larger the UCS for any given porosity and lime content. Finally, the porosity/volumetric lime content ratio, in which volumetric lime content is adjusted by a coefficient (in this case a unique value-0.12-was found for all soil-fly ash-lime mixtures and all curing periods studied) to end in single correlations for each curing period, show to be a good parameter in the evaluation of the unconfined compressive strength of the soil studied (UCS varies non-linearly with the porosity/volumetric lime content ratio in the case of fly ash-lime addition).   

Improvement and stabilization of soils are widely used as an alternative to substitute the lacking of suitable material on site. Soils may be stabilized to increase strength and durability or to prevent erosion and dust generation. The use of nontraditional chemical stabilizers in soil improvement is growing daily. A new stabilizing agent was developed to improve the mechanical performance and applicability of clayey soils. In this study a laboratory experiment is conducted to evaluate the effects of plasticity index and waterborne polymer on the Unconfined Compression Strength (UCS) of clayey soils. The laboratory tests include sieve analysis, hydrometer, Atterberg limits, modified compaction and unconfined compression tests. Three clayey soils with different plasticity indexes were mixed...

In this study, petroleum-contaminated drilling wastes were stabilized by mixing pozzolanic fly ash, lime and cement with them so they could be used as sub-base materials for road construction. This stabilization produced physically, mechanically and chemically stabilized new mixtures. The laboratory study consisted of unconfined compressive strength, permeability, California bearing ratio, freeze/thaw (durability) and leachate on compacted stabilized samples, pH, electrical conductivity, cation exchange capacity and total metal contents on stabilized mixtures. Significant increases in the unconfined compressive strength, California bearing ratio, durability and pH were obtained by treating lime, fly ash and cement with petroleum drilling wastes. Significant decreases were obtained in electrical conductivity, cation exchange capacity, oil content and total metal concentrations both in mixtures and in leachate. The best result in all of the tests conducted was obtained with petroleum-contaminated soil stabilized with 20% lime, 10% fly ash and 5% cement. This mixture can be effectively and safely used as sub-base material. (au)

Earthquakes comprising the ongoing Canterbury sequence, South Island, New Zealand, have exhibited disproportionately large energy magnitude (Me) to moment magnitude (Mw) ratios (Fry and Gerstenberger, 2011). The 22 February 2011 Mw 6.3 event, for example, had an energy magnitude of 6.7 (USGS). The 22 February event may have ruptured immature faults with high apparent stress formed during the emplacement of Banks Peninsula volcanic rocks (12 Ma-6 Ma); these faults may have been further strengthened by cross-cutting intrusive rocks of the Lyttelton volcano (Fry and Gerstenberger, 2011). We measured P-wave velocity (Vp), S-wave velocity (Vs), density, elastic moduli, and unconfined compressive strength of Lyttelton volcano basalt, trachyte and rhyolite. Unconfined compressive strength (UCS) tests were conducted on specimens fitted with axial and radial strain gauges using a stress-controlled unconfined compression apparatus following ASTM standard method. UCS values range between 165 and 232 MPa for the trachyte and basalt samples; rhyolite UCS values range between 122 and 126 MPa. During UCS testing, acoustic emissions were recorded using 2 broadband AE sensors (PAC WS? 20kHz-1MHz) mounted in the end platens. AE event waveforms, magnitude-frequency relationships, and spectrograms were analyzed. Deformation of each rock type involved brittle-failure-generated AE events with broadband waveforms; numbers of AE events increased exponentially at failure. The magnitude-frequency plots of AE events display a sharp decrease in relative energy emitted at frequencies greater than 600 kHz. Quantifying absolute energy emitted at high frequencies remains challenging; we present preliminary results from experiments designed to characterize broadband frequency attenuation. Our experiments quantify the unconfined compressive strengths, elastic moduli, and characteristic AE waveforms emitted during failure of intraplate volcanic rocks comprising the Lyttelton volcano. Reference: Fry, B., and M. Gerstenberger (2011). Large apparent stresses from the Canterbury earthquakes of 2010 and 2011. Seismological Research Letters 82, 833-838.

Bar impact tests, using the techniques described elsewhere in this symposium, were used to measure compressive and tensile strengths of borosilicate glass, soda lime glass, and a glass ceramic. The glass ceramic was 25% crystalline spinel, furnished by Corning Inc. There are two measures of compressive strength: the peak stress that can be transmitted in unconfined compression, and the 'steady state' strength. For borosilicate glass and soda lime glass, these values were similar, being about 1.8 and 1.5 GPa, respectively. The glass ceramic (25% spinel) was almost 50% stronger. Tensile failure in the glass and glass ceramic takes places via surface flaws, and thus tensile strength is an extrinsic, as opposed to intrinsic property.

The effects of sites and plasticity index (Ip) on the inherent strength anisotropy of eleven different clay deposits are quantitatively examined by the unconfined compression test using a small size specimen with a different angle of inclination to the vertical. A new method for a slope stability analysis, taking the effects of the IASIA method (Inherent And Stress Induced Anisotropies) into consideration, is proposed. The applicability of the IASIA method and the optimum embankment design are examined through case histories of embankment failures on soft soils. The undrained strength anisotropy cannot be estimated by parameters such as the Ip value because of the complicated relationship with the factors influencing undrained anisotropic strength. It must be directly measured. The IASIA method was recommended from a study of a failed embankment. The probability of failure (Pf) and consumer's risk (Pc) from half of the unconfined compressive strength (qu/2) were (2.5~25.5)% and (4.7~42.3)% less than those of the Iwai qu/2(IASIA) and Urayasu qu/2(IASIA). Therefore, the design results were underestimated by disregarding strength anisotropies. If, Pf and Pc were considered, the Ct values increased. However, the Pc values drastically decreased to 24.8% from 54.3% concerning the 75-mm sampler and n increased, thus avoiding latent risks. These mean that the IASIA method can be used for optimum embankment design based on performance provisions.   

To assure high-precision designing with respect to ground stability and deformation, analysis is conducted with soil anisotropy taken into consideration. Alluvial clay is collected undisturbed from nine different spots across Japan using a stationary piston type thin wall sampler 75mm in inner diameter, and specimens, 15mm in diameter and 35mm in height and varied in {beta} (angle of cut-off relative to sedimentation direction), are subjected to an unconfined compression test for the determination of undrained strength anisotropy. In this report, a new slope stability analysis is proposed, based on the said strength and taking into account the initial and induced anisotropy. It is found that, in the case of normally consolidated clay, the maximum unconfined compression strength decreases with an increase in the angle {beta} as long as the axial strain is not higher than 15%, to hit the bottom when the angle {beta} is 90deg. Since the anisotropic elements that affect the undrained strength and the impact they exert on the consequence are quite complicated, it is difficult to determine anisotropy univocally from a specific parameter such as plasticity index or overconsolidation ratio. An example of a collapsed mound is cited to show the effectiveness of the proposed slope stability analysis taking into account the initial and induced anisotropy. 24 refs., 7 figs., 2 tabs.

In this paper we develop an aft-body loading function for penetration simulations that is based on the spherical cavity-expansion approximation. This loading function assumes that there is a preexisting cavity of radius a{sub o} before the expansion occurs. This causes the radial stress on the cavity surface to be less than what is obtained if the cavity is opened from a zero initial radius. This in turn causes less resistance on the aft body as it penetrates the target which allows for greater rotation of the penetrator. Results from simulations are compared with experimental results for oblique penetration into a concrete target with an unconfined compressive strength of 23 MPa.

A number of tests were conducted to determine the engineering/physical properties of three (two bituminous-derived and one lignite-derived) samples of furnace sorbent injection (FSI) by-product to provide data for the planning of effective FSI waste management. The relatively flat shape of the moisture-density curves indicates that reasonable compaction densities can be achieved with moisture contents below optimum, thus reducing haulage costs of moist FSI by-product. In terms of unconfined compressive strength development and hydraulic conductivity, the slaked FSI materials show behaviour equivalent to that of fly ash generated by similar coal sources. 2 refs., 4 figs., 6 tabs.

This paper describes the solidification and stabilization of electroplating sludge treated with a high-performance binder made from portland type-I cement, municipal solid waste incineration fly ash, and lighting phosphor powder (called as cement-fly ash-phosphor binder, CFP). The highest 28-day unconfined compressive strength of the CFP-treated paste was 816kg/cm2 at a ratio of cement to fly ash to lighting phosphor powder of 90:5:5; the strength of this composition also fulfilled the requirement of a high-strength concrete (>460kg/cm2 at 28 days). The CFP-stabilized sludge paste samples passed the Taiwanese EPA toxicity characteristic leaching procedure test and, therefore, could be used either as a building material or as a controlled low-strength material, depending on the sludge-to-CF...

Cement/lime-based solidification is an environmentally sound solution for the management of dredged marine sediments, instead of traditional solutions such as immersion. Based on the mineralogical composition and physical characteristics of Dunkirk sediments, the effects of cement and lime are assessed through Atterberg limits, modified Proctor compaction, unconfined compressive strength and indirect tensile strength tests. The variation of Atterberg limits and the improvement in strength are discussed at different binder contents. The potential of sediments solidified with cement or lime for road construction is evaluated through a proposed methodology from two aspects: I-CBR value and material classification. The test results show the feasibility of solidified dredged sediments for beneficial use as a material in road construction. Cement is superior to lime in terms of strength improvement, and adding 6% cement is an economic and reasonable method to stabilize fine sediments. PMID:22519092

Waste spent catalyst is generated in Oman as a result of the cracking process of petroleum oil in the Mina Al-Fahl and Sohar Refineries. The disposal of spent catalyst is of a major concern to oil refineries. Stabilized spent catalyst was evaluated for use in road construction as a whole replacement for crushed aggregates in the sub-base and base layers and as a partial replacement for Portland cement in masonry blocks manufacturing. Stabilization is necessary as the waste spent catalyst exists in a powder form and binders are needed to attain the necessary strength required to qualify its use in road construction. Raw spent catalyst was also blended with other virgin aggregates, as a sand or filler replacement, for use in road construction. Compaction, unconfined compressive strength and leaching tests were performed on the stabilized mixtures. For its use in masonry construction, blocks were tested for unconfined compressive strength at various curing periods. Results indicate that the spent catalyst has a promising potential for use in road construction and masonry blocks without causing any negative environmental impacts. PMID:22704771

The chemical sludge generated from the treatment of textile dyeing wastewater is a hazardous waste as per Indian Hazardous Waste Management rules. In this paper, stabilization/solidification of chemical sludge was carried out to explore its reuse potential in the construction materials. Portland pozzolona cement (PPC) was selected as the binder system which is commercially available cement with 10-25% fly ash interground in it. The stabilized/solidified blocks were evaluated in terms of unconfined compressive strength, block density and leaching of heavy metals. The compressive strength (3.62-33.62 MPa) and block density (1222.17-1688.72 kg/m3) values as well as the negligible leaching of heavy metals from the stabilized/solidified blocks indicate that there is a potential of its use for structural and non-structural applications. PMID:21724323

Geotechnical properties of clay-cement mixtures were examined. Index properties together with compressibility characteristics of laboratory treated clay-cement mixtures in terms of the compression index and pre-consolidation pressure were evaluated. In addition strength characteristics in terms of unconfined compression of different mixtures obtained in the laboratory were compared. Samples of natural lean clay were mixed with Portland cement in different percentages of 4, 6, 8 and 10, in terms of the dry mass of soil using three different water contents of 30, 48 and 70%, and cured for 7, 14 and 28days. All these samples were prepared based on a deep soil mixing method. The unit weight of treated soil increased with cement content. The specific gravity of treated soil solids first increas...

The high concentration of trivalent chromium along with organic/inorganic compounds in tannery sludge causes severe ground water contamination in the case of land disposal and chronic air pollution during incineration. In the present investigation, the sludge was subjected to flow-through column test to evaluate the concentration of leachable organics (tannin, COD and TOC) and heavy metal ions (Cr{sup 3+}, Fe{sup 2+}) present in it. The dried sludge was incinerated at 800 deg. C in an incinerator under starved oxygen supply (starved-air combustion) to prevent the conversion of Cr{sup 3+} to Cr{sup 6+}. The efficiency of starved air combustion was studied under different loading rates of sludge. The calcined sludge was solidified/stabilized using fly ash and Portland cement/gypsum. The solidified bricks were tested for unconfined compressive strength and heavy metal leaching. Unconfined compressive strength of the blocks was in the range of 83-156 kg/cm{sup 2}. The stabilization of chromium (III) in the cement gel matrix was confirmed with scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDX). Leachability studies on solidified bricks were carried out to determine the metal fixation and dissolved organic (as COD) concentration in the leachate.

The apparent mechanical properties of hydroxyapatite (HA) whisker reinforced polyetherketoneketone (PEKK) scaffolds were evaluated in unconfined, uniaxial compression to investigate the effects of the porosity (75%, 82.5% and 90%), HA content (0, 20 and 40 vol%) and mold temperature (350, 365 and 375 C). Increased porosity resulted in a non-linear decrease in the elastic modulus and yield strength for both reinforced and unreinforced PEKK scaffolds, as expected. The increase in elastic modulus and yield strength with increased relative density followed a power-law, similar to trabecular bone and other open-cell foams. HA whisker reinforcement generally resulted in an increased elastic modulus from 0 to 20 vol% HA and a subsequent decrease from 20 to 40 vol% HA, while the yield strength and...

Oil shale solid wastes were evaluated for possible use as soil stabilizers. A laboratory study was conducted and consisted of the following tests on compacted samples of soil treated with water and spent oil shale: unconfined compressive strength, moisture-density relationships, wet-dry and freeze-thaw durability, and resilient modulus. Significant increases in strength, durability, and resilient modulus were obtained by treating a silty sand with combusted western oil shale. Moderate increases in strength, durability, and resilient modulus were obtained by treating a highly plastic clay with combusted western oil shale. Solid waste from eastern shale can be used for soil stabilization if limestone is added during combustion. Without limestone, eastern oil shale waste exhibits little or no cementation. The testing methods, results, and recommendations for mix design of spent shale-stabilized pavement subgrades are presented. 11 refs., 3 figs., 10 tabs.

To establish mechanical properties and failure criteria of silicon carbide (SiC-N) ceramics, a series of quasi-static compression tests has been completed using a high-pressure vessel and a unique sample alignment jig. This report summarizes the test methods, set-up, relevant observations, and results from the constitutive experimental efforts. Results from the uniaxial and triaxial compression tests established the failure threshold for the SiC-N ceramics in terms of stress invariants (I{sub 1} and J{sub 2}) over the range 1246 < I{sub 1} < 2405. In this range, results are fitted to the following limit function (Fossum and Brannon, 2004) {radical}J{sub 2}(MPa) = a{sub 1} - a{sub 3}e -a{sub 2}(I{sub 1}/3) + a{sub 4} I{sub 1}/3, where a{sub 1} = 10181 MPa, a{sub 2} = 4.2 x 10{sup -4}, a{sub 3} = 11372 MPa, and a{sub 4} = 1.046. Combining these quasistatic triaxial compression strength measurements with existing data at higher pressures naturally results in different values for the least-squares fit to this function, appropriate over a broader pressure range. These triaxial compression tests are significant because they constitute the first successful measurements of SiC-N compressive strength under quasistatic conditions. Having an unconfined compressive strength of {approx}3800 MPa, SiC-N has been heretofore tested only under dynamic conditions to achieve a sufficiently large load to induce failure. Obtaining reliable quasi-static strength measurements has required design of a special alignment jig and load-spreader assembly, as well as redundant gages to ensure alignment. When considered in combination with existing dynamic strength measurements, these data significantly advance the characterization of pressure-dependence of strength, which is important for penetration simulations where failed regions are often at lower pressures than intact regions.

The present work describes the change of mechanical properties during the natural weathering of freshly quenched processed bottom ash. An unconfined uniaxial compression to failure test of the unbound material was used to determine compressive strength and modulus of elasticity. Three main stages of mechanical behavior were determined. In the first stage, during a period lower than 30 days, mechanical properties suddenly increase, with a compressive strength and elastic modulus 7 times greater than the initial parameters. During the second stage, compressive strength and modulus of elasticity lightly increase until approximately 90 days of curing time. Starting from this period both mechanical properties remain steady and independent of the curing time. The neoformed phases, the elevated water content, and the improvement of particle contact after compaction act as a binder layer among particles, increasing the mechanical parameters during the short-term natural weathering process. Because of this, the freshly compacted bottom ash progresses from behaving as an unbound material into a bound pavement material. These mechanical properties obtained from freshly quenched bottom ash are 6-7 times greater than those obtained from previously weathered bottom ash. The bottom ash expansion and leaching of metals were also evaluated. PMID:16245851

A fluid effect toward higher strengths for oil-saturated chalk compared with water-saturated chalk has previously been identified and labeled the "water-weakening phenomenon," but has not been further characterized physically. The hypothesis of this paper is that the Biot critical frequency with a strain or stress-rate dependence can be used to explain this behavior on the pore scale and can be extrapolated to the macroscale failure and pore-collapse properties. A large set of previously published laboratory test results on chalk with different pore fluids was collected, and as a supplement we present a new test series on Stevns chalk with unconfined compression and Brazilian strength results. Copyright © 2011 Society of Petroleum Engineers.

Calcium phosphate compounds (CPCs) have unique physicochemical properties. As grout material, they afford many advantages such as adequate physical strength, self-setting property, pH dependence of precipitation, non-toxicity, and recyclability. To apply CPCs to the permeability control and reinforcement of ground soil and rock, we explored suitable conditions for in vitro CPC precipitation, conducted unconfined compressive strength (UCS) tests of Toyoura sand test pieces cemented by CPC, and carried out observations and elemental analysis of precipitated CPC crystals. Two kinds of phosphate stock solution and two kinds of calcium stock solution were used to prepare the reaction mixtures, and CPC precipitation was detected in all reaction mixtures. The volume of CPC precipitation in the re...

