Ladle Furnace Slag (LFS) is a solid waste from steel production that can be used in civil construction due to its high content of calcium oxides (> 50% CaO), contributing to the sustainability of both industries. Seeking to study its function as a supplementary cementitious material, the objective of this work was to determine the properties of coating mortars with the replacement of Portland Cement (PC) by 30% LFS combined with the pozzolanic effect of Rice Husk Ash (RHA). Prismatic specimens were produced in a 1:6 mixture proportion (PC:sand) and subjected to mechanical tests and determination of the dynamic modulus of elasticity. The results indicated that the replacement provided a reduction in mechanical strength, however the presence of LFS+RHA was beneficial to improve water retention. These changes were caused by the bigger surface area of RHA grains and the higher CaO content, in relation to the reference mixture.

Ladle furnace slag is a waste composed essentially of quicklime or hydrated lime, whose contents depend on the raw material and the cooling process that led to the slag batch. With this chemical composition, it is used by civil construction as a hydraulic binder in cement matrices. The chemical compounds mentioned are also present in Portland cement, which are part of the chemical reactions of hydration and hardening. However, the quality of LFS batches calls for attention to volume expansion caused by chemical compounds whose presence and content can be controlled by the cooling method adopted in the production. Considering the use of this material as a partial replacement for Portland cement, the objective of this study was the physicochemical characterization of LFS samples to evaluate the influence of the cooling method on its potential as a complementary binder in cementitious matrices. In this sense, 3 samples from different batches were analyzed and the effects of each cooling process. The results include analysis of specific mass, laser diffraction for particle size analysis, X-ray fluorescence and X-Ray Diffraction tests. It was verified that the sample obtained by slow cooling is the most suitable as binder, as it features less possibility of expansive chemical reactions and presents greater fineness.

Ladle furnace slag (LFS) is used as a supplementary cementitious material (SCM) due to its high calcium oxide (CaO) content. Its binding properties are enhanced in the presence of siliceous materials, such as metakaolin (MK), forming a ternary mixture that can directly replace ordinary Portland cement (OPC). However, despite this blend having already been evaluated in alkali-activated mixtures, knowledge about this mixture in situations of direct replacement of OPC by slag is still lacking. This study evaluates the synergistic effects of combining LFS and MK in cementitious mortars. Due to an insufficient hydration reaction observed in the short term, this study focuses on assessing the long-term performance of these mortars. Both the fresh and hardened states at 28 and 180 days are evaluated, and the resulting microstructural characteristics and constituent phases are also examined. After 180 days of curing, the mortar with MK exhibits superior binding activity compared to the results at 28 days. Although the nominal resistance does not show a clear advantage with the application of MK, a significant reduction in the porosity of the mortar is observed. Microstructural analysis indicates that the addition of MK increases the hydration compounds when mixed with LFS. Importantly, the sample containing MK and LFS showed a 42% reduction in cement consumption, highlighting the potential for resource efficiency. Thus, this study contributes to promoting a circular economy between the steelmaking and civil construction sectors.

Ladle furnace slag (LFS) is a byproduct from steel refining with high calcium oxides and hydroxides contents, making it viable as a supplementary cementitious material (SCM), enhancing microstructure and mechanical properties, particularly in mortars. Therefore, this work evaluated the replacement of 30% of ordinary Portland cement (OPC) with LFS in coating mortars, combined with a water-retaining admixture as well as the pozzolanic addition of Metakaolin (MK). The mortars followed a 1:6 (binder:aggregate) ratio, and the tests evaluated their properties in the fresh and hardened state, such as the water retention and mechanical properties, along with microstructure characterization to investigate the effects of the binder blends. At 28 days, LFS incorporation ensured water retention, less compacted matrix and greater capacity of deformation absorption, which are properties particularly beneficial for masonry mortars. MK’s pozzolanic reactions resulted in pore refinement; however, the improvements in nominal strength were not statistically significant.

Amongst the byproducts of steel industry is ladle furnace slag (LFS), with a chemical composition similar to limes, especially in the high content of calcium oxide and hydroxides. Its binding potential is improved with finer texture, making it viable for use as a supplementary cementitious material (SCM). Therefore, this study investigated the effects of a total replacement of hydrated lime (HL) for LFS in masonry mortars, also exploring whether pozzolanic addition of metakaolin (MK) could enhance it, tested both at 28 and 180 days. The experimental results, obtained at 28 and 180 days, showed that the replacing HL for LFS improved the mechanical properties of the mortars, due to the greater amount of compounds of LFS also present in the OPC, but not in the HL, such as Fe₂O₃, Al₂O₃ and SiO₂. These findings suggest the potential of LFS for application in masonry mortar promoting strategies of circular economy.

The use of lightweight concrete with expanded clay has increased as an alternative for reducing the self-weight of structures. Consequently, techniques that facilitate the analysis of the mechanical and elastic properties, such as ultrasonic pulse velocity (UPV), have gained relevance. Despite this, there is still a lack of studies focusing on the elastic properties of this type of concrete through UPV methods, particularly the dynamic modulus of elasticity (Ed) and Poisson's coefficient. This study aimed to determine the Ed and Poisson's coefficient of concrete containing expanded clay, based on the ASTM C597-16 standard and the stiffness matrix method. Strong correlations between static modulus of elasticity (E) and Ed were observed, with exceptions related to the stiffness matrix method. Nevertheless, this method provided the most suitable Poisson's coefficient for the material studied. The Ed values fell within the expected range, confirming the effectiveness of ultrasonic testing for lightweight concrete.