• Energy Research

Abstract Energy efficiency and the reduction of greenhouse gas emissions are actual key issues in all the economic sectors and, in particular, in buildings which is acknowledged worldwide as one of the most energy-consuming. In this context, it would be desirable to duly address those issues by searching for and assessing proper solutions and strategies: the usage of eco-friendly construction materials can be considered as one of those. This paper reports upon the performance of three facades containing sustainable products that are manufactured using natural resources and, alternatively, post-consumer waste based materials; those are: hemp-concrete; and Recycled PolyEthylene Terephthalate (R-PET), respectively. The energy performance of each facade was assessed in terms of cooling and heating demands, electrical consumptions and indoor thermal comfort including indoor temperature and relative humidity. Additionally, a Carbon Footprint (CF) assessment was carried out considering both the estimated energy demands and the life-cycle emission factors associated with the energy mix of the countries where the facades were located, i.e. France and Italy. Based upon the findings of the study, the R-PET facade represented the most performing solution between the three facades in all the scenarios considered and, moreover, the humidity-sensitive flow rate ventilation system came out as a solution able to reduce the electricity consumptions. Finally, considering the Carbon Footprint results, the energy country mix emerged as a key issue, making the Italian case study the worst one, though the total electrical energy consumption were comparable with those of the other case studies.

The reactivity effect of calcium carbonate, present in ground oyster shells and limestone filler, on the formation of carboaluminate phases in ground granulated blast furnace slag blended cement pastes was reported in this paper. Six different binary and ternary blended cement pastes were prepared using ground granulated blast furnace slag, ground oyster shells and limestone filler with different replacement levels (from 5 to 35%). The carboaluminate formation was assessed and quantified directly using X-ray diffraction (XRD), and indirectly by following the aluminate phase’s reaction (heat flow) and consumed calcium carbonate using Isothermal Calorimetry (IC) and Thermogravimetric Analysis (TGA), respectively. Further, the overall reaction degree calculated based on TGA results and the compressive strength were determined to support the findings obtained. The results revealed that the calcium carbonate present in ground oyster shells is more reactive when compared to that present in limestone filler, where more formed hemi- and monocarboaluminate phases were observed in mixtures containing ground oyster shells. An enhancement in compressive strength and overall reaction degree was observed by adding 5% ground oyster shells as cement replacement.

Abstract The Toarcian Posidonia shale from Dotternhausen, Germany, is quarried and burnt in a fluidized bed reactor to produce electricity. The combustion residue, namely burnt oil shale (BOS), is used in the adjacent cement work as an additive in blended cements. The starting material is a typical laminated oil shale with an organic matter content ranging from 6 to 18%. Mineral matter consists principally of quartz, feldspar, pyrite and clays. After calcination in the range, the resulting product, burnt oil shale, keeps the macroscopic layered texture however with different mineralogy (anhydrite, lime, iron oxides) and the formation of an amorphous phase. This one, studied under STEM, reveals a typical texture of incipient partial melting due to a long retention time (ca. 30 min) and quenching. An in-situ high temperature X-ray diffraction (HTXRD) allowed studying precisely the mineralogical changes associated with the temperature increase.

Hemp shives is a lightweight material known for its insulating properties. Associating these bio-fibers with plant-based matrix instead of a mineral binder in insulation applications is of ecological interest. This article describes the study of a low environmental impact 100% plant-based material made solely from wheat starch and hemp shives. The hemp/starch ratio (H/S) influence and hemp shive size are studied. Samples are evaluated in terms of physical properties, mechanical behaviour and hygrothermal properties through an experimental approach. Results show that increasing 0–5 mm hemp shive proportion from 15% to 30% leads to a significant enhancement of the mechanical and hygric characteristics due to the load transfer and porosity. However, when the H/S ratio increases, mechanical and hygrothermal characteristics decrease slightly. Finally, the hemp-starch agro-material with H/S equal to 8 and 30% of 0–5 mm hemp shive seems to be the optimal composition between the studied samples.