Study on flexural properties of active magnesia carbonation concrete with fly ash content

The fly ash activated magnesia carbonized concrete developed based on cement carbonization technology is a new type of cement-based composite material, the effects of four different proportions of fly ash and active magnesium oxide on the flexural and ductile failure of carbonized concrete were studied. The results show that the early flexural strength of magnesia carbonized concrete decreases with the increase of fly ash content, the flexural strength increases obviously during 0-7 days of carbonation curing. Afterwards, there is a flat growth, then increases significantly after 21-28 days of curing. The increase of fly ash content has a high stimulatory effect on ductility, which slows down the brittle failure of the test block. However, excessive fly ash content will also have a negative impact on the strength and performance. The optimum value is verified by the relationship between strain-time curve, the optimum mixing amount of fly ash is 0.3, and the ratio of water to glue is 1:1. Microscopic test results verify the magnesium carbonized products of Nesquehonite, Dypingite and Hydromagnesite are the main reasons for improving the flexural properties.