# Quark Powder Valorisation in White Self-Compacting Concrete: Mortar Level Study
## 1 Introduction  
Concrete--which the main ingredient is Portland cement (PC), plus aggregates and water--is currently the most used construction material. No alternative material is expected to arise shortly. Concrete responds to the pressing needs of humanity, such as the construction of sewers and basic sanitation--crucial to public health--or water capture and storage infrastructures. It is fundamental in dams, wind tower foundations and public works. Although the production of 1 ton of concrete has a lower environmental footprint than the same amount of other conventional building materials (steel, brick, and asphalt), the dependence on this composite material is a serious problem in terms of sustainability [1, 2]. This is mainly because the essential constituent production, PC, has a high environmental impact. Each tonne of PC produced requires around 1.7 tons of non-renewable natural materials (essentially limestone and clay), 4 G) of energy (electricity and fuel) and 0.7 tons of CO\({}_{2}\) emissions. Each year it is estimated that world cement production is responsible for using 7000 Mt of non-renewable natural materials, 2% of the global primary energy consumption and 5% of the global industrial energy consumption [3]. However, theInternational Energy Agency Cement Roadmap projects cement demand growth by 12-23% by 2050 [4] and the Organisation for Economic Co-operation and Development admits that its demand might double by 2060 [5]. As such, reducing the environmental impact of PC while producing enough cement to meet society's demand will be challenging, especially in developing economies. Thus, cement and concrete are essential for achieving the United Nations Sustainable Development Goals since it has social, economic and environmental effects. According to the Report of the United Nations Environment Program Sustainable Building and Climate Initiative (UNEP-SBCI), at the material level, the main approaches to obtain substantial reductions in cement and concrete global carbonic emissions over the next 20-30 years and most directly contribute to the net zero emissions by 2050 scenario are (i) increase the use of supplementary cementitious materials (SCM) as a partial cement replacement, namely, low embodied CO\({}_{2}\) materials; and (ii) the optimisation of Portland cement dosage in cement based products [5]. In particular, it is important to study waste or by-product materials that can partially replace clinker Portland (low embodied CO\({}_{2}\) materials) [6; 7; 8], similar to what has been performed in the past with other SCM nowadays standardised, such as fly ash (FA), ground granulated blast furnace slag (GGBS) and silica fume (SF) [1]. SCM can be almost quasi-inert materials, usually called fillers or materials with latent hydraulic or pozzolanic properties. The most worldwide used SCM are FA and GGBS. However, the availability of those SCM is relatively modest, with estimated world production between 600 and 900 Mt per year and 300 and 600 Mt per year, respectively [9], considering the actual cement production, and this may be an issue regarding a long-term vision. FA is a by-product of coal combustion during electricity power production in thermal power plants [10]. FA availability worldwide is relatively high compared to other SCM [9]. However, about one-third is unsuitable for cement/concrete incorporation due to quality reasons [11]. A factor that may further aggravate the scarcity of FA for current applications is the decarbonisation policies that forced the closure of coal-based thermal power plants in Europe, making this by-product scarce for current applications. GGBFS is a by-product resulting during the manufacturing process of pig iron at temperatures between 1170 and 1500 \({}^{\circ}\)C [11]. GGBS is a latent hydraulic binder forming calcium silicate hydrates (C-S-H) after contact with water and provides improved concrete properties, namely, strength-enhancing, improved concrete durability, and slow release of hydration heat.