The Performance Study Of Dry-mixed Plastering Mortar

Mortar is one of the most important building materials in construction. It is estimated that about one third of cement in China is used to prepare mortar.Traditionally mortar is prepared and stirred on site, which has the disadvantages of high work intensity, low construction efficiency and environmental pollution. Besides, it is difficult to measure accurately on site so that the mortar prepared on site is easy to spall, crack and drop powder and so on. In order to solve these problems, commercial mortar, that is, dry-mixed mortar was made after the emergence of commercial ready-mixed concrete. Dry-mixed mortar has the advantages of industrial production, high quality and low pollution and high construction efficiency. However, the popularization of it is subject to its high cost in drying, preparing and transporting sand. Therefore, it is imperative to optimize the proportion of mortar preparation to reduce its high cost and improve its quality.The research on the water thickening materials of dry-mixed plastering mortar, the influence factors of its performance, its volume stability and elastic modulus was carried on in this thesis systematically. The research methods are the methods of fixed variable and orthogonal test in this thesis. The research results are that when the medium sand (river sand) is used for aggregate, the mass ratio of cement aggregate is1:3, fly ash replaces50%of the cementing materials, the mortar consistency is controlled for80-90(mm) through adding water, the content of water thickening material is700g for every tons of dry mortar which compound of cellulose ether: organic thickener:calcium lignosulphonate=2:2:3, the workability indicator of the plastering mortar can reach the specifications of national standard; When machine-made sand and superfine river sand are mixed according to1:0.6(mass ratio) and replace quality river sand, the performance requirements of freshly mixed mortar are met with great economic benefits; When fine grinding fly ash replaces70%of the cementing materials, the mass ratio of cement aggregate is for1:3, the content of water thickening materials is suitable, the plastering mortar of strength grade M5can be made; Compared with the pure cement mortar, the mortar with a lot of fly ash has smaller volume shrinkage and elastic modulus, theory and practice prove that the latter has excellent durability (i.e. not crack, not empty drum, dropping powder, etc.).