The Study On Quality Control Of Anufactured Sand Pre-Mixed Mortar Production

Along with the urbanization process of our country, the marketization of premixed mortar is promoted widely in china. In the market, the market share of manufactured sand mortar increased tremendous. However, limited by the mother rock composition, sand production process and other factors, the mechanism of sand itself leads to the instability of its nature. Nevertheless, existing ready mixed mortar production technology and mix design does not take the construction and environmental factors influence on its’ properties. Relevant standards didn’t mention the time of the mortar placing in the construction site. Therefore, the mortar was placing at the construction site for too long, remixed phenomenon happened everywhere, the quality of mortar was impacted by this phenomenon seriously. The influence of sand parameters, additives, construction factors and temperature on the workability and mechanical properties of premixed mortar was studied respectively. The variation equation is obtained by mathematical fitting of the variation of mortar consistency. The main research conclusions are as follows:The close packed state sand gradation is the most reasonable. Fine particles of 0.075~0.15 mm should be included in the powder, powder content cannot exceed 10%, the total amount of fine powder and 0.075~0.15 mm particals should be in the range of 15%~20%.When the HPMC content in 0.14‰~0.21‰, initial consistency and viscosity suitable for plastering mortar. When the content of air entraining agent is 0.43~0.64%, mortar density and mortar initial consistency can be effectively reduced and increased. When the sodium gluconate content between 0.17‰ to 0.26‰, the open time and initial consistency of mortar are suitable. The main function of fly ash on mortar is the improvement on mortar workability, In contrast with the two mixing method, the fly ash replace sand enhanced the mortar more obvious.The following sort of adjustment ability to open time of admixture: retarder>air entraining agent>HPMC.When the temperature is higher than 35 ℃, the opening time of mortar will be shortened more than half. Remodeling can improve the mortar’s consistency temporarily, but the mechanical properties of the mortar will be lost more than 30%, especially the flexural strength of mortar will lose more than 70%, and also lead to bigger shrinkage rate.The fitting equation of ready mixed mortar consistency change can describe the variation of the specified mortar consistency rules. The equation describes the change of the consistency in early stage. Through the analysis to influential factors to initial consistency C0 and decrease rate of consistency R, the open time of the mortar can be calculated by this eauation, every equation’s correlation coefficient is more than 0.92. Based on the above experimental results, sand mortar aided software production process divided whole mortar production process is into three processes, the mechanism of sand production process, the opening time of the design process, mortar strength check, mix proportion output process.In summary, compared to the concrete, ready mixed mortar application range is fixed, and the factors affecting preparation process are limited, so the manufactured sand premixed mortar production can be judged by the equation becomes possible, at the same time can provide a basis for quality control mechanism of sand ready mixed mortar production.