Case Studies in Construction Materials (Jul 2024)
Internal curing of high strength concrete based on saturated microporous cenospheres
Abstract
The development of high-strength concrete is hindered by its substantial autogenous shrinkage. However, the implementation of internal curing technology has been shown to mitigate this autogenous shrinkage of concrete effectively. Nevertheless, the existing internal curing technique encounters issues, including oversized material particles; this heightens disturbance within the concrete and impacts its overall performance. This study used the water-sieving method to propose microporous cenospheres with micrometer-sized pores from the industrial fly ash. Subsequently, a new internal curing material, saturated microporous cenospheres, was prepared by vacuum adsorption. The three additive amounts of saturated microporous cenospheres were added to concrete mixes using the equal volume sand replacement method to study its effect on the autogenous shrinkage and strength of concrete. The results showed that the micron-sized pores of saturated microporous cenospheres were good channels for water release, and the hollow structure inside had ample water storage space. The water absorption rate exhibited by saturated microporous cenospheres reached a significant value of 147.86%. The saturated microporous cenospheres exhibited a water release ability of 11.9% and 99.1% when exposed to humidity levels of 85% and 50%, respectively. The autogenous shrinkage of high-strength concrete was significantly improved by adding saturated microporous cenospheres. The maximum reduction in autogenous shrinkage of high-strength concrete was 87.5%. Although adding saturated microporous cenospheres affected the concrete strength, the concrete strength still met the requirements for use. These results indicate that saturated microporous cenospheres are suitable materials to reduce autogenous shrinkage of high-strength concrete and have great potential for internal curing.
