Influence of precuring on the pore structure of carbonated low heat portland cement paste with or without EVA

Carbonation of low heat Portland cement (LHC) paste without or modified with 5% ethylene/ vinyl acetate (EVA) copolymer under different precuring time in water were investigated. The amount of absorbed CO2 was measured by Total Organic Carbon Analyzer equipped with solid sample module. The pore size distribution was tested with mercury intrusion porosimetry. The results show that precuring is disadvantageous for both samples of LHC paste with or without EVA to absorbing CO2. The amounts of absorbed CO2 decrease with precuring time in water. Precured samples have less large capillary pores, but have comparatively higher total pore volume than those were not precured. The longer precuring time in water it is, the less large capillary pores it has. The pore volume and amount of absorbed CO2 also indicate that without precuring, adding 5% EVA to LHC paste would reduce the total pore volume, but lower the rate of CO2 absorption. The cumulative pore volume rises twice with the decrease of pore diameter in samples without precuring in water, which becomes the unique feature for the samples at longer carbonation time.