ABSTRACT
This project gives an account of the study conducted on the substitution of palm kernel
shell for coarse aggregate in concrete works. It is aimed at determining the properties of palm
kernel shells (PKS) that makes it suitable as a replacement for natural aggregate in concrete
works and the effects of mixing ratios on the strength characteristics of palm kernel shell
concrete. A number of tests were conducted on the Palm Kernel Shells and concrete produced
with palm kernel shells (PKSC). Tests conducted on PKS are; sieve analysis, fineness modulus,
specific gravity, water absorption capacity and moisture content, Aggregate Crushing Value and
Aggregate Impact Value tests respectively. While the tests conducted on palm kernel shell
concrete (PKSC) include slump test, density, compressive strength test, modulus of rupture,
splitting tensile strength test and modulus of elasticity test. Concrete mixes of 1: 2: 4, 1:1½:3,
1:2:4 were used to produce cubes, beams and cylinders which were cured for 28 days before
testing. The results obtained gave the specific gravity of palm kernel shell as 1.29, thickness
ranging from 0.7mm to 4.0mm, fineness modulus of 5.09 and Aggregate crushing value of
5.02% which are less than those of normal weight aggregate but within the specified range of
values for light weight aggregates classifying palm kernel shell concrete as a lightweight
aggregate. The palm kernel shell has bulk density of 580kg/m3 and aggregate impact value of
16.19% which is an indication that PKS can conveniently be used for structural light weight
constructions as light weight aggregate. The Average moisture content of 6.12% obtained for the
PKS which also falls within the specification for light weight aggregates but greater than that of
the normal weight aggregates is an indication that light weight aggregates retains moisture than
normal weight aggregates. The particle size distribution shows that palm kernel shell has a
maximum grain size within the range 16.0mm and 17.0mm, although, this is less than that of
normal weight aggregate being replaced, it is light enough to be used as a coarse aggregate. The
highest slump value of 30cm was obtained for the nominal mix 1:1:2 which makes it the most
workable mix. The results show that concrete mix of 1:1:2 with compressive strength of
9.86N/mm2 at 28 days hydration period is similar to previous research findings that the
compressive strength of palm kernel shell concrete (PKSC) ranges from 5N/mm 2 to 25N/mm2
based on mix design by Okafor; (1988). The density of the PKSC is lower than 2050 kg/m3 but
greater than 1700kg/m3 which characterize PKSC as a lightweight concrete; higher strength can
be achieved by better mix. Result of tests on modulus of rupture and splitting tensile strength
exhibited similar trend as that of compressive strength test and the nominal mix 1:1:2 gave the
highest values of modulus of rupture, splitting tensile strength and modulus of elasticity
respectively. The results show that increase in the ratio of sand to cement relative to increase in
PKS contents results in decreased compressive strength. Hence, to produce a high strength value
of PKSC will require low ratio of sand to cement.