Carbonation and curing of cement stabilised gravels for use in subbases

Abstract

Despite many years ofexperience with chemicalstabilization of road constructiongravelsandthe comprehensivestabilizationspecifications,a noticeableincrease inrelatedproblemshasbeen observed. One of the frequently reported challenges in the use of cement in stabilization is the occurrenceof carbonation during the stabilization process.Classificationtests on thesampled gravels[Laterites andBlack cotton gravel]werecarried outbefore stabilization.Carbonation testing wasconducted on the cured stabilized specimen by exposing themto carbon-dioxide in an accelerated carbonation processand phenolphthalein indicator wasused to determine occurrence of carbonation.Tests showed that, Lateritic gravel(soaked CBRof30%)wassuitable for use in subbaseconstructionwhileBlack cotton gravel(soaked CBRof 4%andLiquidlimit of 65.7%)wasnot suitable.Stabilization of the gravels with cement improved both gravel types to desirable standard.Carbonation in lateritic samples was to a negligible degree while in Black cottongravel,the carbonation depth was significant(between 1 mm to 4 mm).Based on thestudy findings,more research on this study topic should be conducted on gravelsfrom various locations andfield studies on carbonation and its effects on cement stabilized roads should be carried out in order to create better correlation with laboratory outcomes.