Preparation And Study On Dry-mixed And Anti-crack Mortar

Mortar is used largely as a kind of building material in the architectural engineering. The traditional mortar is always mixed in the construction place. It exists in many defects, for example, Computation is not accurate, mixing up is not uniform. It is not easy to control workability of mortar, and it is difficult to ensure quality. Moreover, it pollutes environment, it is not efficient and it is hard to meet the special request of different parts in architecture engineering. Dry-mixed mortar has so many merits with stable quality, high work efficiency, good quality, full variety, good construction performance, convenient use etc, now it is energetically spread and used. On the other hand, walls have crack and leakage after the new type wall material is used. So a sort of mortar with anti-crack performance is urgently needed. Be based on, the paper emphasizes on studying the anti-crack of dry-mixed mortar.There is extra fine sand mortar that its fine degree modulus is less than 1.0 in Chongqing, therefore, the extra fine sand mortar is possessed of beyond 95% in project. The extra fine sand mortar has great shrinkage, low toughness, and it is easy to crack, so the paper focuses on shrinkage ratio, crack index and toughness. It mainly studies sand, cement, ash calcium powder, dual flight powder, polypropylene fiber, redispersible polymer, cellulose ether, woody fiber, expansive admixture on mortar performance influence. The results show that: (1) The anti-crack mortar uses P.O42.5R cement, extra fine sand, 1: 3 C/S. (2) The ash calcium powder and the dual flight powder are not suitably mixed in the anti-crack mortar. (3) The polypropylene fiber influences passively the mortar workability, but it can remarkably improve the mortar toughness and the crack resistance. (4) Redispersible polymer may improve the mortar toughness, enhances adhesive intensity of mortar. (5) Cellulose ether has water-retentive performance, and it can improve the toughness of mortar. (6) The woody fiber has the certain flexibility, it can improve the organizational structure of mortar, and cause the mortar to have the certain tough structural body. (7) The UEA expansive admixture can effectively suppress the contraction of mortar.Through analyzing anti-crack protective layer performance series factors, the anti-crack protective layer belong to external thermal insulating rendering systems made of mortar with mineral binder and using expanded polystyrene granule as aggregate(ETIRS). Dry-mixed and anti-crack mortar is mixed up. It has the good workability, the high adhesive intensity, the strong anti-crack ability. Its performance index meets JC158-2004 " ETIRS " the standard request.