Preparation method and applications of composite super-early strength admixture

Abstract

The invention discloses a composite super-early strength admixture preparation method, which comprises: dissolving octavinyl POSS and a block polycarboxylic acid A containing a thiol group in a tetrahydrofuran solvent, carrying out a thiol-alkenyl click chemistry reaction under the action of a catalyst, and carrying out rotary evaporation to remove the tetrahydrofuran solvent after completing thereaction so as to obtain a POSS-based star block polycarboxylic acid water-reducing agent; and at a temperature of 20-40 DEG C, simultaneously adding a soluble calcium salt B aqueous solution and a soluble silicate C aqueous solution into the POSS-based star block polycarboxylic acid water-reducing agent in a dropwise manner at a uniform speed, and carrying out thermal insulation for 2-5 h after completing the adding so as to obtain the composite super-early strength admixture. According to the present invention, the POSS core inorganic nanometer structure material in the composite super-earlystrength admixture can achieve the compounding of the polycarboxylic acid water-reducing agent and the nanometer material, such that the dispersion efficiency of the inorganic nanometer structure material is high, the inorganic particles are stable and do not easily settle, the early strength is easily increased, and the transportation cost can be reduced.

Description

technical field [0001] The invention belongs to the technical field of concrete admixtures, and in particular relates to a composite super-early-strength admixture, which can accelerate the early hydration speed of cement-based materials and improve the early strength of concrete. Background technique [0002] With the construction of my country's infrastructure, polycarboxylate superplasticizers have been widely used in nuclear power, water conservancy, high-speed rail, subways, bridges, tunnels, etc., but more requirements have been put forward for them. Many large-scale projects will require the early strength of concrete to meet the design requirements. The strength of concrete constructed in low temperature environment in winter develops slowly. How to avoid the influence of inorganic salt early strength agents on its work performance, long-term mechanical properties and durability, and effectively improve its early strength is a hot spot that domestic and foreign schol...

AI Technical Summary

Problems solved by technology

In addition, a large number of mineral admixtures are applied to concrete to improve the resistance of concrete to environmental erosion. However, most mineral admixtures will significantly reduce the early mechanical properties of concrete, which affects its wider application in the field of building materials.

[0003] At present, there are very few early-strength polycarboxylate superplasticizers on the market at home and abroad. They are basically made of polycarboxylate superplasticizers and conventional early-strength agents. Due to compatibility problems, As a result, the expected technical effect of improving the early strength cannot be achieved, and it may also have a negative impact on the long-term compressive strength of concrete.

In patents CN106007452A and CN103373831A, sodium sulfate and thiocyanate are used as inorganic early-strength agents and polycarboxylate superplasticizers to compound, so that it has early-strength effects, and the content of thiocyanate in cement is strictly limited Yes, thiocyanate has great side effects on the human body, and using sulfate as an early-strength material has a negative effect on the later durability of concrete

In addition, it is the early strength technology based on nanomaterials. Patent CN104402288A discloses a calcium silicate hydrate gel solution early strength agent. Its raw materials use calcium materials, silicon materials and gel dispersants. The dispersant is a naphthalene sulfonate formaldehyde condensate, and its dispersing effect is limited, so the prepared gel particle size is relatively thick, and the early strength effect is limited. Due to the influence of the rigid structure, the formed substance is not an intercalation substance, and the nanomaterial after intercalation will have a better early strength effect

Patents CN105585286A and CN103724557A disclose an early-strength polycarboxylate water reducer. The structure of the water reducer prepared by them all has amino cations, but the preparation process is relatively complicated and the cost is relatively expensive

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