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

Abstract

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%.

Keywords

• pozzolanic waste
• wood fly ash
• ground glass
• alkali-silica reaction
• cement mortar
• compressive strength
• expansion