Environmental benefits of corn cob ash in lateritic soil cement stabilization for road works

Abstract

The potential environmental benefits of corn cob ash (CCA) as pozzolan in stabilizing soils for road construction was investigated. Corn cob obtained from Maya in South West Nigeria was processed to ash similar to Class C Fly Ash and blended with ordinary Portland cement (OPC) in the OPC:CCA ratios of 1:1 and 2:1. Each of these blends was then mixed with lateritic soil of classification A-2-7(3) in varying percentages from 0–7.5% and thereafter tested for Unconfined Compressive Strength (UCS). The cost of the binder inputs was determined from the production cost of CCA and the prevailing market price of OPC. Using the processed laboratory results, an optimization problem was set up, with the cost of the OPC-CCA binder as the objective function to be minimized, subject to the constraints of minimum UCS of 1800 kN/m2 and solved. The study showed that OPC-CCA blends used at optimization levels reduced the overall OPC consumption by up to 26.8% and could result in a corresponding reduction in net CO2 contribution to the environment. The paper concluded by recommending the development of bio pozzolan cements for use in soil stabilization to reduce the CO2 contribution of the construction industry to global warming.