In the present study, the feasibility of recycling incinerator bottom ash in cementitious systems by means of chemical activation was investigated. Different Na-, K- and Ca-based hydroxides and salts were selected for the experiments on the basis of their recognized effects on activation of typical pozzolanic materials. The evolution of mechanical properties of bottom ash/Portland cement mixtures and the leaching of trace metals from the materials were a matter of major concern. The experiments were arranged according to a full factorial design, which also allowed to derive a predictive model for unconfined compressive strength as affected by bottom ash content as well as activator type and dosage. Among the activators tested, calcium chloride was found to affect mechanical strength far mo...

The aim of this study was to investigate the novel utilisation of waste precipitates derived from the neutralisation of effluents from mineral processing in controlled low-strength materials (CLSM); maximising the amount of waste used while satisfying performance requirements for classification as CLSM. Mechanical, physical, micro-structural and leaching properties of laboratory-scaled CLSM specimens were evaluated. Waste precipitates chosen were an ochreous minewater sludge and a jarosite residue from zinc extraction; the former containing lower amounts of hazardous components than the latter. The results showed that formulations with 10wt% of the wastes examined could be beneficially re-formed as CLSM with unconfined compressive strength not greater than 2MPa at 28 days, the upper limit ...

Waste spent catalyst is generated in Oman as a result of the cracking process of petroleum oil in the Mina Al-Fahl and Sohar Refineries. The disposal of spent catalyst is of a major concern to oil refineries. Stabilized spent catalyst was evaluated for use in road construction as a whole replacement for crushed aggregates in the sub-base and base layers and as a partial replacement for Portland cement in masonry blocks manufacturing. Stabilization is necessary as the waste spent catalyst exists in a powder form and binders are needed to attain the necessary strength required to qualify its use in road construction. Raw spent catalyst was also blended with other virgin aggregates, as a sand or filler replacement, for use in road construction. Compaction, unconfined compressive strength and ...

The drift of a High Level Nuclear Waste (HLNW) Repository were subjected to 2-D thermal loading resulting from the horizontal emplacement of 125 Ton Multi-Purpose Canisters (MPC). Ten 2-D temperature profiles, resulting from 57 Kw/acre and 114 Kw/acre thermal loading conditions, were used in a finite element analysis of the drift; in which a quadrant of the drift and surrounding rock {+-} 100 m above and below the drift were modeled. Our analysis shows that the 114 Kw/acre thermal loading results in compressive stresses around the drift, 60 years after emplacement, that exceed the unconfined compressive strength of the TSW{sub 2} tuff analyzed. Stresses resulting from a 57 Kw/acre thermal loading are within the acceptable limit in tunnel rock. A parametric analysis of the invert backfill material showed that Young`s modulus for the invert backfill should closely match that of the surrounding unconfined rock in the tunnel in order to prevent an unacceptable stress rise in both rock and backfill.

Zones of pulverized rock have been observed in surface outcrops adjacent to the fault cores of the San Andreas and other major faults in Southern California. These pulverized rocks consist of highly fractured fragments that still fit together and essentially preserve the original rock texture. The origin of these pulverized rocks is not clear, but their structural context indicates that they are clearly associated with faulting; an understanding of their origin might allow inferences to be drawn about the nature of dynamic slip on faults, energy balance of earthquakes, and implications for ground motions and radiation patterns near faults. Our overall experimental study will include both quasi-static and dynamic loading to determine whether pulverized rocks can be produced in the laboratory and whether they indicate anything about the rate of deformation. In the present preliminary study, the first of a series of experiments to be undertaken, laboratory experiments are conducted on Westerly granite samples to investigate whether pulverized rocks can be produced under stress-wave loading conditions and whether they are diagnostic of any particular process of formation. In the first group of experiments a Split Hopkinson pressure bar (SHPB) is utilized to subject cylindrical rock specimens to well-defined uniaxial compressive stress-wave loading. In these experiments the amplitude as well as the duration of the compressive loading pulse is systematically varied to study the initiation and progression of fragmentation in both confined and unconfined granite samples. In the second group of experiments, plate-impact experiments are conducted to obtain the stress threshold for inelasticity in Westerly granite by estimating its Hugoniot Elastic Limit (HEL) under shock-induced compression. These experiments are also designed to provide spall (tensile) strength following shock-induced compression loading in the granite samples. It is expected that the measured spall strength will provide an indication of the extent of the shock-induced damage during compression in the rock samples. The results of the SHPB experiments indicate that the peak stress for Westerly granite under uniaxial compression is ~210 MPa (with a strain to failure of about 0.7%) in the unconfined state; the peak stress increases to 1 GPa under a confinement pressure of 60 MPa. In the unconfined state, the post-impact samples show no apparent fragmentation when the applied compression stress is lower than 180 MPa. However, at stress levels above 210 MPa extensive fragmentation is observed. Under confinement, the post- impact samples appear to be intact macroscopically when the applied compression stress is lower than 1 GPa; they show a few cracks on the impact surface but no extensive fragmentation when the applied compression stress is between 1.1 and 2.2 GPa, and they show extensive fragmentation when the applied compression stress is higher than 2.6 GPa. The HEL for the granite is estimated to be between 4.2 to 5.0 GPa. The spall strength following the shock-compression is measured to be small (~50 MPa), and nearly independent of the applied compression level in the range of 1.2 to 5.0 GPa. Detailed microstructural analysis of the post-test recovered specimens from both the SHPB and plate-impact experiments is currently underway to understand texture of the impacted rocks? The answers to these questions are expected to shed light concerning the origin and significance of the pulverized rocks adjacent to fault cores of major faults.

An experimental study was conducted to measure the mechanical properties of the Thermal Protection System (TPS) materials used for the Space Shuttle. Three types of TPS materials (LI-900, LI-2200, and FRCI-12) were tested in 'in-plane' and 'out-of-plane' orientations. Four types of quasi-static mechanical tests (uniaxial tension, uniaxial compression, uniaxial strain, and shear) were performed under low (10{sup -4} to 10{sup -3}/s) and intermediate (1 to 10/s) strain rate conditions. In addition, split Hopkinson pressure bar tests were conducted to obtain the strength of the materials under a relatively higher strain rate ({approx}10{sup 2} to 10{sup 3}/s) condition. In general, TPS materials have higher strength and higher Young's modulus when tested in 'in-plane' than in 'through-the-thickness' orientation under compressive (unconfined and confined) and tensile stress conditions. In both stress conditions, the strength of the material increases as the strain rate increases. The rate of increase in LI-900 is relatively small compared to those for the other two TPS materials tested in this study. But, the Young's modulus appears to be insensitive to the different strain rates applied. The FRCI-12 material, designed to replace the heavier LI-2200, showed higher strengths under tensile and shear stress conditions. But, under a compressive stress condition, LI-2200 showed higher strength than FRCI-12. As far as the modulus is concerned, LI-2200 has higher Young's modulus both in compression and in tension. The shear modulus of FRCI-12 and LI-2200 fell in the same range.

This paper describes the tensile strength measured for three kinds of statically compacted unsaturated soils; mixtures of clay~silt~sand, Narita-sand and Kanto loam. Specimens were directly prepared either under controlled compaction stress or under controlled dry density by statically compacting them within the tensile mold of the apparatus. Image analysis was done to show the normality of tensile force to the tensile failure plane. Tensile strengths (qt) were compared with the unconfined compressive strengths (qu) for silt~sand mixture, clay~sand mixture, clay~silt mixture and Narita sand, respectively. Increment in tensile strength (also qu/qt ratio) with the increase in the percentage and decrease in the size of finer soils could be seen. Effects of number of compaction layers and tensile pulling rates on the qt were also examined. Increase in the tensile strength with the increase in the number of compaction layers was observed; and it was suggested to prepare the unsaturated compacted specimen by 3 to 4 layers compaction. Increase in tensile strength of 0.3 kPa and 0.003 kPa per one cycle of logarithm of tensile pulling rate was observed for clay~sand-4 (1:3) and clay~sand-5 (3:1) for the pulling rate of 0.01 to 1.0 mm/min.   

Numerous studies demonstrated the possibility of utilizing fly ash in the construction of embankments, road subgrades and stabilization of a wide range of soils. The present investigation aims at determining the optimum fly ash (OFA) for mechanical stabilization of expansive soils. Four different soils were tested for compaction characteristics and unconfined compressive strength with and without the addition of fly ash to determine the OFA. The liquid limit (LL) and the fraction coarser than 425 ? (CF) of these soils range from 50 to 120 and 25 to 70%, respectively. An experimental strategy called two-factor factorial design was adopted in the conducting experiments. LL and CF present in the soil are the two factors considered to influence the OFA content. Factorial experimentation enab...

Soft soil stabilization has been practised for quite some time by mixing additives, such as cement, lime and fly ash to the soil to increase its strength. However, there is a lack of investigations on the use of natural pozzolana alone or combined with lime for ground improvement applications. An experimental programme was undertaken to study the effect of using lime, natural pozzolana or a combination of both on the geotechnical characteristics of soft soils. Lime or natural pozzolana was added to soft soils at ranges of 0?10% and 0?20%, respectively. In addition, combinations of lime?natural pozzolana were added to soft soils at the same ranges. Test specimens were subjected to compaction tests, shear tests and unconfined compression tests. Specimens were cured for 1, 7, 28 and 90?days, ...

We have already developed a new recycling system for high water content mud such as construction sludge by using paper debris (fragments of the newspaper) to increase the recycling rate of the construction sludge. However, recently, the price of old newspaper is increasing. Therefore, development of inexpensive fiber materials are strongly desired in order to reduce the recycling cost. In this study, the applicability of waste gypsum board paper instead of paper debris was experimentally investigated. The waste gypsum board paper was crushed by the hammer mill and crushed paper was used in fiber-cement-stabilized-soil method. It was found through the unconfined compression tests that the failure strength and failure strain of modified soils by using crushed board paper are almost the same as those of modified soils by using paper debris. That is, it was confirmed that the crushed board paper can become a substitute of paper debris.   

This study aims to evaluate the potential of low grade MgO (LGMgO) for the stabilisation/solidification (S/S) of heavy metals in steel electric arc furnace wastes. Relevant characteristics such as setting time, unconfined compressive strength (UCS) and leaching behaviour assessed by acid neutralisation capacity (ANC), monolithic and granular leaching tests were examined in light of the UK landfill Waste Acceptance Criteria (WAC) for disposal. The results demonstrated that all studied mix designs with Portland cement type 1 (CEM1) and LGMgO, CEM1-LGMgO 1:2 and 1:4 at 40% and 70% waste addition met the WAC requirements by means of UCS, initial and final setting times and consistence. Most of the ANC results met the WAC limits where the threshold pH values without acid additions were stable a...

Cement was used to solidify/stabilize the abandoned mine tailings contaminated primarily with arsenic (up to 88mg/kg) and lead (up to 35mg/kg). Solidified/stabilized (s/s) forms with a range of cement contents, 5-30wt%, were evaluated to determine the optimal binder content. Unconfined compression strength test (UCS), Korean standard leaching tests, toxicity characteristic leaching procedures (TCLP), and synthetic precipitation leaching procedure (SPLP) were used for physical and chemical characterization of the s/s forms. Addition of 5% cement was enough for the s/s forms to satisfy the UCS requirements (0.35MPa). The addition of 7.5% cement remarkably reduced the leachability of arsenic in tailings. However, that of lead tends to increase slightly with increase of cement content due to i...

A systematic treatability study was conducted for the treatment of drill cuttings, a waste generated during petroleum exploration and production, by stabilization/solidification with Portland cement (CEM I), with the addition of high carbon power plant fly ash (HCFA), an industrial by-product, as a novel sorbent for organic contaminants. A factorial design experiment was adopted to investigate the effects of waste-to-binder ratio, binder formulation, and curing time on response variables including unconfined compressive strength (UCS), hydraulic conductivity, porosity, leachate pH, and acid neutralization capacity (ANC) of the s/s products. Results show that all factors had significant effects on the properties of the s/s products. Drill cuttings and HCFA addition both reduced UCS, but HCF...

This paper presents the findings of a study on solidification/stabilization (S/S) of lead-contaminated soil using ordinary Portland cement (OPC) and rice husk ash (RHA). The effects of varying lead concentrations (in the form of nitrates) in soil samples on the physical properties of their stabilized forms, namely unconfined compressive strength (UCS), setting times of early mixtures and changes in crystalline phases as well as chemical properties such as leachability of lead, pH and alkalinity of leachates are studied. Results have indicated that usage of OPC with RHA as an overall binder system for S/S of lead-contaminated soils is more favorable in reducing the leachability of lead from the treated samples than a binder system with standalone OPC. On the other hand, partial replacement of OPC with RHA in the binder system has reduced the UCS of solidified samples. PMID:16784809

In this study, solidification/stabilization (S/S) of nickel hydroxide sludge using ordinary Portland cement (OPC) and oil palm ash (OPA) was carried out. The effects of increased substitution of OPA wt% in the S/S mix designs on the treated samples' physical and chemical characteristics were investigated. The physical characteristics studied were unconfined compressive strength (UCS) and changes in crystalline phases while chemical characteristics studied were leachability of nickel and leachate pH. Results indicated the optimum mix design for S/S of nickel hydroxide sludge using both OPC and OPA at B/S(d)=1 in terms of cost-effectiveness and treatment efficiency was 15 wt% OPA, 35 wt% OPC and 50 wt% sludge. The sufficient UCS and low leached nickel concentrations shown for this mix design indicate the viability of using OPA as substitute of OPC as it can significantly reduce cost normally incurred by usage of high amounts of OPC. PMID:17543446

Solidification/stabilization (S/S) is considered to be a well-established disposal technique to reduce sludge handling and disposal obstacles. In this work, the sewage sludge was solidified at variable proportions with magnesium oxychloride cement (denoted as MOC thereinafter) as reagent. The mortar prism samples of 40x40x160mm in dimension were prepared and hardened for 24h at room temperature. Unconfined compressive strength after 10-day curing time, initial and final setting time, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and toxicity leachability of the samples, were used to characterize the macroscopic and microscopic effects caused by the solidified products on the MOC hydration process. The results revealed that the magnesium hydration of phase 3, phase 5 and othe...

An investigation was carried out to establish the physical, mechanical and chemical characteristics of a non-standard (unprocessed) pulverised fuel ash (PFA) and waste tyres from a former landfill site at the Power Station Hill near Church Village, South Wales, United Kingdom. Investigations are on-going to establish the suitability of the fly ash and/or tyres in road construction (embankment and pavement) and also in concrete to be used in the construction of the proposed highway. This paper reports on concrete-based construction where concrete blends (using various levels of PFA as partial replacement for Portland cement (PC), and shredded waste tyres (chips 15-20mm) as aggregate replacement) were subjected to unconfined compressive strength tests to establish performance, hence, optimis...

This article investigates the effects of activator type/concentration and curing temperature on alkali-activated binder based on copper mine tailings (MT). Different alkaline activators including sodium hydroxide (NaOH), sodium silicate (SS), and sodium aluminate (SA) at different compositions and concentrations were used and four different curing temperatures, 60, 75, 90, and 120??C, were considered. Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX), and X-ray diffraction (XRD) were conducted to investigate the effect of these factors on the unconfined compressive strength (UCS), microstructure, and phase composition of the binder. The results indicate that NaOH concentration and curing temperature are two important factors that affect the UCS and micro-structura...

Pb was incorporated to a series of cement matrices, which were submitted to different testes of solidified/stabilized product. The leaching behaviors of aqueous solution were monitored by graphite furnace atomic absorption spectroscopy (GF-AAS). The mechanical strengths were evaluated by unconfined compressive strength (UCS) at 7 and 28 ages. Data are discussed in terms of metal mobility along the cement block monitored by X-ray fluorescence (XRF) spectrometry. Complementary techniques, namely, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), thermal gravimetric analysis (TGA), small angle X-ray scattering (SAXS) and X-ray diffraction spectroscopy (XRD) were employed in the characterization of the modified matrices. The Pb incorporated matrices have shown that a long cure time is more suitable for avoiding metal leaching. At pH 8 lower Pb leaching took place both for both short and long cure time. For a longer cure period there is a decreasing in the compressive strength. TGA and DRIFTS analyses show that the resistance fall observed in the UCS tests in the sample with Pb are not caused by hydration excess. XRF analyses show that there is a lower Ca concentration in the matrix in which Pb was added. PMID:20347519

Three tests were performed to measure the consolidation, permeability, and compressive strength of specimens prepared from bentonite/crushed salt mixtures. Each mixture comprised 30% bentonite and 70% crushed salt based on total dry weight. Brine was added to each mixture to adjust its water content to either 5 or 10% (nominal) of the total dry weight of the mixture. In the consolidation tests, each specimen was subjected to multiple stages of successively higher hydrostatic stress (pressure). During each stage, the pressure was maintained at a constant level and volumetric strain data were continuously logged. By using multiple stages, consolidation data were obtained at several pressures and the time required to consolidate the specimens to full saturation was reduced. Once full saturation was achieved, each specimen was subjected to a final test stage in which the hydrostatic stress was reduced and a permeability test performed. Permeability was measured using the steady flow of brine and was found to range between 1 {times} 10{sup {minus}17} and 5 {times} 10{sup {minus}17} m{sup 2}. After the final test stage, unconfined compressive strength was determined for each specimen and was found to range between 0.5 and 8.1 MPa. Two constitutive models were fitted to the consolidation data. One relatively simple model related volumetric strain to time while the other related instantaneous density to time, pressure, and initial density. 8 refs., 9 figs., 8 tabs.

