José Luís Duarte Granja

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%.

Continuous Monitoring of Concrete Mechanical Properties since an Early Age to Support Construction Phasing

FEDER funds through the Operational Program for Competitiveness Factors - COMPETE and National Funds through FCT - Portuguese Foundation for Science and Technology under the project ViscoDyn EXPL/ECM-EST/1323/2013, as well to the Research Unit ISISE

Assessing Viscoelastic Properties of Concrete during its Early Ages through Forced Dynamic Excitation of Test Beams

This paper aims to demonstrate the feasibility of a recently proposed approach (termed VisCoDyn) to assess the viscoelastic behaviour of concrete from the earliest ages, by introducing a known dynamic excitation to a simply supported specimen. The method involves the continuous monitoring of the response of the tested sample in terms of amplitude (force and displacement), as well as the evaluation of the phase lag between the applied force and the response. The acquired data is then used to calculate the storage and loss moduli, according to procedures that are normally used in the context of material testing in polymer science. Indeed, the loss modulus is known to be relatable to the viscoelastic properties of materials.The paper presents the current state of development of the VisCoDyn test methodology together with several test results obtain in specimens that were tested during the first 24 hours of curing. Parallel testing with other techniques is also presented for reference.

Innovative method for the continuous monitoring of concrete viscoelastic properties since early ages: concept and pilot experiments

FEDER funds (COMPETE program) and by National Funds through FCT (Portuguese Foundation for Science and Technology) in the scope of the Research Project EXPL/ECM-EST/1323/2013