Study On The Polymer Modified High Strength Cement Mortar

In this paper, the effect of re-dispersible emulsion powders, thickening agents, superplas- ticizer, mineral admixtures (containing fly ash, silica fume and U-expansion agent) on the workability, water to binder, air content, water retention, flexural strength, compressive strength and tensile bonding strength of mortar were investigated. It was discussed what the modified mechanism of different components to the high strength cement mortar. The components were optimized according to the application of strengthening structure.Re-dispersible emulsion powders can reduce water consumption and increase air content and water retention of fresh mortar, as well as increasing the cohesion and thixotropy of fresh mortar also increases, so workability of fresh mortars were observably modified. Owing to the lower water to binder and polymer film, the flexural strength and tensile bonding strength of mortars were increased when the addition of re-dispersible emulsion powders more than a certain amount. The compressive strength of the mortars falls with the increasing of polymer to binder. Cellulose ethers can observably entrain air void and increase water retention, the cohesion and resistance against drooping of the fresh mortar are increased, while its workability is effectively modified. But the mechanical properties of mortar would fall due to the addition of cellulose ethers. There were disadvantageous effects to mechanical properties. Composite re-dispersible emulsion powder and cellulose ether can modify the workability of fresh mortar more effectively and in some sort increase mechanical properties.Superplasticizer could evidently modify the performance. But the performances existed observable difference adding different superplasticizers and re-dispersible emulsion powders or cellulose ethers. The results indicated that polycarboxylicate-based superplasticizer is more adaptable than naphthalene-based superplasticizer.The cement mortar modified by polycarboxylicate-based superplasticizer, re-dispersible emulsion powders or cellulose ethers had nice workability and strengthening the mechanical of mortar. But the mechanical properties reduced with the increasing the quantity of re-dispersible emulsion powder or cellulose ether, so the cellulose ether must be controlled if you want to get high strength mortar.In the test condition of this paper, mixing proper fly ash or silica fume or U-expansion agent into the high strength mortar modified by polycarboxylicate-based superplasticizer and re-dispersible emulsion powder not only could modify fresh mortar workability, but also increased the mechanical properties of hardened mortar. Proper re-dispersible emulsion powder can reduce the shrinkage of cement mortar and increase the durability tensile bonding strength. Besides water to binder and sand to binder also affect the workability of fresh mortar and mechanical properties of hardened mortar.Considering comprehensively the effects of superplasticizer, re-dispersible emulsion powder and mineral admixture on the workability of fresh mortar and the mechanical propert- ies of hardened mortar, the experiments showed that optimum cement mortar mix ratio was (C+FA+SF+UEA):S:W:PC:P1:PF=(0.75+0.10+0.05+0.10):2:0.24:0.003:0.02:0.0015. The water retention and trowel finish workability of fresh mortar and the mechanical properties and durability of hardened mortar are all very nice. The polymer modified high strength cement mortar can be used in the method of strengthening member with steel wire mesh and polymer mortar.