Sample records for screeds
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Submicron particle monitoring of paving and related road construction operations.
Freund, Alice; Zuckerman, Norman; Baum, Lisa; Milek, Debra
2012-01-01
This study identified activities and sources that contribute to ultrafine and other submicron particle exposure that could trigger respiratory symptoms in highway repair workers. Submicron particle monitoring was conducted for paving, milling, and pothole repair operations in a major metropolitan area where several highway repair workers were identified as symptomatic for respiratory illness following exposures at the 2001 World Trade Center disaster site. Exposure assessments were conducted for eight trades involved in road construction using a TSI P-Trak portable condensation particle counter. Direct readings near the workers' breathing zones and observations of activities and potential sources were logged on 7 days on 27 workers using four different models of pavers and two types of millers. Average worker exposure levels ranged from 2 to 3 times background during paving and from 1 to 4 times background during milling. During asphalt paving, average personal exposures to submicron particulates were 25,000-60,000, 28,000-70,000, and 23,000-37,000 particles/ cm(3) for paver operators, screed operators, and rakers, respectively. Average personal exposures during milling were 19,000-111,000, 28,000-81,000, and 19,000 particles/cm(3) for the large miller operators, miller screed operators, and raker, respectively. Personal peak exposures were measured up to 467,000 and 455,000 particles/cm(3) in paving and milling, respectively. Several sources of submicron particles were identified. These included the diesel and electric fired screed heaters; engine exhaust from diesel powered construction vehicles passing by or idling; raking, dumping, and paving of asphalt; exhaust from the hotbox heater; pavement dust or fumes from milling operations, especially when the large miller started and stopped; and secondhand cigarette smoke. To reduce the potential for health effects in workers, over 40 recommendations were made to control exposures, including improved maintenance of
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Material selection and embodied energy
CSIR Research Space (South Africa)
Ampofo-Anti, N
2010-11-01
Full Text Available mix concrete apron Non reinforced, ready mix concrete strip foundation Non reinforced, ready mix ground floor slab Concrete block Modular, hollow concrete block Solid concrete block Finishes Floor screed Insulated ceiling panel Perlite... Predicting the embodied energy contribution of a single material is however not as easy as green building practices assume. As illustrated by the example in Box 1, the choice of a material implies the choice of integral constituents such as insulation...
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Voitenko, N G; Garniuk, V V; Prokofieva, D S; Gontcharov, N V
2015-01-01
The work was aimed to find new screeding parameters (biomarkers) for evaluation of health state of workers engaged into enterprises with hazardous work conditions, as exemplified by "Maradykovskyi" object of chemical weapons extinction. Analysis of 27 serum cytokines was conducted in donors and the object personnel with various work conditions. Findings are statistically significant increase of serum eotaxin in the personnel of "dirty" zone, who are regularly exposed to toxic agents in individual filter protective means over the working day. For screening detection of health disorders in the object personnel, the authors suggested new complex biomarker--ratio Eotaxin* IFNγ/TNFα that demonstrates 67.9% sensitivity and 87.5% specificity in differentiating the "dirty" zone personnel and other staffers.
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International Nuclear Information System (INIS)
Kawakami, Hiroto; Yamada, Norikazu; Sasaki, Satoru; Kawasaki, Satoru
2011-12-01
At the request of the Local Nuclear Emergency Response Headquarters, JNES has estimated the effective external exposure dose of car mechanics during the maintenance of the cars from the risk cautionary area. JNES investigated the contamination of the cars from the risk cautionary area and of the average cars at Fukushima city cooperated by the Japan Automobile Dealers Association. Data of screed cars by the Local Nuclear Emergency Response Headquarters is also considered in. Effective external exposure dose of car mechanics treating the cars screened with the emergency situation screening level is estimated to be less than 1 mSv/y under the conservative conditions. This result shows that particular health concern isn't necessary for them. (author)
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Directory of Open Access Journals (Sweden)
Romanov Petr
2017-01-01
Full Text Available Today’s construction projects are highly mechanized. That#x2019;s why selection of right equipment has always been a key factor in the success of any construction project. This decision is typically made by comparison of equipment feature, productivity, capacity and cost. The article describes the approach to selecting the best set of construction equipment from the available options by the set of its quantitative characteristics. It is proposed to carry out the evaluation of options and selection of the best option based on the method of spectral analysis. The article presents the results of the selection of the most appropriate floor screed conveyor for purchasing by construction company using the specified method.
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International Nuclear Information System (INIS)
Klopfer, H.; Engelfried, R.; Ricken, D.; Schmidt, R.
