Research Of Effects Of Mechanism Sand Characteristics On Concrete

With the rapid development of construction industry, concrete consumption isgrowing, the natural sand resources will become more nervous, in many places,combating, diging has caused serious environmental pollution, application of part or allof mechanism sand replace natural sand as fine aggregate concrete is obvious. however,production process has important effect on characteristics of the mechanism sand,characteristics of mechanism sand and performance of mechanism sand concrete areclosely related, effect of stone powder content,MB value,of mechanism sand onworkability, mechanical properties, early cracking,dry shrinkage, resistance to chlorineion permeability, sulfate attack resistance of concrete was studied; Digital imageprocessing technique was used to study the mechanism of grain shape on the surface ofthe evaluation method and effect on properties of concret,software was used to optimizemix proportion of mechanism sand concrete. influence rule and main results as follows:1) Effect of stone powder content on mechanism sand concrete was studied, theresults showed that the amount of powder can improve the working performance andcompressive strength of concrete, under the condition of this experiment, when thestone powder content was3%~20%,For C30, C40and C60concrete, the bestworkability of concrete occurred when stone powder content were15%,10%and15%;When the stone powder c ntent were20%,10%and20%,28days compressive strengthof mechanism sand concrete reach maximum; stone powder content in the mechanismof sand can improve the resistance to sulfate attack of concrete performance.2) A proper amount of powder in the mechanism sand can improve sulfate attackresistance of concrete, against the chloride ion permeability, when the stone powdercontent in the scope of8%~10%, the drying shrinkage of concrete growing fastest.3) Influence factors of mechanism sand of MB value was studied,Effect of stonepowder content on MB value less affected, clay powder content, type and fineness ofclay had a greater influence on MB, correlation coefficient clay powder content and MBwas R2=0.991; Under the condition of such content, MB values increased withfinenessof clay powder or stone powder increasesd;4)Workability of mechanism sand concrete of concrete is along with the increaseof MB value decreases, and the compressive strength is first increases and then decreases with increase of MB value, when the clay powder content increased from0%to5%, MB value increased from0.3to4.65; Plastic cracking of concrete increased withthe increasing of MB value, resistance to chloride ion permeability decreased with theincreasing of MB, under this experimental condition, MB value increased from0.3to0.3, resistance to chloride ion penetration level of C60concrete fell from Q-Ⅳ to Q-Ⅲ.5) Digital image processing technique of MATLAB and IPP software was used toevaluate grain shape on the surface of mechanism sand, two-dimensional roundness andthree-dimensional sphericity were used as evaluation index, correlation coefficientbetween roundness and folw of cement motar was R2=0.717,while sphericity was R2=0.689,, correlation coefficient between sphericity and void rate was highest, R2=0.908;Roundness and the correlation of minimum flow time, R2=0.71.Compared withmechanical of concrete, effect of surface grain shape of mechanism sand on workabilitywas greater.6) Combined with sand stone powder contentof mechanism sand, MB value,MATLAB software optimize function was used to ptimize mix proportion of C30mechanism sand of concrete. workability and mechanical properties of concrete wereensured after optimization, improved economic effect.