Study On Preparation And Performance Of Dry-Mixed Mortar

Dry-mixed mortar is a new kind of building mortar that is made by uniformly mixing binding materials,fine aggregates,mineral additives and chemical additives.It has many advantages such as stable quality,constructing expediently,using byproducts and good to environment.Now,our dry-mixed mortar is only using in several big cities,and is limited in specific mortar at small dosage,normal dry powder mortar and insulation mortar are using little,and those two kinds of mortar were studied in this papei,mainly about the mix proportion design and performance.Normal dry powder mortar composition was designed by the following stages:First,with contrast experiments,proper addition content of HPMC and FA are determined. The second stage,adding the HPMC and FA to the primary normal cement mortar with different c/s ratios such as 1:2,1:3,1:4,1:5,1:7,the dry-mixed mortars with different strength gtade,which strength are to meet M5.0~M30 are prepared.Its mix proportion can be guidelines for the production of normal dry-mixed mortar with different strength grade.The tests on performances showed than it has good workability,proper compression strength and high bond strength.External thermal insulation mortar mix proportion was designed by the following stages:Firsr,choosing EPS/(C+FA) ratio,FA/(C+FA) ratio and EVA/C ratio to be the primary factors on performance of mortar,the study design by orthogonal design,and based on properties test of compression strength and dry apparent density has been carried out;Then,with the help of extreme deviation analysis and regression analysis, the results of cross experiment design were studied,the analysis showed,of the three factors,the EPS/(C+FA) ratio is the most primary factor to compression strength and dry apparent density.Using the regression eqvation,with the EPS/(C+FA) ratio is variable and the other two factors are constant,the scope of EPS/(C+FA) ratio and the primary mix proportion was obtained.According to the thermal conductivity coefficient of EPS thermal insulation mortar and adhesive strength of mineral binder,the last mix proportion is established.Finally,the performances on EPS thermal insulation mortar and mineral binder are researched generally,such as compression strength,pressure and shear adhesive strength,dry apparent density,dry shrinkage conductivity,thermal conductivity coefficient,softening coefficient andseeting time,the results showed that the external thermal insulation mortar what we studied has many advantages of light weight,low heat conductivity factor,high fly ash content and use simplicity.The effect mechanism that the modified mortar with cellulose,emulsion powder,fly ash and fiber was analyzied from the point of microstructure by SEM and MIP,and the macro rules of those modified mortars were understood deeply by combining the microstructure with properties.