CN-121974591-A - Calcium carbonate/calcium silicate composite nanocrystal core early strength agent and preparation method and application thereof

CN121974591ACN 121974591 ACN121974591 ACN 121974591ACN-121974591-A

Abstract

The invention provides a calcium carbonate/calcium silicate composite nanocrystal core early strength agent, a preparation method and application thereof, wherein the preparation method of the calcium carbonate/calcium silicate composite nanocrystal core early strength agent comprises the following steps of respectively preparing a calcium salt solution, a silicate solution, a carbonate solution and a dispersing agent solution; under the stirring condition, the calcium salt solution, the silicate solution and the carbonate solution are simultaneously dripped into the dispersing agent solution, the pH is controlled to be 10-14, and the stirring reaction is continued after the dripping is finished, so that the calcium carbonate/calcium silicate composite nanocrystal core early strength agent is obtained. According to the invention, by introducing carbonate ions, the adsorption of the dispersing agent to C-S-H calcium sites is enhanced, the anchoring capability of the dispersing agent is improved, the aggregation of crystal nuclei is inhibited, the grain size of the crystal nuclei is refined, the nucleation density is increased, and the prepared calcium carbonate/calcium silicate composite nanocrystal core early strength agent can effectively promote early hydration of cement, and especially the early strength effect in a mineral powder cement system is improved remarkably.

Inventors

HU CHUANLIN
LIAO CHENG
WANG FAZHOU
ZHU HONGWEI
QIAN XIONG
XU QINGYUAN

Assignees

武汉理工大学

Dates

Publication Date: 20260505
Application Date: 20260116

Claims (10)

1. The preparation method of the calcium carbonate/calcium silicate composite nanocrystal core early strength agent is characterized by comprising the following steps of: Respectively preparing a calcium salt solution, a silicate solution, a carbonate solution and a dispersing agent solution; and under the stirring condition, the calcium salt solution, the silicate solution and the carbonate solution are simultaneously dripped into the dispersing agent solution, the pH is controlled to be 10-14, and the calcium carbonate/calcium silicate composite nanocrystal core early strength agent is obtained by continuing stirring reaction after the dripping is finished.
2. The method for preparing the calcium carbonate/calcium silicate composite nanocrystal core early strength agent according to claim 1, wherein the molar ratio of calcium salt to silicate to carbonate in the calcium salt solution, the silicate solution and the carbonate solution is (0.5-2.0): 1 (0.04-0.4).
3. The preparation method of the calcium carbonate/calcium silicate composite nanocrystal core early strength agent according to claim 1, wherein the concentration of the calcium salt solution is 5-50 wt%, the concentration of the silicate solution is 5-35 wt%, and the concentration of the carbonate solution is 5-30 wt%.
4. The method for preparing the calcium carbonate/calcium silicate composite nanocrystal core early strength agent according to claim 1, wherein the calcium salt comprises at least one of calcium chloride, calcium nitrate, calcium formate, calcium acetate, calcium bicarbonate and calcium gluconate; And/or the silicate comprises at least one of sodium silicate, potassium silicate and lithium silicate; and/or the carbonate comprises at least one of sodium carbonate, sodium bicarbonate, potassium carbonate and potassium bicarbonate.
5. The preparation method of the calcium carbonate/calcium silicate composite nanocrystal core early strength agent is characterized in that the mass of the dispersing agent is 1-10% of the total mass of a reaction system, and the concentration of the dispersing agent solution is 1-10% by weight.
6. The method for preparing the calcium carbonate/calcium silicate composite nanocrystal core early strength agent according to claim 1, wherein the dispersing agent comprises a polycarboxylate water reducer.
7. The method for preparing the calcium carbonate/calcium silicate composite nanocrystal core early strength agent according to claim 1, wherein the temperature of the stirring reaction is 10-60 ℃, and the rotating speed of the stirring reaction is 100-800 rpm.
8. The method for preparing the calcium carbonate/calcium silicate composite nanocrystal core early strength agent according to claim 1, wherein the dropwise adding time is 0.1-10 h, and the continuous stirring reaction time is 1-72 h.
9. The calcium carbonate/calcium silicate composite nanocrystal core early strength agent is characterized by being prepared by the preparation method of the calcium carbonate/calcium silicate composite nanocrystal core early strength agent in any one of claims 1-8.
10. The use of the calcium carbonate/calcium silicate composite nanocrystal core early strength agent according to claim 9 in cement-based early strength agents and/or mineral admixture cement-based early strength agents.

