振动搅拌工艺下UHPC力学性能研究

Study on Mechanical Properties of UHPC Based on Vibration Mixing Technology

在确定超高性能混凝土的原材料及配合比下,基于振动搅拌工艺研究了超高性能混凝土(UHPC)在不同砂胶比、粗骨料掺量下的工作性能和力学性能。研究结果表明,随着砂胶比的减小,UHPC的扩展度逐渐增大;在不同养护条件下,随着砂胶比的减小,其力学性能呈现出不同的变化规律;对于同一砂胶比条件下的UHPC,热水养护48h的抗压强度普遍大于标准养护28d结果,而抗折强度的结果却相反,但其抗压强度增加幅度明显大于抗折强度降低幅度。与不掺粗骨料的UHPC相比,加入粗骨料的UHPC扩展度增大,流动性更好;掺加粗骨料的抗压强度和抗折强度呈现不同的变化规律;在相同砂胶比下,随着粗骨料增加,抗压强度呈现先减小后增大的变化规律,而抗折强度明显降低。因此,实际工程应用中,在确保抗折强度满足要求的前提下,建议尽量采用热水养护;应在综合考虑UHPC的施工和易性与力学性能的基础上兼顾经济性要求。

In this paper, the working and mechanical properties of ultra-high performance concrete under different sand-binder ratios and coarse aggregate content are studied based on vibration mixing technology. The results show that the expansion degree of UHPC increases gradually with the decrease of sand-binder ratio;Under different curing conditions, the mechanical properties show different changes with the decrease of sand-binder ratio;For UHPC with the same sand-binder ratio, the compressive strength of hot water curing for 48 h is generally greater than that of standard curing for 28 d, while the result of flexural strength is the opposite, but the increase of compressive strength is significantly greater than the decrease of flexural strength. Compared with UHPC without coarse aggregate, UHPC with coarse aggregate has higher expansion and better fluidity;The compressive strength and flexural strength of coarse aggregate show different changes;Under the same sand-binder ratio, with the increase of coarse aggregate, the compressive strength decreases firstly and then increases, while the flexural strength decreases significantly. Therefore, in practical engineering application, on the premise of ensuring that the flexural strength meets the requirements, it is recommended to adopt hot water curing as far as possible;On the basis of comprehensively considering the construction workability and mechanical properties of ultra-high performance concrete, the requirements of economy should be taken into account.