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

Abstract

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%.

Keywords:

• Cement-based materials
• hydration
• admixture
• biodiesel by-product
• glycerol
• experimental testing

Acknolwedgements

The authors also thank Prio Energy Company (www.prioenergy.com) for kindly supplying crude glycerol free of charges, as well as Eng. Carlos Jesus from the University of Minho for his assistance.