UHPC 养护温度对力学性能的影响

Effect of UHPC Curing Temperature on Mechanical Properties

摘要:

众所周知，热养护能够显著提升UHPC的早期强度，但目前工程应用中，较高的养护温度（≥80℃）通常实现较为困难，与日益增长的绿色环保需求相违背。为了推广UHPC应用与指导工程项目的施工，提出相对容易实现的低温（30~70℃）热养护，研究30℃、50℃、70℃、90℃条件下先分别热水养护1 d、2 d、3 d和4 d的力学性能发展情况，同时与标养28 d之后的力学性能进行对比。结果表明，在30℃、50℃和70℃条件下养护4 d后，抗压强度分别是90℃热水养护2 d的69.4%、88.6%和92.9%，是标养28 d的83.8%、107.0%和112.2%。抗弯拉强度随温度和养护时间增长的变化幅度相对较小，几种养护温度4d的抗弯拉强度偏差在4%以内。可见相对低温的热养护能够满足对UHPC力学性能的要求。

Abstract:

As is well known, the thermal curing can significantly improve the early strength of UHPC, but currently in engineering applications, it is more difficult to realize the higher curing temperatures (≥80℃), which departs from the increasing green environmental protection demand. In order to promote the application of UHPC and guide the construction of engineering projects, a low-temperature (30℃~70℃) thermal curing relatively easy to realize is proposed. The mechanical performance development of hot water curing for 1 d, 2 d, 3 d and 4 d under the conditions of 30℃, 50℃, 70℃ and 90℃ is studied, and compared with the strength of standard cured 28 d specimens. The results show that after 4 days of curing at 30℃, 50℃ and 70℃, the compressive strength is 69.4%, 88.6% and 92.9% of the 90℃ hot water curing for 2 d respectively, and is 83.8%, 107.0% and 112.2% of the standard curing for 28 d. The variation of bending tensile strength with the increase of temperature and curing time is relatively small, and the deviation of bending tensile strength at several curing temperatures for 4 d is within 4%. It can be seen that the relatively low temperature thermal curing can meet the requirements for the mechanical properties of UHPC.