With the Concrete Admixture scale of infrastructure in China, cement concrete research and application technology has developed rapidly. Mineral admixture is one of the most important components of modern concrete. The development of new and efficient mineral admixtures to meet the development and demand of modern concrete has become an important part of cement concrete research.

The SuperPlasticizer Admixturer, ground slag powder and fly ash are compounded into composite admixtures instead of cement to form concrete, and the compressive strength and durability of concrete can be studied. The main work and achievements of this paper include the following aspects

1. The relationship between the substitution amount of the composite admixture, the proportion of the admixture, the water-to-binder ratio and the amount of the water reducing agent and the strength of the concrete was studied. The results show that under the condition of 1.6% water-reducing agent and water-to-binder ratio of 0.39~0.42, the composite admixture replaces cement with 30%. Among the admixtures, the ratio of steel slag powder, slag powder and fly ash is 1:2:1.

2. Chloride ion permeation test The effect of admixture content and age on concrete strength was studied. As the amount of admixture increases, the resistance of the concrete to chloride ion penetration is significantly improved. Ordinary concrete is reasonable for 28 days as the evaluation period, and 45 days for the composite type admixture concrete is more reasonable.chemicals additives for Concrete is complicated .

3. The carbonization law of concrete mixed with composite admixture was studied by concrete carbonation test. The anti-carbonization performance of ordinary concrete is better than that of fine-grained steel slag powder composite admixture concrete. The anti-carbonization ability of concrete mixed with composite admixture is better when the admixture content is 30%, with admixture As the amount of addition increases, the ability to resist carbonation decreases.

4. The results of impermeability test show that the anti-penetration ability of concrete mixed with composite admixture is stronger than that of ordinary concrete. When the substitution amount of admixture is 50%, the effect is best. The shrinkage of concrete mixed with composite admixture Performance is better than ordinary concrete

5. The effect of composite admixture on the resistance of concrete to salt corrosion was studied by corrosion test. When the substitution amount of composite admixture was 40%, the ability of concrete to resist salt solution was better, and the ratio of admixture was 1 : 1:1 is better.