煮沸吸水-热干养护对超高性能混凝土强度和收缩率的影响

Effect of Boiling Water Absorption and Heat Dry Curing on Strength and Shrinkage of UHPC

超高性能混凝土(UHPC,Ultra-high Performance Concrete)试块采用常规蒸汽养护,抗压强度最高仅能达到250 MPa。为了进一步提升UHPC的综合性能,文章对脱模后的UHPC试块先进行煮沸吸水,后进行热干养护,考察其对UHPC力学性能、收缩率的影响,并表征分析了试块表层和内部的未水化水泥和空隙率。结果表明,相对于常规蒸汽养护,采用煮沸吸水-热干养护后,UHPC的抗折抗压强度明显提升,收缩率显著降低。EPMA分析结果表明煮沸吸水-热干养护后的试块表层和内部的未水化水泥和空隙率相较于常规蒸汽养护显著降低。

The Ultra-high Performance Concrete(UHPC)test block can achieve the maximum compressive strength of only 250 MPa after it is cured by conventional steam.In order to further improve the comprehensive performance of UHPC,the demoulded UHPC test block is first boiled and water is absorbed,and then cured by the heat drying method,the effect of which on the mechanical property and shrinkage of UHPC are investigated,and the unhydrated cement and voidage on the surface and inside of the test block are also characterized and analyzed.The results show that compared with the conventional steam curing,after boiling water absorption and heat dry curing,the flexural and compressive strength of UHPC is significantly improved,and the shrinkage rate is significantly reduced.The results of EPMA analysis reveal that the unhydrated cement and voidage on the surface and inside of the test block after curing are also dramatically decreased.