Abstract
The cost saving benefits of aggregate replacement in concrete works are well documented. The utilization of Supplementary Aggregate Materials (SAMs) in
concrete engineering without compromising standards in concrete works remain
very attractive to both infrastructure developers and design engineers. However, there is continual search for low cost beneficial substitute materials. The mechanical properties of green concrete produced from Palm Nut Shell (PNS) as coarse aggregate was investigated. The abundance of PNS (light weight waste product of palm oil production) in West Africa created the impetus for the study. Series of laboratory tests such as; Slump, Compaction factor, Density, Schmidt hammer and Compressive strength tests were conducted on specimens of 10, 20, 30, 40 and 50% replacements of dry weight of PNS as coarse aggregate and specimens of natural aggregate as control sample. The specimens were cured at relative humidity (RH) of 95-100% and temperature (T) of 22-25oC in a chamber for periods of 7, 14, 21 and 28 days. The results showed the PNS samples to have relatively medium to high workability ranging from 24-47 mm for slump height and values of 0.85 to 0.90 for compaction factors. A general strength development was observed across the different samples with the PNS sample reaching strength of 48.7 N/mm2 at 28 days curing. The 50% replacement specimens which mobilized
UCS of 28.7 N/mm2 met the requirement for lightweight concrete however, 30% is
the optimum for a partial aggregate replacement in green concrete as UCS of 39.2
N/mm2 was mobilized in 28 days. Thus PNS is a suitable concrete constituent and
can be a major cost reduction factor especially in low cost rural projects with
streamlined loading requirements.