Alkaline activation of mortars made from solid construction waste [Activación alcalina de morteros fabricados a partir de residuos sólidos de construcción]

Abstract

In the present investigation the influence of the percentage by weight of replacement of portland cement (PC) by recycled concrete powder (RCP), alkaline activated, in percentages of 10%, 20%, 30%, 40% and 50%, was evaluated. which were selected from construction rubble left in the Buenos Aires spa, Víctor Larco Herrera district, Trujillo province. After being washed, they went to the grinding and sieving process (400 mesh), using only the through material. Specimens were manufactured according to the ASTM C-109 standard for the compression test in cement mortars, for the alkaline solution NaOH (4M) was used. The mortars obtained were cured in an oven at 70 ° C for 72 hours, and subsequently the curing was completed at room temperature, for a total time of 28 days. The results of the average compression test were 12.15 MPa, in the case of the PC mortar and 14.25 MPa in the best case (PC mortar and RCP-10%), the increase being 17.28%. The mix design using coarse sand and binder was kept constant at (3: 1), while the water / cement ratio (w / c) was 0.6 in all cases. The reason for the increase in compressive strength is due to the reaction between the RCP particles, alkaline solution and the calcium hydroxide produced during the hydration of the cement particles, which generate gels (CASH), which occupy the spaces left by the hydration process of the aforementioned cement particles, as they need calcium hydroxide. For all cases of the compression test, a total of 10 repetitions were carried out.