Exploratory study of crushed periwinkle shell as partial replacement for fine aggregates in concrete
An exploratory study of crushed periwinkle shell (CPWS) as partial replacement for fine aggregate in concrete was carried out. Mechanical and Physical properties of the CPWS and fine aggregate (river sand) were determined and compared. Concrete cubes of 1:2:4 and 1:3:6 by weight of cement were prepared in the laboratory, using the following proportions, 0:100, 30:70, 50:50 and 100:0 CPWS to fine aggregate (river sand). 14, 21 and 28 days compressive strength test were carried out on the concrete cube. The CPWS had an average moisture content of approximately 11.65%, the highest amongst the aggregates. Physical examination of the CPWS particles showed that the grains were angular in shape with rough surface texture. The sieve analysis test revealed that the particle sizes were fine aggregates with about 98.8% passing through the British sieve No. 4 (4.75mm). The CPWS had a bulk density of 1504kg/m3, while that of the river sand was 1636kg/m3. The workability test revealed that the slump values decreased in the concrete mixture as the quantity of CPWS increased. It was also discovered that the compressive strength decreased with increased percentage of replacement of the river sand with CPWS. The control (highest) 28 days compressive strength of the concrete produced with zero percent CPWS and 100% river sand was 24.89N/mm2. 28 days compressive strength of concrete cubes with 50% CPWS and 50% river sand for mix proportion of 1:2:4 was 18.00N/mm2.From the results of this exploratory study, it can be safely stated that CPWS can be used as a partial replacement of river sand in the production of light weight concrete in areas where the periwinkle shells are in abundance. The purpose of the study is to explore the possibility of turning waste to wealth. A significant factor is that concrete will be produced cheaper in areas with large population of periwinkle shells, while the environment that these periwinkle shells are usually dumped will become better protected.
Keywords: periwinkle shell, river sand, coarse aggregate, workability, compressive strength, concrete