Study On Modification Of Polymer Cement Waterproof Mortar

With the rapid development of China ’s construction industry,many problems have been exposed in the leakage of buildings.Due to the poor performance of engineering waterproof materials,the building structure has cracked or even destroyed.Based on this problem,rigid polymer cement waterproof mortar is modified in order to provide reference and guidance for repairing building leakage.In this paper,the modification of polymer cement waterproof mortar is studied,and the influence of different components of polymer cement waterproof mortar on its performance is investigated.On this basis,the effects of fly ash,slag powder,silica fume and other factors on the performance of polymer cement waterproof mortar were studied by single mixing and orthogonal test.Finally,the effects of polypropylene fiber and modified polypropylene fiber on the compressive strength,flexural strength,compression ratio and durability of polymer cement waterproof mortar were studied,and the polymer cement waterproof mortar with ideal comprehensive performance was prepared.The specific research contents are as follows.(1)The influence of polymer redispersible powder on the performance of polymer cement waterproof mortar.The effects of A ethylene-vinyl acetate copolymer,B butadiene-styrene latex copolymer and C vinyl acetate/tert-vinyl carbonate copolymer powder on various properties of mortar were studied.After adding polymer latex powder,the 28 d flexural strength of the three polymer mortars increased to varying degrees,but their compressive strength decreased.The flexural strength of mortar with 8% A latex powder reaches the best value of 12.1MPa.With the increase of polymer latex powder content,the setting time of mortar gradually extends.With the increasing amount of polymer latex powder,the 28 d bond strength of mortar showed a growing trend.When the content of A latex powder reaches 8%,the 28 d bond strength of mortar reaches the best value of 2.2MPa.With the increase of polymer content,the28 d drying shrinkage rate of mortar decreases continuously,and is much lower than that of ordinary mortar.When the content of latex powder is within 8%,the water absorption rate of mortar decreases rapidly.When the content exceeds 8%,the downward trend tends to be gentle.The latex powder can significantly improve the impermeability of mortar.Considering the cost performance,adding 8% A ethylenevinyl acetate copolymer latex powder is an excellent performance of mortar.(2)The influence of the amount of defoamer,cellulose ether and hydrophobic agent on the performance of polymer cement waterproof mortar.Based on the fixed mix ratio,the effects of defoamer,cellulose ether and hydrophobic agent on the comprehensive properties of polymer mortar were investigated.When 8% A latex powder is added alone,with the increase of defoamer content,the 28 d compressive strength and flexural strength of mortar increase first and then decrease,and reach the maximum value of 45.6MPa and 14.5MPa respectively when the content is 0.5%.The 28 d drying shrinkage rate of polymer mortar decreases with the increase of the amount of defoamer,and the minimum 28 d drying shrinkage rate of mortar is 0.068% when the dosage is 0.6%.When the defoamer content is 0.5%,the impermeability pressure of the mortar reaches a maximum of 2.5MPa.The comprehensive performance of mortar is excellent when the content of defoamer is 0.5%.On the basis of fixed mix ratio and 8% A latex powder,the effect of cellulose ether content on mortar performance was further investigated.With the increase of cellulose ether content,the 28 d flexural strength of mortar increased slowly,reaching the highest value of 13.6 MPa at 0.2%.When the content of cellulose ether is 0.15%,the 28 d bond strength of mortar reaches the maximum value of 2.6Mpa.With the increase of cellulose ether content,the 28 d water absorption of polymer mortar decreases continuously,and the 28 d impermeability pressure increases continuously.When the content of cellulose ether is 0.3%,the impermeability pressure of mortar reaches the maximum value of2.5MPa.Considering comprehensively,the performance of mortar is better when0.2% cellulose ether is added.On the basis of fixed mix ratio,the effect of hydrophobic agent content on mortar performance was investigated by adding 8% A latex powder.With the increase of hydrophobic agent content,the compressive strength and flexural strength of mortar gradually increased.When the amount of hydrophobic agent is 0.6%,the 28 d drying shrinkage rate of mortar reaches the lowest value of 0.069%.With the increase of the amount of hydrophobic agent,the water absorption performance of polymer mortar decreases gradually.When the amount of hydrophobic agent is 0.6%,the water absorption rate of 28 d is 5.6%,but the overall impermeability pressure of polymer mortar increases continuously.Considering comprehensively,when the amount of hydrophobic agent is 0.5%,the performance of polymer mortar is excellent.(3)The influence of mineral admixtures(fly ash,slag,silica fume)content on the performance of polymer mortar.The influence of mineral admixture content on the performance of polymer cement waterproof mortar was studied by single mixing and orthogonal test.The increase of fly ash content reduces the 28 d compressive strength and flexural strength of polymer cement waterproof mortar.With the increase of fly ash content,the 28 d drying shrinkage rate of mortar decreased gradually.When the fly ash content was higher than 15%,the 28 d drying shrinkage rate decreased slowly.Its 28 d impermeability pressure showed a trend of increasing first and then decreasing;after50 and 100 freeze-thaw cycles,the mass loss rate decreased first and then increased,while the strength loss rate continued to increase.With the increase of mineral powder content,the 28 d compressive strength and flexural strength of polymer cement mortar increased first and then decreased,and the 28 d compressive strength reached the maximum value of 43.7MPa when the mineral powder content was 15%.The 28 d flexural strength reaches its maximum value of 13.7MPa when the mineral powder content is 12%.The 28 d drying shrinkage rate continued to decrease,while the 28 d impermeability pressure increased first and then decreased,and reached the best when the mineral powder content was 16%.The mass and strength loss rates after 50 and 100 freeze-thaw cycles decreased first and then increased with the increase of mineral powder content.With the increase of silica fume content,the 28 d compressive strength and flexural strength of polymer cement waterproof mortar increased first and then stabilized.The drying shrinkage rate decreased gradually at28 d.The impermeability of 28 d is gradually improved.When the content of silica fume exceeds 10%,the growth trend of impermeability of 28 d tends to be gentle.When the content of silica fume increases,the mass loss rate and strength loss rate of mortar after 50 and 100 freeze-thaw cycles decrease first and then increase.The compressive strength,flexural strength and durability of polymer cement waterproof mortar increased significantly after adding water reducer,and the optimum dosage of water reducer was 1%.Finally,through the results of single factor and orthogonal test,the optimum dosage is determined to be 5% fly ash,8% slag powder and 6% silica fume.At this time,the compressive strength,flexural strength and impermeability of mortar are significantly improved.(4)The effect of polypropylene fiber and silane coupling agent modified fiber content on the properties of polymer mortar.The flexural strength,flexural-compression ratio and impermeability of polymer cement waterproof mortar are improved by adding polypropylene fiber.The optimum volume content of polypropylene fiber is 0.3%,and the optimum length of polypropylene fiber is 12 mm.However,the improvement effect of polypropylene fiber on the compressive strength and shear bond strength of mortar is not obvious.The compressive strength,flexural strength,compression ratio,shear bond strength and impermeability of silane coupling agent modified polypropylene fiber reinforced polymer cement waterproof mortar are significantly better than those of unmodified fiber reinforced polymer cement waterproof mortar.