Properties Evaluation of Repair Mortars Containing EVA and VA/VeoVa Polymer Powders
The repair of damaged structures is a complicated problem in the construction industry and it is no uniform standard for evaluating the effectiveness of repair materials. Two different redispersible polymer powders, ethylene vinyl acetate (EVA) and polyvinyl acetate-vinyl carboxylate (VA/VeoVa), were added in the repair mortars with two water-cement ratios and three polymer-cement ratios. The effectiveness of repair materials was evaluated according to the physical, mechanical properties and micrographs. Testing program includes setting time, drying shrinkage, thermal expansion, compressive strength, tensile strength, flexural strength, bond strength, X-ray diffraction analysis, scanning electron microscopy observation. Test results show that the specimens with VA/VeoVa and w/c of 0.5 have highest compressive strength, tensile strength, flexural strength and bond strength. The specimen with EVA also has higher strength than control one at the age of 28 days. The drying shrinkage deformation of VA/VeoVa specimen is close to the control one. The specimens with VA/VeoVa have lower thermal expansion than EVA specimen when the water-cement ratio is 0.5 and there is no difference between EVA and VA/VeoVa specimens for the water-cement ratio of 0.6. The micrographs show that adding polymer powder can reduce the pore and improve the durability.