Parametric study on the behaviour of bagasse ash – calcium carbide residue stabilized soil

A series of experiments including unconfined compression tests, three-axial tests, compaction tests, and split tensile tests were undertaken to investigate the influence of compaction parameters on the behaviour of bagasse ash–calcium carbide residue stabilized soil. A preliminary study on soil with the addition of 4%, 6%, 8%, 10%, and 12% calcium carbide residue established that the lime fixation point (LFP) was 4%. Then 9% bagasse ash was added to soil with 4% calcium carbide residue, and the cation exchanges and pozzolanic reactions were investigated. The addition of calcium carbide residue to bagasse ash stabilized soil caused short-term changes due to cation exchange reactions, including an increase in the friction angle and cohesion in the stabilized soil. In addition, due to the short-term reaction, the maximum stiffness in three-axial tests occurred in the samples moulded with less than their optimum moisture content (OMC), whereas the peak strength occurred in the samples moulded at their OMC. After a 28-day curing period, pozzolanic reactions improved significantly the three-axial peak strength and stiffness of the stabilized soil, and the maximum three-axial shear strength and stiffness occurred in the samples prepared below their OMC.

husk ash-lime have been investigated . • The effect of the combination of bagasse ash-calcium carbide residue on the shear strength of expansive soil has been performed • Research concerning fly ash and lime for soil improvement has been conducted. • The physical and chemical performance of both short term and long term reactions related in soil-lime-fly ash mixtures have been written on the literatures.
The previous studies have discussed the effects of temperature and curing period, proportion of lime and fly ash, on the behavior of stabilized soil. However, they were performed without considering the effects of compaction parameters (on the shear behavior of stabilized soil. maximum dry density and optimum moisture content)

PURPOSE OF STUDY
To investigate the effect of compaction parameters : maximum dry density(MDD), optimum water content (OMC), and curing period of Bagasse Ash-Calcium Carbide Residue Stabilized Soil
The bagasse ash is non-cohesive fine residue and classified as nonhazardous, non-plastic waste material. The specific gravity is 2.05 .The grain size distribution :1.5% is clay size, 72.9% is silt, 17.9% is fine sand and the rest is medium sand (Fig.1)

Compaction
In general, all samples used in this study were prepared at (MDD) and (OMC) obtained from standard Proctor compaction tests as indicated in Fig. 2. The effects of MDD and OMC on the shear behavior of calcium carbide-fly ash stabilized soil were also analyzed. In this study, soil samples were also prepared on the water content more than and less than their optimum moisture content. It is indicated that the addition of bagasse ash to the soil resulted in the decrease of the OMC and reduction of MDD compared to those of original soil.

Unconfined compression and split tensile tests
The specimens were compacted into a cylindrical mold in the condition of MDD and OMC. The dimension is 38 mm diameter and 76 mm high. Then the sample were wrapped in polybag and stored in humid chamber. The curing times were: 7, 14, 28, 36, 56 and 100 days.

Traxial test
The dimension : 38 mm diameter and 76 mm high. All specimens were molded on their MDD and OMC. Confining pressures : 20, 50, and 100 kPa that are inherent with practical conditions in engineering applications. The only curing time was 28 days

Unconfined compression and split tensile tests
The effect of curing period on unconfined compression strength.
Short curing period does not show improvement ---cation exchange reaction. ---Ca ++ in calcium carbide replaces the position of Na + and K + in the soil ---reduces the plasticity index---does not change the shear stress parameters of stabilized soil.
Long curing period, after 60 days--significant improvement of both unconfined compression and split tensile strength of stabilized soil due to chemical pozzolanic reaction between bagasse ash-soil and lime in calcium carbide. The formation of calcium silicate hydrate (C-S-H) that is the first stage of pozzolanic reaction takes place after 36 days curing time.
Triaxial Test strain response and volumetric-axial strain of compacted stabilized soil : 20 kPa Confined Pressure and 28 days curing time.
Axial strain response for compacted samples without curing time Volumetric-Axial strain for compacted samples without curing time