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The paper evaluates the feasibility of reducing clinker in the Portland Cement production using local metakaolin in Burkina Faso. Standardized testing methods have been used for this purpose, and experiments were performed on mortar prisms containing different amounts of metakaolin. Important results about the physical, mechanical and durability characterization of blended mortars were carried out in this study. The obtained results are discussed based on available literature data. These results have shown increased physical and durability properties for blended mortars. Although the mechanical strengths remained relatively low for higher MK incorporations, the latter grow to surpass these of PC mortars (the reference) at 28, 56 and 90 days of curing. The results in the paper, have confirmed the possibility of using metakaolin to partially substitute cement, a possibility to reduce the CO2 production by the cement industry in Burkina Faso.

In the UK context, miscanthus is a potential alternative perennial crop for the development of bio-based building materials. This paper presents the environmental benefits of using miscanthus shives in lightweight blocks and their potential application in wall assemblies. A systemic life cycle assessment (LCA) is carried out for miscanthus-lime blocks, and the effects of binder type and binder content are discussed. The environmental performance-based analysis reveals that miscanthus blocks can capture 135 kg CO 2 eq/m 3 for an assumed 100years life period. The impact analysis using the University of Leiden, institute of environmental science (CML) baseline (v4.4) method shows that 75% of the greenhouse gas emissions are attributable to the production of mineral binders. A reduction of binder to aggregate ratio from 2.0 to 1.5 reduces greenhouse gas emissions by 32.9%. The use of 10 wt% mineral additions can potentially stabilise blocks while having little effect on their overall environmental impacts. The environmental profiles of wall systems incorporating miscanthus-lime blocks have been evaluated in this this study. Combining miscanthus blocks with fired clay bricks enables a potential low carbon retrofitting technique for the current stock of residential buildings in the UK. Timber-framed system filled with miscanthus blocks enables a carbon storage of~97.3 kg CO 2 eq/m 2 , which presents a potential carbon offsetting strategy in new-build dwellings. Consideration should be given to the potential negative impacts related to agricultural activities for the production of miscanthus shives. The largest negative environmental impact was ozone layer depletion, where a relative difference of 12.8% was recorded between miscanthus timber-framed wall and a typical solid wall insulated with mineral wool. It appears that miscanthus-lime composites can substantially improve the environmental profile of wall assemblies and sustainability be applied in existing uninsulated masonry walls or incorporated in timber-framed new-build houses.

Alkali activated binders are a promising alternative to the use of Portland cement in the manufacture of concrete for curbing CO2 emissions. Novel sources of silicates have been investigated in recent years for reducing cost and environmental impacts associated with the use of chemical activators. This study describes the production of solid sodium silicate (SS) activating powder from bamboo leaf ash (BLA). Bamboo leaves were calcined at 550–800°C, mixed with NaOH pellets, and heated in an oven at 300°C. The obtained silicate powder was used for activating blended fly ash/slag samples. Mechanical and microstructural properties of BLA‐based samples were compared to those of samples made with commercially available chemicals. The strength of BLA‐activated mortars matched the commercially‐sourced activators, being 25–30 MPa at 7 days and exceeding 40 MPa at 28 days. The microstructural analysis suggested that BLA‐based SS showed a lesser degree of dissolution of precursors at 7 days, but the quality of the matrix was higher than that of NaOH‐activated samples. These results confirmed that the reactivity of BLA‐silicate powder was similar to that of commercial SS solutions, and show the potential valorization of future biomass renewable waste in the production of low carbon, alkali‐activated concretes.

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The environmental burdens attributable to buildings remain relatively high. The built environment is responsible for more than one-third of the global energy consumption and nearly 40% of global CO2 emissions. In the context of increasing the sustainability of the built environment, bio-based building materials have gained a growing interest for their application in building envelopes. Miscanthus giganteus (elephant grass) is a perennial, cost effective and sustainable source of fibres for the development of bio-composites. This experimental study evaluates mechanical and acoustic properties of miscanthus - lime composites for their potential use in renovations and new-build houses, in South West England. The impact of binder to aggregate mass ratio and density on compressive strength is investigated. Moreover, the effect of aggregate particle size on the acoustic performance of miscanthus - lime composites is presented. It is shown that the initial fresh density has little effect on compressive strength compared with that of binder content. The acoustic tests results show that the use of small size particles improves the acoustic performance of miscanthus - lime composites with recorded high transmission loss and sound absorption coefficient values.

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