Volume stabilizer for cement-based composite material and preparation method thereof

Abstract

The invention discloses a volume stabilizer for a cement-based composite material and a preparation method thereof. The volume stabilizer comprises the following components in part by weight: 180 and 220 parts of periclase, 18 to 21 parts of polycarboxylate, 27 to 32 parts of polyacrylate and 0.8 to 1.1 parts of sodium polyphosphate, wherein the periclase is ground into fine powder; the fine powder is sieved by a 85mu m sieve; and residue on the sieve is less than 10 percent. The method comprises the following steps: a, grinding magnesite serving as raw materials into fine power and sieving the fine powder with the 85mu m sieve, wherein residue on the sieve is less than or equal to 10 percent; b, calcining the ground magnesite powder at the temperature of between 900 and 1,250 DEG C, preserving the heat for 30 to 120 minutes, and cooling the calcined magnesite powder to room temperature after the heat preservation is finished to prepare the periclase; c, grinding the periclase into fine powder and sieving the fine powder with a 85mu m sieve, wherein residues on the sieve is less than or equal to 10 percent; and d, mixing the periclase obtained in the step c, the polycarboxylate, the polyacrylate and the sodium polyphosphate in proportion. The volume stabilizer and the preparation method can solve the problem of cracking of cement-based materials caused by contraction.

Description

technical field [0001] The invention relates to the technical field of additives for cement-based composite materials, in particular to a volume stabilizer for cement-based composite materials. Background technique [0002] At present, the admixture to solve the shrinkage and cracking of cement-based composite materials is mainly ettringite-type expansion agent, which mainly has the following shortcomings: [0003] (1) The expansion characteristics of the ettringite type expansion agent determine that it must use steel bars or other restrictions to generate self-stress during use, which is equivalent to storing the expansion energy in advance, and then releasing it slowly, and the early expansion will play a premature role. The properties and plasticity of the concrete and the creep relaxation in the unhardened stage are doomed to a large loss of expansion energy, which cannot fully compensate for the drying shrinkage in the later stage. [0004] (2) Cement-based composite ...

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Problems solved by technology

[0003] (1) The expansion characteristics of the ettringite type expansion agent determine that it must use steel bars or other restrictions to generate self-stress during use, which is equivalent to storing the expansion energy in advance, and then releasing it slowly, and the early expansion will play a premature role. Properties and plasticity of concrete and creep relaxation in the unhardened stage are doomed to a large loss of expansion energy, which cannot fully compensate for later drying shrinkage

[0004] (2) Cement-based composite materials mixed with ettringite-type expansion agent require a large amount of water for early maintenance, and are sensitive to water curing conditions. Water shortage can easily cause compensation for shrinkage failure. Cement-based composite materials mixed with ettringite-type expansion agent may even If the shrinkage is larger than that of the blank curing, the shrinkage compensation effect will not be achieved. When it expands with water in the later stage, cracks will easily occur and develop

[0005] (3) Due to the influence of ambient temperature and cement hydration temperature, the ettringite-type expansion agent may transform at high temperature, and after cooling down, it will form delayed ettringite, resulting in cracking of cement-based materials

[0006] (4) It cannot overcome plastic shrinkage, carbonization shrinkage and temperature mutation, and cannot well compensate for later drying shrinkage

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