Mix Proportion Optimization Of Ordinary Pumping Concret

For commonly used in yinchuan and nearby strength grade of pumping concrete are prone to bleeding,segregation,poor uniformity,plastic shrinkage,such as surface pores more unhealthy phenomenon,a partnership with the Ningxia Ginza Commercial Concrete Co,Ltd.C30concrete as the research object,the application of the orthogonal experiment scheme L25(56),experiment research on the grey water ratio,sand ratio,unit water consumption,replacement ratio,excess rate,pumping agent dosage on the pumping effect of the common concrete workability and strength,discusses the mechanism of action.At the same time with fine aggregate silt content and fineness modulus as single factor,establishing single factor experiment,find out the different silt content and fineness modulus of relations with the workability and strength of concrete. Through the experimental study,obtained the following main conclusions:(1) the influence of slump concrete is the most important unit water use,followed by the amount of admixture,then fly ash replacement rate,again is the excess rate of fly ash. Cement water ratio and the influence of sand percentage minimum. Increase the slump with cement water ratio,fly ash excess rate increases slightly with increasing; sand ratio increases first,then decreases; rate increases with the fly ash replacement; water content increase obviously with the increase of unit,but when the water content is greater than a certain value,but also has the tendency of reduction with the increase of pumping agent; dosage increases,but when the content exceeds a certain value,the slump increases with pumping agent to reduce the extent.(2) The unit water and pumping agent content is the main influence factor of concrete expansion. When water and pump units send agent content increases to a certain extent,the concrete mixture slurry is too thin,the slurry flows rapidly since the stones,and stones separation,the stones together,but does not flow with the slurry,showing the slump reduce the expansion trend of increasing. With bleeding, bleeding phenomenon.(3) The effect of concrete expansion is the most important unit water use,followed by the amount of admixture,after four the expansion effect,and basically the same. The influence of sand percentage is minimum.(4) With increasing clay content of sand,concrete slump sharply decreased. The slump gradually decreased with increasing clay content. When the clay content≤3%,concrete slump is large,high mobility,strong workability.In>3%,slump sharply decreased. As the sand fineness modulus increases,the slump of concrete increases first and then decreases. Sand fineness modulus each decreased0.2,slump reduce about10-15cm.When the fineness modulus≤2.1.Concrete manifestation of dry,poor workability. In practice must be mixed with coarse sand; when the fineness modulus at2.7,the concrete workability is good;and>2.7,a downward trend slump,with the emergence of a bleeding phenomenon.(5) With the increase of clay content,pressure bleeding rate decreases,pump increases,but liquidity decrease. When5%,the fluidity of concrete is small;<3%,concrete fluidity is big and easy construction.But adjust sand ratio to avoid bleeding. When the fineness modulus of2.1,the bleeding rate was2.9,the minimum,the bleeding rate is close to40%. A significant increase in the rate of bleeding,when fineness modulus>2.9,is not conducive to the construction,pumpability is very small, will appear easily problem blocking the pump etc.(6) Cement water ratio is the main factor affecting the strength of concrete,substitution rate,the excess rate and pumping agent times,sand ratio and water content with minimal impact.(7) The relationship between strength and level of factor curve of7d,28d and56d showed that the age of concrete strength increased linearly with the increase of ash water ratio; little change with sand rate; and decreases approximately linearly with the increases the replacement rate of fly ash,but the decline decreases with increasing of age;with the increase of fly ash excess rate increases,and the increase along with the age tends to increase with the increase of water;with the increase of unit water,strength increased first and then decreased;with the increase of pumping agent dosage,strength also increases at first and then decreases.(8) Analysis of a linear relationship between the cement water ratio and strength:7d:fcu=24.276(c/w)-14.752R2=0.990028d:fcu=23.461(c/w)-2.2652R2=0.980956d:fcu=25.812(c/w)+0.5808R2=0.9782Seen from the R2value,ratio showed a strong linear correlation strength and ash water.(9) With the increase of clay content concrete strength decreases gradually. The early strength of concrete is growing faster and the late grow slow.The age of mud content and strength have a strong linear relationship. Display the compressive strength of7d,each increase of clay content of2%,the strength of concrete is reduced by about3MPa;display the compressive strength of28d,every increase mud weight2%,strength reduced about4MPa.When the clay content≥5%,28d concrete strength can not meet the design strength of38.2MPa.With the increase of the fineness modulus of sand,concrete strength decreased slightly,decreased greatly in between2-3MPa.(10) On the basis of the experimental results,considering the production cost and the optimum combination scheme. After many experiments the results successfully applied in production,the workability,the uniformity and the surface hole cut of concrete is improved significantly.Take each m3concrete cost5.00～10.00yuan saved.