Study On Performance Of Polyurethane Cement Mortar

Cement concrete ( mortar ) is porous material which has complex structure , so the performance of the concrete is largely affected by the porosity , pore shape and permeability of the material . Consequently , concrete easily degrades by free-thawing impact , acid corrosion , alkali-aggregate reaction and so on , and carbonation and chloride corrosion in concrete surely cause the rust of rebar , which certainly destroyed the concrete structures . So developing composed cement concrete ( mortar ) by using polymer becomes important and effective means of advancing the durability of concrete structures.Choosing different raw materials can synthesize all sorts of polyurethane which relevantly has good different properties . Therefore , in this paper, polyurethane is firstly used to modify cement mortar . And the development of the performance of the mortar is studied in this paper . The paper try to find a new polymer modified cement mortar that has excellent performance.In this paper , according to contrastive experiment results , a new solvent-free polyurethane is chosen to modify cement mortar . The main performance of the ordinary cement mortar ( OCM ) and polymer modified cement mortar ( PCM ) is studied by contrastive tests . The results show that the strength of PCM is lower than that of OCM , but the durability of PCM is better than that of OCM . Because although the shrinkage and the carbonation in PCM is a little less than that in OCM , the influence of permeability and freezing and thawing impact to PCM is very less than the influence to OCM . The microstructure and constituents of mortar specimens are studied by MIP , SEM , XRD in this paper . It shows that polyurethane can fill up the pore in mortar and the microstructure of the mortar is improved , so the durability of PCM is developed.In addition , the study in this paper shows that the PCM condenses and hardens quickly , and can achieve high early strength . Accordingly , after optimizing the polyurethane modified cement mortar , the mortar can be used to mend concrete structure fast . The paper also find that after adding water-reducing and set-retarding admixture , the strength and workability of the PCM is improved largely . Therefore , the PCM alsocan be used in ordinary condition , but the realization of the application should be based on comprehensive studies.