Assessing the Flow Properties of Self-Compacting Concrete when Grewia Mollis is used as a Viscosity Modifying Admixture.
Atuhaire, Tugume Tumwebaze Jr
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Self-Compacting Concrete is concrete that flows under its own weight with little or no compaction effort. This kind of concrete can be produced using the same constituent materials that produce conventional type of concrete; however, self-compacting concrete is incorporated with admixtures like super plasticizer and Viscosity Modifying Admixtures (VMAs) that cause it to behave more as a fluid. The VMAs that are currently used in SCC are imported from Europe and America and this makes the production cost of SCC much higher than that of conventional concrete. This research was aimed at investigating the use of Grewia Mollis powder from the stem bark of Grewia Mollis plant as VMA in Self-compacting Concrete while using Cassava starch as a control. Grewia Mollis powder used in the study was prepared by drying and crushing the stem bark of the Grewia Mollis plant. Cassava starch was prepared by sun drying the residue obtained from decanting blended cassava tubers. SCC was prepared using an iterative mix design approach of the constituent materials. The contents of Grewia Mollis and Cassava starch were varied from 0.1, to 2 percent of the cement content. The different mixes of SCC were tested for the flowing ability, passing ability, segregation resistance and compressive strength using the Slump test, V-funnel test, L-Box test, J-Ring test, Sieve segregation test and Compressive strength test. The results of each test were tabulated and graphs showing the variation of results were drawn. The results were compared to the European guidelines for Self-compacting Concrete by EFNARC.The results of the tests showed that SCC containing Grewia Mollis portrays more flow and passing abilities than SCC containing Cassava starch. SCC containing Grewia Mollis also showed greater resistance to segregation than that containing Cassava starch. However, the compressive strength of SCC containing Cassava starch was slightly higher than that of SCC containing Grewia Mollis. The results show that Grewia Mollis can be used as a natural VMA in Self-compacting Concrete. However, further research is recommended to obtain the optimum dosage and conditions of usage of Grewia Mollisin SCC. These findings contribute to obtaining a solution to the high cost of SCC production in sub-Saharan Africa