Study of Mechanical Properties of Stabilized Lateritic Soil with Additives.

The overdependence on the USAge of industrially manufactured soil improved or conventional additives have resulted in unaffordable cost of construction of better infrastructure in Third World and poor countries which are mostly agriculturally dependent across Globe. This study is aimed at studying the mechanical properties of lateritic soil stabilized with mixture of conventional and locally available additives. Soil samples collected from the study area were subjected to laboratory tests (i.e. Grain Size and Atterberg Limits tests) after stabilized with cement, ESA and RHA additives at proportion of 2% to 10% by sample weight. It is observed that the LL, PL and PI values varied from 30.1% to 35.5%, 9.9% to 12.5% and 20.1% to 23.2% respectively for sample A. While LL, PL and PI values varied from 35.2% to 41.5%, 10.8% to 14.5% and 24.4% to 27.1% respectively for sample B. It could be generally observed that PI values reduced while PL values increased for the soil samples after increase in addition of cement additive from 6% to 8%. All the LL, PL and PI values also reduced as the percentage of RHA additive added increased. Soil sample A has group classifications of A – 2 – 6 while soil sample B has A – 7 and tend towards A – 2 - 6 and A - 6 after stabilization. The stabilization process using local additives as partial replacement of conventional one generally improved the soils Engineering properties. Though it is more felt in ESA than RHA. Further research work should be carried out

Assessment of Performance Properties of Stabilized Lateritic Soil for Road Construction in Ekiti State.

Soil Stabilization usually enhances performance properties of soil. This can foster waste to wealth policy in country like Nigeria. The aim of this study is to assess performance properties of a stabilized lateritic soil with a view to obtain a cheap and more effective additive. Soil samples were collected from the study area and subjected to Compaction and California Bearing Ratio (CBR) laboratory tests with the addition of 2%, 4%, 6%, 8% and 10% Rice Husk Ash (RHA) and Egg Shell Ash (ESA). Results showed that MDD, OMC and CBR values varied from 1575Kg/m3 to 1930Kg/m3, 7.55% to 18.50% and 20% to 131% respectively for sample A. And 1566Kg/m3 to 1896Kg/m3, 7.53% to 16.90% and 16% to 98% respectively for sample B. The MDD values decrease with increase in the additives contents due to the replacement of soil by the additives in the mixture, coating of the soil by additives which resulted in large particles with larger voids and density; and addition of the additives which decreased the quality of free silt, clay fraction and coarse materials with large surface areas formed. OMC values also increase as the additives increase, though, that of RHA increases more than that of ESA. This is due to the increase in additives which resulted to increase in the amount of water required in the system to adequately lubricate all the particles in the mixture equally increase. Generally, CBR values also increase with increase in the additives contents. This could be attributed to gradual formation of cementitious compound between the additives and Calcium Hydroxide (Ca(OH)2) present in the soil, thus increase in coarse particles of the soil through cementation

Adsorption and desorption studies of Carica papaya stem activated with zinc chloride for mining wastewater treatment

The adsorption of eight selected potentially toxic metal ions from actual mining wastewater obtained from Igbeti, Nigeria, was established using activated carbon chemically prepared from Carica papaya stem with zinc chloride (CPSAC-ZnCl2) as activating agent. Characterization of the prepared CPSAC-ZnCl2 sample for surface morphology and functional groups was done by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy, respectively. An atomic absorption spectrophotometer (AAS) was utilized for characterization of the selected metals in the mining wastewater. Batch adsorption and desorption studies were conducted on removal of the metals from the sample using CPSAC-ZnCl2. The data obtained were fitted to isotherm (Freundlich and Langmuir); kinetic (pseudo-second-order and intra-particle diffusion) and thermodynamic (standard enthalpy change – ΔH°, entropy change – ΔS° and free energy change – ΔG°) models. These were considered under two error functions (sum of absolute errors – SAE,  coefficient of determination – R2) of linear and non-linear regression analyses. The SEM micrograph revealed that the CPSAC-ZnCl2 sample was 2.0–50.0 nm with FTIR spectra absorption peaks ranging from 746.2 to 3 987.0 cm-1. The initial concentrations of selected metals in the wastewater varied from 5.7 to 756.5 mg/L. The adsorbent dosage, agitation rate, contact time, pH and temperature for optimum condition of CPSAC-ZnCl2 were 0.6 g, 150.0 r/min, 60 min, pH of 7.0 and 30°C, respectively. The selected metals’ adsorption onto CPSAC-ZnCl2 followed Freundlich and Langmuir isotherm models pseudo-second-order kinetics with intra-particle diffusion mechanism. The ΔH°, ΔS° and ΔG° for the processes were 134.5, 64.5 and 22 012.0 kJ/mol, respectively. The adsorbent achieved an adsorption efficiency of above 95.0%, and is thus recommended for industrial application in remediating potentially toxic metals from wastewater. &nbsp