Development of New Ultra-High-Early- Strength Superplasticizer and Its Application

Abstract

This paper describes how a new class of polycarboxylate superplasticizer with a grafted pendant group of polyethylene oxide has been developed and extensively used in the construction field because of its outstanding water reducing ratio, high workability retention at small dosages and excellent compatibly with higher dosage rates of industrial by-products. Nevertheless, a drawback of this new generation superplasticizer is their effects in delaying the rate of cement hydration, especially when they are used at higher dosages and in low temperatures environment. These aspects limit their industrial application because of the slow mechanical strength development at the early age. In order to overcome this drawback, a new polycarboxylate superplaticizer (SSP) has been developed by means of optimizing the comb copolymer structure so as to meet ultra-early strength development requirements of construction projects. The results of mortar or concrete tests clearly indicate that SSP has the capacity to considerably accelerate the development of early age mechanical strength in conditions of low curing temperature, in comparison with the ordinary superplasticizers. The compressive strength of concrete containing SSP can reach 500% and 480% at an early age of 24 hours and 30 hours, respectively, when compared with ordinary polycarboxylate polymers at the same dosages. Engineering experimental results proved that the SSP can meet the requirements of concrete admixtures for high-speed railway construction projects.