The Influences Of Wastewater In Concrete Pump On The Performance Of Different-strength Grades

Wastewater from concrete batching plant has a high Ca(OH)₂ content,which leads to the pH over 13. Some cement hydration products and residual additives are also found in the wastewater. The influences of wastewater recovery on moderate strength concrete haven't been researched systematically, and the effects on high strength concrete haven't been studied in detail. In view of this condition, the Influences of wastewater of concrete mixing plant on the performance of different-strength grade of pump concrete were systematically studied .The effects of different dosages of wastewater on the performance of moderate strength concrete have been studied. The results show that these properties and their effect on the performance of cement unnoticed; The differences in compressive strength of low strength grade of concrete contained different dosage wastewater were not significant. However, resistance in carbonation ability was reduced significantly by mixing wastewater. With the increasing dosage, the carbonation depth decreased.The influences of the wastewater of concrete plant on the compressive strength of C80 concrete made of A-type mineral admixture without silicon fume and B-type mineral admixture with silicon fume were investigated. Based on XRD and SEM analyses of 7d and 28d hardened cement pastes made of wastewater, tap water and two types of mineral admixture, the influence mechanism was discussed. The results show that for C80 concrete made of A-type mineral admixture,the wastewater added can decrease the early strength due to the retardering action of wastewater; for C80 concrete made of B-type mineral admixture, the wastewater can increase the early strength due to the stronger secondary hydration of silicon fume resulting from the high early pozzolana reactivity of silicon fume and high content of Ca(OH)₂ in wastewater; the wastewater added slightly affects concrete late strength because the high content of Ca(OH)₂ in wastewater is helpful to improve the secondary hydration of mineral admixtures, the late strength of concrete mixed by wastewater is slightly more than that of concrete mixed by tap water.