Effect of size variation of palm kernel shells as replacement of coarse aggregate on lightweight concrete

Abstract

The utilization of Palm kernel shell (PKS) as alternative to conventional materials for the Ghanaian construction industry is very desirable to promote sustainable development. This is in line with the Sustainable Development Goals (SDGs 11) which promote safe sustainable cities and communities. The purpose of this current study was to investigate the effects of size variation of PKS as coarse aggregate in lightweight concrete. Appropriate sieves were used to get the right various sizes of PKS for this experimental work; these are sizes retained on the sieves 6mm, 8mm, 10mm and 12mm. The study employed a series of mixes which resulted in casting and testing 60 cubes and 60 beams at 7,14,21 and 28 days of curing. The materials phase of this research evaluated the key mechanical properties of hardened concrete, thus compressive strength, flexural strength and density. The compressive strength of the samples increases as the curing age increases. The aggregate sizes 6mm, 8mm,10mm, 12mm and Mixed PKS content, at 7-day recorded an average compressive strength of 3.533 N/mm2 , 3.133 N/mm2 , 3.400 N/mm2 ,5.567 N/mm2 and 4.700 N/mm2 respectively. The average compressive strength for 28-day of curing were 4.100 N/mm2 , 3.833 N/mm2 , 5.167 N/mm2 , 6.500 N/mm2 and 5.767 N/mm2 for aggregate sizes of 6mm, 8mm, 10mm,12mm and Mixed PKS content respectively. Then also the average flexural strength recorded for 28-days of curing were 0.836 N/mm2 ,0.936 N/mm2 ,1.761 N/mm2 ,2.185 N/mm2 and 1.467 N/mm2 for the various aggregate sizes 6mm, 8mm, 10mm, 12mm and Mixed PKS content respectively. The average dry density for 28-days of curing were 1509.73kg/m3 , 1497.0 kg/m3 , 1624.13 kg/m3 , 1685.0 kg/m3 and 1610.47 kg/m3 for aggregate sizes 6mm, 8mm, 10mm, 12mm and Mixed PKS content respectively. The Scanning Electron Microscopy (SEM) test indicated a highly porous structure of PKS and the Energy Dispersive Spectroscopy (EDS) test was done to find out the chemical composition of PKSC specimens. It can be observed that aggregate size 12mm recorded maximum values for most of the test results. The PKS aggregate size 12mm can be partially mixed with granite to produce a desirable concrete for a sustainable construction. The study concluded that, PKS is useful for concrete production as lightweight aggregate. The use of PKS must be encouraged in order to effectively address the environment pollution caused by indiscriminate dumping and burning of PKS(s).