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At least 19 recordsLinked to original sources
PubMed2006

Environmental acceptability of beneficial use of waste as construction material--state of knowledge, current practices and future developments in Europe and in France.

Since a decade, numerous industrial and public initiatives have been launched in order to make knowledge, practices and mentalities evolve in relation to the acceptability of using waste instead of raw material as construction product. The objectives of these initiatives have been to evaluate current practices and to make new solutions and beneficial use channels emerge. At the same time scientific and standardisation communities have developed methodologies and tools to fit with the assessment needs expressed by industrialists and public decision-makers. In spite of that, some factors, some of them being cross-linked, make the perpetuation of beneficial use channels or even the concretisation of research projects difficult. To cope with this situation, in the framework of sustainable development applied to natural and alternative material, the French Directorate of Road has launched a project aiming at providing public contracting authorities with a document gathering both technical and environmental requirements that they can prescribe in public market tender calls to promote the use of waste and out-of-technical-specifications-material. This paper deals with the presentation of this project focusing more specifically on the approach to assess both technical and environmental acceptability of waste and out-of-technical-specifications-material to be used as alternative material in road construction in France. The current European situation is first described and this paper finally discusses briefly the other key aspects--than environmental acceptability--that have to be taken into account to succeed waste beneficial use.

Construction Materials↗
PubMed2006

[Immunological aspects of pathogenesis of stomatological constructional materials intolerance].

In blood and the mixed saliva of patients with intolerance of stomatologic constructional materials the maintenance of cytokines, factors of humoral answer were investigated. It was established, that in formation of intolerance the increased sensitivity stomatologic constructional materials which is not connected to allergic reaction of immediate type and is, apparently, pseudoallergic or develops on other type. There is an activation of the local immune answer including local synthesis of proinflammatory cytokines, sIgA and hyperactivation of complement system to formation of C3a component. Toxic and allergic action of stomatologic constructional materials grows in patients having antibodies to Candida albicans in the mixed saliva.

Adult↗
PubMed1984

Measurements of radon-daughter concentrations in and around dwellings in the northern part of The Netherlands; a search for the influences of building materials, construction and ventilation.

The concentration of radon daughters has been determined in and around 80 dwellings located in the northern part of the Netherlands by using a one-filter method. Median values of 2.0 and 0.4 mWL were measured for the indoor and outdoor concentrations, respectively. The average outdoor concentration was about an order of magnitude higher for wind directions between SE and SW than for SW-NW. On the average, dwellings with double-pane windows and/or concrete floors were found to have significantly higher radon concentrations than those with single-pane windows and/or wooden floors. For the living room of a particular dwelling 18 measurements were carried out. The data for this dwelling indicate a linear relation between the concentration indoors and outdoors with a slope of 3.8 +/- 2.0. This unexpected behaviour is thought to be related to ventilation via the crawl space. Measurements of ventilation patterns and measurements of radon concentrations in the living room and the crawl space are consistent with this picture.

Air Pollutants↗
PubMed2001

BaSO4-loaded agarose: a construction material for multimodality imaging phantoms.

RATIONALE AND OBJECTIVES: Phantom studies are an important part of the evaluation of imaging techniques; however, presently available phantom construction materials are not adequate for studies involving both magnetic resonance (MR) imaging and computed tomography (CT). The purpose of this study was to design a phantom construction material useful for multimodality imaging experiments. MATERIALS AND METHODS: Iodinated contrast agent or BaSO4 was added during the formation of agarose gels. Both CT and MR imaging were performed, and T1 and T2 values and CT numbers (in Hounsfield units) were obtained for multiple combinations of contrast material and agarose. Results. The T2 values of agarose gels span the range of those values found in biologic tissues. Phantoms containing iodinated contrast agent were not stable; contrast agent diffused across concentration gradients. BaSO4-loaded agarose phantoms were stable, however, and varying barium concentrations produced phantoms that spanned the range of CT numbers found in biologic tissues. Addition of BaSO4 did not substantially alter T1 or T2 values of agarose gels. Agarose concentration had only a small effect on the CT numbers of BaSO4 suspensions. CONCLUSION: BaSO4-loaded agarose is an effective material for construction of multimodality imaging phantoms. It provides adequate signal intensity for MR imaging and attenuation for CT, with independently variable contrast in both modalities.

