Effect of Saw Dust Ash on Index and Engineering Properties of a Weak Lateritic Soil

Abstract

The effect of saw dust ash on index and engineering properties of a weak lateritic soil was carried out in this study. Specimens prepared from lateritic samples were tested for its gradation (sieve analysis), unconfined compressive strength (UCS) and compaction parameters (MDD and OMC) at energy level of British Standard Light (BSL). The samples were admixed with varying percentages of saw dust ash (SDA) and the tests were repeated on the admixed samples. The general trend of the results shows that the gradation of the soil improved from A-7-5 to A-5 at 4% SDA content by American Association of State Highway and Transportation Officials (AASHTO) soil classification system, UCS values also peaked to 237.12 kN/m2 at 4% SDA content while the compaction parameters were still best at the natural stage at BSL energy level. The peak UCS value, though, shows an improvement of 26.9% when compared to that of natural soil, it still falls below the minimum specified value for base material stabilization using OPC (1710 kN/m2) as well as that for sub-base material (687-1373 kN/m2). From the work, 4% stabilization of weak lateritic soil with SDA can improve some index and engineering properties of a weak lateritic soil. It is also evident that the resulting stabilized soil should not be used for pavement construction. Nevertheless, addition of 4% SDA to weak lateritic soil should be encouraged when slight gradation improvement is the only target. Keywords: index properties; engineering properties; lateritic soil; saw dust ash; stabilization.

Mechanical and Structural Correlation of Lateritic Soil Road Base Stabilized with Cement and Selected Biochars

“…The increase in the UCS values is probably caused by the cementitious properties of the stabilizing binder which aids in the solidification of the soil matrix, thereby increasing strength [4]. The reduction in CBR value at 9% may be due to the excess cement that was not mobilized in the reaction, therefore reducing the bond in the cement-soil matrix [35,36]. The strength gain due to cement is attributed to decreased soil porosity [28,29].…”

“…The increase in the values of CBR upon the addition of cement may be attributed to the presence of adequate amounts of calcium required for the formation of Calcium Silicate Hydrate (CSH) and Calcium Aluminate Hydrate (CAH), which are the major compounds responsible for strength gain [42]. The reduction in CBR value at 9% may be due to the excess cement that was not mobilized in the reaction, therefore reducing the bond in the cement-soil matrix [35,36]. The UCS at 28 days increased from 0.275 MPa to 2.729 MPa with the increase in cement content as shown in Table II.…”