Reactivity and hydration behavior in groundnut shell ash based pozzolanic concrete

There is a global yearning for enactments enforcing down scaling of industrial processes that contribute to global warming to be adopted by the committee of nations, as part of measures to realize a sustainable environment before year 2030. Conventional cement production technologies have long been identified as one of the major contributors to global warming, hence the quest for green source alternative materials, which can serve as whole scale or partial scaling measure to cement production. One of promising scaling methods discovered is the partial replacement of cement with pozzolans especially agro-based pozzolans. It is therefore necessary to study the behavior of these pozzolans to optimize their usage in partially replacing cement. The Pozzolanic reaction mechanisms and hydration behavior of groundnut shell ash (GSA) in concrete were investigated. Different blend ratios of GSA (between 0 and 16%) were used as replacement for Portland cement in the production of the concrete mixes. X-Ray diffractometry, X-Ray fluorescent spectrometer, scanning electron microscopy, pozzolanic reactivity in suspension, and compressive strength measurements were used as basis to assess the reaction mechanism and hydration behaviour of the concrete and paste mixes produced. The principal chemical constituent of GSA is silica, and the SiO₂ + Al₂O₂ + Fe₂O₃ sum of 69.2 wt% observed for the GSA falls into class C pozzolans. Hydration efficiency evaluated by assessing the amount of calcium silicate hydrate formed, quantity of calcite present in the hydrated paste and integrity of microstructural interlocking of particles indicated the efficiency use of 8 wt% GSA.