CO2 concrete and its practical value utilising living lab methodologies

Abstract The sequestration of carbon dioxide into recycled aggregates for the enhancement of recycled aggregate concrete has provided an abundance of potential over recent years. The injection of carbon dioxide creates a strong concrete, known as CO2 Concrete, which can rival virgin aggregate concrete in overall performance. However, previous research only delves into small-scale testing. This paper demonstrates the potential for CO2 Concrete to be used in large-scale practical applications through living lab methodology. The compressive strength of CO2 Concrete offers great potential. After the carbon-conditioning of aggregate, the recycled aggregate concrete achieved the 95.1% strength when compared to the virgin aggregate concrete. Furthermore, it greatly surpassed the untreated recycled aggregate concrete which only exhibited a compressive strength of 64.76% when compared to the virgin aggregate concrete. This trend is also demonstrated by the two living lab projects. The living labs project consisted of two biosecurity platforms with a size of 780 mm long, 560 mm wide and 120 mm deep as well as four cattle drinking station slabs with a size of 3 m in length, 2.6 m in width and 0.2 m in thickness for agricultural use for Hawkesbury Campus, Western Sydney University. The biosecurity platforms are used for the cleaning of boots between paddocks in order to prevent the spread of disease whilst the slabs are utilised for the support of cattle drinking basins and to retain a desirable ground level, which would normally be eroded by cattle. The living labs achieved an outstanding 28-day compressive strength even surpassing virgin aggregate concrete on some occasions. The labs also demonstrated great durability. The employment of non-destructive testing shows the CO2 Concrete can preserve compressive strength under harsh agriculture conditions, which can include chemical attack, cattle movement and heavy machinery loading. After over a year and a half of practical application, the biosecurity platforms have not experienced depreciation according to the non-destructive testing. Visual inspections also reveal minimal degradation with only the sharp edges of the biosecurity platforms rounding over after a year and a half. The overall performance of CO2 Concrete is outstanding and has the potential to replace the typical virgin aggregate concrete.