EFFECT OF EXTERNAL SULPHATES ON PROPERTIES OF LIME-POZOLANA CONCRETE

الملخص

This study aims to evaluate the resistance of Lime-Pozzolana concrete mixtures to external sulfate attack, represented by studying their effect on compressive strength, splitting tensile strength, dynamic modulus of elasticity, and weight loss. Three types of pozzolanic materials are used in concrete mixtures; Silica fume (as LS mix), Silica fume-Fly ash (LSF), and Metakaolin (LMK). LS and LSF mixture was exposed to 5% concentration of MgSO4 solution, while LMK mix was exposed to 5% concentration of NaSO4 solution until 210 days after moist curing in tap water until 14 days age. Results indicate that specimens of mixtures (LS and LSF) didn’t disintegrate when subjected to the very harsh environment of MgSO4 solution until 210 days of age. There was no visual sign of deterioration nor a significant loss in specimens weight of the two mixes at the end period of exposure of 210 days age. While LMK mix specimens disintegrate at 180 days of age due to exposure to Na2SO4 solution.