Experimental study on the effect of lime and aluminium content on porosity, introduced porosity, compressive strength and thermal conductivity of a lightweight cellular concrete based on limestone sand

Abstract

The aim of this work is to promote the valorization of limestone sand coming from limestone crushing stations residues in aerated concrete manufacturing without autoclaving process. This study has been undertaken to investigate the effect of lime and aluminum content on the porosity, especially the introduced porosity, compressive strength and thermal conductivity of cellular concretes elaborated from limestone sand, hydraulic binder (cement and lime mix) and aluminum powder as expansive agent. A series of 20 compositions of limestone sand cellular concretes (LSCC) with different percentages of cement, lime and aluminum powder are manufactured and tested herein.

A preliminary optimisation study was carried out to optimise the rate of fines in limestone sand and the composition of the control mortar. This study concluded that the exploited limestone sand can be used in its raw state and without any preliminary treatment. Experimental results on physicomechanical and thermal properties of elaborated materials reveal that: (i) The introduction of lime as partial substitution of cement tended to increase the total porosity as well as the introduced porosity of LSCCs matrix. It was shown that the porosity introduced by the expansion phenomenon increases as a function of the aluminium content, while the porosity introduced by the effect of lime dosage decreases as the aluminium content increases. (ii) The compressive strength of manufactured materials decreases considerably with increasing aluminium content and for different lime dosages.. (iii) The thermal conductivity of LSCCs decreases with increasing lime dosage and aluminium content. (iv) Finally, the limestone sand can be used in the fabrication of lightweight cellular concrete under the condition that, the lime and aluminium content must not exceed 50% and 0.50% respectively with respect to the weight of binder.