1986-02-01
Considerable cooling (removal of heat) of materials leads to contractions and embrittlement. This permits a commutation of substances to be achieved. Through the application of very cold media on coated surfaces of concrete, screed, plaster and steel, such a considerable amount of heat is to be removed, that the arising inherent stresses lead to a separation of substrate in the coating. A carryout of radioactively contaminated components through arising primary and secondary waste must not occur here. Test specimens were produced with practical system structures, from substrate and coating. Using a specially constructed experimental plant, liquid nitrogen was applied to the coating surfaces. Under certain circumstances, it is possible to separate clods of coating from the substrate. Fine dusts or thaw water, which could cause a carryout of the radioactivity, were not observed. Application on an item, must be preceded by clarification of various influence, e.g. diffusion of stress in the compound system during nitrogen application, coating structure optimisation. (orig./HP) With 5 refs., 10 tabs., 25 figs [de
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Schaefer, Cecília Ogliari; Cheriaf, Malik; Rocha, Janaíde Cavalcante
2017-08-17
An experimental study was conducted to investigate the potential use of phosphogypsum (PG) to produce self-leveling underlayments. The study was designed in two stages. Initially a phosphoanhydrite (PA) was produced by heating phosphogypsum at temperatures of 350 °C, 450 °C, 550 °C, and 650 °C. Two periods of heating were applied (2 and 4 h). The formation of anhydrite was determined by thermogravimetric analysis (DTA-TG) and confirmed by X-ray diffraction (XRD). The results show that anhydrite II was obtained at temperatures above 450 °C, and at higher calcination temperatures the PA solubility was lower. In the second stage of this research, the PA was used in self-leveling underlayments as the main binder in the ternary system comprised of calcium sulfate, calcium aluminate cement, and Portland cement. Self-leveling mortar screeds produced using PA (550 °C/4 h) and PA (650 °C/4 h) showed the best performance in terms of mechanical strength and no degradation was observed after immersion and immersion-drying tests. The formation of ettringite, identified by scanning electron microscopy (SEM), may have contributed to these results. Morphological changes were studied using the scanning electron microscopy (SEM) technique.
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New application technology for 'in situ' pipeline protection using pigging techniques
Energy Technology Data Exchange (ETDEWEB)
Pretorius, Louis Charles [Corrocoat SA (PTY) Ltd., Durban (South Africa)
2005-07-01
Pigging of long pipelines is a technique for in situ (field) coating, creating seamless internal structural linings. Originally developed for cleaning pipes, the system was adapted to apply internal anti-corrosion protection to pipes using a thin epoxy layer, which had some problems in weld coverage, stress cracking, poor cold weather curing and the inability to fill pitting corrosion metal loss. New coating materials, revised application methods and modified pigging equipment have made it possible to apply in situ liquid film coatings up to 1 mm thick, as an internal corrosion barrier to pipes, in a single application (similar to continuous screeding) resulting in a bonded 'GRP pipe within a steel pipe'. The method can be used for new projects on fully welded pipe lines avoiding coating problems associated with flange joints and/or couplings, or for refurbishment of old pipelines, varying from 150-900 mm diameter, up to 12 km long. Pipes can be buried, submerged, continuously welded or flanged. Many different pipes, such as oil platform to shore based pipelines, can all be treated using this method. Thick film polymer pigging techniques create new possibilities for Engineers to extend the life of pipeline systems, with significant cost savings compared to replacement pipe. (author)
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Monomaterial ecological buildings, with Mopatel® and Ecopierra® concrete
Directory of Open Access Journals (Sweden)
Livia Miron
2013-09-01
Full Text Available This paper presents a case study performed on a pilot building from Gainesti, Suceava county. The constructive system used is unique in that it employs a monomaterial, namely ecological concrete of type MOPATEL® or ECOPIERRA®. These types of concrete, created by eng. Petrache Teleman, possess international patents and have received awards in Brussels, but they are not yet used in Romania. These materials can be used integrally to make all the constructive elements of a building – load-bearing elements (floors, beams, pillars, walls as well as the secondary elements of a partly finished building, such as screeds or non-load-bearing masonry. The constructive system also uses ecological mortars which integrally ensure the interior and exterior finishing. The final result is a building practically made from a single type of material, in which the effect of thermal bridges is reduced to a maximum. The MOPATEL and ECOPIERRA types of concrete have a mechanical resistance similar to regular concrete, but they also have superior thermal insulation qualities (between 0.09 and 0.28 W/mK, they are permeable to the transfer of water vapours from the interior to the exterior of the building, and, in certain compositions, they can also be considered waterproof.
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MANAJEMEN RISIKO KESELAMATAN DAN KESEHATAN KERJA (K3 PADA PROYEK PEMBANGUNAN CIPUTRA WORLD JAKARTA
Directory of Open Access Journals (Sweden)
I Wayan Wiyasa
2015-02-01
Full Text Available Abstract :Generally, in Indonesia the subject of Occupational Health and Safety is often forgotten. This is proven with the high number of work accidents in Indonesia. In 2011, there were 99.491 incidents or on average 414 work accidents cases per day. In 2010 there were 98.711 work accidents, 96.314 cases in 2009, 94.736 cases in 2008 and 83.714 cases in 2007. This reserch is intended to asses the possible major risk of Occupational Health and Safety for The Ciputra World Jakarta building Project, and offer solutions to deal with any unexpected risk. This research was conducted with a descriptive and qualitative method. Survey was carried out to get opinions from respondents on Occupational Health & Safety risks during the construction of the Ciputra World Jakarta. There are Seventy eight (78 high risks were identified with the most being Tower Crane operation job, installation of steel column, beam, and wall with 5 risks. The 2 extreme risks were found in column casting and screeding exterior wall with 1 risk. Suggestion given is to organise training relation to Occupational Health and Safety risk to every employee, introduve shift system, allocate alternate day off to employees, provide health/medical check up, and eliminate high risk and dengerous work environment.
