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Indirect Assessment of Soil-Binding Strength of Clay Bricks

Clay bricks are the most common building material used in the current day’s construction industry. The main components of a clay brick include natural clay, and water. Due to the limited availability of natural soil, practitioners and researchers started exploring the ways to substantiate the natural soil with alternate construction materials such as fly ash (FA), pond ash, sugarcane bagasse ash (SBA), and rice husk ash. These materials are regarded as wastes/byproducts from various industries and food processing. Due to the presence of high pozzolanic activity, these materials are generally considered as alternative replacements for natural soil in the manufacture of clay bricks. There are many factors that influence the quality of a brick namely constituent materials, binding properties of materials, casting conditions, burning temperature, and other factors that may directly or indirectly influence the brick strength. 

Problem statement: 

The client M/s. SBR Enterprises has approached ProVatsalya with a serious concern pertaining to manufacture of bricks. The breakage of manufactured bricks is found to be 10 to 15% which is of serious concern. ProVatsalya has taken up the task of providing a cost-effective and viable solution to enhance the quality of bricks and reduce the breakage. It is inferred that the combined influence of rice husk inclusion and excessive usage of sugarcane bagasse ash resulted in breakage of bricks. 

As a part of the study, the raw materials used for the study are tested at the in-house laboratory facility of ProVatsalya. The mix design for the manufacture of brick is adopted based on the comprehensive literature review conducted to study the influence of constituent materials on the compressive strength of brick. The properties of constituent materials used for brick making along with their proportions were studied. The selection of additives suitable for brick were chosen based on the properties of virgin soil. 

In order to assess the binding capacity of soil with constituent materials, Adams and Stewart Soil Binding (ASSB) test is adopted. Accordingly, the soil mix is prepared and left to air dry for 10 hours. The soil is molded into the shape of a ball as in the figure and is burnt in the muffle furnace for specific duration according to the requirements.

These samples, after being burnt were allowed to cool until they attain room temperature and then they are tested to determine the strength. The conventional unconfined compressive strength apparatus was used to determine the compressive strength of specimens. Accordingly, the specimens are tested and the respective strengths are reported. Based on these values, the optimum mix design is recommended to the client M/s. SBR Enterprises.