• Energy Research

[EN] The service life of real construction elements is usually long, so the study of the behavior of cement-based materials with new pozzolanic additions in the very long term, after several hardening years, could be interesting. Here, the influence of using waste brick powder as 10% and 20% clinker substitution in microstructure and several durability-related parameters of mortars after 1500 hardening days (approximately 4 years) has been studied. According to the results obtained, the incorporation of brick powder overall improved the performance of mortars after 4 years, compared to reference mortars without addition, especially regarding the pore structure and chloride diffusion. This work was supported by the Conselleria de Educacion, Inves-tigacion, Cultura y Deporte (at present re-named as Conselleria de Innovacion, Universidades, Ciencia y Sociedad Digital) de la Generalitat Valenciana (Spain) [grant number GV/2019/070] ; and by the Agencia Nacional de Investigacion y Desarrollo de Chile (ANID) [grant number FONDECYT REGULAR 1211135]

At present, the cement industry still constitutes an important pollutant in the industrial sector. As such, strategies to reduce its environmental impact are a popular research topic. One of these strategies consists of partially replacing clinker with other materials, such as waste glass powder. Here, the effects of the addition of glass powder on the microstructure and durability properties of mortars that incorporate 10% and 20% of this addition as a clinker replacement after 1500 hardening days were analyzed. Reference mortars prepared with ordinary Portland cement without additions were also studied. The mortars were kept in optimum conditions (20 °C and 100% relative humidity) until the testing age. Their microstructure was characterized using mercury intrusion porosimetry and impedance spectroscopy. The steady-state chloride diffusion coefficient and the absorption after immersion were determined as durability parameters. According to the results obtained in the present study, the mortars with the added glass powder showed similar porosities and more refined microstructure compared to the reference mortars. Furthermore, the durability properties of the mortars that incorporate glass powder were similar or even better than those noted for the reference mortars without any additions after 1500 hardening days, especially regarding the resistance against chloride ingress, with the added value of contributing to sustainability.

This article focuses on the research of gas emissions in two types of brick kilns located in the Maule Region, Chile. One of them is an artisanal brick kiln known as a “chonchón” (AKC), while the other is a semi-artisanal brick kiln with an improved design. The latter is referred to as the Ecokiln. This study focuses on the assessment of the emission profiles of key pollutants such as particulate matter (PM), CO, CO2, SO2, and NOx. The emission measurements of gasses, temperature, and flow were conducted during the operation of the kilns. These measurements were carried out following the protocol established by Chilean standards. The Ecokiln’s design facilitates optimal fluid dynamics. In direct comparison to the AKC, it exhibits reduced fuel consumption, shorter operation periods, an increased brick processing capacity, decreased burnt brick losses, and notably lower emissions, with a concentration of SO2 that is 83% less than that of the AKC, NOx emissions, 58% lower than the AKC, and a remarkable 74.3% reduction in PM10 emissions. Moreover, the Ecokiln reduces pollutant emissions, improving the well-being of brickmakers and their communities. These results offer insights into the environmental impact of local brick production and support sustainable manufacturing practices.

At present, reducing the environmental impact of the construction industry is a major subject of study. In terms of the use of recycled concrete aggregates (RCA), most recently conducted studies have shown that the use of a limited percentage of those aggregates does not significantly affect the properties of concretes. This work analysed the mechanical properties of medium-strength concretes with a high contribution to sustainability, where cement and natural coarse aggregates (NCA) were partially replaced by volcanic powder (VP) and RCA, respectively. Three mixing ratios of VP replacement were tested in concretes without RCA and concretes with 30% RCA replacing NCA. Results show that when VP is used without RCA, up to 10% of the cement can be replaced by VP without a significant loss in the mechanical properties. When a combination of 5% VP and 30% RCA is used, the weakness of the recycled concrete is strengthened, obtaining stronger concretes than a control concrete with no recycled materials. Finally, the greenhouse gas assessment showed that the simultaneous incorporation of VP and RCA reduces CO2 emissions produced in the manufacture of concrete by up to 13.6%.

Lately EU has promoted several policies with the aim of reducing buildings energy impact. Despite such policies have successfully contributed to reduce residential buildings (RBs) energy consumption, non-residential buildings (NRBs) have shown an increasing of operational energy demand by 15.7%, during last decade. On the one hand, energy impacts are underestimated since only primary energy consumption (PEC) is considered while other energies, such as those related to the construction phase, replacements, or end-use phase, are missed. On the other hand, policies commonly lack of specific standards regarding NRBs since NRBs heterogeneity makes its standardization difficult. Therefore, with the aim of contributing to literature and in order to show the true impact of the overall energy consumption, this paper assesses a new school building. This was erected in partnership with constructors and energy consumption has been measured for two years. Calculations have been based on the Life cycle energy assessment methodology by taking into account the pre-use phase, the use phase and the estimated post-use phase. It has been concluded that, despite the building was designed for a very low PEC (<92 kWh m−2 year−1) this consumption only represents 56% of the total demanded energy along the building life cycle.

One of the ways of lessening the CO2 emissions of cement industry consists of replacing clinkers with supplementary cementitious materials. The required service life of real construction elements is long, so it is useful to characterize the performance of these materials in the very long term. Here, the influence of incorporating waste glass powder as a supplementary cementitious material, regarding the microstructure and durability of mortars after 1500 hardening days (approximately 4 years), compared with reference mortars without additions, was studied. The percentages of clinker replacement by glass powder were 10% and 20%. The microstructure was studied using impedance spectroscopy and mercury intrusion porosimetry. Differential thermal and X-ray diffraction analyses were performed for assessing the pozzolanic activity of glass powder at the end of the time period studied. Water absorption after immersion, the steady-state diffusion coefficient, and length change were also determined. In view of the results obtained, the microstructure of mortars that incorporated waste glass powder was more refined compared with the reference specimens. The global solid fraction and pores volume were very similar for all of the studied series. The addition of waste glass powder reduced the chloride diffusion coefficient of the mortars, without worsening their behaviour regarding water absorption after immersion.

One way to reach a more sustainable cement industry is replacing clinker by additions, such as waste brick powder. The objective of this research is to analyse the influence in the long-term (until 400 days) of waste brick powder in the microstructure, durability and mechanical properties of mortars which incorporate up to 20% of this addition as a clinker replacement. The microstructure has been studied with the non-destructive impedance spectroscopy technique. According to the obtained results, mortars with 10% and 20% of brick powder, showed good service properties in the long-term, even better than those made with ordinary Portland cement. The research work included in the paper has been financially supported by project DFP17-0006 ‘‘Aplicación de un tratamiento térmico para mejorar las prestaciones mecánicas de residuos de mampostería como reemplazo de cemento”, funded by Universidad de La Frontera (Chile).