1. CMC and HPMC added to the mortar can play the dual role of water retention and thickening. With the increase of dosage, the layering degree of mortar will decrease. CMC is an ionic cellulose ether, and can react with Ca(OH)2 when added to the mortar. CMC has no obvious improvement in the water retention property of mortar, and the dosage is relatively large. However, HPMC is a nonionic cellulose ether, with stable performance.A small addition amount added to the mortar,only one-tenth of CMC dosage, can greatly reduce the layering degree of mortar and play a very good role in water retention.
2. When CMC and HPMC mix with mortar, air bubbles will be introduced. Especially when the HPMC dosage is very low, lots of tiny bubbles will be introduced. These bubbles can have the ball bearing effects in the mortar, so that the workability of fresh mortar can be improved. But a large number of air bubbles can reduce the wet density of mortar, and after hardening of the slurry, pores will be formed inside the slurry, so that the internal structure of mortar will become loose, and thus the mortar strength will also be significantly reduced.
3. Adding HPMC into the mortar, there will be a smaller decrease in the flexural strength of mortar but a larger decrease in the compressive strength. The upward trend of ratio curve of flexural strength to compressive strength indicates that the addition of HPMC can improve the toughness of mortar.
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