IT was contracted to assist in designing and performing a statistically based series of treatability studies on stabilization and solidification of various waste streams from DOE`s Oak Ridge Reservation. The waste streams were generated by a variety of processes used in the manufacture of nuclear weapon components and fuel. The treatability studies were designed to provide information on the effects of various quantities of stabilization reagents on the characteristics of the final waste form. Primary performance criteria were no free liquid and meet or exceed LDR leachability levels at 28-day cure. Secondary performance criteria were various implementability parameters. Characteristics monitored were unconfined compressive strength (UCS), rate of set, free liquids, metals leachability, unit weight, and radionuclide leachability. Stabilization reagents used in the study included Portland cement, fly ash, perlite, and blast furnace slag. Twenty formulations were tested for each waste stream. These formulations are statistical extreme vertices desired that was formulated by PNL. Oak Ridge National Laboratory (Energy Systems) and IT were conducting parallel programs on different waste streams. A standardized set of test procedures and stabilization reagents were used by IT and Energy Systems. By design formulations were determined that failed and met all primary and secondary performance criteria. The 28-day cured waste-grout mixtures had the consistency ranging form pudding-like to soil-like to monoliths with UCS greater than 5000 psi. Generally, formulations that were monoliths with greater than 100 psi compressive strength had lower leachabilities and liquid bleed. The effect of waste chemical composition on the leachability is discussed.

This work involve a systematic treatability study of the treatment of acid tars (AT), a waste generated during the processing of petroleum and petrochemical, by stabilization/solidification with Portland cement (CEM I), with the addition of high carbon fly ash (HCFA), an industrial by-product, as a novel sorbent for organic contaminants. A factorial design experiment was adopted to investigate the effects of organic content, HCFA:AT ratio, percentage CEM I addition, and curing time on response variables including unconfined compressive strength (UCS), hydraulic conductivity, porosity, and leachability-related properties of the stabilized/solidified (s/s) products, and to assess management options for the s/s products based on performance criteria adapted from regulatory and other guidance. Results show that all studied factors had significant effects on the tested properties of the s/s products. Acid tar reduced UCS, but strength increase was observed with increased curing time. Increased HCFA addition led to an improvement in hydraulic conductivity. Assessment of management options indicates that the treated acid tars could find application as controlled low-strength materials, landfill liner, and landfill daily cover. The work demonstrates how a systematic treatability study can be used to develop a S/S operating window for management of a particular waste type. PMID:20473807

Colloidal silica is a low-viscosity chemical grout. Samples of grouted sand were made by pouring sand into liquid grout in molds, with the grout diluted to concentrations ranging from 5 to 27% silica by weight. The unconfined compressive strength of the grouted sand, measured after 7 days, was proportional to the silica concentration, up to a maximum of 400 kPa. The hydraulic conductivity of the grouted sand decreased with increasing silica concentration in a nearly log-linear manner down to a minimum of 2 {times} 10{sup {minus}9} cm/s, and was below 1 {times} 10{sup {minus}7} cm/s for grouts with 7.4% silica or more. Inclusion of 5% volumetric saturation of organics (tetrachloroethene, CCl{sub 4}, or aniline) in the samples had little effect on the strength or hydraulic conductivity. Samples were immersed in test liquids (organics, HCl diluted to pH 3, distilled water saturated with organics, and distilled water control) for up to 1 year. All samples increased in strength except for those immersed in aniline; samples immersed in water saturated with aniline were also weaker than control samples.

The apparent mechanical properties of hydroxyapatite (HA) whisker reinforced polyetherketoneketone (PEKK) scaffolds were evaluated in unconfined, uniaxial compression to investigate the effects of the porosity (75%, 82.5% and 90%), HA content (0, 20 and 40 vol%) and mold temperature (350, 365 and 375 ( composite function)C). Increased porosity resulted in a non-linear decrease in the elastic modulus and yield strength for both reinforced and unreinforced PEKK scaffolds, as expected. The increase in elastic modulus and yield strength with increased relative density followed a power-law, similar to trabecular bone and other open-cell foams. HA whisker reinforcement generally resulted in an increased elastic modulus from 0 to 20 vol% HA and a subsequent decrease from 20 to 40 vol% HA, while the yield strength and strain were decreased in scaffolds with 40 vol% HA compared to those with 0 or 20 vol% HA. Increased mold temperature resulted in an increased elastic modulus, yield strength and yield strain. These effects enabled the mechanical properties to be tailored to mimic human trabecular bone. The elastic modulus was greater than 50 MPa, and the yield strength was greater than 0.5 MPa, for scaffolds with 75% porosity at all combinations of reinforcement level and mold temperature. Scaffolds with 75% porosity and 20 vol% HA molded at 375 ( composite function)C exhibited a mean elastic modulus and yield strength of 149 MPa and 2.2 MPa, respectively, which was the highest of the conditions investigated in this study and similar to human vertebral trabecular bone. Therefore, HA whisker reinforced PEKK scaffolds may be advantageous for permanent implant fixation, including interbody spinal fusion. PMID:19716108

Over the past 30 years, design with geofoam has been based on either factored strength or limit strain approaches. Geofoam parameters for design have been derived from unconfined compression testing of small laboratory samples. Closer examination of performance observations indicate extrapolation of small sample laboratory results can lead to misleading interpretation of field results. The potential for creep deformations is exaggerated and design modulus values are underestimated when based on small sample laboratory tests. Possible reasons for these shortcomings, in reference to field observations, are examined on the basis of creep tests on small samples, uniaxial loading of large samples, compression tests using tactile pressure sensors and review of enlarged images of geofoam surfaces. Creep deformations in geofoams under uniaxial loading remain mainly in primary stages where strain rates continually decrease. Modulus values for design that are derived from small sample laboratory tests are about half of the values that were estimated from field observations. Accordingly, the suggestion is made to increase small sample based modulus values from laboratory tests for design applications.   

To investigate the rate effects on post-peak structural behavior accompanying the compression softening of structural concrete, experimental studies were carried out on over-reinforced concrete beams with and without confinement under varied rates of flexural loading. The effects of loading rate on the capacity and ductility of RC beams were found more pronounced in confined cases than unconfined cases. The generic time-dependent constitutive model of compression-softened concrete was applied to nonlinear collapse analysis and its applicability was verified by experiments. The strain rate in the compressive localized zone in structures rapidly increased after the member reached its peak capacity even though the rate of displacement was kept unchanged especially in the case of unconfined beams. In the case of confined RC beams, localization of weak strain occurred but with comparatively greater time-dependent plasticity and fracturing within the structure. These deformation characteristics were adequately simulated by nonlinear analysis using a time-dependent constitutive model for softened concrete in compression.   

A systematic treatability study was conducted for the treatment of drill cuttings, a waste generated during petroleum exploration and production, by stabilization/solidification with Portland cement (CEM I), with the addition of high carbon power plant fly ash (HCFA), an industrial by-product, as a novel sorbent for organic contaminants. A factorial design experiment was adopted to investigate the effects of waste-to-binder ratio, binder formulation, and curing time on response variables including unconfined compressive strength (UCS), hydraulic conductivity, porosity, leachate pH, and acid neutralization capacity (ANC) of the s/s products. Results show that all factors had significant effects on the properties of the s/s products. Drill cuttings and HCFA addition both reduced UCS, but HCFA improved hydraulic conductivity, relative to CEM I only s/s products. Drill cuttings addition had little effect on the ANC of products prepared with CEM I only, and improved that of products containing HCFA. Management options assessment based on performance criteria adapted from regulatory and other guidance suggests that the s/s products could find application as controlled low-strength materials, landfill liner, and landfill daily cover. This work demonstrates how a systematic treatability study can be used to develop a s/s operating window for the management of a particular waste type. PMID:19818552

Realistic finite element modelling and simulation of neurosurgical procedures present a formidable challenge. Appropriate, finite deformation, constitutive model of brain tissue is a prerequisite for such development. In this paper, a large deformation, linear, viscoelastic model, suitable for direct use with commercially available finite element software packages such as ABAQUS is constructed. The proposed constitutive equation is of polynomial form with time-dependent coefficients. The model requires four material constants to be identified. The material constants were evaluated based on unconfined compression experiment results. The analytical as well as numerical solutions to the unconfined compression problem are presented. The agreement between the proposed theoretical model and the experiment is good for compression levels reaching 30% and for loading velocities varying over five orders of magnitude. The numerical solution using the finite element method matched the analytical solution very closely. PMID:10327007

Abstract in portuguese Este trabalho teve por finalidade analisar algumas características de misturas de solo, cimento e cinzas de bagaço de cana-de-açúcar para sua possível utilização na fabricação de materiais alternativos de construção. Para tal, amostras de cinzas de bagaço de cana-de-açúcar foram submetidas a um tratamento prévio que consistia de peneiramento e moagem, antes de serem incorporadas às misturas de solo e cimento. Diferentes combinações de cimento-cinzas fora (more) m estudadas, determinando-se, para cada uma delas, a consistência normal e a resistência à compressão simples, aos 7 e 28 dias. Posteriormente, corpos-de-prova moldados com tais misturas de solo-cimento-cinzas foram submetidos a ensaios de compactação, compressão simples e absorção de água. Os resultados indicaram a possibilidade de substituir até 20% do cimento Portland, na mistura, por cinzas de bagaço de cana-de-açúcar, sem prejuízo da resistência à compressão simples. Abstract in english This work was done with the objective of studying some physical and mechanical characteristics of the sugarcane bagasse ash added to a soil-cement mixture, in order to obtain an alternative construction material. The sugarcane bagasse ash pre-treatment included both sieving and grinding, before mixing with soil and cement. Different proportions of cement-ash were tested by determining its standard consistence and its compressive resistance at 7 and 28 days age. The variou (more) s treatments were subsequently applied to the specimens molded with different soil-cement-ash mixtures which in turns were submitted to compaction, unconfined compression and water absorption laboratory tests. The results showed that it is possible to replace up to 20% of Portland cement by sugarcane bagasse ash without any damage to the mixture's compressive strength.

The authors mapped the hardness of the rock surrounding shaped-charge perforations with an indentation technique based on the Brinell method. They fired conventional perforators (3.2-g explosive weight) into a friable sandstone (approximately 6.9 MPa unconfined compressive strength) under 10.3 MPa effective stress. They observed substantial reductions in hardness extending more than 10 cm away from the perforation tunnel. The severity and extent of the damage wa snot uniform and was greatest near the perforation at the entrance hole, decreasing toward its tip. A comparison with a similar test with a drilled hole demonstrated that the observed damage was caused by the impact of the shaped-charge jet on the rock. The extent of the damage was independent of the diameter of the rock specimen used during the test. By assuming that permeability reduction is proportional to mechanical damage (i.e., hardness reduction), they obtained numerical simulations of flow rate and distribution. The calculated flow rates were consistent with those measured after perforating the samples. Careful analysis of the data suggested that the mechanical damage and permeability reduction were related to increases in finer particle sizes and smaller pore sizes that were observed by other workers. These led to increased tortuosity in the flow paths.

Solidification/stabilization (S/S) of automotive phosphate coating sludge (PS) containing potentially toxic heavy metals was studied. The hazardous characteristics of this waste were assessed according to both Turkish and U.S. Environmental Protection Agency (EPA) regulations for hazardous solid waste. Unconfined compressive strength (UCS) and leaching behavior tests of the solidified/stabilized product were performed. Solidification studies were conducted using Portland cement (PC) as the binder. UCS was found to decrease with increasing waste content. It was found that recovery of the waste for construction applications was possible when the waste content of the mortar was 20% and below, but solidification for safe disposal was achieved only when higher waste concentrations were added. Cu, Cr, Ni, Pb and Zn were found to be significantly immobilized by the solidification/stabilization process. Ni and Zn, which were present at particularly high concentrations (2.281 and 135.318 g/kg respectively) in the PS, had highest the retention levels (94.87% and 98.74%, respectively) in the PC mortars. The organic contaminants and heavy metals present in PS were determined to be immobilized by the S/S process in accordance with the BS 6920 standard. Thus, the potential for hazardous PS waste to adversely impact human health and the environment was effectively eliminated by the S/S procedure. We conclude that S/S-treated PS is safe for disposal in landfills, while recovery of S/S-treated PS constituents remains possible. PMID:22542981

This report discusses fourteen tests which were conducted to investigate the perforation of thin unreinforced concrete slabs. The 4340-steel projectile used in the test series is 50.8 mm in diameter, 355.6 mm in length, has a mass of 2.34 kg. and an ogive nose with caliber radius head of 3. The slabs, contained within steel culverts, are 1.52 m in diameter and consist of concrete with a nominal unconfined compressive strength of 38.2 MPa and maxima aggregate size of 9.5 mm. Slab thicknesses are 284.4, 254.0, 215.9 and 127.0 mm. Tests were conducted at impact velocities of about 313 m/s on all slab thicknesses and about 379 and 471 m/s on the 254.0-mm-thick slab. All tests were conducted at normal incidence to the slab. All tests were conducted at normal incidence to the slab. Information obtained from the tests used to determine the loading (deceleration) on the projectile during the perforation process, the velocity-displacement of the projectile as it perforated the slab, and the projectile position as damage occurred on the backface of the slab. The test projectile behaved essentially as a rigid body for all of the tests.

The dynamic behavior of particulate materials is important to a wide range of problems. When dealing with energetic particulate materials, mechanical ignition is an added concern for safety and performance issues. Mechanical work done on an explosive can lead to heating and subsequent reaction. Though the yield strength of these materials is very low and not generally thought high enough to generate adequate heat for ignition, the phenomenon of stress bridging has allowed for stress and strain concentrations to develop in these materials. Micrographs from unconfined impact tests show specific crystal damage paths within the matrix. Under loading conditions consistent with real world applications, these materials can be subjected to large hydrostatic pressures combined with shear deformation. Subsequent stress chain formation concentrates the compressive load into small regions, providing ignition sites within the material. In this work, post mortem examination results of impacted specimens are presented. The damage characteristics of the particle bed are shown to exhibit particle fracture along certain paths without permanent bulk deformation. A photoelastic experiment with high speed photography has been developed to record chain formation. In this experiment, a simple geometry is used to determine stress concentrations in a particle bed. Simulations of the experiment are conducted with ALE3D. These simulations illustrate the effects of the boundary on stress localization and on the formation of the stress chain. Homogenization of the data to real engineering systems and specifications is discussed, and applicability of mesoscale analysis to other disciplines is considered.

In this work coal fly ash has been employed for the synthesis of geopolymers. Two different systems with silica/alumina ratios stoichiometric for the formation of polysialatesiloxo (PSS, SiO2/Al2O3=4) and polysialatedisiloxo (PSDS, SiO2/Al2O3=6) have been prepared. The alkali metal hydroxide (NaOH or KOH) necessary to start polycondensation has been added in the right amount as concentrated aqueous solution to each of the two systems. The concentration of each alkali metal solution has been adjusted in order to have the right liquid volume to ensure constant workability. The systems have been cured at four different temperatures (25, 40, 60, and 85 degrees C) for several different times depending on the temperature (16-672 h at 25 degrees C; 72-336 h at 40 degrees C; 16-120 h at 60 degrees C and 1-6h at 85 degrees C). The products obtained in the different experimental conditions have been submitted to the quantitative determination of the extent of polycondensation through mass increase and loss on ignition, as well as to qualitative characterization by means of FT-IR spectroscopy. Furthermore, physico-structural and mechanical characterization has been carried out through microscopic observations and the determination of unconfined compressive strength, elasticity modulus, apparent density, porosity and specific surface area. The results have indicated that the systems under investigation are suited for the manufacture of pre-formed building blocks at room temperature. PMID:17382528

Stabilisation/solidification with cementitious or pozzolanic binders (S/S) is an option for reducing leachability of contaminants from residual, predominantly inorganic, industrial wastes and contaminated soils before disposal or reuse. Treatment by S/S is complicated by the fact that the presence of impurities, such as the contaminants and bulk matrix components present in industrial wastes, can have deleterious effects on cements. Therefore, careful laboratory development and testing of S/S formulations are required prior to full-scale application, to avoid technology failures, including problems with handling and contaminant retention. An understanding of cement chemistry and contaminant immobilisation mechanisms has been used to propose a series of test methods and performance thresholds for use in efficient evaluation of the treatability of industrial wastes by S/S, and optimising S/S formulations: measurement of stabilised/solidified product workability, bleeding and setting time (for flowable mixtures) or Proctor compaction (for compactable mixtures), together with unconfined compressive strength, leachability in a batch extraction with distilled water, and hydraulic conductivity. PMID:18456403

Ferm classified lithological units have been identified and described in the Waikato Coal Measures in open pits in the Waikato coal region. These lithological units have been classified geotechnically with mechanical tests and discontinuity measurements. Using these measurements, slope stability probability classification (SSPC) have been quantified based on an adaption of Hack's SSPC system which places less influence on rock quality designation and unconfined compressive strength than previous rock mass rating systems. An attempt has been made to modify the Hack weathering susceptibility rating by using chemical index of alteration values from XRF major element analysis. Another major component of this adapted SSPC system is the inclusion of rock moisture content effects on slope stability. The paper explains the systematic initial approach of using the adapted SSPC system to classify slope stability in the Waikato open pit coal mines. The XRF major element results obtained for lithologies in the Waikato coal region may be a useful mine management tool to quantify stratigraphic thickness and palaeoweathering from wash drill cuttings. 14 refs., 7 figs., 3 tabs.

