Papers by Keyword: Strength Recovery

Abstract: The self-healing capsule was prepared with paraffin as wall and EVA (ethylene vinyl acetate) emulsion as core through melting condensation dispersion method. The morphology and chemical structure of capsules were characterized by optical microscope and Fourier transform infrared spectroscopy (FTIR). The influence of the stirring rate and emulsion to paraffin ratio on core content of the capsule was investigated. The flexural strength of mortar incorporated with capsules was tested to assess the effect of capsule on mechanical property. In addition, the compressive strength of the mortar was tested before and after self-healing to evaluate the healing efficiency of the capsule. The result showed that the highest core content of the capsule can reach up to 55% under the conditions that stirring rate was 400 rpm and emulsion to paraffin ratio was 1:1. FTIR and optical micrograph of the capsule indicated that the EVA emulsion was contained in paraffin successfully. The dosage of capsules had little effect on mechanical properties of mortar when it was less than 5 wt%. The healing efficiency of mortar for compressive strength was up to 99% at capsule content of 5 wt%, preload of 60% f_max and curing time of 7 days, which meant that the microcracks can be healed efficiently with the EVA emulsion capsule.

Abstract: This research is aimed at investigating the effect of elevated temperature, curing duration and curing methods on the strength recovery of lightweight concrete. Concrete specimens were subjected to elevated temperatures ranging from 300 to 600°C in a controlled heating environment. The specimens were subjected to three types of curing conditions: continuous water curing at 27°C, curing in a relative humidity of 95% at 27°C and curing in water at 60°C for three days and then curing in water at 27°C. The curing duration ranged from 7 to 56 days. The results indicated that the re-curing of concrete for the recovery of compressive strength is most effective in the temperature range from 300 to 500°C. For temperatures outside the range of 300 to 500°C, re-curing was either not effective or had limited application.