Influência da área específica na reatividade do sistema pozolana-cal visando a obtenção de aglomerantes alternativos.

Abstract

The constant looks for alternative materials of low cost and good mechanical properties, besides the ecological problems, caused by the growing of solid volume residues from civil construction industry, motivated the development of this work. The main objective of this work is to study the influence of specific area of rejects of ceramic industry and waste of civil construction in the system pozzolana-lime, also to obtain alternative cement of low cost. For this purpose, two samples of lime (hydrated lime), two samples of rejects (waste from civil construction), one sample from rejects of bricks and tiles (from the industry) and one sample of artificial pozzolana (as reference) were selected. All sample were characterised by chemical analysis, thermal differential analysis, thermogravimetry and X-ray diffraction. The wastes samples and ceramic residue were ground in a ball mill for periods of 10, 30, 60 and 90min, while the sample of artificial pozzolana, was ground in a disk mill, with different opening between the disks, to obtain different specific areas, determined by the Blaine method. The pozolanic activity, as function of the specific area of the rejects and the pozzolanics materials, was evaluated through the consumption of lime, index of pozzolanic activity with lime and simple compression strength (for mortars of lime pozzolana cement). Those mortars were prepared in the proportion of 1:3 (one part of lime pozzolana cement, and three parts of standard sand), in the normal consistency and in the compositions of 30-70%, 40-60% and 50-50% of lime and pozzolana. The specimens were cured for periods of 7, 28 and 60 days. Additionally, it was made a statistical analyses of the results, through simple linear correlations, to verify the correlation degree between the specific area (of the rejects and pozzolanics materials) and the mechanical properties of the mortars prepared with these materials. The obtained results shown the specific area of ceramic rejects and wastes from the civil construction has a great influence in the pozzolanic properties.