Mechanical tests were performed on pouched and bare lithium-ion cells under five loading conditions. These included through-thickness compression, in-plane unconfined compression, in-plane confined compression, hemispherical punch indentation and three-point bending. From the measured load-displacement data, the individual compression stress-strain curves were calculated for the separator, the active anode and cathode materials. The FE model was developed, composed of shell elements, representing the Al and Cu foil, and solid elements for the active material with a binder lumped together with the separator. Very good correlation was obtained between LS Dyna numerical simulation and test results for the through-thickness compression, punch indentation and confined compression. Closed form s...

In recent times there has been an increasing shift towards finding more environmentally sustainable practices in an effort to tackle modern challenges related to climate change, population growth and pollution. This study presents the latest research in the performance of recycled construction and demolition material as a road building material in Western Australia and recommends new technology for this growth industry. Crushed concrete waste is a by-product from building demolition and constitutes a principal component of municipal solid waste consisting of concrete, sand, brick, rock, metals and timber. Over 50% of this waste is commonly sent to land-filled sites, resulting in the impact on the limited capacity of land-filled sites. Nowadays, the sources of virgin natural aggregates are depleted by increases in demand of using a virgin material in building and infrastructure construction and maintenance facilities. This depletion leads to the utilisation of crushed concrete waste to replace natural aggregates in road and highway construction. Of key significance of this study is to present alternative materials for road and highway construction on the production of the proper guideline for road base by using crushed concrete waste. Sophisticated tests were conducted to investigate the mechanical responses of compacted crushed concrete subjected to applied loads simulated from traffic loads. Unconfined compressive strength, shear strength parameters and the resilient modulus of such material were determined. Our findings showed that crushed concrete waste is able to be utilised as a road base material. The results of this study will enhance increased use of crushed concrete waste in road and highway construction and will, therefore, alternatively reduce consumption and costs in manufacturing virgin aggregates.

Cement-based solidification/stabilization (S/S) procedure is one of the cost effective methods for treating metal waste in situ. Hence its efficiency in treating hexavalent chromium, Cr(VI), contaminated soils was evaluated in this study. Due to its oxidizing potential and high solubility in water Cr(VI) is highly toxic. Contaminated soils were prepared in the laboratory by spiking soils with hexavalent chromium (K{sub 2}CrO{sub 4}) up to a concentration of 25,000 mg/kg. The control soil was prepared by mixing sand, kaolinite clay and organic matter to represent a clayey soil. Contaminated soils were treated with cement with and without a reducing agent ferrous chloride. Cement-to-soil ratio was varied from 0.2 to 1.0 in the treatment study. Treated soils were cured for 28 days before testing. Contaminated soil with 500 mg/kg of K{sub 2}CrO{sub 4} was effectively treated with cement (cement-to-soil ratio of 0.2) to meet the TCLP limit of 5 mg/L. However, S/S treatment was not successful with the contaminated soil with a contamination level of 25,000 mg/kg K{sub 2}CrO{sub 4}. Increasing the cement-to-soil ratio reduced the leaching of chromium and improved the unconfined compressive strength. Reaction products after treatment were identified using X-ray diffractometry (XRD). Ferrous chloride (FeCl{sub 2}) (4% by weight) was used in S/S treatment to reduce the leaching of chromium by reducing the soluble Cr(VI) to some insoluble forms of chromium. However, adding FeCl{sub 2} had a deleterious effect on cement setting and strength. An empirical model was used to predict the leaching of total chromium and Cr(VI) from the binder matrix.

Fly Ash (FA) from a power station in South Africa was investigated to neutralise and remove contaminants from Acid Mine Drainage (AMD). After this primary treatment the insoluble FA residue namely solid residue (SR) was investigated as a suitable mine backfill material by means of strength testing. Moreover, SR was used to synthesise zeolite-P using a two-step synthesis procedure. Furthermore, the zeolite-P was investigated to polish process water from the primary FA-AMD reaction. The main objective of this series of investigations is to achieve zero waste and to propose an integrated AMD management using FA. Fly Ash was mixed with AMD at various predetermined FA-AMD ratios until the mixtures achieved circumneutral pH or higher. The supernatants were then analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Ion Chromatography (IC) for cations and anions respectively. The physical strength testing of SR was carried out by mixing it with 3% Ordinary Portland Cement (OPC) and curing for 410 days. Synthesis of zeolite-P using SR was carried out by two step synthesis procedure: ageing for 24 hours followed by a mild hydrothermal synthesis at 100°C for 4 days. The polishing of process water from primary AMD treatment using FA was ascertained by mixing the process water with zeolite at a liquid to solid ratio of 100:1 for 1 hour. The results indicated that FA can be successfully used to ameliorate AMD. High removal of major AMD contaminants Fe, Al, Mg, Mn and sulphate was achieved with the ash treatment and trace elements such as Zn, Ni, Cu and Pb were also removed by the FA. Strength testing over 410 days indicated that the material gained strength over the testing period. The maximum unconfined compressive strength and elastic modulus was observed to be approximately 0.3 MPa and 150 Mpa respectively. The X-ray diffraction (XRD) analysis of the synthesized product indicated that SR was successfully converted into zeolite-P with some mullite phase remaining as a result of incomplete conversion of the feedstock SR. The zeolite-P was used as an ion exchange material to remove selective elements from the process water. Elements such as Ca, Sr, Ba and V were successfully removed from the process water with the zeolite-P. Only marginal removal of Mo was observed during the experiments. It was also observed that Na was exchanged into the solution. This study successfully demonstrated zero waste concepts and an integrated AMD management scheme using FA was developed in this study. The implementation of this technology will address FA storage problem as well as costs associated with AMD treatment. PMID:22217083

Ferm classified lithological units have been identified and described in the Waikato Coal Measures in open pits in the Waikato coal region. These lithological units have been classified geotechnically by mechanical tests and discontinuity measurements. Using these measurements slope stability probability classifications (SSPC) have been quantified based on an adaptation of Hack's [Slope Stability Probability Classification, ITC Delft Publication, Enschede, Netherlands, vol. 43, 1998, 273 pp.] SSPC system, which places less influence on rock quality designation and unconfined compressive strength than previous slope/rock mass rating systems. The Hack weathering susceptibility rating has been modified by using chemical index of alteration values determined from XRF major element analyses. Slaking is an important parameter in slope stability in the Waikato Coal Measures lithologies and hence, a non-subjective method of assessing slaking in relation to the chemical index of alteration has been introduced. Another major component of this adapted SSPC system is the inclusion of rock moisture content effects on slope stability. The main modifications of Hack's SSPC system are the introduction of rock intact strength derived from the modified Mohr-Coulomb failure criterion, which has been adapted for varying moisture content, weathering state and confining pressure. It is suggested that the subjectivity in assessing intact rock strength within broad bands in the initial SSPC system is a major weakness of the initial system. Initial results indicate a close relationship between rock mass strength values, calculated from rock mass friction angles and rock mass cohesion values derived from two established rock mass classification methods (modified Hoek-Brown failure criteria and MRMR) and the adapted SSPC system. The advantage of the modified SSPC system is that slope stability probabilities based on discontinuity-independent and discontinuity-dependent data and a maximum slope height are predicted. The modified SSPC system may be useful in predicting initial optimum pit slope designs in proposed greenfield mine sites. XRF major element and chemical index of alteration (CIA) results obtained for lithologies in the Waikato coal region may be a useful mine management tool to quantify stratigraphic thickness and palaeoweathering from wash drill cuttings. This paper explains the systematic approach of using the adapted SSPC system to classify slope stability in the Waikato open pit coal mines.

Abstract in portuguese Analisou-se a influência do tratamento térmico do resíduo grits na resistência mecânica de misturas solo-grits para aplicações em pavimentos de estradas florestais. O programa de ensaios de laboratório englobou: (i) dois solos residuais de gnaisse da Zona da Mata Norte de Minas Gerais; (ii) um resíduo da indústria da celulose denominado grits, que é composto de cal não-hidratada e areia, entre outros produtos; (iii) amostras de grits submetidas ao tratamento t (more) érmico em mufla sob temperaturas de 600, 700, 800 e 900 ºC antes da moldagem dos corpos-de-prova das misturas solo-grits; (iv) corpos-de-prova das misturas preparadas com o grits tratado termicamente, com 24% de grits em relação ao peso seco dos solos, compactados nas energias dos ensaios Proctor intermediário e modificado e curados por 7 e 28 dias em câmara úmida, sob condições de aproximadamente 22 ºC de temperatura e 100% de umidade relativa do ar; e (v) imersão completa dos corpos-de-prova das misturas solo-grits em água, pelo período de quatro horas, antes da determinação de suas resistências em ensaios de compressão não-confinada. Os resultados do programa de ensaios de laboratório indicaram que o tratamento térmico produziu amostras de grits mais reativas, podendo-se associar melhor desempenho mecânico às temperaturas de 800 e 900 ºC para o solo 1 e 800 ºC para o solo 2. Abstract in english The objective of this paper was to analyze the influence of grits thermal treatment on the mechanical strength of soil-grits mixtures. The laboratory testing program included: (i) two residual gneiss soils from the Zona da Mata, Northern Minas Gerais; (ii) waste from the cellulose industry, namely grits, composed by non-hydrated lime and sand, among others by-products; (iii) grits samples submitted to thermal treatment in a muffle at the temperatures of 600, 700, 800 and (more) 900 ºC before soils-grits specimens preparation; (iv) soils-grits specimens containing 24% of treated grits in relation to soil dry unit compacted at the intermediate and modified Proctor compaction test, and cured during 7 and 28 days in a moist room at the temperature of 22 ºC and relative humidity close to 100 %; and (iv) complete immersion of cured specimens in water (4 hours) before testing for compressive strength using the unconfined compression test. Data from the laboratory testing program support that: (i) thermal treatment produced more reactive grits samples; and (ii) best soils-grits mechanical responses were associated to grits treatment temperatures of 800 and 900 ºC for soil 1, and to 800 ºC for soil 2.

The rate-dependency of the stress-strain behavior of EPS (Expanded Polystyrene) geofoam with densities of 19.3 and 28.0 kg/m3 was investigated by performing unconventional unconfined compression tests. A set of monotonic loading (ML) tests were performed at different constant values of vertical (axial) strain rate, ?v. The ?v value was stepwise changed many times and several sustained loading (SL) tests were performed during otherwise ML at a constant ?v in other tests. A number of SL tests were performed during global unload and reload cycles to infer the stress-strain relation when ?v=0. The elastic properties were evaluated by applying minute unload/reload cycles during otherwise ML. The rate-dependent stress-strain behaviour observed in these tests was described by an elasto-viscoplastic model (i.e., a non-linear three-component model), for which the vertical (axial) stress, ?v, consists of inviscid and viscous components, ?vf and ?vv, while ?v consists of elastic and irreversible components, ?ve and ?vir. It is shown that the viscous property of EPS geofoam is of Isotach type in that, under the loading conditions where ?vir is always positive, the current ?vv value is a unique function of instantaneous ?vir and ?vir, therefore the strength increases with ?v. This viscous property was quantified based on the test results and incorporated into the model. The rate-dependent stress-strain behaviour, including the creep behaviour, observed in the experiment is simulated very well by the proposed model. In particular, the fact that the creep strain becomes significant when the sustained ?v value becomes larger than the inviscid yield vertical stress is well simulated.   

This study aims to evaluate the potential of low grade MgO (LGMgO) for the stabilisation/solidification (S/S) of heavy metals in steel electric arc furnace wastes. Relevant characteristics such as setting time, unconfined compressive strength (UCS) and leaching behaviour assessed by acid neutralisation capacity (ANC), monolithic and granular leaching tests were examined in light of the UK landfill Waste Acceptance Criteria (WAC) for disposal. The results demonstrated that all studied mix designs with Portland cement type 1 (CEM1) and LGMgO, CEM1-LGMgO 1:2 and 1:4 at 40% and 70% waste addition met the WAC requirements by means of UCS, initial and final setting times and consistence. Most of the ANC results met the WAC limits where the threshold pH values without acid additions were stable and between 11.9 and 12.2 at 28d. Granular leaching results indicate fixation of most of the metals at all mix ratios. An optimum ratio was obtained at CEM1-LGMgO 1:4 at 40% waste additions where none of the metals leaching exceeded the WAC limits and hence may be considered for landfill disposal. The monolithic leaching test results showed that LGMgO performed satisfactorily with respect to S/S of Zn, as the metal component present at the highest concentration level in the waste exhibited very little leaching and passed the leaching test requirement at all mix ratios studied. However, its performance with respect to Pb, Cd and Cr was less effective in reducing their leaching suggesting a higher cumulative rate under those leaching regimes. PMID:22172635

Pozzolanic-based stabilization/solidification (S/S) is an effective, yet economic technological alternative to immobilize heavy metals in contaminated soils and sludges. Fly ash waste materials were used along with quicklime (CaO) to immobilize lead, trivalent and hexavalent chromium present in contaminated clayey sand soils. The degree of heavy metal immobilization was evaluated using the Toxicity Characteristic Leaching Procedure (TCLP) as well as controlled extraction experiments. These leaching test results along with X-ray diffraction (XRD), scanning electron microscope and energy dispersive x-ray (SEM-EDX) analyses were also implemented to elucidate the mechanisms responsible for immobilization of the heavy metals under study. Finally, the reusability of the stabilized waste forms in construction applications was also investigated by performing unconfined compressive strength and swell tests. Results suggest that the controlling mechanism for both lead and hexavalent chromium immobilization is surface adsorption, whereas for trivalent chromium it is hydroxide precipitation. Addition of fly ash to the contaminated soils effectively reduced heavy metal leachability well below the non-hazardous regulatory limits. However, quicklime addition was necessary in order to attain satisfactory immobilization levels. Overall, fly ash addition increases the immobilization pH region for all heavy metals tested, and significantly improves the stress-strain properties of the treated solids, thus allowing their reuse as readily available construction materials. The only potential problem associated with this quicklime/fly ash treatment is the excessive formation of the pozzolanic product ettringite in the presence of sulfates. Ettringite, when brought in contact with water, may cause significant swelling and subsequent deterioration of the stabilized matrix. Addition of minimum amounts of barium hydroxide was shown to effectively eliminate ettringite formation.

Portland cement(PC) was used to solidify the lead-zinc mine tailings contaminated soils(CS) in this work. The soils were heavily polluted by heavy metals with lead(up to 19592 mg/kg), zinc(up to 647mg/kg), Cd(up to 14.65mg.kg) and Cu(up to 287mg/kg). Solidified/stabilized(s/s)forms with a range of cement contents, 40-90 wt%, were evaluated to determine the optimal binder content. Unconfined compression strength test(UCS), Chinese solid waste-extraction procedure for leaching toxicity - Horizontal vibration method, toxicity characteristic leaching procedures(TCLP) were used for physical and chemical characterization of the s/s forms. The procedure of Tessier et al.(1979) was used to separate S/S forms Pb, Zn, Cd, Cu into different fractions. The results show that addition of 50% cement was enough for the s/s forms to satisfy the MU10 requirements (0.10 MPa). Under the 50% addition, the content of the water-exchangeable fraction of Pb reduced from 2.25% to 0.2%, the carbonate-bound fraction and organic-bound fraction reduced by about half, while the Fe-Mn oxide-bound fraction was more than doubled. The residual fraction decreased 8% on the contrary. For Zn, except for the carbonate-bound fraction increased slightly, the features of other items were same as that of Pb. For Cd, the water-exchangeable fraction was reduced largely, the residual fraction and Fe-Mn oxide-bound fraction increased 2-3%. For Cu, A distinct feature is the organic-bound fraction reduced with the reduction in consumption of cement, at the same time, the residual fraction increased corresponding. Leaching test results indicate that the leaching contents of Pb2+ of the six specimens are quite different at low pH value(

Abstract The effect of dynamic mechanical shear and compression on the synthesis of human tissue-engineered cartilage was investigated using a mechanobioreactor capable of simulating the rolling action of articular joints in a mixed fluid environment. Human chondrocytes seeded into polyglycolic acid (PGA) mesh or PGA-alginate scaffolds were precultured in shaking T-flasks or recirculation perfusion bioreactors for 2.5 or 4 weeks prior to mechanical stimulation in the mechanobioreactor. Constructs were subjected to intermittent unconfined shear and compressive loading at a frequency of 0.05-Hz using a peak-to-peak compressive strain amplitude of 2.2% superimposed on a static axial compressive strain of 6.5%. The mechanical treatment was carried out for up to 2.5 weeks using a loading regime...

