Influence of Curing Conditions on Properties of Normal and High Strength Concrete with and without Pre-Wetted Lightweight Aggregates

Abstract

This paper presents the results of an experimental study conducted to evaluate the effect of curing conditions on the properties of normal and high strength concrete (NSC and HSC) with and without pre-wetted lightweight aggregates (LWAs). Cylinder specimens were drilled out from square concrete slabs subjected to four curing regimes (i.e. standard, water, natural and sealed curing) respectively, and then tested to obtain the compressive strength after 60 days. Three discs cut along the height direction of cylinder specimens (top, middle and bottom) were used to orderly measure the ultrasonic pulse velocity (UPV), open porosity, water absorption and splitting tensile strength. Afterwards, the comprehensive evaluation index, i.e. relative curing efficiency (RCE), was proposed based on the testing results above to quantitatively assess the effect of curing conditions on the physical properties of concrete. The experimental results indicated that curing conditions significantly influence the strengths and durability-related properties of NSC and HSC. The linear correlation can be obtained between sorptivity and open porosity of concrete under various curing conditions. Furthermore, in terms of the RCE analysis, the durability-related properties are more sensitive to the curing conditions than strengths for NSC and HSC.

Effect of the curing type on the mechanical properties of lightweight concrete with polypropylene and steel fibres

“…This may be due to the fact that over time the free water in concrete mixes under air-dry uncontrolled curing evaporated and the trapped water molecules in LECA were given back to the empty capillary pores to react with cement particles and complete the hydration process at older ages ( Fig. 7), similarly to what Wang et al [57] reported. The fibres content has no effect on the hydration process of concrete materials.…”

“…Wang et al [57], while the external water vapour particles in the 90 °C vapour curing are much less dense than those of external liquid water as reported by Firestone [73]; thus, they can easily penetrate the concrete specimens in depth as seen in Fig. 8.…”

“…For further investigation, the present study is an effort to assess the effect of SF and PF at various volume contents on the mechanical properties of concrete incorporating LECA with W/B ratios of 0.37 and 0.42 at 3, 7, 28 and 60 days. Since the curing regime and age can affect the mechanical properties of concrete materials [50][51][52][53][54][55] and wet curing condition appear to be highly effective in improving the compressive strength of fibre reinforced concrete (FRC) and LC [56,57], cubic and cylindrical specimens were cured under six curing conditions: wet, 3-day wet, 14-day wet, air-dry controlled, air-dry uncontrolled, and 90 °C vapour. Therefore, the concrete specimens were cured by immersion in a water tank and taken out after different ages; then, the results of these specimens were compared with those cured under 90 °C vapour curing condition.…”