Influence of the addition of 2%, 3% and 5% of fly ash on the physical-mechanical properties of cement mortar

Abstract

The objective of this work was to evaluate the influence of the addition of coal fly ash, a residue from the manufacture of clay brick, in the manufacture of cement mortar; in order to reuse construction waste in the creation of new materials, reducing the cost of raw materials and contributing to the environment. The standard cement mortar designed for a resistance of 125 Kg / cm2 was compared with additions of 2%, 3% and 5% of fly ash, in axial compression, absorption and capillarity tests. The mortars with addition of 2% and 3% of fly ash reached the designed strength but did not exceed the standard mortar, with strengths of 129.04 Kg / cm2 and 128.33 Kg / cm2 respectively, while the addition of 5% reached 123.05 Kg / cm2. Capillarity with the addition of 2% decreases 29.59% in relation to the standard mortar, at 3% it increases 1.52% and at 5% it decreases 2.49%; the absorption in the 2% addition varies with the standard by 0.29%, in the other additions it increases. It is shown that the fly ash works as an artificial pozzolana, favoring the physical-mechanical properties of the hydraulic cement mortar, being viable its use in small additions.