Abstract in portuguese Avaliou-se o efeito da imersão em água dos corpos-de-prova sobre a resistência mecânica de misturas solo-grits. Trabalhou-se com dois solos da cidade de Viçosa, localizada na Zona da Mata Norte de Minas Gerais, Brasil, respectivamente de texturas predominantemente argilosa e arenosa e com o resíduo sólido industrial grits, um subproduto da indústria de celulose. Determinaram-se os parâmetros de resistência mecânica California Bearing Ratio (CBR) e Resistência (more) à Compressão Não-Confinada (RCNC) de corpos-de-prova compactados nas energias de compactação referentes aos ensaios Proctor intermediário e Proctor modificado, com teores de grits na faixa de 4 a 28% e períodos de cura de 0, 7 e 28 dias. Com relação ao parâmetro CBR, os ensaios foram realizados segundo a metodologia tradicional (imersão em água dos corpos-de-prova por 96 horas) e sem a imersão em água, visando determinar possíveis perdas na capacidade-suporte das misturas. No que tange ao parâmetro compressão não-confinada, os ensaios foram realizados em obediência à norma brasileira para misturas solo-cimento (imersão em água durante quatro horas antes da ruptura dos corpos-de-prova) e sem a fase de imersão em água. Os resultados indicaram que a imersão em água dos corpos-de-prova influenciou significativamente a resistência mecânica das misturas solo-grits, que foram dependentes do tipo de ensaio empregado, tipo de solo, teor de grits, energia de compactação e período de cura. Abstract in english This paper address the influence of water submersion on mechanical strength parameters of soil-grits specimens. Two residual soils, predominantly clayey and sandy soils from the city of Viçosa, located in the State of Minas Gerais, "Zona da Mata Norte", Brazil, and waste from cellulose industry were used in the study. The laboratory testing program consisted of CBR (California Bearing Ratio) and UCS (Unconfined Compression Strength) of specimens prepared with waste conte (more) nts ranging from 4 to 28 %, compacted at the intermediate and modified compaction efforts, and cured during 0, 7 and 28 days. Laboratory tests were performed as follow: (i) CBR: tests were performed following the standard procedure, i.e. after 4 days water submersion before specimen penetration, and without submersion; and (ii) UCS: tests were performed following the Brazilian standard procedure, i.e. after 4 hours specimen submersion before testing, and without water submersion. The laboratory testing program data support that water submersion significantly influenced the tested mechanical strength parameters, which were dependent of the type of assay and soil, percentage of grits waste, compaction effort and cure.

The physical properties of both rigid and flexible urethane foams as a function of various fiber fillers were investigated. Varying levels of glass, carbon, and wollastonite fibers were added to two urethane foam formulations. The compressive strength, compressive modulus, flexural strength, and tensile strength of these urethane foam systems were determined.

Hydrogels formulated from single polymers are often insufficient in terms of their mechanical properties for use as bone substitute materials. Hence, hydrogels synthesised from combinations of polymers have been investigated to optimise the performance of such materials. In the current study, polypropylene glycol dimethacrylate was added to polyethylene glycol dimethacrylate of a variety of molecular weights and photopolymerised to form a series of hydrogels. Polyethylene glycol and polypropylene glycol have the same chemical structure with the exception of a methyl group on the later. Herein, the influence of the methyl group of polypropylene glycol on the mechanical properties of hydrogels for bone regeneration applications is reported. For both unconfined and cyclic compression testing,...

For Low Heat Cement (LHC), its hydration reaction properties and compressive strength development were studied by quasi-elastic neutron scattering (QENS) and compressive strength test. In the QENS experiments, the amount of hydration products was estimated and the hydration behavior of LHC was revealed in the early hydration times of 7 days. Simultaneously, we compared the compressive strength of a mortar specimen made from LHC with the amount of hydration products. It was found that the compressive strength is strictly proportional to the amount of hydration products in the range from 15 h to 7 days of hydration.

The effects of traffic induced vibrations on concrete-steel bond strength and concrete compressive strength was studied for full depth repairs of reinforced concrete bridge decks. The specimens had blockouts to represent full depth patch repair areas. Two...

Exploitation of unconventional gas and oil reservoirs requires injection of large quantities of water-based fluids during hydraulic fracturing treatments. On average only 5 - 30 % of treatment fluids are recovered during flowback from these wells. The large quantity of residual treatment water remains either in the created fracture network, or imbibes into the rock matrix immediately surrounding the fracture network. As such this residual water is spatially located at the critical junction between the reservoir and the hydraulic fracture completion. Besides potentially causing the loss of relative permeability to hydrocarbons in the matrix rock surrounding the fracture, this residual water disrupts the chemical equilibrium of the rock, hydrocarbon and connate water system - leading to a physically and chemically altered zone of rock immediately adjacent to the fracture face. Loss of rock strength in the altered zone due to chemo-mechanical effects is a serious problem. Clearly it is important to understand the rate of fluid imbibition, the total quantity of fluid imbibed into the rock matrix, the depth of the altered rock zone adjacent to the fracture, and the loss of rock strength in this zone. A new laboratory method has been developed to quantitatively measure fluid leakoff and imbibition at the fracture face of ultra-low permeability unconventional reservoir rocks. Plugs taken from shale, mudstone, or ultra-low permeability carbonate reservoir cores are placed under confinement pressures and temperatures, simulating reservoir conditions. A low-flow rate imbibition/leakoff experiment is performed on the plug. The mechanisms of invasion are both pressure driven leak-off and imbibition. In the second stage of the experiment the core is dissected using a mechanical scratch tester. Leak-off into the pore structure of the matrix can be discriminated from artifacts such as leakoff into coring induced micro-fractures. The results show that fluid imbibition can be highly variable depending on the specific rock. Results are being correlated with the petrology of the rock. In addition to the quantitative determination of leak off and imbibition rates, the method measures the unconfined compressive strength (UCS) of the rock as a function of depth. Precise determination of the water content as a function of plug depth results in a water saturation profile throughout the plug and enables us to correlate rock strength, water saturation and exposure time. Experimental results show that imbibition and fluid loss into ultralow permeability shales, mudstones and carbonates can be substantial but are also highly variable depending on the texture and composition of the rock. The depth of water invasion in the experimental time frame of three days ranges from 0.5 to 3 cm in nanoDarcy permeability shales. The rock strength declines with exposure time to the fracturing fluid and correlates with the invading fluid saturation. Depending on the rock - softening due to fluid exposure can reduce the UCS by 25 - 50% over a 3 day exposure period. Loss of rock strength can lead to increased proppant embedment and a reduction in fracture conductivity. Increased embedment of proppant in turn can lead to fines generation due to displacement of rock matrix material with the risk of reducing proppant pack conductivity.

Laboratory experiments conducted in the past century have shown that exposure of coal to CO2 under unconfined, hydrostatic conditions leads to reversible adsorption and swelling. However, several authors also report irreversible changes in sorption capacity, sample volume, equilibration time and brittle failure strength. Some relate these effects to the formation of microfractures, while others consider "structural rearrangements" in the macromolecular structure of coal to be responsible. In this study, we investigate the magnitude of irreversible swelling effects and changes in equilibration time in high volatile bituminous coal (Brzeszcze, Seam 364, Poland), and attempt to explain the results in terms of the operative microphysical processes. We also assess the implications for Enhanced ...

The computer program 'Point Load Index' which undertakes to obtain preliminary rock and coal strength data for strata mechanics research programs is described. The program which is written in BASIC A version 3.10 for an BMI-PC/AT, calculates the point load strengths, standardized index strengths and uniaxial compressive and tensile rock strengths. 5 refs.

The dynamic behavior of porcine brain tissue, obtained from a series of in vitro observations and experiments, is analyzed and described here with the aid of a large strain, nonlinear, viscoelastic constitutive model. Mixed gray and white matter samples excised from the superior cortex were tested in unconfined uniaxial compression within 15h post mortem. The test sequence consisted of three successive load-unload segments at strain rates of 1, 0.1 and 0.01s-1, followed by stress relaxation (n=25). The volumetric compliance of the tissue was assessed for a subset of specimens (n=7) using video extensometry techniques. The tissue response exhibited moderate compressibility, substantial nonlinearity, hysteresis, conditioning and rate dependence. A large strain kinematics nonlinear viscoelast...

Results are presented from an experimental evaluation of IM7/8551-7 and IM6/18081, two new toughened epoxy resin, high strain graphite fiber composite materials. Data include ply-level strengths and moduli, notched tension and compression strengths and compression-after-impact assessments. The measured properties are compared with those of other graphite-epoxy materials.

Wood chips colonized by white rot fungi provide pulps with higher strength properties and reduced energy inputs. Compression of fresh wood chips causes changes which enhance the growth of biopulping; fungi without the need for wood heating, nutrient addition, or specialized bioreactor conditions. Hardwood (aspen) chips inoculated at compression and baled had a 16% reduction in acid lignin and provided kraft pulp with up to 80% higher burst strength as well as a 33% reduction in beating time to desired freeness. Compression and inoculation of green jack pine chips reduced refiner energy requirements and improved colonization by two biopulping fungi. Compression benefit to paper strength was also noted for presteamed pine chips.

The dynamic behavior of porcine brain tissue, obtained from a series of in vitro observations and experiments, is analyzed and described here with the aid of a large strain, nonlinear, viscoelastic constitutive model. Mixed gray and white matter samples excised from the superior cortex were tested in unconfined uniaxial compression within 15h post mortem. The test sequence consisted of three successive load-unload segments at strain rates of 1, 0.1 and 0.01 s?¹, followed by stress relaxation (n=25). The volumetric compliance of the tissue was assessed for a subset of specimens (n=7) using video extensometry techniques. The tissue response exhibited moderate compressibility, substantial nonlinearity, hysteresis, conditioning and rate dependence. A large strain kinematics nonlinear viscoelastic model was developed to account for the essential features of the tissue response over the entire deformation history. The corresponding material parameters were obtained by fitting the model to the measured conditioned response (axial and volumetric) via a numerical optimization scheme. The model successfully captures the observed complexities of the material response in loading, unloading and relaxation over the entire range of strain rates. The accuracy of the model was further verified by comparing model predictions with the tissue response in unconfined compression at higher strain rate (10 s?¹) and with literature data in uniaxial tension. The proposed constitutive framework was also found to be adequate to model the loading response of brain tissue in uniaxial compression over a wider range of strain rates (0.01-3000 s?¹), thereby providing a valuable tool for simulations of dynamic transients (impact, blast/shock wave propagation) leading to traumatic brain injury. PMID:20603231

The tensile strength of dry Kevlar narrow fabrics was investigated as a function of moisture present during folding and compression. Fabric samples were exposed to 96% relative humidity, or soaked in water prior to compression; or moisture was introduced while the samples were compressed. The fabrics exhibited a 10 to 30% tensile strength loss after wet compression relative to data for samples compressed dry. Similar tests on nylon did not show this effect. Warp yarns removed from fabrics compressed with moisture present exhibited nominally the same strength as those obtained from fabrics compressed dry or from uncompressed fabrics. These results are consistent with test data from a parachute that had been exposed to moisture and with packing difficulties encountered under high humidity environments.

The verification regime of the Comprehensive Test Ban Treaty (CTBT) provides for the possibility of on-site inspections (OSI`s) to resolve questions concerning suspicious events which may have been clandestine nuclear tests. The initial phase of an OSI may provide enough evidence to justify a request to the CTBT Organization for allowing drilling, so as to recover further evidence of a nuclear event. The equipment that was used for such `re-entry` drilling in the days of U.S. underground nuclear testing is considered too heavy and cumbersome for OSI deployments. So, an effort was initiated in 1995 to define, assemble, and demonstrate a new OSI drilling capability. Coiled-tubing (C-T) was selected as the most attractive technology because of its portability and its directional drilling capability (1). Following this selection, a preliminary engineering design was performed in 1996 for a Rapid Deployment Drilling System (RDDS). This system must have capabilities for downhole diagnostics of temperature and gamma-rays, since both types of data could be used to confirm the presence of an underground nuclear explosion. The study then identified two candidate downhole diagnostic systems operating with CT: the VIPER system of Schlumberger-Anadrill, and the Transocean system (2). In the current phase of this continuing effort the VIPER system has been retained as the first candidate because, everything else being equal, it is readily accessible domestically. One project, conducted by Maurer Engineering of Houston, TX, is specifying the details of the proposed CT system, its footprint, its modalities of air transport, and its costs of deployment and operation. The expected rate-of-penetration in rocks with unconfined compressive strength up to 14,500 psi (100 MPa) is also being estimated, based on laboratory-scale drilling tests on rock cores. Another project, which is the object of this report, has for an objective to develop and calibrate a downhole gamma-ray diagnostic capable of operating in the expected high-intensity environment near an underground nuclear cavity. The commercially available Anadrill VIPER logging assembly is calibrated to operate at levels of 0 to 250 American Petroleum Institute (API) units. These levels are much smaller than those necessary to confirm a clandestine nuclear explosion. The scope of the project is to make the necessary modifications to the VIPER gamma-ray module to meet minimum detection requirements of 50,000 API. At such a level, which is more than two orders of magnitude higher than seen in natural formations, the origin of gamma-rays could only be from underground nuclear test products.

Mechanical property data are reported for Epon 828/T403, an amine-cured epoxy adhesive. Data include compression modulus, compression yield strength and compression stress relaxation as a function of stress level, strain rate, and temperature and Mode I fracture toughness as a function of temperature. This data was generated to support a study investigating how temperature effects joint strength and the corresponding interface comer fracture toughness for adhesively bonded butt joints.

The mechanical properties (flexural strength, compressive strength, toughness and fracture energy) of steel microfiber reinforced reactive powder concrete (RPC) were investigated under different curing conditions (standard, autoclave and steam curing). Portland cement was replaced with ground granulated blast furnace slag (GGBFS) at 20%, 40% and 60%. Sintered bauxite, granite and quartz were used as aggregates in different series. The compressive strength of high volume GGBFS RPC was over 250MPa after autoclaving. When an external pressure was applied during setting and hardening stages, compressive strength reached up to 400MPa. The amount of silica fume can be decreased with increasing amount of GGBFS. SEM micrographs revealed the tobermorite after autoclave curing.

In this study, the shear behavior of discontinuities possessing two different rock wall types with distinct separate compressive strengths was investigated. The designed profiles consisted of regular artificial joints molded by five types of plaster mortars, each representing a distinct uniaxial compressive strength. The compressive strengths of plaster specimens ranged from 5.9 to 19.5 MPa. These specimens were molded considering a regular triangular asperity profile and were designed so as to achieve joint walls with different strength material combinations. The results showed that the shear behavior of discontinuities possessing different joint wall compressive strengths (DDJCS) tested under constant normal load (CNL) conditions is the same as those possessing identical joint wall strengths, but the shear strength of DDJCS is governed by minor joint wall compressive strength. In addition, it was measured that the predicted values obtained by Barton's empirical criterion are greater than the experimental results. The finding indicates that there is a correlation between the joint roughness coefficient (JRC), normal stress, and mechanical strength. It was observed that the mode of failure of asperities is either pure tensile, pure shear, or a combination of both. Therefore, Barton's strength criterion, which considers the compressive strength of joint walls, was modified by substituting the compressive strength with the tensile strength. The validity of the modified criterion was examined by the comparison of the predicted shear values with the laboratory shear test results reported by Grasselli (Ph.D. thesis n.2404, Civil Engineering Department, EPFL, Lausanne, Switzerland, 2001). These comparisons infer that the modified criterion can predict the shear strength of joints more precisely.

A prospective comparison was made of standard two-dimensional MRI sequences, at both high and midfield strength, with CT myelography in 23 patients with cervical spondylosis. MRI is adequate for assessment of cord compression, where high field strength is superior to midfield strength. MRI using 4-mm sections is inadequate for presurgical assessment of root compression. It remains to be proven whether thin-section white-CSF volume sequences or gadolinium-enhanced volume studies can replace CT myelography. (orig.). With 6 tabs.

Micro-buckling characteristic of a carbon mono-fiber in matrix was studied. A fiber was modeled in matrix as a column on elastic foundation. Buckling stress of the fiber was calculated incorporating the initial fiber misalignment and non-linearity of the matrix. The effect of bending on compressive stress was also taken into considered to estimate failure initiation at fiber surface. Two processes of ultimate fiber failure were considered. First one is a compressive fracture at fiber surface due to compression and bending. Second one is a matrix-yielding initiated unstable fiber deformation. Compression test of a carbon fiber in matrix was performed by means of a four point bending test. Electrical resistance of the carbon fiber was measured during the compression test to recognize initiation of the compressive fracture. Fiber breaks at two adjacent locations were observed, which was caused by micro-buckling of the fiber. Apparent compressive strength of the fiber was measured in the experiment. Actual compressive strength of the fiber was predicted from the apparent compressive strength. Correlation between compressive strengths based on the elastic foundation model and the kink band model was discussed.   

This research investigated the compressive strength, microstructure and thermal analysis of autoclaved and air cured structural lightweight concrete made with coal bottom ash and silica fume. The results show that bottom ash lightweight concrete autoclaved for 6h gives compressive strength similar to the bottom ash lightweight concrete air cured for 28 days and found that the compressive strength of both bottom ash lightweight concrete increased when silica fume was added to the mix. The highest compressive strength obtained for all mixes was found when coal bottom ash was used at 20% with the addition of silica fume at 5% and that this strength value is significantly higher than that of Portland cement control. The thermal conductivity of all bottom ash lightweight concrete at 28 days and...

Braided preforms of carbon fiber are under consideration for structural applications because of the potential for automated fabrication and possible improvement in through-the-thickness properties, although some loss of in-plane properties is expected. In the present investigation, the biaxial compressive strength properties of triaxial braided cylinders are measured experimentally, and the effects of four different sets of braid architectures are considered. The results show that fiber direction strain can correlate the results of biaxial tensile and compression failure tests. The braid parameters are found to have an effect on measured strengths, primarily through the introduction of defects into the fiber paths. The axial compression strength was found to be sensitive to waviness in the fiber path that was produced by uneven braiding coverage. Braid direction compression and tension strength is significantly lower than axial strength, and is also affected by braid parameters.