Agar↗
PubMed1989

[The role of construction materials as secondary sources of the air pollution of manufacturing premises with dicyclopentadiene].

The experimental data proposed deals with the adsorption properties of the construction materials used in the dicyclopentadiene (DCPD) production sites. Evaluation of secondary sources of DCPD air contamination is made. Construction materials with the lowest DCPD adsorption are proposed which seem to be of specific practical value in DCPD production sites planning.

Adsorption↗
PubMed2003

Engineering the interaction between micro-organisms and construction materials.

The influence of micro-organisms on degradation of mineral materials, cement bound systems, wood and steel is a rather new subject of research slowly becoming recognised by the 'classical' technical disciplines. An increasing amount of literature appears on biodeterioration of construction materials and microbial activity can not be neglected as a determining factor in the deterioration process. Microbial communities interact in many different ways with mineral materials and their external environment. They can be present on the surface or in crevices and fissures within the material and often their actions become organized in a biofilm. The interaction with the material and its environment can give rise to biodeterioration. Yet recent findings show that in some cases the microbial interaction can lead to protection of materials. It is our mission for the future to engineer the microbiological processes with positive impact on construction materials with a view to practical applications.

Biodegradation, Environmental↗
PubMed1993

Effect of some properties of metal strengtheners on the fracture resistance of acrylic denture base material construction.

In this study we investigated the effect of metal wire bonding to acrylic resin on the fracture resistance of an acrylic denture base material construction. Two different bonding methods were tested, and after measuring the resistance, the surface of the wires were examined by a scanning electron microscope. The effect that the placing of metal strengtheners in different positions in the acrylic resin had on the fracture resistance of the denture base material construction was also clarified. When three different positions of the metal wires in the acrylic resin were compared, the results showed that bonding of metal wire to acrylic resin somewhat enhanced the fracture resistance of test specimens, while the different positions of the wires had no effect on the fracture resistance.

Acrylic Resins↗
PubMed2001

Indoor radon concentrations caused by construction materials in 23 workplaces.

The aim of this study was to compare the measured and the calculated concentrations of indoor radon caused by building materials at 23 workplaces. The measured concentrations of radon were clearly higher than the calculated radon concentrations from the building materials, which indicated that the main source of indoor radon was the soil under and around the buildings. The highest means of continuously (933 Bq m(-3)) and integrated (169 Bq m(-3)) measured and calculated (from 70 to 169 Bq m(-3)) concentrations of radon were found in hillside locations. On the other hand, the median (27 and 43 Bq m(-3)) and maximum (626 and 1002 Bq m(-3)) values of calculated indoor radon concentrations exhaled from construction materials were the highest at the ground level places. On average, only 7-19% of the radon seemed to originate from the construction materials.

Air Pollution, Indoor↗
PubMed2001

Legislative and environmental issues on the use of ash from coal and municipal sewage sludge co-firing as construction material.

