Use of carbonated water to improve the mechanical properties and reduce the carbon footprint of cement-based materials with recycled aggregates

Carbon curing of cement-based materials shows great potential for reducing the carbon footprint and improving the physical-mechanical properties. Accelerated carbonatation is usually carried out by increasing the CO2 concentration in the curing atmosphere. The use of carbonated water (source of CO2) as mixing water is an alternative that has great potential in the manufacture of in-situ cement-based materials. This study evaluated the effect of the use of carbonated water used as the mixing and/or curing solvent on cement-based material properties at an early curing age, as well as the CO2 sequestration capacity. Three variables of a porous cement-based material were tested: (i) type of aggregate (natural aggregate (NA) or recycled masonry aggregate (RMA)), (ii) type of water mixing (normal water or carbonated water), and (iii) type of curing regime (air curing or water curing with normal or carbonated water). The use of commercial carbonated water as the mixing solvent and RMA increased the CO2 sequestered by 181 % with respect to the reference material after 7 d of curing. Commercial carbonated water as the mixing solvent favoured the carbonation phenomenon and improved the physical-mechanical properties of cured samples, except for cement-based materials prepared with NA having a curing age of 1 d. Curing with normal or carbonated water is not recommended to increase the CO2 capture capacity or increase the physical-mechanical properties of cement-based materials. The best variable compared to the others tested was the use of carbonated water as mixing water.