Preparation method of crystal nucleus type concrete super-early strength agent

Abstract

The invention relates to a preparation method of a crystal nucleus type concrete super-early strength agent. The method comprises the specific steps as follows: firstly, stirring hydrated magnesium silicate in an ethylene glycol aqueous solution by use of a transition metal complex to obtain a modified magnesium silicate solution; then, modifying a calcium compound and silica sol with nano titanium dioxide to obtain a modified calcium-silicon aqueous solution; next, placing a telechelic polymer and the modified magnesium silicate solution at the bottom of a kettle, and meanwhile, dropwise adding the modified calcium-silicon aqueous solution to obtain the crystal nucleus type concrete super-early strength agent after a reaction. A C-S-H crystal nucleus nano gel structure is modified with the telechelic polymer, the super-early strength of concrete can be effectively improved, the concrete workability and later strength development are not affected, and the concrete super-early strengthagent is low in cost and stable in performance.

Description

technical field [0001] The invention relates to the application field of concrete admixtures, in particular to a preparation method of a crystal nucleus type concrete super early strength agent. Background technique [0002] Concrete is currently the most used building material in the world, and its main advantages are low price, strong bearing capacity and high durability. Due to the slow hydration reaction process of Portland cement and the influence of ambient temperature, the strength of concrete develops slowly. Generally, it takes more than 24 hours to reach the strength of the demolition formwork, and the strength can only reach 40-50% of the design strength in 3 days. 28 The design strength can only be achieved after more than one day. In addition, high brittleness and poor crack resistance are also very important shortcomings. In order to overcome these defects of concrete materials, scientists and engineers in the field of civil science and material science have ...

AI Technical Summary

Problems solved by technology

In order to improve the early strength of concrete, speed up mold turnover, and improve production efficiency, the following methods are generally adopted: (1) Add early strength agent: chlorine salt early strength agent is the earliest inorganic salt early strength agent, which can improve the early strength of concrete. Strength, but it seriously affects the later strength of concrete, and because it contains Cl - , easy to cause corrosion of steel bars, and is restricted in application

Sulfate early strength agents are likely to lead to poor performance in the later stage, and "white frost" is easy to precipitate on the concrete surface, affecting the appearance

(2) The method of reducing the water-binder ratio, increasing the amount of cement, or using ultra-fine cement: the problem brought about by this method is that the autogenous shrinkage of the concrete increases significantly, and the risk of cracking increases, and the low water-binder ratio not only deteriorates the concrete's flexibility. Sexuality makes the production operation difficult, and the amount of admixture increases significantly, which greatly increases the production cost

(3) Use high-temperature steam curing: under the condition of high-temperature steam curing, the crystal size of cement hydration is coarse, the brittleness is further increased, and the durability is reduced

However, it is difficult for fibers to disperse in concrete, which will seriously affect the working performance of concrete, and will greatly increase the cost of concrete

(4) Polymer emulsion can improve the toughness of concrete to a certain extent, but it will seriously reduce the compressive strength of concrete, and its application will be limited

There is no systematic research on the effect of modified C-S-H gel on the ultra-early strength of concrete, and there is also a lack of connection between the modification of C-S-H gel at the nanometer level and the improvement of the macroscopic performance of concrete

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