The Study On Self-curing With Ceramisite For Performance Of Concrete

Curing of is very important to develop various performance and indicators of concrete. But for some easy parts cracking, such as cast-in-situ concrete side wall etc, regular curing is very difficult to carry out. Especially water-cement ratio of concrete decreasing continuously, compaction increasing ceaselessly and strength grade enhancing unceasingly, external water is also hard to permeate into concrete for hydration, even if it is external to water or r store water for curing. So it should be carried out to research self-curing technology of concrete, specific to development status of concrete and the particularity of engineering structures.Concrete self-curing is refered to introducing a kind of component as curing material in concrete,curing material is evenly dispersed in concrete as internal reservoir.When water is deficiency in the process of the hydration, the curing material can supply water for hydration, and support hydration continuous.This topic is using prewet ceramisite for the self-curing materials, volumetricly replaced gravel and mixing expansive agent, fly ash and mineral powder at the same time.It researchs the rule of strength, Cl - diffusion coefficient and free shrinkage of self-curing concrete through orthogonal experiment. And it explores self-curing mechanism of prewet ceramisite and adaptability of prewet ceramisite and other materials. At the same time,it is validated through further parallel tests, for the theory basis about application of self-curing technology in concrete works.The research results show that when the dosage of only mixed prewet ceramisite is 20%, the strength is the highest, Cl - diffusion coefficient is the least and free shrinkage is small. After mixing prewet ceramisite and expansive agent, it also can enhance the strength of concrete, reduce Cl - diffusion coefficient and reduce shrinkage when the admixtures of both are proper, because expansion agent can compensate for the defect that elastic modulus of ceramisite is small and shrinkage is big under stress. But ,with the admixture of ceramisite increasing, porous structure of ceramisite is disadvantageous to the post strength of concrete and Cl - diffusion coefficient and free shrinkage. Test results show that self-curing of prewet ceramisite is weakened gradually after 11d ,and self-curing of prewet ceramisite and expansion of expansive agent can vanish after 28d. The results show self-curing of prewet ceramisite is only beneficial to early age concrete, and the performance of post concrete is not improved by adding expansive agent and prewet ceramisite.