Research On The Pumpability Evaluation Of Ready-mixed Concrete

With the development of concrete pumping technology, along with the problems also gradually increased, how to realize the smooth progress of pumping concrete, and make it keep its workability has become a hot topic in today’s engineering.In practical engineering, the concrete will be affected by many factors in the process of pumping interference, The phenomenon such as "tube", "pump". Investigate its reason, on the one hand, the reasion is that the diversity of the material, another important factor is lacking of evaluation methods of pumping concrete mixture, with is becoming a important problem whether the pumping construction smoothly, therefore, pumpability of concrete evaluation method research is particularly important.This paper is based on the study of working performance of common concrete, considering concrete fluidity and segregation resistance and adhesiveness, by examining the actual pumping process, selecting commonly ordinary concrete（strength grade is: C30, C40, C50）, dividing a good pumping performance area, and seting up the relationship between pumpability and guideline of workability. The results show that: 1) the trend of the concrete to the high fluidity, most of slump is concentrated in more than 180mm;2) when the concreteis betweenof 190mm≤slump≤240mm, and 400mm≤expansion≤600mm;or400mm≤expansion≤600mm, and when the flow empty time slump is between 4¹0 s, the pumpability is good, 3) the V₁₀, S₁₀of concrete should be small, S_140-10 keep between 60 to 85%; Ratio is associated with the misjudgement of pumpability of concrete, when the slump ≥ 160 mm, or 2<R≤3, it can reduce the misjudgement of good pumpability.Using grey theory to analyze the evaluation method and the results show that the comprehensive correlation of concrete pumpability which are used evaluation indexes and ratio method are around 0.5, the reliability of the evaluation method is also low.This paper try to adopt a towed concrete pump tester, using P/Q curve to forecast the concrete pumping pressure loss. On this basis, the analysis of pumpability evaluation index, the results show that in P_t60 start/P_t0 start <1.3 and P_t60 lubrication/P_t0 lubrication <1.2, the pumpability of concrete is good. By the tester to evaluate the pumpability of pumping concrete, avoid pumping "accidental" problems in the construction. At the same time, it has important guiding significancethe for pumping concrete mixture.