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Abrams' law (also called Abrams' water-cement ratio law) [1] is a concept in civil engineering. The law states the strength of a concrete mix is inversely related to the mass ratio of water to cement. [1] [2] As the water content increases, the strength of concrete decreases. Abrams’ law is a special case of a general rule formulated ...
Calcium silicate hydrate (also shown as C-S-H) is a result of the reaction between the silicate phases of Portland cement and water. This reaction typically is expressed as: 2 Ca 3 SiO 5 + 7 H 2 O → 3 CaO · 2 SiO 2 · 4 H 2 O + 3 Ca(OH) 2 + 173.6 kJ. also written in cement chemist notation, (CCN) as: 2 C 3 S + 7 H → C 3 S 2 H 4 + 3 CH + heat
H 2 SO 4 + Ca(OH) 2 → CaSO 4 · 2H 2 O. When concrete is carbonated by atmospheric carbon dioxide (CO 2), or if limestone aggregates are used in concrete, H 2 SO 4 reacts with calcite (CaCO 3) and water to also form gypsum while releasing CO 2 back to the atmosphere: H 2 SO 4 + CaCO 3 + H 2 O → CaSO 4 · 2H 2 O + CO 2
Note that the especially high molar values, as for paraffin, gasoline, water and ammonia, result from calculating specific heats in terms of moles of molecules. If specific heat is expressed per mole of atoms for these substances, none of the constant-volume values exceed, to any large extent, the theoretical Dulong–Petit limit of 25 J⋅mol ...
Ultimately, Ca 2+ ions in equilibrium with portlandite (Ca(OH) 2) and C-S-H and dissolved in the concrete interstitial water can also react with SO 2− 4 ions to precipitate CaSO 4 ·2H 2 O . A fraction of SO 2− 4 ions can also be trapped, or sorbed, into the layered structure of C-S-H. [3] These successive reactions lead to the ...
Likewise, when water evaporates from concrete, the loss of water impedes the expansion of cement matrix by shrinking. Moreover, when the temperatures reach 57.3 °C (135.1 °F), siliceous aggregates transform from α-phase, hexagonal crystal system, to β-phase, bcc structure, causing expansion of concrete and decreasing the strength of the ...
Hydrophobic concrete is concrete that repels water. It meets the standards outlined in the definition of waterproof concrete . Developed in Australia in the mid-20th century, millions of cubic yards of hydrophobic concrete have been laid in Australia, Asia , and Europe , and in the United States since 1999.
Much building waste is made up of materials such as bricks, concrete and wood damaged or unused during construction. Observational research has shown that this can be as high as 10 to 15% of the materials that go into a building, a much higher percentage than the 2.5-5% usually assumed by quantity surveyors and the construction industry. Since ...