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Experimental Investigation into Pull-Out Strength of Foamed Concrete Using Different Types of Screw
Directory of Open Access Journals (Sweden)
Othuman Mydin M.A.
2014-01-01
Full Text Available This study focuses on the results of the comprehensive strength test to quantify the mechanical properties of the screw’s pullout strength on foamed concrete. Foamed concrete is classified as lightweight concrete that been produced by cement paste or mortar in which air-voids are entrapped in the mortar by a suitable foaming agent. These days, the use of foamed concrete has been recognized in the construction industry as wall blocks, wall panels and also material floor and roof screeds. Hence, the applications of this material should be maximized as it is multi-functional. As we know, the use of screws on the wall or ceiling is common in a building. The objective of this research is to examine and determine the pullout strength of various properties and types of screws in lightweight foamed concrete with various densities that may depict the best result of the pullout strength on foamed concrete. To visualize the different results of pullout strength, screws with and without wall plug will be used as well. The pullout strength will be tested using the Universal Testing Machine where it shall measure the ultimate load of the screws attached to the foamed concrete may resist.
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Impact of Volcanic Ash on Road and Airfield Surface Skid Resistance
Directory of Open Access Journals (Sweden)
Daniel M. Blake
2017-08-01
Full Text Available Volcanic ash deposited on paved surfaces during volcanic eruptions often compromises skid resistance, which is a major component of safety. We adopt the British pendulum test method in laboratory conditions to investigate the skid resistance of road asphalt and airfield concrete surfaces covered by volcanic ash sourced from various locations in New Zealand. Controlled variations in ash characteristics include type, depth, wetness, particle size and soluble components. We use Stone Mastic Asphalt (SMA for most road surface experiments but also test porous asphalt, line-painted road surfaces, and a roller screed concrete mix used for airfields. Due to their importance for skid resistance, SMA surface macrotexture and microtexture are analysed with semi-quantitative image analysis, microscopy and a standardised sand patch volumetric test, which enables determination of the relative effectiveness of different cleaning techniques. We find that SMA surfaces covered by thin deposits (~1 mm of ash result in skid resistance values slightly lower than those observed on wet uncontaminated surfaces. At these depths, a higher relative soluble content for low-crystalline ash and a coarser particle size results in lower skid resistance. Skid resistance results for relatively thicker deposits (3–5 mm of non-vesiculated basaltic ash are similar to those for thin deposits. There are similarities between road asphalt and airfield concrete, although there is little difference in skid resistance between bare airfield surfaces and airfield surfaces covered by 1 mm of ash. Based on our findings, we provide recommendations for maintaining road safety and effective cleaning techniques in volcanic ash environments.
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Das, Dipankar; Zhang, Shengmin; Noh, Insup
2018-01-24
A biocompatible hybrid film has been fabricated using alginate (Alg), α-tricalcium phosphate (α-TCP) microparticle and calcium chloride through ionic crosslinking as a biomaterial. The 'screeding method' (like a concrete finishing process) has been employed to develop the Alg-α-TCP film. For this method, the Alg/α-TCP blend has been prepared using an ultra-sonicator and then put on a glass slide. After that, the excess volume of blend has been cut off by skidding another slide along with the surface of the blend to achieve proper grade and flatness. The mechanical strength and flexibility of the film (Alg-α-TCP) has been controlled by changing its compositions. The crosslinking phenomenon has been confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), 13 C nuclear magnetic resonance (NMR), x-ray diffraction and thermogravimetric analyses. The ATR-FTIR and 13 C NMR analysis results suggest that carboxylate groups of the alginate are ionically cross-linked with Ca 2+ ions, while the α-TCP particles reside in the network by physical interaction. The micro-fatigue test results imply high tensile strength (up to 257 MPa) and flexibility (up to 13% elongation) of the Alg-α-TCP hybrid films. The SEM analysis suggests the α-TCP particles are homogeneously distributed on the surface of Alg-α-TCP films, whereas cross-sectional images confirmed the presence of α-TCP in the cross-linked network. TGA results demonstrated that thermal stability of the hybrid film was enhanced due to ionic crosslinking and interfacial interaction between alginate and α-TCP. The incorporation of α-TCP particles diminished the swelling ratio of the hybrid film. The in vitro bone cell (MC3T3) culture and cytotoxicity tests showed that the hybrid film is biocompatible. The hybrid film releases bovine serum albumin and dimethyloxaloylglycine in a controlled way at pH 7 and 7.4, and 37 °C. Overall, the biocompatible Alg-α-TCP hybrid film with