Abstract: Thermal curing can improve the early mechanical properties of UHPC and promote hydration of UHPC, but it also brings about the water stability in the long-term of UHPC. The mechanical properties, SEM, XRD and pore structure analysis were used to study the long-term mechanical properties and microstructure of UHPC under three curing systems: 20 ℃ standard curing, 90 ℃ steam curing and 250 ℃ dry and hot curing which contact moisture and isolate moisture. The test results indicated that the contact and isolation water had little influence on the strength and microstructure of the specimen under 20 ℃ standard curing and 90 ℃ steam curing. The contact water could better improve the strength of the specimen in the later stage. The contact water would significantly increase the microscopic pores of the specimen, leading to obvious strength shrinkage in the later period and causing serious water stability problems under 250 ℃ dry curing.
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2021, Vol. 35 
