含粗骨料超高性能混凝土静态稳定性研究

Static Stability of Ultra-High Performance Concrete Containing Coarse Aggregate

为改善含粗骨料超高性能混凝土(CA-UHPC)整体静态稳定性,采用图像技术分别研究了拌合物(未加纤维)流变参数、粗骨料掺量和粗骨料级配对不含纤维和含纤维CA-UHPC静态稳定性的影响规律。结果表明:粗骨料整体均匀性随粗骨料平均初始净距的减小而升高;当拌合物的屈服应力和塑性粘度较小时,纤维分布的均匀性会因纤维沉降而降低;纤维的加入降低了粗骨料的整体均匀性,同时粗骨料也会影响纤维的整体均匀性;对CA-UHPC体系而言,粗骨料平均初始净距的减小可以增加粗骨料分布稳定性,但过小的粗骨料平均初始净距会影响纤维的分布。因此,在粗骨料掺量一定时,可以通过适当调整粗骨料级配或砂率,在不影响粗骨料分布稳定性的前提下,提高纤维分布系数。

In order to improve the overall static stability of ultra-high performance concrete containing coarse aggregate(CA-UHPC),the image analysis was employed to investigate the effects of rheological parameters of the mixture(before adding fiber),coarse aggregate content and coarse aggregate gradation on the static stability of CA-UHPC without fiber and with fiber.The results show that the overall uniformity of coarse aggregate increases with the decrease of the average initial clear distance of coarse aggregate.When the yield stress and plastic viscosity of the mixture are small,the uniformity of fiber distribution decreases due to fiber settlement.The addition of fiber reduces the overall uniformity of coarse aggregate,and the coarse aggregate also affects the uniform distribution of fiber.For the CA-UHPC system,the reduction of the average initial clear distance of coarse aggregate particles increases the distribution stability of coarse aggregate,but too low average initial clear distance between coarse aggregate particles affects the distribution of fiber.Therefore,when the content of coarse aggregate is constant,the fiber distribution coefficient can increase without affecting the stability of coarse aggregate by adjusting the coarse aggregate gradation or sand ratio.