EFFECT OF BLENDING SAND FROM DIFFERENT SOURCES ON COMPRESIVE STRENGTH OF CONCRETE 'CASE STUDY OF WESTERN KENYA

Abstract

which exhibit different formation process. Previous research has extensively examined sand properties according to standards such as BS 812 and KS-02-21. However, limited information is available concerning the blending of sands from diverse sources, encompassing their properties and contribution of silt content, to optimize concrete production. Therefore, the study is to address the application of blending to enhance a sustainable use of sand within the construction industry. This study aims to assess silt levels of sand in use and its effect on concrete compressive strength. In examining the impact of utilizing blended sands from 13 sources, characterized by varying silt content, on concrete strength within the context of western Kenya. To achieve this objectives, an experimental method approach was adopted, involving the sampling of sands from different formation of pits, river bed, seasonal rivers beds and lake shores in 13 sand mining sites. Silt content analysis on neat sand revealed values ranging from 2.4% to a maximum of 24.1%, with a prescribed limit of 4% as per BS 812. Concrete specimens made solely from the sampled neat sands exhibited compressive strengths of 18.33 kN/m². and 28.94 kN/m². Blending experiments were conducted using sand mix proportions of 10%, 30%, and 50% blended sand, leading to improvements in silt content of up to an average of 48%, contingent on the initial silt content of the blending sand. Applying a design mix with a target strength of 25 kN/m², results indicated that an average of 42% of the blended sand mixtures achieved the specified target strength. To interpret the findings, a Regression analysis tool was employed in the simulations with respect to silt content, water content, workability and compressive strength . This research affirms the presence of silt content within the sands, exerting a discernible influence on concrete strength. Furthermore, blending strategies exhibited a dual benefit of enhancing silt content and improvement on concrete strength. The practical implications of this study extend to the development of sand mix and the guidance it offers to counties in western Kenya, enabling them to establish sand blending standards, formulate sand use guidelines, and identify optimal sand sources within the study region. Consequently, this research contributes to the refinement of concrete production processes and promotes the sustainability of construction practices within the studied area