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Oldcastle Materials Inc. is a supplier of asphalt, concrete, and other building materials, and also offers construction and paving services. The Atlanta-based company is a subsidiary of CRH plc, a publicly traded international group of diversified building materials businesses, [2] [3] and has approximately 18,000 employees at 1,200 locations, as of March 2018.
A w/c ratio higher than 0.60 is not acceptable as fresh concrete becomes "soup" [2] and leads to a higher porosity and to very poor quality hardened concrete as publicly stated by Prof. Gustave Magnel (1889-1955, Ghent University, Belgium) during an official address to American building contractors at the occasion of one of his visits in the ...
Their addition allows to decrease the water-to-cement ratio of concrete or mortar without negatively affecting the workability of the mixture. It enables the production of self-consolidating concrete and high-performance concrete. The water–cement ratio is the main factor determining the concrete strength and its durability. Superplasticizers ...
Changes of pore water content due to drying or wetting processes cause significant volume changes of concrete in load-free specimens. They are called the shrinkage (typically causing strains between 0.0002 and 0.0005, and in low strength concretes even 0.0012) or swelling (< 0.00005 in normal concretes, < 0.00020 in high strength concretes).
A compressed earth block (CEB), also known as a pressed earth block or a compressed soil block, is a building material made primarily from an appropriate mix of fairly dry inorganic subsoil, non-expansive clay, sand, and aggregate. Forming compressed earth blocks requires dampening, mechanically pressing at high pressure, and then drying the ...
The sorptivity is widely used in characterizing soils and porous construction materials such as brick, stone and concrete. Calculation of the true sorptivity required numerical iterative procedures dependent on soil water content and diffusivity.
Hemp concrete has a low thermal conductivity, ranging from 0.06 to 0.6 W m −1 K −1, [24] [15] [25] a total porosity of 68–80% [24] [26] and a density of 200 kg /m 3 to 960 kg/m 3. [ 15 ] [ 27 ] Hemp concrete is also an aerated material with high water vapour permeability and its total porosity very close to open porosity allowing it to ...
The characteristic strength is defined as the strength of the concrete below which not more than 5% of the test results are expected to fall. [ 16 ] For design purposes, this compressive strength value is restricted by dividing with a factor of safety, whose value depends on the design philosophy used.