Experimental Study On Modification Of Charcoal Limestone Sand Dry Mixed Mortar By Cellulose Ether

Due to the long-term disorderly exploitation of river sand in many parts of our country,a large number of natural river sand is near depleted,seriously destroying the ecological balance.However,the mechanism of sand material performance is stable,the production process is easy to operate and control,and it can meet the needs of the construction market.Therefore,it is a trend to use the machine-made sand to produce dry mixed mortar instead of the river sand.Cellulose ether has a good water retention performance,and it also can improve the bonding performance of the mortar,therefore,it is often used as additive in the production process of dry mixed mortar.In this paper,the working performance and mechanical properties of dry sand mortar under different addition amount of hydroxypropyl methyl cellulose ether(HPMC)is studied and analyzed by laboratory test,and the modification mechanism of HPMC is explored.The main research ideas and related conclusions of this paper are as follows:Firstly,the effect of different grading machine-made sand on the performance of dry-mixed mortar was studied.The sand was divided into six groups according to the gradation,and the performance of the dry mortar was tested.According to the comparative analysis of the test results,when the mass ratio of the four kinds of sand is 25%,50%,10%and 15%,the comprehensive performance of the dry mortar under the S4 group is the best.Secondly,the text studied the effect of HPMC on the working performance of dry-mixed mortar made of machine-made sand,and the consistency,water retention and coagulation time test were carried out,the effects of HPMC under different addition amount on the performance of S4 dry graded mortar is studied.The results showed that when the HPMC is used as the admixture of dry mortar,it was recommended to use HPMC with the viscosity of HPMC2 and HPMC3,and the appropriate dosage range is from 0.1%to 0.3%under the two kinds of viscosity.Thirdly,the text studied the effect of HPMC on the mechanical property of dry-mixed mortar made of machine-made sand,and the compressive strength,flexural strength and bond strength test were carried out,the effects of HPMC under different addition amount on the performance of S4 dry graded mortar is studied.The results showed that when the HPMC is used as the admixture of dry mortar,it was recommended to use HPMC with the viscosity of HPMC1 and HPMC2,and the appropriate dosage range is from 0.1%to 0.3%under the two kinds of viscosity.Therefore,the comprehensive performance of hydroxypropyl methyl cellulose ether modified sand dry mortar work performance and mechanical properties can be drawn,the final recommendation of the selected viscosity of HPMC2,and the viscosity of the appropriate dosage range is from 0.1%to 0.3%.Finally,the microstructure of the dry-mixed mortar mixed with HPMC was analyzed by SEM,and the modification mechanism of HPMC was explored in the text.