Evaluation of Physical and Mechanical Properties of Concrete Using Coffee Husk Ash and Ichu as Cement Substitutes

Resumen

Due to its durability and strength, concrete is the most widely used material in construction. However, its production requires large amounts of resources and is responsible for global CO2 emissions, primarily due to cement manufacturing. This situation underscores the need for sustainable alternatives that reduce environmental impact without compromising concrete's properties. This research evaluates the effect of partially replacing cement with coffee husk ash (CHA) at proportions of 3%, 6%, and 10% and ichu ash (IA) at proportions of 1% and 4%, analyzing their impact on the physical and mechanical properties of the concrete. Ten mix designs were developed using fifty cylindrical specimens through multifactorial analysis. The results of the fresh-state tests showed that increasing the ash content reduces slump due to its high water absorption, while the temperature remains stable. Furthermore, in the hardened state, the best performance was obtained with 6% CCC and 4% CI, achieving a compressive strength of 36.76 MPa and an indirect tensile strength of 3.90 MPa, representing increases of 24% and 39%, respectively, compared to the control concrete. Taken together, the results demonstrate that the controlled use of these ashes is viable and contributes to improving concrete performance. They also prove that it is possible to enhance the structural performance of concrete through eco-efficient partial substitutions.