Concrete Building Materials Research Articles

Radiological dose assessment of naturally occurring radioactive materials in concrete building materials

Previous studies have shown that the natural radioactivity contained in building materials have significantly influenced the dose rates in dwelling. Exposure to natural radiation in building has been of concerned since almost 80 % of our daily live are spend indoor. Thus, the aim of the study is to assess the radiological risk associated by natural radioactivity in soil based building materials to dwellers. A total of 13 Portland cement, 46 sand and 43 gravel samples obtained from manufacturers or bought directly from local hardware stores in Peninsular of Malaysia were analysed for their radioactivity concentrations. The activity concentrations of 226Ra, 232Th and 40K in the studied building materials samples were found to be in the range of 3.7–359.3, 2.0–370.8 and 10.3–1,949.5 Bq kg−1 respectively. The annual radiation dose rates (μSv year−1) received by dwellers were evaluated for 1 to 50 years of exposure using Resrad-Build Computer Code based on the activity concentration of 226Ra, 232Th and 40K found in the studied building material samples. The rooms modelling were based on the changing parameters of concrete wall thickness and the room dimensions. The annual radiation dose rates to dwellers were found to increase annually over a period of 50 years. The concrete thicknesses were found to have significantly influenced the dose rates in building. The self-absorption occurred when the concrete thickness was thicker than 0.4 m. Results of this study shows that the dose rates received by the dwellers of the building are proportional to the size of the room. In general the study concludes that concrete building materials; Portland cements, sands, and gravels in Peninsular of Malaysia does not pose radiological hazard to the building dwellers.

Characterization of a lateritic geomaterial and its elaboration through a chemical route

The development of a laterite-based geomaterial, mimicking naturally occurring concretions in lateritic soils, through a chemical route has been investigated in this paper. The elaboration process involves an acidic dissolution reaction of iron compounds followed by a neutralization reaction with a strong base. The first step needs a 24 h reacting time before adding the base. Afterwards, the consolidation that involves an iron-bonding of the particles, is performed at 60 °C for 18 days under water-saturated atmosphere. The products elaborated using nitric acid and calcium hydroxide exhibit the best characteristic compressive strength, namely 20 MPa and a good resistance towards water seeping and wearing. Nevertheless, the use of fulvic acid, an organic ecological acid, leads to a water-resistant geomaterial with a good characteristic compressive strength of 12 MPa, thus competitive towards usual stabilized earth and concrete building materials.

Carbon Dioxide Balance of Wood Substitution: Comparing Concrete- and Wood-Framed Buildings

In this study a method is suggested to compare the net carbon dioxide (CO2) emission from the construction of concrete- and wood-framed buildings. The method is then applied to two buildings in Sweden and Finland constructed with wood frames, compared with functionally equivalent buildings constructed with concrete frames. Carbon accounting includes: emissions due to fossil fuel use in the production of building materials; the replacement of fossil fuels by biomass residues from logging, wood processing, construction and demolition; carbon stock changes in forests and buildings; and cement process reactions. The results show that wood-framed construction requires less energy, and emits less CO2 to the atmosphere, than concrete-framed construction. The lifecycle emission difference between the wood- and concrete-framed buildings ranges from 30 to 130 kg C per m2 of floor area. Hence, a net reduction of CO2 emission can be obtained by increasing the proportion of wood-based building materials, relative to concrete materials. The benefits would be greatest if the biomass residues resulting from the production of the wood building materials were fully used in energy supply systems. The carbon mitigation efficiency, expressed in terms of biomass used per unit of reduced carbon emission, is considerably better if the wood is used to replace concrete building material than if the wood is used directly as biofuel.

Variability in energy and carbon dioxide balances of wood and concrete building materials

A variety of factors affect the energy and CO 2 balances of building materials over their lifecycle. Previous studies have shown that the use of wood for construction generally results in lower energy use and CO 2 emission than does the use of concrete. To determine the uncertainties of this generality, we studied the changes in energy and CO 2 balances caused by variation of key parameters in the manufacture and use of the materials comprising a wood- and a concrete-framed building. Parameters considered were clinker production efficiency, blending of cement, crushing of aggregate, recycling of steel, lumber drying efficiency, material transportation distance, carbon intensity of fossil fuel, recovery of logging, sawmill, construction and demolition residues for biofuel, and growth and exploitation of surplus forest not needed for wood material production. We found the materials of the wood-framed building had lower energy and CO 2 balances than those of the concrete-framed building in all cases but one. Recovery of demolition and wood processing residues for use in place of fossil fuels contributed most significantly to the lower energy and CO 2 balances of wood-framed building materials. We conclude that the use of wood building material instead of concrete, coupled with greater integration of wood by-products into energy systems, would be an effective means of reducing fossil fuel use and net CO 2 emission to the atmosphere.

Validation of an automated capacity planning in the concrete building materials industry using an industrial case study

Production planning, in general, is the allocation of resources to jobs in a manner that should satisfy criteria of minimizing cost and satisfying customers. It is a complicated process and demands well defined techniques, time and experience to achieve satisfactory results. The work reported in this paper concerns the development of the second stage of a research project that has been undertaken to develop, validate and implement an automated capacity planning system in the concrete building materials industry. The first stage of the project was aimed at developing the specifications of the automated model and the software and has been published previously. The objective of this paper is to validate the model through running an industrial case study and comparing the output of the model with that of a human scheduler. The model has also been tested by introducing a realistic band of fluctuation to the monthly and annual demand forecast. This was designed to show whether the strategies applied in the model could cope with the variation in sales demand. The results of the study show that the model is a practical and significant managerial tool for exploring and testing options open to production managers.

Absorption of phase change materials in concrete

Increasing interest is being shown in the use of organic phase change materials (PCMs) in concrete building materials for heat storage. This had led to studies in means of improving their thermal performance. A principal factor in the effective use of PCM concrete is the amount of PCM which can be absorbed. This study examines the mechanisms of absorption and establishes a means of developing and using absorption constants for PCM concrete to achieve diffusion of the desired amount of organic PCM and hence the required thermal storage capacity. The effects of temperature. PCM viscosity, concrete density and hydrogen bonding on PCM penetration were demonstrated. Void fractions in the concrete and the manner in which they were filled with PCM was also observed.

Glaze-raise, a new concrete building material

Glaze-raise, a new concrete building material