Carbonation resistance of concrete: limestone addition effect

Systematic analysis and evaluation of experimental results on carbonation and carbonation-induced corrosion resistance of concrete made with Portland limestone cement (PLC) are presented; these results have been extracted from 143 globally published studies in the literature since 1986, by 274 researchers from 131 institutions and 34 countries, and yielding a 19 000 data matrix are presented. It is shown that the carbonation of concrete increases with increasing limestone content, within the range permitted by standard BS EN 197-1:2011. This effect, however, is less marked for concrete designed on an equal strength basis to the corresponding Portland cement (PC) concrete than concrete designed on an equal water/cement (w/c) basis. Eurocode 2 standard specifications for XC3 carbonation exposure for characteristic cube strength of concrete (or its w/c ratio) may need to be reviewed for the addition of limestone. Other influencing factors: curing, limestone fineness, total cement content, were also studied. A comparison has been conducted for the carbonation performance of concrete made with PLC and cement containing fly ash and ground granulated blast-furnace slag. Procedures to reduce the carbonation of PLC concrete are proposed. Response to accelerated carbonation, at 3–5% carbon dioxide concentration, of PLC concrete is similar to natural indoor exposure. A conversion factor of 1 week accelerated carbonation equal to 0·75 year natural indoor exposure was determined.