Effects of prestress or stress during oxidation on the reactivities and strengths of PGX and H451 graphites were examined at oxidation temperatures of 450 to 600/sup 0/C in air and 550 to 750/sup 0/C in 2% H/sub 2/O/He. Little or no effect of compressive prestress at stress levels of up to 75% of the mean fracture strengths, was found. A small effect on the reactivity of H451 graphite was observed in the case of 2% H/sub 2/O/He, i.e., the rate was enhanced by no more than 30% for compressive prestress levels of up to 90% of the fracture strength. Tensile and compressive stresses during oxidation did not affect the reactivities of these graphites at stress levels of up to 28% of the mean compressive strength and 35% of the mean tensile strength for H451 graphite, and 44% and 56% for PGX graphite, respectively. 13 refs., 18 figs.

In this paper a comparison between the analytical expressions for the prediction of the load carrying capacity of strengthened reinforced concrete (RC) columns with steel angles and strips is made. Expressions examined consider: the strength contribution due to the confinement effects induced by transverse strips; the composite action due to steel angles and unconfined concrete core; the strength contribution due to the composite actions of angles and concrete core taking into account that steel angles are subjected to axial force and bending moment and concrete core is confined by transverse strips. Design rules given by recent codes for the design of the strengthened columns are given. Therefore, results here generated, in terms of load carrying capacity, were compared with good agreemen...

Syntactic foams of polybenzoxazine, containing moderately high volume percentage of glass microballoons, were prepared. The specific gravity decreased with increase in microballoon content. The disproportionate decrease in specific gravity was ascribed to entrapment of air voids during compaction. The high content of microballoon increased the possibility for air voids that tended to get accumulated. The effect of microballoon concentration on tensile, compressive, and flexural strengths of the foams was studied. Tensile and compressive properties were optimized at about 68% by volume of microballoon while flexural strength decreased marginally on increasing the microballoon content. Althought the specific tensile and compressive strength showed a maximum followed by a decrease, the specif...

Unit operations are generally considered as separate pieces of the manufacturing processing line. This work investigated the link between high shear granulation and tablet compression. More specifically, the objective of this study was to quantitatively investigate the influence of granule density on granule strength and compact strength. Parametric high-shear wet granulations were conducted according to impeller speed, quantity of water and wet massing time resulting in granules with varying physical attributes. Upon characterizing the granule density, the purpose of confined uni-axial compression tests was two-fold, to determine the compressive strength of the granules and to prepare compacts for further mechanical testing. Compact hardness was determined using indirect tensile testing, ...

The influence of sewage sludge ash (SSA) on cement mortars strength has been studied. To evaluate better the increase of strength compared to control mortar, relative compressive strength gain (CSGr) and flexural strength gain (FSGr) were calculated. The experience shows that SSA behaves as an active material, producing an increase of compressive strength compared to control mortar, probably due to pozzolanic properties of SSA. It can be emphasized that high sulfur content of SSA (12.4%) does not seem to have influence on compressive strength of mortars containing SSA. When CSGr of mortars containing different types of cements are compared, no clear correlation is observed between CSGr and C{sub 3}A content in cement.

Investigations on the mechanical behavior of compacted gravel lateritic soils have been the subject of several studies. Used as road materials, soils tests were mainly performed using standard tests. Static loads as unconfined compression test (UCT) remain the only engineering approach used. Alternative testing techniques can be chosen as supplementary tests for characterizing pavement materials. These researches were conducted so as to determine the response of these particular and problematic soils in its compacted form with road traffic loads. This paper presents the results of research conducted to investigate the effect of the soil compacity on the resilient modulus of lateritic soils. The influence of the percentage of cement added so as to stabilize each sample at the optimum modifi...

Reducing the high embankments associated with road construction especially in low-land areas to within the design flood level, will offer project overall cost reduction amidst enhancing environmental friendliness. This is necessary to mitigate the global environmental concerns of flooding envisaged to be more critical in low-land areas and to keep up with the pressure exacted on land due to road infrastructural development projects, it is important therefore to develop more sustainable technologies. The utilisation of marginal, waste and/or by-product materials such as Ground Granulated Blastfurnace Slag (GGBS) to modify the engineering properties of locally available geomaterials such as local soils could be handy. Laboratory tests such as Unconfined Compressive and linear expansion tests...

Objective: The objective of this study was to elucidate the role of the superficial region of articular cartilage in determining the dynamic properties of the tissue. It is hypothesised that removal of the superficial region will influence both the flow dependent and independent properties of articular cartilage, leading to a reduction in the dynamic modulus of the tissue. Methods: Osteochondral cores from the femoropatellar groove of three porcine knee joints were subjected to static and dynamic loading in confined or unconfined compression at increasing strain increments with and without their superficial regions. Equilibrium moduli and dynamic moduli were measured and the tissue permeability was estimated by fitting experimental data to a biphasic model. Results: Biochemical analysis co...

Due to environmental reasons and the shortage of natural resources, it is greatly valuable to recycle construction and demolition waste (CDW) as much as possible. One of effective ways to reuse more CDW is to produce a cemented road base material. The recycled CDW however is a mix of recycled masonry and concrete with a wide variation in composition. This implies that the mechanical properties of cement treated demolition waste are not only determined by cement content and degree of compaction, but also by the ratio of crushed masonry content to crushed concrete content. In order to optimize its mixture proportioning, this paper explores the response surface and contour plot of the combined effect of mixture variables on the mechanical properties including the unconfined compressive streng...

The shear strength of human trabecular bone may influence overall bone strength under fall loading conditions and failure at bone-implant interfaces. Here, we sought to compare shear and compressive yield strengths of human trabecular bone and elucidate the underlying failure mechanisms. We analyzed 54 specimens (5-mm cubes), all aligned with the main trabecular orientation and spanning four anatomic sites, 44 different cadavers, and a wide range of bone volume fraction (0.06-0.38). Micro-CT-based non-linear finite element analysis was used to assess the compressive and shear strengths and the spatial distribution of yielded tissue; the tissue-level constitutive model allowed for kinematic non-linearity and yielding with strength asymmetry. We found that the computed values of both the shear and compressive strengths depended on bone volume fraction via power law relations having an exponent of 1.7 (R(2)=0.95 shear; R(2)=0.97 compression). The ratio of shear to compressive strengths (mean±SD, 0.44±0.16) did not depend on bone volume fraction (p=0.24) but did depend on microarchitecture, most notably the intra-trabecular standard deviation in trabecular spacing (R(2)=0.23, phuman trabecular bone is generally much weaker in shear than compression at the apparent level, reflecting different failure mechanisms at the tissue level. PMID:22884967

Equilibrium response of articular cartilage to indentation loading is controlled by the thickness (h) and elastic properties (shear modulus, mu, and Poisson's ratio, nu) of the tissue. In this study, we characterized topographical variation of Poisson's ratio of the articular cartilage in the canine knee joint (N=6). Poisson's ratio was measured using a microscopic technique. In this technique, the shape change of the cartilage disk was visualized while the cartilage was immersed in physiological solution and compressed in unconfined geometry. After a constant 5% axial strain, the lateral strain was measured during stress relaxation. At equilibrium, the lateral-to-axial strain ratio indicates the Poisson's ratio of the tissue. Indentation (equilibrium) data from our prior study (Arokoski et al., 1994. International Journal of Sports Medicine 15, 254-260) was re-analyzed using the Poisson's ratio results at the test site to derive values for shear and aggregate moduli. The lowest Poisson's ratio (0.070+/-0.016) located at the patellar surface of femur (FPI) and the highest (0.236+/-0.026) at the medial tibial plateau (TMI). The stiffest cartilage was found at the patellar groove of femur (micro=0.964+/-0.189MPa, H(a)=2.084+/-0. 409MPa) and the softest at the tibial plateaus (micro=0.385+/-0. 062MPa, H(a)=1.113+/-0.141MPa). Comparison of the mechanical results and the biochemical composition of the tissue (Jurvelin et al., 1988. Engineering in Medicine 17, 157-162) at the matched sites of the canine knee joint indicated a negative correlation between the Poisson's ratio and collagen-to-PG content ratio. This is in harmony with our previous findings which suggested that, in unconfined compression, the degree of lateral expansion in different tissue zones is related to collagen-to-PG ratio of the zone. PMID:10807987

This study investigated the preparation and characterization of the solid fuel briquette, which was made from rice straw and rice bran. This work included: (1) developing a machine to smash the rice straw into pieces; (2) compressing the smashed rice straws and the rice bran into the biomass briquette; and (3) characterizing the properties of the briquette (such as the percentage of change in briquette volume, the percentage of loss of briquette mass, the air-dry density, the compressive strength, and the heating value) at room temperature. The hot-pressing temperature strongly affects the compressive strength of the briquette. As the percentage of the rice bran increases, the compressive strength and the heating value of the biomass briquette increase. Most interestingly, the thermo-energy, which is used to compress the briquette of the rice straw, will be minimized if a certain percentage of the binder (such as rice bran, sawdust, or the other biomass waste) is mixed with the smashed rice straw. (author)

The objective of this study is to investigate the properties of concrete made with recycled concrete coarse aggregates. Two grades of concrete compressive strength are considered. Results showed reduction in concrete properties (compressive strength, tensile strength, bond strength and porosity) of concrete containing recycled aggregates especially at higher contents. Hence, this study proposed three techniques to enhance properties of recycled aggregates concrete. These techniques involve process of self healing of recycled aggregates, mixing method and adding silica fume. Self healing, by immersing recycled aggregates in water up to 30days, improved mechanical properties of recycled aggregates concrete especially for low cement content. Mixing water, cement, addition and recycled aggrega...

This study assesses the mechanical performance of metakaolin-based geopolymers reinforced with refractory aluminosilicate particles and fibers, after exposure to elevated temperatures. Compressive strength, shrinkage and flexural strength data reveal that the inclusion of refractory particles, both with and without additional refractory fibers, promotes improved post-exposure compressive and flexural strengths compared with samples without reinforcement. Specimens exposed to temperatures between 600^oC and 1000^oC exhibited reduced shrinkage with the inclusion of higher contents of particles and fibers, while retaining good mechanical strength. This behavior is attributed to the cracking control achieved in these materials, which contributes to the enhancement of their volumetric stability...

Silicified microcrystalline cellulose (SMCC) has been shown to have advantages over conventional microcrystalline cellulose (MCC). These advantages are (i) improved tablet strength compared to that achieved with MCC, (ii) the retention of compressibility after wet granulation, whereas MCC produces w...

mechanical properties to thin-layer composites without. TTT reinforcement yarns. A ..... Kevlar yarn is a ii00 denier. Kevlar-49 yarn. Both the stitched and integrally ..... then their compression strengths are degraded less. The. TTT reinforcement ...

Contents: Modeling Route Choice Behavior in Transportation Networks by Using Fuzzy Logic and Logistic Regression Techniques; Compressive Strength-Color Change Relationship in Mortars Subjected to High Temperature; Determination of Intensity-Duration-Frequ...

... is considered along with the honeycomb sandwich in this paper. A ... strength- of a sandwich panel in compression is illustrated in figure 2. The panel is .... tion, the more even distribution of temperature through the thickness of the sandwich ...

Silicified microcrystalline cellulose (SMCC) has been shown to have advantages over conventional microcrystalline cellulose (MCC). These advantages are (i) improved tablet strength compared to that achieved with MCC, (ii) the retention of compressibility after wet granulation, whereas MCC produces w...

Jun 13, 2006 ... Performance Analysis, Strength Analysis, and Fracture Control ....... 16 ..... for other systems such as ground support equipment (GSE). .... Where possible, compression springs shall be used in lieu of tension or torsion springs.

Production of Monocrystals and High-Strength Polycrystals of Diamond with Specified Properties by Shock and Quasi-Static Compression of Different Carbonaceous Materials Including Amorphous Carbon, Ultra-Dispersive Diamonds, Fullerits, etc.

The client submitted 5 sets of porcelain and stoneware subsurface (radioactive site) marker prototypes (31 markers each set). The following were determined: compressive strength, thermal shock resistance, thermal crazing resistance, alkali resistance, color retention, and chemical resistance.

The results of high-pressure tests of four railgun designs and four projectile types are presented. All tests were conducted at the Los Alamos explosive magnetic-flux compression facility in Ancho Canyon. The data suggest that the high-strength projectiles have lower resistance to acceleration than the low-strength projectiles, which expand against the bore during acceleration. The railguns were powered by explosive magnetic-flux compression generators. Calculations to predict railgun and power supply performance were performed.

A martensitic phase transformation from the B2 to the B19’CuZr phase in the Cu-Zr-Al bulk metallic glass (BMG) composite was induced by cryogenic treatment (CT). The martensitic transformation causes the improvements of the microhardness and the ultimate compression fracture strength. When the cryogenic treatment time was 72 h, the microhardness and the ultimate compression fracture strength of the BMG composite increased about 18.55% and 37.5%, respectively.

Measurements are reported of the gas permeability of several Japanese coals during triaxial compressive fracturing tests. The authors give an approximation equation for the decrease in gas permeability accompanying compression. The gas permeability begins to increase again when the axial stress reaches 70-80% of the triaxial compression fracture strength. This increased permeability persists past the breaking point. The degree of recovery depends on peripheral pressure. 7 references.

The formation of high sludge strength agglomerates is a key concern to the Sludge Treatment Project (STP) to ensure the sludge can be retrieved after planned storage for up to 10 years in Sludge Transport and Storage Containers (STSC) at T Plant. This report addresses observations of agglomerate formation, conditions that the data shows lead to agglomeration, the frequency of agglomerate formation and postulated physiochemical mechanisms that may lead to agglomeration. Although the exact underlying chemistry of K Basin sludge agglomerate formation is not known, the factors that lead to agglomeration formation, based on observations, are as follows: (1) High Total Uranium Content (i.e., sample homogeneity and influence from other constituents); (2) Distribution of Uranium Phases (i.e., extent of conversion from uraninite to uranium oxide hydroxide compounds); (3) Sample Dry-out (loss of cover water); (4) Elevated temperature; (5) Solubility ofU(IV) phases vs. U(VI) phases; and (6) Long storage times. Agglomerated sludge has occurred infrequently and has only been observed in four laboratory samples, five samples subjected to hydrothermal testing (performed for 7 to 10 hours at {approx}185 C and 225 psig), and indirectly during six sampling events in the KE Basin. In the four laboratory samples where agglomerates were observed, the agglomerates exhibited high shear strength and the sample container typically had to be broken to remove the solids. The total uranium content (dry basis) for the four samples (KE Pit, KC-2/3 SS, KC-2/3 M250 and 96-13) were {approx}8 wt%, {approx}59.0 wt%, 68.3 wt% and 82 wt%. The agglomerates that were present during the six sampling events were undoubtedly disturbed and easily broken apart during sample collection, thus no agglomerates were observed in subsequent laboratory analyses. The highest shear strengths measured for K Basin sludge samples were obtained after hydrothermal treatment (7 to 10 hr at 185 C) of high-uranium-content KE canister sludge. The unconfined compressive strength of samples from this testing, measured by a pocket penetrometer, infers that their shear strength may be between 120 kPa and 170 kPa (PNNL-16496). These short-duration hydrothermal tests were conducted at temperatures much greater than the temperature of the T Plant canyon cells (-7 C to 33 C); however, the strength results provide an initial bounding target for sludge stored for many years, and an upper range for simulants (042910-53451-TP02 Rev 1). Sampling and characterization activities conducted in 2009 have measured the total uranium content and speciation for sludge stored in Engineered Containers SCS-CON-220, -240, -250, and -260 (PNNL-19035). Based on on-going testing that has measured the shear strength of uranium samples containing varying uranium (IV) to uranium (VI) ratios and the characterization of the Engineered Containers SCS-CON-220, -240, -250, and -260, it is unlikely that agglomerates will form on a large scale in this sludge. The highest measured total uranium concentration in the Engineered Container SCS-CON-220 sludge is 35.2 wt% and only 4 wt% to 6 wt% (dry) in Engineered Containers SCS-CON -240, -250, and -260. The uranium concentrations in Engineered Containers SCS-CON-220, -240, -250, and -260 sludge are below the threshold for agglomerate formation. Settler sludge however is estimated to contain {approx} 80 wt% (dry) total uranium, which could lead to the formation of high strength agglomerates depending on the relative concentrations of U(IV) and U(VI) compounds. One of the chief concerns of the STP is sludge dry-out. Samples archived in PNNL hot cells have been known to dry out and form hard clods of material, which are then difficult to reconstitute (HNF-6705). In 1996, all but one of the samples archived at the 222-S Laboratory dried out. These samples were composed of sludge collected from the KE Basin floor and Weasel Pit. However, in the STP's current design plans for sludge stored in STSCs at T Plant, there are provisions for continual water level observation and periodic water replenishment when needed, which dramatically lowers the risk of a dryout event. Recent 2009 KE Engineered Container sludge and KW Engineered Container sludge physical characterization lead to opportunistic data on the behavior of dried sludge. As shown in section 5 of this report, sludge core samples taken from Engineered Container 220 that have inadvertently dried after characterization activities indicate that the sludge is mostly composed of very 'weak' and friable solids. Since Engineered Container SCS-CON-220 sludge has the highest total uranium (uranium metal and uranium oxide) concentration of the four Engineered Containers sampled to date, if a dry-out event should occur in the STSC while stored at T Plant there is qualitative evidence to suggest that the solids would be 'weak' and friable in nature and thus easily mobilized.

