Study On Rapid Repair Of Cement Based Composite With Polymer Modification

The fast hardening sulphoaluminate cement as the crack repair of matrix material which damaged concrete harm maximum size greater than 5 mm of the cracks,using polymers change of rapid repair cement mortar to repaired rapidly for meeting the 6 h traffic requirements.This paper studied the effects of polymer,silica fume,early strength agent and cellulose ether on the mechanical properties,fluidity and setting time of cement mortar. Experimental results show that in water cement ratio was 0.38,cement sand ratio is 1:2.Adding cementitious material,3% of total mass of redispersible emulsion powder and 6% of silica fume,and 0.9% sodium nitrite early strength agent,rapid repair of cement mortar 6 h flexural strength is 5.5 MPa,the compressive strength is 31.6 MPa to 30 MPa,the setting time is moderate(about 30 minutes) to facilitate the construction operation. In standard hydroponic conditions,the flexural bond strength of 3 d is the highest bond flexural strength reached 2.7 MPa,and low shrinkage,micro expansion.Also this paper research on the mechanism of polymer modified cement mortar with the aid of AC impedance measurement technology,FT-IR,XRD and SEM to study the hydration degree and hydration process of polymer modified cement,whether there is a new material production,the morphology of hydration products and hydration mechanism. Research findings show that adding the redispersible latex powder inside the cementitious material has no chemical reaction occurs,but the early hydration of cement to the delay,at the late stage of cement hydration,re dispersible latex powder can fill the cement stone and enhance the bond strength,and the intensity of the latter. Redispersible emulsion powder mixed with water to form emulsion,it in the middle and late can not only filtration film,but also can fill in pores and cracks in the mortar,film and the hydration products of cement formation is not completely continuous and hydration of dense space grid structure,makes the material structure improved significantly,reduce the hydration product orientation,the structure more compact.