The addition of supplementary cementitious materials (SCMs) to low-carbon concrete mixtures has been investigated in recent years as part of the sustainability of the concrete sector. Recently, most traditional SCMs, such as fly ash and blast furnace slags, have become unavailable in several developed countries, mostly due to environmental restrictions. Consequently, several new by-products from fast-growing sectors are being considered as potential replacements for traditional SCMs. However, the durability of these new by-products in low-carbon concrete has not been thoroughly explored. As a result, this paper presents the first part of a project related to an extensive experimental characterization, in which low-carbon concrete with high compactness, paste optimization, and partial cement replacement by the addition of waste by-products from the agricultural, metallurgical, paper, and glass industries is studied. Alternative SCMs including rice husk ash, biomass fly ash, rock wool residues, or waste foundry sand are incorporated into corresponding mortar matrices and the results concerning the mechanical properties (flexural and compressive strength) and durability (capillary water absorption, surface electrical resistivity, and carbonation resistance) are presented and analyzed. The outcomes indicate that it is possible to reduce the Portland cement content without compromising the mechanical and durability properties of the concrete.

This article presents the characterizations of mechanical and durability properties on diverse concrete formulas with a lower carbon footprint. The contribution of mineral additions in the binder is currently limited by the NF EN 206/CN (2022) standard with the concept of the equivalent binder. It is now necessary to change these normative provisions to expand low-carbon concrete solutions and accelerate their development in construction. The objective of this study is to formulate concretes based on ternary binders and to evaluate their use properties compared to traditional concrete defined today in the normative context. Several types of addition have been used to form ternary binders: limestone addition, blast-furnace slag, and flash metakaolin. The results obtained with substitution rates ranging from 40% to 60% of clinker have allowed positioning these different concretes regarding the thresholds defined for the performance-based approach according to FD P 18-480 (2022).

Hemp lime concrete (HLC) is an environment-friendly material increasingly used in building construction. Many studies have focused on the moisture buffer capacity of HLC, but its pollutant buffering capacity remains unknown. To address this research gap, the potential for moisture and toluene buffering capacity of hemp concrete is presented in this article. The sorption capacity toward toluene (TOL), a typical indoor volatile organic compound (VOC) of HLC, has been measured and investigated with a 50 L environmental chamber at 23°C and a relative humidity of 50%. The moisture buffering capacity of HLC has been determined according to the Nordtest protocol. The experimental data have been used to evaluate the model parameters of the CHAMPS-bio model (coupled heat, air, moisture, and pollutant simulation transport model dedicated to bio-based building materials) that assesses VOC transfers and hygrothermal behavior of building materials under dynamic conditions. The results are innovative and new for hemp concrete, and evidence that this bio-based material can mitigate the indoor toluene concentration and regulate indoor relative humidity thanks to its buffering capacity.

The development of low carbon footprint and high initial compressive strength binders for the precast industry is presented. Binders with a substitution of up to 75% of a normal Portland cement (CEM I) with a mixture of metakaolin and two different limestone additions were developed on mortars. Water/binder ratio reduction (down to 0.25) and thermal treatment (up to 50°C) have been applied to improve initial compressive strength (> 14 MPa at 8 hours). Pozzolanic reaction improved 28 days compressive strength (> 50 MPa). The most technically and environmentally performant binders have been applied to concrete. Concretes with low clinker contents have been produced to achieve the C25/C30 and C40/50 strength classes. Durability performances corresponding to XC4 were assessed via a performance approach (FD P 18-480). A wall with integrated formwork has been industrially manufactured which allowed a carbon footprint reduction of around 30% over its whole life cycle.

The Production of Portland cement used in concrete and the large amount of industrial waste generated worldwide represent critical environmental and economic issues. The reuse of bauxite residue generated during alumina production by Bayer’s process to replace Portland cement and produce sustainable and environmentally friendly geopolymer concrete is a promising solution. This paper presents the development and characterization of bauxite residue and class F fly ash-based geopolymer mortar and concrete. The parameters studied for the mixture proportions are the bauxite residue to class F fly ash ratio, the water-to-binder ratio, and the curing condition, in terms of duration and temperature. Then, the compressive strength of the geopolymer mortar and concrete is characterized with experimental tests. Results show that, with appropriate mixture proportions and curing conditions, a large amount of bauxite residue (up to 70%) can be used to replace fly ash and obtain geopolymer concrete with improved quality characteristics that meet the construction field’s sustainable development criteria.