Zee-stiffened compression test panels, fabricated with dispersion-strengthened, high-temperature 8009 aluminum alloy sheet, were evaluated to determine the alloy's feasibility for compression-critical applications. A compression panel design configuration was obtained using a strength analysis program that predicts the post-skin buckling strength of flat or curved-skinned, metallic-stiffened structure. The 8009 alloy exhibited pronounced, compressive strength anisotropy, necessitating panel orientation to take advantage of the higher compressive yield in the sheet transverse direction. Compression test results were in good agreement with the predicted compression allowables since they were within 5 percent of the test strength. The 8009 aluminum riveted panel exhibited superior skin buckling resistance and failed in the wrinkling mode, as predicted, at a load approximately 15 percent higher than that of the baseline 2024 panel. The spotwelded 8009 panel did not fail in the wrinkling mode since the spot welds failed in tension shortly after the skin locally buckled. The latter test indicates that the spot welded skin-stringer combinations should not be used above the buckling stress. Due to its excellent microstructural stability at elevated temperatures, high-temperature compression panels of 8009 alloy offer potential weight savings of 25 percent compared with conventional aluminum alloys.

This method covers determination of the compressive properties of flat structural sandwich constructions in a direction parallel to the plane of the sheet of sandwich. Significance of the edgewise compressive strength of flat sandwich constructions, apparatus, dimensions, number and preparation of specimens, conditioning, procedure and reporting are discussed.

In project 'Developing compressing method for long-distance transportation of loose logging residues' different loading methods and trailer constructions are studied in Finland and Sweden. Compression tests are made with prototype trailer in VTT to define forces and strength of trailer construction. (orig.)

Recent developments in computer-integrated and robot-aided surgery--in particular, the emergence of automatic surgical tools and robots--as well as advances in virtual reality techniques, call for closer examination of the mechanical properties of very soft tissues (such as brain, liver, kidney, etc.). The ultimate goal of our research into the biomechanics of these tissues is the development of corresponding, realistic mathematical models. This paper contains experimental results of in vitro, uniaxial, unconfined compression of swine brain tissue and discusses a single-phase, non-linear, viscoelastic tissue model. The experimental results obtained for three loading velocities, ranging over five orders of magnitude, are presented. The applied strain rates have been much lower than those applied in previous studies, focused on injury modelling. The stress-strain curves are concave upward for all compression rates containing no linear portion from which a meaningful elastic modulus might be determined. The tissue response stiffened as the loading speed increased, indicating a strong stress-strain rate dependence. The use of the single-phase model is recommended for applications in registration, surgical operation planning and training systems as well as a control system of an image-guided surgical robot. The material constants for the brain tissue are evaluated. Agreement between the proposed theoretical model and experiment is good for compression levels reaching 30% and for loading velocities varying over five orders of magnitude. PMID:9456379

Bone cements have been widely used for orthopedic applications. Previous studies have shown that calcium silicon-based bone cements (CSC) were injectable, bioactive, biodegradable, and mechanically strong in the long term, while their short-term compressive strength was low and setting time was too long. On the other hand, plaster (CaSO(4) ·1/2H(2) O, POP) sets quickly upon contact with water and has excellent short-term compressive strength. The aim of this study is to prepare CSC/POP composite cements and investigate the effect of POP on the compressive strength, setting time, injectability, degradation, and in vitro bioactivity of the composite cements. The results have shown that POP content plays an important role to modulate the physicochemical property of CSC. The addition of POP into CSC significantly decreased the initial and final setting time and enhanced the short-term compressive strength and degradation rate. The obtained composite cement with 30% POP has been found to possess optimal setting time and short-term compressive strength. In addition, the prepared composite cements still maintain apatite-mineralization ability in simulated body fluids and their ionic extracts have no significant cytotoxicity to L929 cells. The results suggested that the addition of POP into CSC is a viable method to improve their setting properties and short-term compressive strength. The obtained composite cements with the optimized composition of 70% CSC and 30% POP could be potentially used for bone repair application. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012. PMID:23166057

Based on a statistical model first applied for prediction of compressive strength up to 28 d from the microstructure of Portland cement, potential compressive strength of clinker has been predicted from its mineralogy. The prediction model was evaluated by partial least squares regression. The mineralogy was described by patterns from X-ray diffraction analysis in the 20-regions 29.88-30.70 degrees and 32.90-34.10 degrees (using CuK alpha-radiation). It has been shown that prediction of potential compressive strength of clinker up to 28 d from the observed variation in the mineralogy gave a significant variation of the strength at both 1 and 28 d. Sensitivity analysis based on simulation, optimisation and prediction made it possible to study the influence of the mineralogy on the strength in more detail.

In the recent years we have performed various experiments on the collision dynamics of highly porous dust aggregates and although we now have a comprehensive picture of the micromechanics of those aggregates, the macroscopic understanding is still lacking. We are therefore developing a mechanical model to describe dust aggregate collisions with macroscopic parameters like tensile strength, compressive strength and shear strength. For one well defined dust sample material, the tensile and compressive strength were measured in a static experiment and implemented in a Smoothed Particle Hydrodynamics (SPH) code. A laboratory experiment was designed to compare the laboratory results with the results of the SPH simulation. In this experiment, a mm-sized glass bead is dropped into a cm-sized dust aggregate with the previously measured strength parameters. We determine the deceleration of the glass bead by high-speed imaging and the compression of the dust aggregate by x-ray micro-tomography. The measured penetration...

Tests on glulam were simulated to determine the compressive strength. Based on the values obtained, three strength models were derived. They describe the compressive strength in terms of the density of the sawn timber used, the moisture content of the glulam and, optionally, of the knot area ratio. One of the models, based on density and moisture content, provides satisfying accuracy for engineering applications. Accordingly, glulam with 12 % moisture content has a predicted strength which is 50 % higher compared to glulam with 20 %. If the moisture content amounts to 20 % and the characteristic density of the sawn timber exceeds 350 kg/m3, the predicted strength is lower compared to corresponding nominal values in current product standards. It is suggested to separate the compressive stre...

This paper presents a numerical study on FRP-wrap strengthened reinforced concrete columns subjected to eccentric axial loads using ABAQUS(R). For modeling of concrete dilation under non-uniform confinement pressure, a smooth cap plasticity model was combined with concrete damaged plasticity model. This model includes different concrete compaction-dilation behaviors which is pressure-dependent. Proposed model has been calibrated and verified for concrete in number of unconfined and full-wrapped columns under combination of axial force and bending moment. Presented numerical predictions are shown to be in close agreement with existing experimental results. The effect of laminate stacking sequences and column slenderness on strength and ductility of members was examined thoroughly. The resul...

The effect of dynamic mechanical shear and compression on the synthesis of human tissue-engineered cartilage was investigated using a mechanobioreactor capable of simulating the rolling action of articular joints in a mixed fluid environment. Human chondrocytes seeded into polyglycolic acid (PGA) mesh or PGA-alginate scaffolds were precultured in shaking T-flasks or recirculation perfusion bioreactors for 2.5 or 4 weeks prior to mechanical stimulation in the mechanobioreactor. Constructs were subjected to intermittent unconfined shear and compressive loading at a frequency of 0.05?Hz using a peak-to-peak compressive strain amplitude of 2.2% superimposed on a static axial compressive strain of 6.5%. The mechanical treatment was carried out for up to 2.5 weeks using a loading regime of 10?min duration each day with the direction of the shear forces reversed after 5?min and release of all loading at the end of the daily treatment period. Compared with shaking T-flasks and mechanobioreactor control cultures without loading, mechanical treatment improved the amount and quality of cartilage produced. On a per cell basis, synthesis of both major structural components of cartilage, glycosaminoglycan (GAG) and collagen type II, was enhanced substantially by up to 5.3- and 10-fold, respectively, depending on the scaffold type and seeding cell density. Levels of collagen type II as a percentage of total collagen were also increased after mechanical treatment by up to 3.4-fold in PGA constructs. Mechanical treatment had a less pronounced effect on the composition of constructs precultured in perfusion bioreactors compared with perfusion culture controls. This work demonstrates that the quality of tissue-engineered cartilage can be enhanced significantly by application of simultaneous dynamic mechanical shear and compression, with the greatest benefits evident for synthesis of collagen type II. PMID:22095592

A simple way for obtaining compressive strength of unidirectional composites by three-point bending tests is proposed in the present work. The interpretation of test results includes the stress singularity induced by the applied concentrated load and the determination of the contact zone between loading roller and specimen. Unidirectional carbon/epoxy composite T6T/F593 from Hexcel Composites has been tested by three-point bending with different thicknesses and spans. When failure occurs by compressive stresses, experimental results agree with the strength obtained by compressive tests. The best agreement is obtained in the case of 7 mm nominal thickness and span of 120 mm.

A method is presented for evaluating the liquefaction strength of partially saturated sand using the compression wave velocity (P-wave velocity), a new indicator of saturation. Based on laboratory test results, an empirical correlation that relates the liquefaction strength with the pore pressure co...

The compressive strength, the tensile splitting strength, the stress strain relationship and the thermal deformation of concrete are determined experimentally as a function of temperature. Theoretical formulae are derived based on the classical bond stress-slip theory to predict crack width and spac...

A substantially alkaline resistant calcium-iron-phosphate (CFP) glass and methods of making and using thereof. In one application, the CFP glass is drawn into a fiber and dispersed in cement to produce glass fiber reinforced concrete (GFRC) articles having the high compressive strength of concrete with the high impact, flexural and tensile strength associated with glass fibers.

Mechanical properties of standard decorticated and hand isolated flax bast fibres were determined in tension as well as in compression. The tensile strength of technical fibre bundles was found to depend strongly on the clamping length. The tensile strength of elementary flax fibres was found to ran...

The purpose of this research was to identify possible test procedures for the evaluation of the strength of chewable tablets with respect to prevention of damage to teeth or mandibular joints when tablets are consumed. Diametral compression and flexure tests were employed to evaluate the strength of...

  High temperature compressive strength and Vickers hardness as well as bending strength at room temperature were measured on high C high speed steel type alloys (HCHS) and high Cr cast iron. As the temperature rises, the compressive strength and hardness fall in every specimen. The strength of HCHS maintains a higher level up to 823K, while the strength of high Cr cast iron lowers significantly over 773K. In HCHS with 5% Co, higher strength is kept even at 873K. Both the addition of Ni and precipitation of graphite reduce the strength of HCHS, while W shows little influence. The compressive strength is proportional to the hardness at 293?923K. Co raises the bending strength of HCHS too. Since the crack propagates along eutectic M2C carbides, to control the distribution of M2C carbide is also important for getting the high strength. The distribution as well as the amount of M2C carbide are dependent on Mo and W contents.   

An analytical method employing the strain-based shear strength model was developed to predict the shear strength of prestressed concrete beams. The proposed method assumes that the shear force acting in a concrete beam is resisted primarily by the compression zone of intact concrete in the cross section. The shear capacity of the compression zone is evaluated at the inclined failure surface using the material failure criteria for concrete, considering the interaction with the compressive normal stress. Because the compressive stress is developed by the flexural action of the beam and the prestress applied to the cross section, the shear capacity is defined as a function of the flexural deformation and the prestress applied to the cross section. Then, the shear strength of the beam is deter...

Biaxial failure criteria and stress-strain response for plain concrete of containment structure on nuclear power plants are studied under uniaxial and biaxial stress(compression-compression, compression-tension, and tension-tension combined stress). The concrete specimens of a square plate type are used for uniaxial and biaxial loading. The experimental data indicate that the strength of concrete under biaxial compression, f{sub 2}/f{sub 1}=-1/-1, is 17 percent larger than under uniaxial compression and the poisson's ratio of concrete is 0.1745. On the base of the results, a biaxial failure envelope for plain concrete that the uniaxial strength is 5660 psi are provided, and the biaxial failure behaviors for three biaxial loading areas are plotted respectively. And, various analytical equations having the reliability are proposed for representations of the biaxial failure criteria and stress-strain response curves of concrete.

The effect of boron (between 0.06 and 0.11 wt%) on the microstructure, hardness and compression properties of cast Ti-6Al-4V was investigated. Compression properties were examined in the temperature range from room temperature to 1000°C. It was found that the addition of boron refines the as-cast microstructure in terms of prior beta grain size and alpha colony size. This microstructural refinement led to an increase in compressive yield strength from room temperature up to 700°C. Three different strain rates (0.001, 0.1 and 1 s?1) were evaluated during compression testing from which it was found that the compressive yield strength decreased with decreasing strain rate from 600°C up to the beta transus temperature.

Low-density monolithic silica and hexylene-bridged polysilsesquioxane aerogels were chemical vapor deposition (CVD) treated with hexamethyldisilazane or hexachlorodisilane silylating agents producing TMS (trimethylsilane) or Si layers on the aerogel. Reinforcing the weak aerogels by controlled deposition process improved their compressive strength and preserved their properties characteristic of low-density aerogels. When the silica and hexylene-bridged polysilsesquioxane aerogels were CVD treated with hexamethyldisilazane, the compressive modulus more than doubled in some cases. However, when treating hexylene-bridged aerogels with hexachlorodisilane the compressive modulus increased six fold. Not only did CVD treatment of the aerogels improve the compressive modulus, but the low densitie...

The main aim of the present study was to enhance the understanding of damage evolution in wind turbine blades by a combination of structural- and material modelling. Basic damage modes were identified in wind turbines tested to failure under static and cyclic loadings. Two of the observed damage types, compression failure and crack growth along adhesive joints, were studied in details. Modelling of a load carrying composite spars as well as composite columns were performed for assessing the compressive strength. A fracture mechanics approach was developed for prediction the strength of adhesive joints. The effect of porosity on the strength of adhesive joints was also investigated. (au)

Water erosion is one of the major factors for performance degradation of cement asphalt mortar (CAM). In the paper, the strength variations of CAM exposed to water was investigated at various water temperatures (20^oC, 40^oC and 60^oC) and pressures (0.0MPa, 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa and 0.5MPa) and the microstructure evolution was analyzed by mercury intrusion porosimetry (MIP) and scan electronic microscope (SEM). Results indicate that temperature and pressure both cause the deterioration of CAM, the compressive strength of CAM decreases with higher water temperature and its compressive strength decreases with increases of water pressure.

The calcium polyphosphate (CPP) reinforced ZK60A magnesium-matrix composites are fabricated using powder metallurgy. In this study, the microstructure, mechanical and corrosion properties of the composites are investigated. The CPP particles are uniformly distributed throughout the composite with firmly bounded CPP-matrix interface. The composites consisted of 20wt.% CPP achieved a maximum compressive strength of 494.88MPa. Effective load transfer from matrix to particle results in particle fracture observed during compressive tests. Tensile tests show that the ultimate strength and yield strength of the composites were reduced by CPP addition. The fracture surfaces of composites observed during tensile tests show matrix deformation, interfacial detachment and particle breakage coupled wit...

The injectability of Portland cement (PC) with calcium chloride and calcium nitrate additives was investigated using a syringe with a 2 mm aperture for potential clinical applications such as vertebroplasty. Addition of either additive at 10 wt % increased the quantity of cement extruded through the syringe from approximately 25 wt % for the PC standard, to over 95 wt %. 10 wt % additions of either additive also decreased setting times from over 2 h to below 25 min. The compressive strength of the modified cements was all greater than the compressive strength of a human vertebral body. Decreasing either additive to 5 wt % generated compressive strengths after 24 h setting equal to polymethylmethacrylate, the cement used for the majority of vertebroplasty procedures. An initial early exotherm in the chloride cements was coupled with an X-ray diffraction (XRD) peak that indicated the early formation of the ettringite cement phase. In contrast, Fourier transform infrared (FTIR) spectroscopy and XRD data indicated that calcium nitrate may have stimulated early calcium silicate hydrate (C?S?H) production (the main strength producing phase of PC). Combining the two additives produced a synergistic effect with cements having increased injectabilities and compressive strengths compared with either addition used individually. This study has demonstrated that by modifying PC with nonproprietary chemicals it was possible to significantly increase cement injectability and reduce setting times whilst maintaining compressive strengths, making PC suitable for potential orthopedic applications. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012. PMID:22887643

Abstract in portuguese Estudou-se o comportamento mecânico das misturas solo-alcatrão, solo-cal-alcatrão e solo-cimento-alcatrão, com base nos ensaios de limites de liquidez e plasticidade, CBR, compressão simples e permeabilidade, visando a aplicabilidade destas em rodovias. Trabalhou-se com três amostras de solos (ETA, NV e VS), representativos das ocorrências da microrregião de Viçosa-MG. Foram empregados alcatrão, nos quantitativos de 0,25, 0,5, 1, 2, 4 e 6%, cal hidratada e cimen (more) to Portland, em conjunto com o alcatrão, na dosagem de 2%, considerando-se a energia do ensaio de compactação AASHTO Normal. A adição de alcatrão reduziu significativamente os valores de LL dos solos, mas com pouca variação nos valores de IP. Conclui-se que o alcatrão contribuiu para melhorar as características mecânicas e hidráulicas dos solos, para alguns tratamentos, não atingindo, entretanto, os padrões de resistência mecânica exigida pelo DNER para camadas de sub-base de pavimentos flexíveis. Quanto às misturas solo-cal-alcatrão e solo-cimento-alcatrão, constatou-se melhoria substancial nos parâmetros de resistência mecânica em relação aos solos, principalmente devido à ação cimentante da cal e do cimento, e que para alguns tratamentos esta ação foi potencializada pelo alcatrão, incidindo em resistência mecânica superior à das misturas solo-cal e solo-cimento. O alcatrão, em alguns tratamentos, ocasionou decréscimos na permeabilidade das misturas, com relação ao solo, de até dez vezes. O alcatrão mostrou ser um estabilizante de interesse para fins rodoviários apenas para determinadas condições, envolvendo tipo de solo e tipo e teor de alcatrão, o que indica que estudos nesta direção devem apresentar uma característica regional. Abstract in english The behavior of the mechanical mixtures soil-wood tar, soil-lime-wood tar and soil-cement-wood tar, based on the Atterberg limits California Bearing Ratio (CBR), Unconfined Compression Strength (UCS) and permeability, were studied for application in forest road pavement. Three soil samples of (ETA, NV and VS) representative of Viçosa-MG occurrences were used. Wood-tar was used 0.25, 0.5, 1, 2, 4 and 6% and lime and cement mixture.The addition of wood-tar reduced the Atte (more) rberg values significantly. It was concluded that wood-tar improved the mechanical and hydraulic characteristics of the soils, for some treatments without, however, reaching however, the patterns of mechanical resistance demanded by DNER sub-base layers of flexible pavements. Regarding the mixtures soil-lime-wood tar and soil-cement-wood tar, substantial improvement was verified in the mechanical resistance parameters in relation to the soils, mainly due to the action of lime and cement. This action was found to be stronger for the wood tar in some treatments, leading to a higher mechanical resistance than that of the mixtures soil-lime and soil-cement. Wood tar caused a decrease in mixture permeability in relation to the soil up to 10 times. Wood tar was found to be an important stabilizer only for some forest road pavement conditions, involving soil type, and wood tar type and level, suggesting that studies on this area should present a regional characteristic.

