Comparación de la resistencia a compresión de hormigones con una dosificación de 210 kg/cm², fabricados mediante un método convencional y con la incorporación del 5%, 10% y 15 % de la ceniza de la pepa de aguacate

Abstract

Agro-industrial waste has become a major nuisance for the population and, more importantly, has a significant impact on the environment, as these residues are often not disposed of in an environmentally friendly manner. For this reason, the present experimental study focused on producing a sustainable concrete through the partial incorporation of avocado pit ash, aiming to achieve a mix with a compressive strength of 210 kg/cm². To accomplish this, the largest possible quantity of avocado pits was collected and subjected to several processes to obtain the ash, including crushing, drying, dehydration, grinding, and calcination. Once the ash was obtained, the materials used for the concrete mixtures were collected and tested in the laboratory through moisture content, specific gravity, water absorption capacity, and particle size distribution analyses. After obtaining the necessary parameters, the mix design was developed using the ACI 318-11 method, which guided the preparation of the test specimens and the calculation of the partial replacement percentages of fine aggregate with avocado pit ash. After an exhaustive preparation of each cylinder used as samples for evaluating the compressive strength of the concrete, the results showed that the incorporation of avocado pit ash (APA) did not provide any improvement in the mechanical properties of the material. At 7 days, the 5% replacement reduced compressive strength by 93.64%, while the 10% and 15% mixtures showed reductions of 96.46% and 98.20%, respectively, due to the high K₂O content, which hindered initial hydration and the formation of C-S-H gel. At 14 days, the specimens exhibited unusual behavior, as no strength gain was observed; instead, strength values decreased by 95.07%, 97.20%, and 98.58% compared with the control mix. Finally, at 28 days, the control mixture reached a compressive strength of 242.68 kg/cm², exceeding the target value. In contrast, the specimens with partial APA replacement showed extremely low strengths: 8.87 kg/cm² (5%), 5.05 kg/cm² (10%), and 2.57 kg/cm² (15%), reflecting reductions greater than 95% compared with the conventionally produced specimen. These results demonstrate that, unlike other agro-industrial wastes, avocado pit ash used as a partial replacement of fine aggregate cannot be considered a viable material for improving the mechanical behavior of concrete.