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Properties of concrete. Concrete has relatively high compressive strength (resistance to breaking when squeezed), but significantly lower tensile strength (resistance to breaking when pulled apart). The compressive strength is typically controlled with the ratio of water to cement when forming the concrete, and tensile strength is increased by ...
H2SO4 + Ca (OH)2 → CaSO4 · 2H2O. When concrete is carbonated by atmospheric carbon dioxide (CO 2), or if limestone aggregates are used in concrete, H2SO4 reacts with calcite (CaCO3) and water to also form gypsum while releasing CO 2 back to the atmosphere: H2SO4 + CaCO3 + H2O → CaSO4 · 2H2O + CO2.
The attack arises from soils containing SO2−4 ions, such as MgSO 4 or Na 2 SO 4 soluble and hygroscopic salts. The tricalcium aluminate (C 3 A) hydrates first interact with sulfate ions to form ettringite (AFt). Ettringite crystallizes into small acicular needles slowly growing in the concrete pores. Once the pores are completely filled ...
Ready-mix concrete. The inside of a volumetric mixer. It uses a simple Archimedes' screw to mix (clockwise) and to lift the concrete to the delivery chute. Ready-mix concrete (RMC) is concrete that is manufactured in a batch plant, according to each specific job requirement, then delivered to the job site "ready to use".
A single concrete block, as used for construction. Concrete is a composite material composed of aggregate bonded together with a fluid cement that cures to a solid over time. Concrete is the second-most-used substance in the world after water, [ 1 ] and is the most widely used building material. [ 2 ] Its usage worldwide, ton for ton, is twice ...
0.75 m³ (1 cubic yard) cart-away mixing trailer. A variant of standard concrete transportation is the concrete (or, cement) mixing trailer. These small versions of transit-mix trucks are used to supply short loads of concrete. They have a concrete mixing drum with a capacity of between 0.76 and 1.34 cubic metres (1 and 1.75 cu yd).
Sulfur concrete has a low porosity and is a poorly permeable material. Its low hydraulic conductivity slows down water ingress in its low porosity matrix and so decreases the transport of harmful chemical species, such as chloride (pitting corrosion), towards the steel reinforcements (physical protection of steel as long as no microcracks develop in the sulfur concrete matrix).
Permeable paving surfaces are made of either a porous material that enables stormwater to flow through it or nonporous blocks spaced so that water can flow between the gaps. Permeable paving can also include a variety of surfacing techniques for roads, parking lots, and pedestrian walkways. Permeable pavement surfaces may be composed of ...