Accelerated Carbonation of Portland Limestone Cement: Fid-Bau Portal

Accelerated Carbonation of Portland Limestone Cement

Shao, Yixin / Rostami, Vahid / He, Zhen / Boyd, Andrew J.

Accelerated carbonation is a process in which ${CO}_{2}$ is intentionally introduced to concrete at an early age for a short period of time to promote rapid strength gain. The accelerated carbonation of portland limestone cement (PLC) was studied to examine the possibility of replacing ordinary portland cement (OPC) by PLC in carbonation curing of precast concrete products. Carbonation behavior was characterized by strength gain, ${CO}_{2}$ uptake, pH change, XRD, TG, SEM, FTIR, and ${}^{29}{Si}$ NMR spectroscopy. It was found that PLC was a ${CO}_{2}$ reactive material. Its ${CO}_{2}$ uptake reached 12% based on dry cement mass. In reference to hydrated PLC, the strength of carbonated PLC was 79% higher at 20 h and of close value at 28 days, even though the ultimate ${CaCO}_{3}$ content in carbonated PLC was over 40%. The calcium carbonates produced by accelerated carbonation were found to be imbedded in calcium silicate hydrates, forming an intermingled microstructure. The high carbonation reactivity of PLC was possibly attributed to its fine particle size and the existence of limestone powder nuclei for calcium carbonate precipitation. The use of PLC in accelerated carbonation of concrete products can significantly contribute to a net gain in carbon emission reduction.