THE EFFECT OF POZZOLANIC WASTE AS CEMENT SUBSTITUTE ON THE PROPERTIES OF CEMENT MORTAR AND RESISTANCE TO ALKALI-SILICA REACTION

The article analyses the effect of pozzolanic waste on the properties of cement mortar.Seven batches of specimens were made for the tests: control specimens without any pozzolanic waste, three batches of specimens where cement was replaced with 5, 10 and 15 % of wood fly ash, and three batches of specimens where cement was replaced with 5, 10 and 15 % of ground glass.The replacement of 5 % of cement with pozzolanic waste in the mix increased the density, the ultrasonic pulse velocity, compressive and flexural strengths of the mortar.A further increase of pozzolanic waste content degraded the values of physical and mechanical properties, as the lower amount of cement did not ensure a strong bond between the aggregate and the cement matrix.The alkali-silica reaction tests revealed that the expansion of the specimens containing 5 % of pozzolanic waste as cement replacement does not the permissible limit of 0.1 %.With the increase of pozzolanic waste content up to 15 %, the expansion of specimens modified with wood fly ash continues decreasing down to the limit of 0.01 %, whereas the expansion of the specimens modified with ground glass starts increasing to the limit of 0.05 %.