Sub-level caving has been introduced at Samtan and a knowledge of the coal strength on an experimental face was required. Measurements were made using Protodyakonov's drop hammer test and the results were compared with those from a plaster cast test. The coal strength was found to be 15-19 kg/cm/sup 2/. A formula was derived from the plaster cast test for the compressive strength.

High-resolution, time-resolved shock compression measurements have been performed on high-strength monolithic ceramics to assess equation-of-state, phase transformation and flow properties. A substantial base of data has been obtained on a range of ceramics including aluminium nitride, aluminum oxide, boron carbide, silicon carbide, titanium diboride and zirconium dioxide. These data provide material response properties for nonlinear elastic compliance, pressure-induced phase transformation, shear strength and tensile fracture strength. 14 refs., 8 figs.

This work investigates the effects of adding residual rice husk ash (RHA) from South Vietnam, generated when burning rice husk pellets in the boiler, to cement. To improve pozzolanic reactivity, RHA was ground for 1 h. The non-ground RHA and ground RHA were used to test strength activity index according to ASTM C311. The properties of the concrete were investigated, including compressive strength, concrete electrical resistivity, and ultrasonic pulse velocity. Results show that the non-ground RHA can be applied as a pozzolanic material. Decreasing the non-ground RHA average particle size provides a positive effect on the compressive strength of mortar. Compressive strength of cylindrical concrete in the 47-66 MPa range was obtained in this study. The results also indicate that up to 20% of...

Based on experimental work conducted at NGL the following major factors controlling the permeability of single fractures and fracture cross-flow have been identified: the stress dependent fracture aperture (e), the fracture internal flow paths (tortuosity), the fracture surface properties such as roughness (JRC), fracture wall strength (JCS) and the intact rock uniaxial compressive strength ({sigma}{sub c}), the fracture normal stress ({sigma}{sub n}) and shear displacement ({delta}{sub s}) related dilation (d{sub n}) and gouge formation. Fracture asperity damage (crushing, gouge formation and pore size reduction) depends strongly on the ratio of the fracture wall compression strength (or intact rock uniaxial compressive strength if the fracture surface is not altered) to the normal stress level (JCS/{sigma}{sub n}) and the fracture surface morphology, expressed by the joint roughness coefficient (JRC).

Graphite was bonded to nickel in a vacuum using an RF-induction furnace with temperature, keeping time and joining compressive stress as variables. The bending strength of graphite/nickel joints, the changes of microstructure and hardness of nickel near the interface were investigated. Thermal stress induced in the joints was estimated by means of finite element analysis. On the basis of these results, the influences of joining compressive stress on bonding were examined. Joining compressive stress and joining temperature are important factors for close contact and strong bonding between the joining surfaces of graphite and nickel. At a high joining temperature, nickel is plastically deformed even under low joining compressive stress so that full contact and strong bonding are accomplished. At a low joining temperature, strong bonding was not achieved when joining compressive stress is low, because plastic deformation of nickel is restrained. The plastic deformation of nickel plays an important role in enabling good contact and strong bonding. The strength of the joints increased with joining compressive stress. The plastic deformation of nickel near the joining interface increases with the joining compressive stress so that graphite is elastically deformed during annealing. Therefore, compressive stress is retained on the graphite surface near the joining interface. Thermal tensile stress induced on the graphite surface after cooling is relaxed by this compressive stress.   

The small-strain stress-strain properties of expanded polystyrene (EPS) geofoam with densities of about 20 kg/m3 and 30 kg/m3 were evaluated by laboratory unconfined compression tests on specimens of 75 mm in diameter and 150 mm in height. Two series of tests were conducted, which were continuous monotonic loading (ML) tests and ML tests intervened by sustained creep loading and minute cycles of unload and reload. Relatively small vertical and horizontal strains were locally measured by means of a pair of local deformation transducers (LDTs) and a set of three clip gauges, respectively. The paramount importance of measuring local strains in compression tests on EPS to reliably evaluate its stress-strain properties, in particular those at relatively small strains, is demonstrated. The initial modulus, E0, and Poisson's ratio, ?0, were evaluated from initial stress-strain relations at small strains obtained by these ML tests. The tangent parameters, Etan and ?tan, were also evaluated from the ML stress-strain behaviour. The equivalent parameters, Eeq and ?eq, were evaluated from the stress-strain behaviour during minute cycles of unload and reload. The stress-strain behaviour is essentially linear only at small strains, and it becomes highly non-linear and a significant drop of stiffness occurs as observed in the overall stress-strain behaviour. The Poisson's ratio for inelastic deformation is found to be negative.   

Achieving sufficient functional properties prior to implantation remains a significant challenge for the development of tissue engineered cartilage. Many studies have shown chondrocytes respond well to various mechanical stimuli, resulting in the development of bioreactors capable of transmitting forces to articular cartilage in vitro. In this study, we describe the production of sizeable, tissue engineered cartilage using a novel scaffold-free approach, and determine the effect of perfusion and mechanical stimulation from a C9-x Cartigen bioreactor on the properties of the tissue engineered cartilage. We created sizable tissue engineered cartilage from porcine chondrocytes using a scaffold-free approach by centrifuging a high-density chondrocyte cell-suspension onto an agarose layer in a 50 mL tube. The gross and histological appearances, biochemical content, and mechanical properties of constructs cultured in the bioreactor for 4 weeks were compared to constructs cultured statically. Mechanical properties were determined from unconfined uniaxial compression tests. Constructs cultured in the bioreactor exhibited an increase in total GAG content, equilibrium compressive modulus, and dynamic modulus versus static constructs. Our study demonstrates the C9-x CartiGen bioreactor is able to enhance the biomechanical and biochemical properties of scaffold-free tissue engineered cartilage; however, no additional enhancement was seen between loaded and perfused groups. PMID:21274847

Notice was given on chitosan to discuss fabrication of hardened body in calcium carbonate-aspartic acid-chitosan system. First, aspartic acid (Asp) was adsorbed into surface of amorphous calcium carbonate (ACC). Then, discussions were given on effects of water-solid mass ratio and chitosan amount on compressive strength of the hardened body in the calcium carbonate-chitosan system made by using a flow-in molding process. As a result, approximately the same compressive strength as that of calcium carbonate (calcite type) was obtained when anhydrous ACC as a product of ACC heated at 250 deg C is used as the raw material. Thus, the hardened body in calcium carbonate-aspartic acid-chitosan system was fabricated by using the Asp adsorbed anhydrous ACC as the starting material. The compressive strength decreased with increasing Asp adsorption amount. Therefore, a hardened body was fabricated by using compression molding at 10 MPa, rather than using the flow-in molding process. It was revealed from the results of infrared absorption spectroscopy that the compression molding strengthens the compounding of Asp chemically adsorbed on the ACC surface with chtosan, and improves the compression strength. 23 refs., 8 figs.

Detailed statistical analysis of the experimental data from testing of alumina-loaded epoxy (ALOX) composites was conducted to better understand influences of the selected compositional properties on the compressive strength of these ALOX composites. Analysis of variance (ANOVA) for different models with different sets of parameters identified the optimal statistical model as, y{sub l} = -150.71 + 29.72T{sub l} + 204.71D{sub l} + 160.93S{sub 1l} + 90.41S{sub 2l}-20.366T{sub l}S{sub 2l}-137.85D{sub l}S{sub 1l}-90.08D{sub l}S{sub 2l} where y{sub l} is the predicted compressive strength, T{sub l} is the powder type, D{sub l} is the density as the covariate for powder volume concentration, and S{sub il}(i=1,2) is the strain rate. Based on the optimal statistical model, we conclude that the compressive strength of the ALOX composite is significantly influenced by the three main factors examined: powder type, density, and strain rate. We also found that the compressive strength of the ALOX composite is significantly influenced by interactions between the powder type and the strain rate and between the powder volume concentration and the strain rate. However, the interaction between the powder type and the powder volume concentration may not significantly influence the compressive strength of the ALOX composite.

Abstract in english The heat treatment of wood is an environment-friendly method for wood preservation. The heat treatment process only uses steam and heat, and no chemicals or agents are applied to the material during the process. Tests have shown no harmful emissions are apparent when working with the material. This process improves wood?s resistance to decay and its dimensional stability. In this study, the density, compression strength and hardness of heat treated hornbeam (Carpinus bet (more) ulus L.) wood were investigated. Wood specimens that had been conditioned at 65% relative humidity and 20ºC were subjected to heat treatment at 170, 190, and 210 °C for 4, 8, and 12 hrs. After heat treatment, compression strength and hardness were determined according to TS 2595 and TS 2479. The results showed that the decreases of compression strength and hardness were related to the extent of density loss. Both compression strength and hardness decreased with the increasing temperatures and durations of the heat treatment. While the maximum density loss observed was 16.12% at 210 ºC and 12 hour, at these heat-treatment conditions, the compression strength approximately decreased 30% and hardness values in tangential, radial, and longitudinal directions approximately decreased by 55%, 54%, and 38%, respectively. Hence, it was concluded that there might be a relationship between changes of these wood properties.

The experimental study of air-entrained concrete specimens subjected to different cycles of freeze-thaw was completed. The dynamic modulus of elasticity, weight loss, the cubic compressive strength, compressive strength, tensile strength and cleavage strength of air-entrained concrete were measured after 0, 100, 200, 300, 400 cycles of freeze-thaw. The experimental results showed that the dynamic modulus of elasticity and strength decreased as the freeze-thaw was repeated. The influences of freeze-thaw cycles on the mechanical properties, the dynamic modulus of elasticity and weight loss were analyzed according to the experimental results. It can serve as a reference for the maintenance, design and the life prediction of dams, hydraulic structures, offshore structures, concrete roads and b...

The shear strength of human trabecular bone may influence overall bone strength under fall loading conditions and failure at bone-implant interfaces. Here, we sought to compare shear and compressive yield strengths of human trabecular bone and elucidate the underlying failure mechanisms. We analyzed 54 specimens (5-mm cubes), all aligned with the main trabecular orientation and spanning four anatomic sites, 44 different cadavers, and a wide range of bone volume fraction (0.06–0.38). Micro-CT-based non-linear finite element analysis was used to assess the compressive and shear strengths and the spatial distribution of yielded tissue; the tissue-level constitutive model allowed for kinematic non-linearity and yielding with strength asymmetry. We found that the computed values of both...

Compressive and flexural strength, fracture energy, as well as fatigue property of pervious cement concrete with either supplementary cementitious materials (SCMs) or polymer intensified, were analyzed. Test results show that the strength development of SCM-modified pervious concrete (SPC) differs from that of polymer-intensified pervious concrete (PPC), and porosity has little effect on their strength growth. PPC has higher flexural strength and remarkably higher flexural-to-compressive strength ratio than SPC at the same porosity level. Results from fracture test of pervious concrete mixes with porosity around 19.5% show that the fracture energy increases with increasing the dosage of polymer, reflecting the ductile damage features rather than brittleness. PPC displays far longer fatigue...

The possibility of using incinerator bottom ash as a substitute for natural aggregates was investigated. Rough, porous surface of bottom ash, which diminishes the strength of solidified products, was improved by colloidal silica solution. As a result, a significant increase of mechanical strength was accomplished by a slight amount of silica (cement hydration due to the nano-particle size of about 20 nm in colloidal silica solution. Cylindrical specimens and bricks were prepared from bottom ash added to a colloidal silica (SiO2) solution and cement, and then their compressive strengths were evaluated. Cylindrical specimens showed an increase of approximately 60% in compressive strength when colloidal solution containing 4 wt% silica particles was sprayed onto the bottom ash. The strength of bricks containing colloidal silica was in excess of 20 MPa, which meets the requirement of construction materials. Results of leaching tests based on Toxicity Characteristic Leaching Procedure (TCLP) proved that the solidified bottom ash possessed good chemical stability. PMID:17081741

This paper presents experimentally investigated the effects of pozzolan made from various by-product materials on mechanical properties of high-strength concrete. Ground pulverized coal combustion fly ash (FA), ground fluidized bed combustion fly ash (FB), ground rice husk-bark ash (RHBA), and ground palm oil fuel ash (POFA) having median particle sizes less than 11mm were used to partially replace Portland cement type I to cast high-strength concrete. The results suggest that concretes containing FA, FB, RHBA, and POFA can be used as pozzolanic materials in making high-strength concrete with 28-day compressive strengths higher than 80MPa. After 7 days of curing, the concretes containing 10-40% FA or FB and 10-30% RHBA or POFA exhibited higher compressive strengths than that of the control...

We dedicate this work to Wolfgang Pompe, a very good friend and a good friend of the Materials Faculty at UCSB where he and his wife, Gisela, shared their lives and fellowship. Three different zirconia-alumina laminates, AZ50, AZ80, and AZ95, were fabricated via tape-casting thick Zr(3Y)O{sub 2} layers, dip-coating the zirconia tapes in a slurry containing a mixture of zirconia and alumina, stacking and bonding the coated zirconia tapes, followed by densification. Each composite had a different compressive stress by using different mixtures of alumina and zirconia (the number associated with each composite system refers to the volume fraction of alumina in the thin, compressive layers). After densification, the Zr(3Y)O{sub 2} layers were {proportional_to}425 {mu}m thick, and the thin alumina/zirconia layers were 60 {proportional_to} 65 {mu}m thick. The threshold strengths, below which the probability of failure is zero, were determined to be 255 {+-} 8 MPa, 311 {+-} 7 MPa, and 421 {+-} 12 MPa for AZ50, AZ80, and AZ95 laminates, respectively. These values are about 60 {proportional_to} 70% of those calculated from a previously reported function. The surface and interior stresses were determined using a finite element analysis. The compressive stresses of the outer alumina/zirconia layers were determined using a piezospectroscopy method. The surface stresses for the thick zirconia layers were estimated using an indentation-crack length relation. The piezospectroscopy, analytical and finite element analysis results for the outer compressive layer were in good agreement. But, the finite element analysis showed that the compressive stress component on the surface of the compressive layers was approximately half the value of the biaxial compressive stresses deep within the thin, compressive layers. It appears that the much smaller compressive stresses on the surface of the compressive layers is one important factor that resulted in the lower threshold strength than predicted by the previously developed function used to estimate the threshold strength. (orig.)

This paper summarizes the trends in researching the methods for measuring direct axial and transverse compression characteristics of single carbon fibers. A carbon fiber is an inorganic fiber with a diameter of about 10 {mu} m. The fiber is mostly of the PAN system obtained by sintering the acrylic systems. The world`s production capacity for the PAN system fiber has reached 12,000 tons in the fiscal 1990. Majority of the carbon fibers is used for carbon fiber reinforced plastics and carbon fiber reinforced concrete. Because their properties differ on an interface of a fiber and a matrix, the conventional indirect compression characteristics values do not provide accurate values, hence a method of measuring the direct compression in single fibers is required. The direct axial and transverse compression measuring methods are listed below: a method using a micro particle compression tester to deform fibers into a direction perpendicular to the fiber axis, and analyze it by using a finite element method, a method to measure compression strength of pitch-based carbon fibers by utilizing a micro-compression tester and a microscope, and a method to measure compression characteristics of single fibers by fabricating columnar carbon fiber test pieces, and compressing and breaking them to test the micro-particle compression. 15 refs., 11 figs., 4 tabs.

An index in a database system is a data structure that utilizes redundant information about the base data to speed up common searching and retrieval operations. Most commonly used indexes are variants of B-trees, such as B+-tree and B*-tree. FastBit implements a set of alternative indexes call compressed bitmap indexes. Compared with B-tree variants, these indexes provide very efficient searching and retrieval operations by sacrificing the efficiency of updating the indexes after the modification of an individual record. In addition to the well-known strengths of bitmap indexes, FastBit has a special strength stemming from the bitmap compression scheme used. The compression method is called the Word-Aligned Hybrid (WAH) code. It reduces the bitmap indexes to reasonable sizes and at the same time allows very efficient bitwise logical operations directly on the compressed bitmaps. Compared with the well-known compression methods such as LZ77 and Byte-aligned Bitmap code (BBC), WAH sacrifices some space efficiency for a significant improvement in operational efficiency. Since the bitwise logical operations are the most important operations needed to answer queries, using WAH compression has been shown to answer queries significantly faster than using other compression schemes. Theoretical analyses showed that WAH compressed bitmap indexes are optimal for one-dimensional range queries. Only the most efficient indexing schemes such as B+-tree and B*-tree have this optimality property. However, bitmap indexes are superior because they can efficiently answer multi-dimensional range queries by combining the answers to one-dimensional queries.