Experimental Study about Various Factors that Influence Quantitative Accuracy of CO2 Content in Carbonated Cementitious Material

We investigated a method to accurately quantify the amount of CO2 fixed in concrete. There are major measurement methods which have different sample decomposition process by acid (AC) and thermal decomposition (TC) method, and the type of CO2 which is able to be quantified is determined by the decomposition methods. Theoretically AC method can quantify only inorganic carbon in cementitious materials. On the other hand, CO2 content by TC method would be affected by organic and elemental carbon containing in the sample, because TC method cannot recognize those. In this study, we designed to compare the CO2 content of cement paste that does not contain organic carbon in the mix design by using AC and TC method. As the result, the TC measurement method showed higher CO2 content than AC method. It could be caused by the presence of carbon that cannot be decomposed by AC. In addition, analysis result of the residue after AC showed the CO2 which was not completely decomposed by AC seems to be remained on silica gel.