Experimental Study On The Performance Of Carboniferous Limestone Machine-made Sand Dry Mixing Mortar

With the deepening reform of market economy system,China is promoting the construction of environment-friendly society.The traditional mix mortar has been unable to meet the development requirement of modern construction industry.Driving mechanism of high quality sand dry mortar application not only solve the problem of the discharge of wastes a lot of,also can reduce the resource depletion due to excessive river sand mining ecological problems,such as protection of the environment at the same time improve the economic benefits,this is in line with the new goal of our country's harmonious and beautiful socialist country.Therefore,this paper chose the carboniferous limestone mechanism sand in yongzhou,hunan province.The optimum particle size distribution of sand was determined by experiment.At this stage,the mechanism sand dry mortar with different glue sand ratio and cementing material was prepared,and its working performance,mechanical properties and durability were studied.The conclusions are as follows:1.The effect of different sand particle size on the performance of mixed mortar was studied.The particle size of the sieve was divided into six groups(J1 ~ J6)according to the particle size of 1.18~0.6,0.6~0.15 ? 0.15~0.075.?0.075.For different grain group,preparation of dry mortar for consistency,water retention,compressive strength,flexural strength and bond strength test,according to the analysis of the test results,the comprehensive performance of dry mixed mortar was the best in J3 group.the quality ratio of the four particle diameters of the mechanism sand is 25%,50%,10% and 15%respectively.2.Experimental study on the effect of the substitution rate of fly ash on the physical properties,mechanical properties and durability of the mechanism sand dry mortar,the results show that:With the decrease of the ratio of cement sand,the water consumption of the mechanism sand dry mortar was reduced first and then increased.When the sand ratio was 1:4,the water consumption was the least,the stratification degree and the gas content and the coagulation time increased,and the apparent density decreased.When the cement-sand ratio is constant,with the increase of fly ash instead of cement in the cementing material,the mechanism sand dry mixing mortar mix and water use firstdecrease and then increase.When the replacement rate is 10%,water is the least,the stratification decreases first and then increases,the gas content and apparent density decrease,and the coagulation time increases.The anti-bending strength and compressive strength of sand-dry mortar are increasing with the increase of age.When the sand ratio is 1:3,fly ash has a great contribution to the strength of dry mixed mortar.When the sand ratio is 1:4,1:5 and1:6,with the increase of the cement content in the cementitious materials,the compressive strength of 28 d is generally decreasing,and the increase of fly ash volcanic effect is obvious in the later stage.With the decrease of the ratio of the cement sand,the anti-freeze performance of the sand dry mixing mortar decreased,and the shrinkage rate decreased.When the sand ratio is 1:6,the frost resistance does not meet the requirements;When the sand ratio is constant,with the increase of fly ash in place of cement,the frost resistance and shrinkage decrease,when the replacement rate is 10%,the antifreeze performance is the best,the shrinkage rate is only 1/3~1/2 of the blank sample when the replacement rate is 20%.