Comparison of the Strength and Durability of Plinth walls constructed from locally manufactured clay bricks to concrete blocks in Kampala

Abstract

This study was pursued to compare the strength and durability of plinth walls constructed with locally manufactured clay bricks with those constructed with concrete blocks. This documentation contains four chapters and below is a brief summary of the work content in each chapter. Chapter one contains the background, problem statement, main objective and specific objectives, justification and scope of works of the study. According to UBOS, 2017, 58% of the plans approved were for residential buildings most of which use clay bricks for their plinth walls. According to UN-Habitat, 2010, the construction materials manufactured in the Uganda are not standardized with bricks being most predominant. This is because the brick manufacturing industry is dominated by workers with insufficient technical knowledge. Hence, the choice of masonry units for plinth walls is guided by cost and availability of masonry units thus sidelining their structural capacity which leads to unexplainable structural failure. Chapter two contains the literature review of the study. As discovered by Taguchi and Cuadra (2005) the strength of the masonry units contributes more to the strength of the masonry wall than the strength of mortar. The compressive strength of masonry is also affected by the brick-mortar bond, mortar strength, eccentricity and slenderness ratio. The durability of plinth walls is majorly affected by the moisture content of the surrounding soil. The influx of water in the masonry units reduces their compressive strength thus leading to a reduction of strength of the plinth wall. Chapter three contains the study methodology. Locally manufactured clay bricks were obtained from five different manufacturers and concrete blocks were obtained from three concrete block manufacturers in Kampala. Several tests were carried out in order to evaluate the strength and durability of plinth walls such as compressive strength test of clay brick units and concrete blocks, water absorption test for bricks and blocks and compressive strength test of clay brick masonry prism constructed in header bond and concrete block masonry prism constructed in stretcher bond. Chapter four contains analysis of test results. The results from the tests indicate that the concrete blocks generally have a higher compressive strength than clay bricks, together with an acceptable water absorption according to UNBS, unlike clay bricks with very high water absorptions. However, the analysis went on to reveal that both clay brick and concrete block plinth walls have sufficient strength to withstand the loads that they are usually subjected to. Chapter five contains the recommendations and conclusions. Concrete block plinth walls are stronger and more durable than clay brick plinth walls. However, both plinth walls have sufficient strength to support the loads that are usually applied to plinth walls. We recommend protecting clay brick plinth walls with water proof membranes to preserve their strength, and extra research to be conducted on effects of Initial rate of suction and chemical properties of various clay soils on compressive strength of clay bricks.