CARBONATION OF CONCRETES WITH HIGH AMOUNT OF MINERAL ADDITIONS AND HYDRATED LIME / CARBONATAÇÃO DE CONCRETOS COM ALTOS TEORES DE ADIÇÕES MINERAIS E CAL HIDRATADA

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

The present worked aimed to study the effect of the addition of lime hydrated on the carbonation of concretes with high amount of mineral additions of fly ash, rice husk ash and blast furnance slag, in binary and ternary mixtures. The amount substitution varied of 50% to 90% of cement mass. The amount of lime were of 15% and 18%, on the aglomerant mass. They were accomplished to the whole 5 mixtures with mineral additions, with and without lime and the mixture of reference of 100% of Portland cement. The water cementitious materials (w/mc) ratio was of 0,35, 0,45 and 0,55. The mixtures was tested for carbonation, axial compression strength and remaining calcium hydroxide amount. The accelerated carbonation tests was with 5% of CO2 content, 75 2% of UR and temperature of 20 2 C. Rehearsals carbonation accelerated to 4, 8 and 12 weeks of exhibition in the conditioned camera were accomplished. The tests results were compared the mixtures with lime in relation to the mixtures without lime and the reference mixtures were analysed, in equality of w/mc ratio and in equality of resistance of 35, 45 and 55 MPa. The carbonated depths, the carbonation coefficients and the amount of remaining CH were compared. It is observed that the addition of hydrated lime in the mixtures decreases the carbonated depths and consequently the carbonation coefficients. As carbonation coefficient limits the value of 4 mm/sem0.5 being adopted, in equality of w/mc ratio of the 33 mixtures studied, 14 presented smaller coefficient. Of these 14 mixtures 8 they are with hydrated lime. In strength equality, of the 33 mixtures, 11 had smaller coefficient than the limit, and 7 were with addition of hydrated lime. The mixtures with blast furnance slag and the reference mixtures presented the best performance in front of the carbonation, the fact is due to the largest amount of calcium hydroxide of the same ones. The blast furnace slag presents superior calcium hydroxide results than fly ash and rice husk ash. It is concluded that the addition of lime is beneficial in the reduction of the carbonated depths of the mixtures with high mineral additions contents, and that the mixture with blast furnance slag presents very similar performance and even superior the reference one .

ASSUNTO(S)

carbonatação engenharia civil concreto cal hidratada construção civil engenharia civl

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