Abstract
One of the most popular ways to lessen the impact of the cement industry on the environment consists of substituting clinker by additions. The service life required for real construction elements is generally long, so it would be interesting to obtain information about the effects of new additions after a hardening period of several years. Analyzed here are the effects of the incorporation of volcanic ashes, coming from Calbuco volcano’s last eruption (Chile), as clinker replacement, in the durability and pore structure of mortars, after approximately 4 hardening years (1500 days), in comparison with reference specimens without additions. The substitution percentages of clinker by volcanic powder studied were 10% and 20%. The microstructure was characterized with mercury intrusion porosimetry and impedance spectroscopy. In order to evaluate the pozzolanic activity of the volcanic powder after 1500 days, differential thermal analyses were performed. Water absorption after immersion, steady-state diffusion coefficient and length change were also studied. In accordance with the results obtained, the 10% and 20% substitution of clinker by volcanic powder from the Calbuco volcano showed beneficial effects in the mortars after 4 years, especially regarding the microstructure and chloride diffusion, without noticeable influence in their water absorption.
Highlights
At present, the cement industry still constitutes an important pollutant sector [1,2], and it is necessary that this industry contributes to the current worldwide goals regarding global warming reduction
This porosity was slightly greater for the VP20 mortars in comparison to the REF and VP10 ones
Regarding the mercury intrusion porosimetry technique, the similar total porosity in the very long term noted for the mortars tested would indicate that they would have a similar fraction of solids and overall volume of pores, independently of the binder used
Summary
The cement industry still constitutes an important pollutant sector [1,2], and it is necessary that this industry contributes to the current worldwide goals regarding global warming reduction. For lessening its greenhouse gas emissions and making the cement industry and construction sector in general more sustainable, several strategies have been developed, such as the research on eco-friendly materials, which has experienced great progress in recent years [3,4,5]. With respect to cement-based materials, one of the most popular ways of reducing the greenhouse gas emissions, due to their manufacture, consists of substituting clinker with supplementary cementitious materials [6,7,8,9]. Among the supplementary cementitious materials available, it is important to highlight silica fume [10,11], ground granulated blast-furnace slag [12,13], and fly ash [14], which have all been commonly used in recent decades. Some examples of these new supplementary cementitious materials are brick powder [15], rice husk ash [16], glass powder [17,18], red mud [19], etc
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