PARTIAL REPLACEMENT

Concrete is one of the most widely used construction materials in Nigeria due to its strength, durability, and versatility. However, the increasing cost of granite and the environmental impact of quarrying have created the need for alternative, sustainable materials. At the same time, palm kernel shell (PKS), a by-product of palm oil processing, is generated in large quantities and often disposed of as waste, leading to environmental pollution. This study investigates the suitability of palm kernel shell as a partial replacement for granite in Grade 20 concrete.Granite was partially replaced with PKS at 0%, 10%, 20%, and 30% by weight. The physical properties of PKS, including specific gravity, bulk density, and aggregate impact value, were determined. Concrete mixes were produced and tested for workability using the slump test, as well as fresh and hardened density. Concrete cube specimens were cast and cured for 7, 14, and 28 days before compressive strength testing in accordance with relevant British Standards The results indicated that the incorporation of PKS reduced the density of concrete, confirming its potential for lightweight applications. Workability and compressive strength decreased with increasing PKS content due to the high water absorption and lower strength of PKS compared to granite. However, concrete containing up to 20% PKS achieved compressive strength values close to the target strength for Grade 20 concrete at 28 days. It was concluded that palm kernel shell can be used as a partial replacement for granite up to an optimum level of 20%, offering a cost-effective and environmentally friendly alternative for sutainable concrete production

This research was carried out to investigate the feasibility of using recycled waste glass as a partial replacement for coarse aggregate in concrete. The aim was to evaluate the mechanical,
physical and durability characteristics of concrete containing different proportions of crushed waste glass, thereby promoting sustainable construction practices. The methodology involved collecting, cleaning, crushing and sieving waste glass bottles into
particles of 10–20 mm in size. Five concrete mixes were prepared using a 1:2:4 mix ratio, with 0 %, 10 %, 20 %, 30 %, and 40 % waste glass as partial replacements for granite. All specimens were cured in water for 7, 14 and 28 days. Tests conducted included slump (for workability), compressive strength, density, setting time and water absorption capacity. The results showed that workability increased with higher waste glass content, with slump values ranging from 30mm for the control mix to 60mm at 40% replacement. The compressive strength of 30% replacement after 28 days was 20.30 Mpa, hence it was the optimum replacement level. The density of the concrete decreased slightly from 2.612g/cm3 (0%) to 2.391 g/cm3 (40%), indicating lighter concrete at higher glass content. The setting time test recorded an initial setting time of 65 minutes and a final setting time of 172 minutes, both within standard limits. Water absorption decreased from 1.6% at 0% replacement to 1.2% at 30%, showing improved durability and reduced porosity. From the findings, it was
concluded that waste glass could be used effectively as a partial replacement for coarse aggregate in concrete up to 20% without significant loss in strength or durability.