The Workability And Performance Optimization Of Hot Dry Mortar In Summer

At present, ordinary dry mortar industry is generally confronting some technicalproblems, such as the segregation in the process of production; the cracking and emptydrum of the plaster caused by poor quality and sand with largely fluctuating quality; thecracking and empty drum of the plaster on concrete shear caused by excessively highwater retention, hot cement mortar caused by the shortage of drying capacity, etc. Sincethe ordinary dry mortar is in the early stage of development in most domestic cities,these abovementioned problems may not be realized. Therefore, the research about thehigh temperature cement mortar is rarely reported so far. But the problem of hot mortaris serious and urgent in the cities with natural sand as the main source of sand and moremature developing regions, such as Chengdu and Changzhou, especially in summer.Hot slurry exists many problems, such as higher losses of the consistency; thedecrease of water retention caused by the partial or all invalidation of the admixture andthe larger shrinkage. These problems will affect the efficiency of plastering and thequality of construction. To solve the problem, this paper studied the influence of thetemperature, relative humidity and various components of the additive on waterretention, the evaporation rate of water and the rate of cement hydration of high-temperature dry cement mortar, and found that temperature, relative humidity and thecomponents of admixture all can affect the performance of hot mortar. The influencelaw is as follows: with the rise of temperature, the rate of cement hydration and theevaporation rate of water are accelerated, the loss of consistency is higher and the waterretention is lower. With the reduce of relative humidity, the evaporation rate of water isfaster and the loss of consistency is higher. In hot mortar, HPMC can improve the waterretention and delay the rate of cement hydration. With the increase of HPMC dosage,the water retention is enhanced, but it can’t restrain the evaporation of water in themortar. HPMC with higher gel temperature is more suitable for hot mortar. STPP candelay the rate of cement hydration and reduce the loss of consistency, but it can’teffectively restrain the evaporation of water in the mortar. Coarse whiting powder canimprove the water retention and the compressive strength of28days, reduce theshrinkage of the mortar, and can restrain the evaporation of water, thus reduce the loss of consistency and improve the workability of the mortar.The important way to optimize the workability and other properties of hot cementmortar is to optimize the dosage proportion of the admixture components. Through theorthogonal experiment， the best proportion is75HD100000S:PAV29:FDN-1:STPP:Coarse whiting powder=0.3:2.0:2.0:0.3:10.0.And the proportion is verified by testing the performance of DM5masonry mortar andDP M5and DP M10plaster mortar with the selected compound admixtures.To verifythat the selected compound admixture is practical, apply it to engineering. The useeffect is good.