| Recent years,in some place where usual sand resources is gradually scarce,and use ultra-fine sand instead of sand used before in hydraulic concrete became an important way as resource conservation,and reduce costs,but with ultra-fine sand used in the hydraulic pump concrete,water-based secretion on the strength and durability of concrete has a certain impact on the rate of bleeding hydraulic pump concrete effect of a very important economic and practical significance.In this paper,single-factor test designed to pressure bleeding,slump and compressive. strength tests on the raw materials including sand fineness module,with coarse aggregate level,fly ash content,content and preparation superplasticizer Parameters such as water-cement ratio,unit consumption of water,sand,etc.on the concrete bleeding rate of impact.At the same time integrate the engineering,analysis of ultra-fine sand pumping concrete in the Palestinian home Reservoir Project of the spillway.The main conclusion of the study are as follows:(1) Sand rate has a significant impact on concrete workability,under the same conditions when the concrete slump maintain 180mm,the sand rate was 29 percent,cementing material amount of the province.Sand rate of less than 29 percent of the variation will be concrete and easy,not conducive to pumping.Sand rate is more than 29 percent of cement consumption increased at a lot of strength but growth is slow,not conducive to the hydraulic mass concrete cracking.(2) When the sand rate unchanged for the slump control 180 mm～200mm,ultra-fine sand fineness modulus increased from 1.3 to 1.5,the pressure on the bleeding rate increased from 34.3 percent to 37.8 percent,did not exceed 40 percent.That instead of using ultra-fine sand,sand preparation of the mobility of concrete,with the two concrete is totally feasible.(3) Ultra-fine sand pumping water reducer in concrete mixing units can cementitious material consumption and reduce the dosage,and slump remain the same.With the increased amount of water reducer,the compressive strength of concrete first and then cut,concrete pressure decreased after the first bleeding increased.When the water reducer content of 0.75%,the highest concrete strength,the pressure was minimal bleeding,this is the optimal amount of water reducer.(4) Fly Ash to improve the workability of concrete and fly ash content in 20 percent to 30 percent between changes,the compressive strength of concrete little changed;fly ash content of 15%to 35%range,the pressure on the secretion With the water rate increases reduce the amount of fly ash that using fly ash instead of cement will not only cost savings, reducing the amount of cement and hydration heat,but also conducive to concrete pumping.(5) With the pressure on the bleeding rate of the water-cement ratio increases with the increase,but the water-cement ratio 0.30 to 0.40 changes,bleeding rate of increase in the flat, according to other performance requirements of concrete decisions water-cement ratio.(6) The greater consumption of water units,the greater the pressure on the bleeding rate, the unit had 180 kg/m3 water consumption,pressure bleeding rate of over 40 percent,to the detriment of pumping.(7) Palestinian home in Tsui reservoir reinforcement project,through the examination and selection of raw materials,the use of doped with additives and admixture,and other technical means to lower the amount of cement and lower water-cement ratio,to the successful preparation of a special Fine sand as raw materials of high flow pumping concrete, visible in the large volume of hydraulic concrete application of ultra-fine sand pumping concrete is feasible,the quality is reliable. |
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