For the economy of any co-firing process, it is important that the common waste management options of ash remain practical. Ash from bituminous coal combustion is typically handed to the construction industry. This paper describes the current European legislation on use of ash for construction purposes. Also, it presents an experimental study on the suitability of fly ash from combustion of mixtures of bituminous coal and municipal sewage sludge as additive to cement and concrete, and for use in open-air construction works, based on the ash chemical composition and the characteristics of the extract of the ash. Presently, two European standards forbid the use of ash from co-firing as additive to cement or concrete. This study shows that ash derived from coal and sewage sludge co-firing contains generally less unburned carbon, alkali, magnesium oxide, chlorine, and sulfate than coal ash. Only the concentration of free lime in mixed ash is higher than in coal, even though, at least up to 25% of the thermal input, still below the requirements of the standards. This ash also meets the requirements for the use of fly ash in open-air construction works--concentration and mobility of few elements--although this management option is forbidden to ash from co-firing. The leaching of Cd, Cr, Cu, Ni, Pb and Zn was investigated with three leaching tests. The concentration of these metals in the extracts was below the detection limit in most cases. The concentration of Cu and Zn in the extract from fly ash was found to increase with increasing share of sewage sludge in the fuel mixture. However, the concentration of these two metals in the extract is not regulated. This study indicates that excluding a priori the use of ash from co-firing as a suitable additive for construction material could cause an unnecessary burden on the environment, since probably ash would have to be disposed of in landfill. However, allowing this requires the modification of current European standards to include limitations on all elements and compounds, absent in coal but which might be present in other fuels, that are deleterious for the quality of construction materials.

Air Pollution↗
PubMedDate not supplied

[The cabin microflora of manned space vehicles and the problem of the biological destruction of the construction materials used in them].

It is found that during operation of manned space objects there can occur the microbial growth on the structural materials of cabin interior and equipment which results in their biological destruction. The biodestructing processes can involve single parts of cabin interior, trainer linkages, connectors, cables, illuminators. Ninety four microbial species have been identified in spacecraft environment. The bacterial flora was presented by 19 genera pertaining to 11 families and involved 58 species. The mold and yeast-like fungi were presented by 12 genera and consisted of 36 species. The significant quantities of isolated microbial species were classified as potentially pathogenic microorganisms; many of them are known as biodestructers of polymeric materials. The isolated microbial cultures in space missions have become the basis of strain bank intended for further study and practical use in validating the construction materials.

Bacteria↗
PubMed2001

Red mud of aluminium production waste as basic component of new construction materials.

The work presented here shows the possibility of using the red mud waste from the Bayer process used for aluminium production as the main component of new construction materials. It describes some recent experiments lasting 180 days as well as some 1 year old samples. The best part of materials used are industrial wastes, but some of them contain small (no more the 2%) additions of CaO or Portland Cement (PC) to increase the strengthening rate of the samples. The high strength values of these materials allow their use as new materials for road and airfields bases, levee core, dumps, foundations, etc. They can also be used to make bricks, tiles, and similar items. In addition to the economic factors, these materials are very easy to use and no new residues are generated. The results of the heavy metal leaching tests, not included in this paper, show very low levels of their leachability in acid solutions, far below the demands of the Spanish environmental standards. This can be explained by the strong chemical binding of heavy metals in practically insoluble chemical compositions.

Aluminum↗
PubMed1996

The Effects of Prophylactic Brace Construction Materials on the Reactive Responses of the MCL During Repetitive Impacts.

OBJECTIVE: The purpose of the present study was to investigate the effect of different construction materials on the ability of a prophylactic brace to reduce the stresses sustained by a surrogate medial collateral ligament (MCL) under low-energy repetitive impact conditions. DESIGN AND SETTING: A surrogate leg was fixed at both the hip and foot with the knee in full extension. A prophylactic brace was attached to the surrogate leg and the system struck by an impactor weighing either 6.68 kg or 16.9 kg. SUBJECTS: A single brace design (Am Pro Knee Guard) was used. Three different materials (nylon, aluminum, graphite) were used in constructing the brace uprights. MEASUREMENTS: Tension in the MCL was measured under all conditions of brace material and impactor weight. In addition, the impact impulse response of the system was evaluated. RESULTS: The graphite and aluminum uprights showed significant reductions in both MCL peak tension magnitude (from 12 to 21% improvement) and in the impulse response of the MCL (from 36 to 47% improvement) when compared to the no-brace condition. CONCLUSIONS: The present study indicates that the choice of brace upright material does have a significant effect on the transmission and absorption of low-level repetitive impact forces at the MCL and should be an important consideration in the design of better knee braces.

Journal Article↗