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Application and Research Status of New Early Strength Agent for Concrete

Release time:

2022-06-13

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Given the traditionearly strength agentmany concrete science and technology workers are committed to the research and development of new early strength agent. So far, although the research is not very mature, but some results are still promising. The main research directions and ideas are as follows:

1. The development of early strength effect of calcium salt: calcium salt can reduce the PH value of C3S-H2O system, thus accelerating the hydration of C3S, and then accelerating the hydration and hardening of cement. Calcium salts which have this function and are free of chloride ions, sodium ions and potassium ions include calcium nitrate, calcium formate, calcium bromide and the like. Calcium formate is an ideal substitute for calcium chloride, but it is currently difficult to be accepted by contractors due to its high price. Calcium nitrate also has a good early strength effect on Portland cement, but it has a weak effect on Portland cement mixed with admixtures. But I believe that with the deepening of research, calcium salt will be a new typeearly strength agentOne of the better development varieties.

2. Further discussion on the early strong effect of the new generation of organic and inorganic compounds: at present, there are many organic compounds compounded with sulfate or chloride saltearly strength agent. Although their early strength and a series of effects on improving concrete performance have been improved, the adverse effects of traditional early strength agents on concrete have not been changed. Organicearly strength agentThe series has no damage to concrete, so the main problem when applied to concrete is how to enhance the expected early strength. At present, many experts believe that the main research can still be carried out along the direction of the combination of organic and inorganic substances, but the choice of inorganic substances needs further research. In addition, there has been another solid alcohol amine organic early strength agent, which is easier to compound with inorganic early strength agent, so it can obtain better effect of early strength agent.

3. Study on the properties and functions of early strong high valence cations: Most of the hydration products of cement are C- S-H gels, which are formed by hydration of C3S and C2S. Because the high valence cations compress the diffusion double layer of C- S-H colloidal particles, it can accelerate the agglomeration of C- S-H colloidal particles, thereby reducing its concentration in the liquid phase, accelerating the hydration reaction of C3S and C2S, and further accelerating the hardening process of cement and concrete. There are many similar high-valent cations, once the formation of compositeearly strength agentProducts, will be a good early strength agent development direction.

4. Embryo materialearly strength agentThe application of practice: the role of the embryo material has also been the attention and research of concrete science and technology personnel. The test results show that adding 2% ground cement slurry to concrete can increase the early strength of concrete by 10%-15%, and the later strength has no adverse effect. It should be pointed out that if the concrete mixed with the same kind of cement cement hydration, the effect is better.

From the above analysis, it can be seen that the shortcomings of chloride and sodium (potassium)-based early strength agents make the research and development of chloride-free and sodium (potassium)-based early strength agents imperative. Although many concrete science and technology workers have noticed the shortcomings of chloride and sodium (potassium)-based early strength agents and have begun to develop new early strength agents, there are no stereotyped products with strong adaptability, good effect and low cost. Therefore, chloride-free sodium (potassium)-based concreteearly strength agentresearch, development and application of concrete construction and scientific research workers more and more attention.

Key words:

Early strength agent

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