Super Early Strength Polycarboxylate Superplasticizer And Its Application In Precast Concrete

The prefabricated building industry has received extensive and high attention in our country in recent years.The requirements for formwork turnover efficiency are increasing day by day because of the demand for precast concrete components is on the rise.Therefore,higher requirements are also placed on the early strength of concrete.At present,polycarboxylate superplasticizers lead to poor concrete retardation or early strength performance due to their own characteristics.Which is unfavorable for formwork turnover and production efficiency.Therefore,it is very urgent and important to develop super-early-strength polycarboxylate superplasticizers suitable for precast concrete requirements.In this paper,an super early-strength polycarboxylate superplasticizers for precast concrete was prepared by improving the molecular structure and nanotechnology,It was tested for the properties of cement,mortar and concrete,and finally its application was studied through precast concrete.The main research contents and research results of this paper are as follows: First,a series of polycarboxylate superplasticizers with different molecular structures were obtained by changing the acid-ether ratio and side chain length of the polycarboxylate superplasticizer.Then screened out the best through the tests of cement paste dispersibility and concrete compressive strength.Second,introduction of early-strength functional monomer AMPS and cationic monomer DMC to prepare amphoteric polycarboxylate superplasticizers.The results of the experimental study of cement paste,cement mortar and concrete show that: When the introduction amount of AMPS is 3% of the mass of macromonomer,and the amount of DMC introduced is 2% of the mass of macromonomer,the early strength performance,dispersion performance and dispersion retention performance of amphoteric early strength polycarboxylate superplasticizer are the best.Third,the amphoteric early-strength polycarboxylate superplasticizers is compounded with C-S-H/PCE to prepare a super early-strengthpolycarboxylate superplasticizer.Finally,the research on precast concrete components of super early-strengthpolycarboxylate superplasticizer under strict steam curing system is carried out to achieve the purpose of saving energy and speeding up mold turnover.