# Design Procedures for Sustainable Structural Concretes Using Wastes and Industrial By-Products
###### Abstract
Fly ash (FA) is a fine mineral powder and is generated from the coal used in thermoelectric power plants, and therefore characterized as an industrial by-product. Its incorporation adds several advantages to concrete compositions such as: increased resistance to chemical attack and to the aggressiveness of different environments; increased long-term mechanical strength; reduction in shrinkage cracking and increased physical-mechanical concrete resistance [17; 18; 19]. However, fly ash is becoming a scarce product, as coal-based thermoelectric power plants are being discontinued. Electric arc furnace slag (EAFS) is a waste product resulting from the steelmaking process in an electric arc furnace, where recycled steel scrap is melted. This material is characterized as a dense by-product [7; 8; 20]. Many of the studies conducted incorporating EAFS have found quite satisfactory results, and although some research may be found in this study area [21; 22; 23; 24; 25; 26], it is still important to deepen this knowledge regarding the mechanical and durability properties, as well as on the design methodology. [PERSON] et al. [27] focused their research on the design of structural concrete compositions based on two discrete particle packing models, namely the compressible packing model and the 3-parameter particle packing model. Concrete compositions were designed to obtain the most compact structure of commercial natural limestone (NL) and EAFS aggregate. The water/cement (\(w\)/\(c\)) ratio was fixed equal to 0.55 to reach a concrete composition with a strength class above 30 MPa. The maximum content in solid weight of EAFS aggregates used were between 49.4% and 70.5%. It was concluded that the slump of all concrete mixtures designed with a cement amount of 260 kg/m\({}^{3}\) of concrete corresponded to a dry consistency. On the other hand, when a higher amount of cement was added to the concrete (i.e., 320 kg/m\({}^{3}\)), the workability improved. They also confirmed the validity of using the particle packing models for the mixtures studied. [PERSON] et al. [28] showed that the replacement of conventional limestone aggregates in reference concrete mixtures, to produce concrete mixtures of C25/30 and C30/37 strength classes, by EAFS and ladle furnace slag (LFS) led to an improvement of their mechanical and physical properties, as well to their service life extension. In their study, they used a cement amount of 350 kg/m\({}^{3}\), \(w\)/\(c\) ratio of 0.51, and 30% and 50% of slag aggregates (EAFs and LFS) by volume. The increase in compressive strength at 7 days was 50% and in the case of frost resistance, after exposure, the scaling leads to a weight reduction 3.5 times lower than that of the reference concretes. These alternative concrete mixtures also showed reductions of CO\({}_{2}\) of 55% in natural carbonation and 40% in accelerated carbonation. The reduction of chloride penetration was of 57%. Additionally, they verified that the structures constructed with these alternative concrete mixtures resulted in a cost reduction per cubic meter of concrete of 35% per year of life, and a service life increase by up to 130%, considering the mechanism of deterioration due to chloride penetration. Other researchers did not find such favorable results in terms of physical properties compared to typical concretes, with a cement amount of 275 kg/m\({}^{3}\), as in the case of the previous study [29]. In fact, they verified that concrete mixtures with approximately 79% (in solid weight) of EAFS presented higher depth of water penetration under pressure, due to the high porosity of EAFS aggregates, a slightly higher expansion, higher carbonation depth and similar resistance against freeze-thaw cycles in relation to reference mixtures.