Effect of Curing Regime on the Mechanical Strength, Hydration, and Microstructure of Ecological Ultrahigh-Performance Concrete (EUHPC)

Abstract

This paper investigates the effect of curing regimes (standard and steam curing) on the mechanical strength, hydration, and microstructure of ecological ultrahigh-performance concrete (EUHPC). The flowability, compressive strength, flexural strength, hydration, porosity, pore size distribution, and microstructure of UHPC with different contents of supplementary materials (silica fume, fly ash, and ground granulated blast furnace slag) were assessed. The test results showed that the compressive strength of EUHPC under steam curing was increased considerably compared to that under standard curing, while the flexural strength was mildly decreased. The steam curing could decrease the porosity of EUHPC, which ranged between 7% and 9% for standard curing, and between 3.5% and 5% for steam curing. The aperture of EUHPC was below 20 nm, mainly located in the range of 10 nm to 20 nm under standard curing, while it was less than 10 nm for steam curing. C–S–H gel was produced under steam curing, while unhydrated fly ash, mineral powder, and Ca(OH)2 crystal were observed in the amorphous C–S–H gel. The microstructure of EUHPC under steam curing was denser than that under standard curing, and the interfacial transition zones under both curing regimes were compact.

Ultra-high Performance Concrete as a Sustainable Structural Composite

“…Tanvir Ahmed found that compressive strength, flexure and tensile strength reduced 54%, 56% and 54% due to varying percentages of fly ash and w/b ratio of mixes [18]. Zhiwu Zuo found an increase in compressive and flexural strengths of UHPC at 28 days, 161.5 MPa and 44.9 MPa under steam curing, compared to standard room curing [19]. Šahmenko used short steel fiber (SSF), carbon fiber (CF), and combination for both high strength and fracture energy [20].…”

Experimental Study on Compressive Strength of Concrete Under Simple Curing and Encased in Steel Mould

“…Also ascertained that concrete attained higher strength and durability with Wet sand curing method than other curing methods (Immersing in water, Water spraying, apply curing compound and No curing) and immersing in water curing concrete properties closer to Wet sand curing concrete properties. Zuo et al [15] investigated the effect of curing regimes (standard and steam curing) on the mechanical strength, hydration, and microstructure of ecological ultrahigh-performance concrete (EUHPC). The test results showed that the compressive strength of EUHPC under steam curing was increased considerably compared to that under standard curing, while the flexural strength was mildly decreased.…”