Description

Calcium carbonate/calcium silicate composite nanocrystal core early strength agent and preparation method and application thereof Technical Field The invention relates to the technical field of building material additives, in particular to a calcium carbonate/calcium silicate composite nanocrystal core early strength agent, a preparation method and application thereof. Background The method uses a large amount of industrial solid waste as an auxiliary cementing material to replace part of cement clinker, so that the high-efficiency resource utilization of solid waste resources can be realized, and the production dosage of the cement clinker can be greatly reduced, thereby directly reducing the carbon emission level of the cement industry. However, it should be noted that the early hydration activity of industrial solid waste is far lower than that of silicate cement, and when cement is replaced by a large amount of solid waste, the early strength of cement-based materials is slowly increased, and it is difficult to match the core requirement of the construction engineering on the high efficiency, so that the improvement of the early strength of such cement-based materials has become a key problem to be solved urgently. The existing mainstream early strength technology has the remarkable defects that although steam curing can accelerate hydration through thermal activation, the steam curing is high in energy consumption and high in carbon emission, and can cause coarsening of a microstructure of a hydration product C-S-H gel to damage later durability, and traditional chemical additives (such as calcium chloride and sodium sulfate) promote early hydration through changing ion balance, but easily damage long-term hydration balance, and cause problems of strength shrinkage and volume stability. Therefore, developing an early strength agent which is efficient, environment-friendly and has no negative effect on the later strength is a research hotspot. In recent years, researchers have explored A variety of novel early strength agents such as C-A-S-H (calcium aluminosilicate) and C-M-S-H (calcium magnesium silicate) gels. The C-A-S-H gel can remarkably improve the early strength of the cement-based material by introducing aluminum element. The C-M-S-H gel accelerates the hydration process of cement and improves the early strength by introducing magnesium element. The C-S-H/PCE (polycarboxylate) nanocomposite is highly similar in structure and chemical nature to the primary hydration product (C-S-H gel) and thus serves as an ideal nucleation core. However, the optimization of the existing C-S-H/PCE nanocrystal cores focuses on cationic regulation (e.g., mg 2+、Al3+、Fe3+ modification) and synthesis parameter adjustment (pH, temperature, PCE species), and the regulatory potential for anionic environments has not been fully exploited. The active object of the cation regulation modification strategy is mainly focused on cement clinker, the core mechanism is to accelerate the hydration process of the cement clinker, promote the generation and setting and hardening of hydration products, and for mineral powder and other common mineral admixtures, the active component reactivity of the mineral admixtures is difficult to excite, the mineral admixtures are always in an inert state and do not participate in early hydration reaction, so that the early strength improvement effect of the modified nanocrystal cores in mineral admixtures cement systems such as mineral powder cement is greatly limited, and the early strength requirement of the systems in the scenes such as prefabrication engineering is difficult to be met. Therefore, an early strength agent which can simultaneously and efficiently excite the hydration of cement clinker and the activity of mineral admixture and has no negative effect on the later strength is developed and has great significance. Disclosure of Invention In view of the technical problems in the background art, the invention provides a calcium carbonate/calcium silicate composite nanocrystal core early strength agent, a preparation method and application thereof, and aims to solve the technical problem that the existing early strength agent has poor early strength effect in cement systems and mineral admixture cement systems. In a first aspect, the invention provides a method for preparing a calcium carbonate/calcium silicate composite nanocrystal core early strength agent, which comprises the following steps: Respectively preparing a calcium salt solution, a silicate solution, a carbonate solution and a dispersing agent solution; Under the stirring condition, the calcium salt solution, the silicate solution and the carbonate solution are simultaneously dripped into the dispersing agent solution, the pH is controlled to be 10-14, and the stirring reaction is continued after the dripping is finished, so that the calcium carbonate/calcium silicate composite nanocrystal core early strength agent is obta