外加剂对聚丙烯喷射混凝土强度的影响

Effects of Admixtures on the Strength of Polypropylene Sprayed Concrete

目的研究高效外加剂对聚丙烯喷射混凝土工作性能和力学性能的影响。方法通过拌合物性能测试和力学试验,分析速凝剂、减水剂和膨胀剂对混凝土坍落度和强度的影响。利用多项式拟合的方法,预测速凝剂和减水剂掺量对混凝土28d抗拉和抗压强度的影响规律。结果4%的速凝剂可以提高混凝土早期强度78%;0.5%的聚羧酸减水剂,相比0.3%和0.7%的掺量可以提高9%的抗压强度和29%的抗拉强度,且具有良好的和易性;6%的CSA膨胀剂,可以提高混凝土28d抗压强度10%。拟合曲线的决定系数均高于0.975。外加剂的最佳掺量为0.5%的聚羧酸减水剂、4%的速凝剂和6%的CSA膨胀剂。结论多项式拟合曲线的预测结果和试验结果较吻合。掺入适量外加剂的聚丙烯喷射混凝土具有良好的流动性和较高的早期强度,且后期强度损失较小。

To study the effect of high-efficiency admixtures on polypropylene sprayed concrete,experimental study for its slump and strength had been taken.The admixtures contain accelerator,plasticizer and expansion agent.Polynomial fitting was used to predict the strength of sprayed concrete at the age of 28 days,influenced by the dosage of accelerator and plasticizer.The results show that the early strength of concrete increases by 78%when the dosage of accelerator is 4%.Comparing with 0.3%and 0.7%,0.5%of polycarboxylate superplasticizer increases the compressive strength of concrete by 9%and the tensile strength by 29%,while having good workability.6%of CSA expansion agent increases the 28d compressive strength of concrete by 10%.The determination coefficients of fitting curves are higher than 0.975.The optimal dosages of accelerator,plasticizer and expansion agent are 4%,0.5%and 6%,respectively.The predicted results of polynomial fitting curves are in good agreement with the test results.Polypropylene sprayed concrete with appropriate amount of admixtures has good workability and higher early strength,while having less later strength loss.