Evaluation of Laterite Soil Reinforced with a Mixture of Periwinkle and Palm Kernel Shells as Road Construction Materials in Niger Delta, Nigeria

Authors

Pollution is a very predominant problem in Nigeria. As a developing

nation, we face challenges of constant economic recession which

have an effect on so many facets of life including construction. In

order to combat pollution and bad roads, waste can be used with

other construction materials to construct better roads. This study

evaluated laterite soil reinforced with a mixture of palm kernel and

periwinkle shells as materials for road construction. The soil

samples were obtained from a burrow pit at Iguosa Housing Estate,

Benin City, Edo State Nigeria at 6°26’55’’N 5°36’16’’E. The

geotechnical properties of natural soil were determined, which

included specific gravity, mechanical sieve analysis, consistency

limit, compaction, and California Bearing Ratio (CBR) tests. The

strength properties of the soil reinforced with periwinkle shell (PS)

and palm kernel shell (PKS) were carried out. These were done in

proportions of 6%, 9%, 12% and 15% by volume. For the control

sample, the average result of the specific gravity obtained was 2.47

which was below the standard of 2.50 to 3.0 for lateritic soils. The

plasticity index was 19.49% which indicated that the soil is of

medium plasticity. The sieve analysis indicated that the soil is

classified as an A-2-6 soil. The Maximum Dry Density and the

Optimum Moisture Content were 1.78 g/cm3 and 10.3% respectively.

The average value for the soaked CBR was 15.11%. When the soil

was reinforced with equal proportion of PS and PKS, the OMC

ranged from 11.30% to 11.70%, the MDD ranged from 1.73g/cm3

to

1.75g/cm3 and from the CBR tests, the value for the soaked CBR

ranged from 1.26% to 23.21%. The optimum mix proportion was

obtained to be 12% (6% for PS and 6% for PKS). This did not meet

the requirement of 30% for subbase stated by the Federal Ministry

of Works and Housing. Therefore, these soil reinforcement

techniques with PS and PKS can only be used for Trunk D roads or

as subgrade materials which require a minimum soaked CBR of 5%.