Improving the geotechnical properties of a Nigerian termite reworked soil using pretest drying conditions and sawdust ash

Abstract

The environments of tropical regions favour the activities and growth of termitaria on soils and woods. The aim of this study is to determine the effect of pretest drying conditions and sawdust ash (SDA) on the strength properties of termite reworked soil for pre and post engineering construction. Twelve disturbed subsoil samples; six termite reworked soil samples and six neighboring residual soils of each of the termite reworked soils were obtained in Akungba Akoko, South-western Nigeria. The termite reworked soil and the surrounding residual soil met the Nigeria requirement of a good sub-grade soil. However, termite reworked soil shows better geotechnical ratings when compared to the surrounding residual soil samples. This result attested to the fact that termites’ activities promote forces of attraction and adhesion among the soil particles. On the addition of sawdust ash to termite reworked soil at 6% of the weight of the soil samples; the geotechnical properties of the termite reworked soils slightly improved. Again, the geotechnical properties of termite reworked soils were considered under varying pretest drying conditions; of air-dried condition as well as conditions obtained by drying the soils at 50°C ± 5, 75°C ± 5 and 110°C ± 5. The index and strength properties of the termite reworked soils improved with increase in pretest drying temperature. Statistical analysis of ANOVA shows that there is no significant statistical difference in the values of the geotechnical parameters of the sampled soils under pretest drying conditions. For Pearson’s correlation, SDA improved soil and pretest drying temperatures for fine contents with CBR and MDD values; the obtained test values of correlation are higher than the critical r value (0.497). Again we reject null hypothesis in favour of the test hypothesis.