Glycerol resulting from biodiesel production as an admixture for cement-based materials: an experimental study

Concrete admixtures are frequently expensive and may carry relevant ecological footprints, reason why there is a growing necessity and interest in finding cheaper and more sustainable alternatives. The present work focused on the evaluation of the potential benefits that might be harvested by adding a partially purified biodiesel by-product as an admixture to cement-based materials. An experimental programme was carried out on several mixes of cement paste and mortar, incorporating the by-product in the cementitious mix in the following mass fractions (as a function of cement content): 0.5, 1 and 3%. Several testing techniques have been deployed for characterising material properties of the tested cement pastes and mortars, namely: flowability, setting time, compressive strength, elastic modulus, shrinkage and permeability. The obtained results led to the main observation that biodiesel-derived glycerol can be used as an accelerating admixture with the optimum mass faction of 1%.