Desenvolvimento de matrizes cimentícias de baixa alcalinidade para a produção de compósitos reforçados em benefício da Construção Civil.

Abstract

In the building site the composites to the cement base are the more used. However, the matrix of those composites don't present good resistance to traction efforts, in that way it is made the reinforcement of the matrix with other materials. The reinforcement with vegetable fibers has been having notable highlights for the fact of those fibers be renewable organic elements and no aggressive to the man. The portland cement matrix presents high alkalinity, that if it turns harmful to the resistance and durability of the composites for the fact of the fibers they be degraded by the hydroxide of dissolved calcium, reducing his/her capacity to check resistance wanted to the composite. With the purpose of reducing the alkalinity of the cement composites without altering their mechanical properties, in the present research it was substituted 50% of the portland cement by metakaolin and ceramic residue, that it are material addictive minerals. This research has as objective the obtaining of a cement matrix of low alkalinity through the partial substitution of Portland cement for metakaolin and ceramic residue. That substitution seeks the complete consumption of the hydroxide of calcium generated starting from the hydration of present calcium silicates in the cement, reducing the alkalinity of the matrix. In that way, it is permitted a subsequent reinforcement of that matrix with vegetable fibers. Five proportions different from substitution were used to the cement. To analyze the effect of the substitutions in the mechanical properties of the matrix rehearsals of simple compression they were accomplished. Rehearsals of differential thermal analysis (ATD) they were accomplished to observe the reduction of the alkalinity. Before the obtained results, it was verified in the rehearsal of ATD the reduction of the alkalinity for the substitution tenors used. Already for the resistance, it was verified that the largest values came in the largest metakaolin concentrations associated to a line with smaller percentile of sand.