Lateritic soil was treated with 0%, 4%, 8%, 12%, and 16% Rice Husk Ash (RHA) by dry soil weight to determine its consolidation properties. Test carried out include particle size distribution, specific gravity, compaction test with varying compactive efforts (British Standard Light (BSL), West African Standard (WAS) as well as British Standard Heavy (BSH)) and consolidation test. Samples for consolidation test were compacted and then cured for 7, 28 and 56 days; then subjected to one dimensional consolidation testing to observe the influence of curing period and compactive effort on its consolidation characteristics. Index tests showed improved geotechnical properties. The Maximum Dry Density (MDD) for BSL compaction decreased with a rise in RHA content from 1.72 to 1.42 Mg/m3 while optimum moisture content (OMC) increased from 16.5% to 27.3% with rise in RHA doses from 0% up to 16%. Similar trend was observed for WAS and BSH energies. Pre-consolidation pressure rise with increment in RHA content and also with increase in both compactive efforts and curing period with few exceptions. At 12% RHA content, Pre-consolidation pressure increased from 65 to 66.5 kN/m2 at 7 days and 56 days respectively. Increase in RHA content caused a decrease in Compression Index and Swelling Index. Compression Index also decreased with increase in both compactive efforts and curing period. There was no observed trend in the Swell Index with curing period. As the compactive efforts increased, the swell index decreased. The RHA reduced the Coefficient of Volume Compressibility (Mv) and the Coefficient of Consolidation (Cc). Curing period and compactive effort have no effect on Mv and Cc. Based on the results obtained, curing period at least 28 days using up to 12% RHA compacted at energy level of BSH improved the properties of the treated soil and can be used for geotechnical engineering applications like embankment or rural roads.

Gassmann’s equation can be used to determine the velocity of compressional waves that pass through rocks with various pore fluid contents, using fluid substitution concept, but is generally applied to certain conditions only (physical rock properties). Carbonate rock has properties in contrary of Gassmann’s assumption; is a heterogenic, anisotropic rock and does not have a well-interconnected pores. In this research, secondary data from laboratory measurements are used, consisting of carbonate rocks (limestone and dolomite) to test modified Gassmann’s equation on carbonate rocks. Two approaches of Gassmann’s equation are used by using k-dry and k-1 components, which are the value of compressional modulus bulk of saturated rocks. The result of both approaches shows that the usage of k-1 component is more optimal to be applied to carbonate rocks because it does not use k-dry component, which should only be used on field measurements, as there is a difference in the environment condition (air, temperature, and pressure) on reservoir and laboratory.