The Development And Performance Of High Water Retention Polymer Modified Mortar

Thinking about the building energy efficiency and environmental protection, In aerated concrete block, concrete hollow block represented new building has become a major part of modern building wall material, however, these materials generally have a high water absorption, high shrinkage deformation characteristics, the wall is easy to crack, requirements overlay mortar with good water retention and toughness, reduce the water-absorbing matrix, deformation caused by the wall cracking, shedding phenomenon. In this paper, by improving water retention to start building mortar, explore a variety of water-retention components, such as hydroxypropyl methyl cellulose ethers, sodium carboxymethyl cellulose, bentonite, fly ash and mineral, which influence of mechanical properties of mortar(compression, folding and bonding strength), performance(retention, consistency and fluidity) and anti. cracking performance, and observing microstructure and morphology after hydroxypropyl methyl cellulose ethers, sodium carboxymethylcellulose and bentonite disperse in the mortar by SEM scanning, analysis of the mechanism of water retention.The results show that: Hydroxypropyl methyl cellulose ether has a more significant improvement to the mortar of bond strength, it has a slight improvement to Flexural strength, but it does not increase the compressive strength. When incorporate 0.3%, the mortar has highest bond strength. When incorporate 0.4%, the mortar has highest flexural strength; Sodium carboxymethyl cellulose has a significantly improvement to bond strength of mortar, but for compressive strength and flexural strength are not obvious. With content increasing the bond strength gradually increases, when incorporate 0.3%, the mortar has highest bond strength; Bentonite can effectively improve the mortar of flexural strength and bond strength, the early compressive strength has been significantly improve, but for the latter compressive strength is not obvious. When bentonite incorporates 5%, the mortar of flexural strength and bond strength appear the highest value; Fly ash can make a loss of the mortar of the early compressive strength and flexural strength, but the late strength has significantly improved. But for bond strength has a slight improvement, when incorporate into the mortar, we must strictly control its alternative amount. When the amounts of fly ash replace 24%, the mortar of 28- day bond strength appears highest value. And when replace 16%, the 7-day bond strength appears highest value. When the amounts of fly ash replace 28%, the mortar of 28-day compressive strength and flexural strength appears highest value; Mineral can make a loss of the mortar of the early flexural strength, for compressive strength and bond strength has obviously improved, so mineral like fly ash, when consider the optimization of bond strength, we must strictly control its alternative amount. When the amounts of mineral replace 24%, the mortar of bond strength appears highest value. When the amounts of mineral replace 32%, the mortar of compressive strength and flexural strength appears highest value; If hydroxypropyl methyl cellulose ethers add excessive amount, the mortar of performance improvement is not significant, and even affects the operation of the experiment, but it can be improved the mortar of performance, if add a little, and the highest water retention can reach the rate of 99.7%;These five components that hydroxypropyl methyl cellulose ethers, sodium carboxymethyl cellulose, bentonite, fly ash and mineral make varying degrees of improvement to the mortar of the cracking performance. Just mineral components of admixtures are weaker than polymer component of admixture on the cracking performance. From considering the cracking performance, cellulose ethers cracking index is 31.2, it is better than the other components and is the best additive to improve the performance of mortar cracking; By SEM electron microscope watching, the component of polymer can hydrolyze mesh or sheet membrane structures, at the same time, they insert in the mortar, and the polymer group having a high water absorption, can absorb water very well, can prevent water loss, and have a high water retention capacity.