Assessing the viability of industrial production of Bio Binders in Sub-Saharan Africa (Case study - Uganda)

Abstract

This study assessed the viability of industrial production of bio binders on the African continent. Rice Husk Ash was taken as the bio binder due to its high silica content. More so rice husks pose a disposal challenge since it is non-bio degradable. Literature established that the contents and pozzolanic properties of Rice Husk Ash (RHA) generally are as a result of the conditions of its processing (e.g burning temperatures), rice species, soil conditions, the regional climate and even geographical location. Since RHA is high in silica composition, hence very suitable for partial replacement of cement in concrete and mortar. The study was therefore conducted to evaluate the extent to which this was true and the effectiveness of its industrial production.

Two types of technology were used in this study to burn the Rice Husks to ash, open and controlled burning. Open burning was done locally in a kiln while controlled burning was done in a furnace under controlled temperatures of 550-600oC.It was envisaged that the method of burning the Rice Husks in order to form the ash affect the ash properties and therefore a need to test the reliable technology. This study was aimed at providing such information to the blended cement manufacturers and concrete industry. Also the study aimed at the market of the Rice Husk Ash to be blended in cement through different interviews and questionnaires from different manufacturers and consumers of cement. For the pozzolanic properties, blended cement pastes were cast in different percentage levels, sealed then placed in a curing tank at test ages of 1,3,7 and 28 days. Thermo gravimetric Analysis (TGA) was done for different samples to determine the degree of hydration of the paste at different curing ages. This was done mainly to characterize the Rice Husk Ash in Uganda as pozzolanic material. Statistics was read from the abstracts in order to analyze the availability of rice paddy in Uganda. These were gotten from the Uganda National Farmers Federation (UNFFE). The relevance was to help in estimating how much rice husks ash can be produced altogether to facilitate the industrial production of RHA as a bio binder.

The results showed that RHA has pozzolanic properties due to reduction of hydration products especially Calcium hydroxide in partially replaced cement compared to Ordinary Portland cement. The reliable technology would be controlled burning as Open burning production of RHA has high carbon content which adversely affected the properties of the cement pastes. Quality of RHA is controlled by controlled by incineration process to form amorphous which is essential for structural concrete (Fapohunda C, 2017).

The cement manufacturers and the concrete industry are ready to buy the RHA and it with cement and therefore market of RHA as a bio binder is available. They are of a view that it is economical and ecological. Using the results from the statistical abstracts, analysis showed that rice ash will be sustainable for industrial production.