This paper explains the assessment of plastic limit of soil and model development that can be applied to examine the impact of plasticity of soils on the design and construction of roads in the study location. Samples collected from nine locations were subjected to laboratory analysis and the results from these location produced the following model equations: y = -2.51x2+9.881x+14.95 and R2 = 0.978, Y= -3.957x2+11.85x+14.34 and R2 = 0.816, Y =2.967x2 -12.53x+30.76 and R2 = 0.878, Y =8.816x3-37.12x2+35.90x+18.42 and R2 =0.975, Y = 0.163x3-2.625x2 +7.609x+18.84 and R2 =0.971, Y = 0.713x3-5.095x2+8.506+16.42 and R2 = 0.968, Y=6.647x3- 34.45x2+51.74x+2.040 and R2 = 0.97, Y= -3.098x2+13.11x +11.68 and R2=0.876 and Y =5.304x3- 28.43x2+45.10x+3.030 and R2 = 0.96. The model equations were developed from the results obtained and can be resolved to generate other theoretical values that can be applied in design and construction of roads. The generated model equations will produce a predictive model for plastic limit of soil in the study locations. Hence, this model will solve the problem from clay and lateritic earth materials for sub grade in road construction, considering the deltaic environment, the geologic history and predominance of some clays and lateritic soils depositing medium and high plastic limit in the study area.
