Integrating industrial wastes into soils to enhance their properties is a potential solution to current waste management challenges. Since the current literature lacks systematic studies on the mechanical performance of mixtures of soil, ladle furnace slag (LFS) and fly ash (FA), this research investigated the chemical stabilization of two different soils (clayey or sandy soil) using a concomitant mix of distinct types of industrial wastes: LFS and FA. A design of experiments (DoE) methodology was employed to systematically generate distinct mixtures for each soil sample, utilizing a simplex-centroid design. The mixtures were subjected to unconfined compressive strength (UCS), California Bearing Ratio (CBR) and resilient modulus (RM) tests. The industrial by-products improved the mechanical properties of the soils, providing UCS, CBR index and RM increases up to 130.5%, 324.4% and 132.6%, respectively. Synergistic and antagonistic effects related to the combination of different wastes were discussed, based on mathematical models with coefficients of determination ranging from 0.760 to 0.998, in addition to response surfaces generated for each response variable. The desirability function was applied to identify the optimal component proportions. The best mixture proportion was 80% soil, 20% LFS and 0% FA, which improved the formation of cemented compounds that contributed to the enhanced mechanical strength. The use of industrial waste for soil stabilization has therefore proven to be technically feasible and environmentally friendly.

The urgent demand for environmentally responsible construction practices has intensified interest in geopolymer concrete mixtures, which offer low-carbon alternatives to conventional Portland cement by enabling the valorization of industrial by-products. Since the large volume of waste generated by mining activities represents a significant environmental liability, this research aimed to utilize the alkali activation technique in mixtures of soil and bauxite residue, commonly known as red mud (RM), for application in green construction. All raw materials were characterized based on their physical and chemical properties. To evaluate the influence of waste content on the mechanical behavior of the geopolymers, specimens were prepared with soil contents ranging from 70% to 100% and RM dosages ranging from 0% to 30%. These mixtures underwent compaction tests using the standard Proctor energy method to determine maximum dry density and optimum moisture content. Using the optimal mixture compositions, specimens were prepared for unconfined compressive strength (UCS) tests, with NaOH at a concentration of 6 mol/L added as an activator. The experimental tests provided UCS results ranging from 2.23 MPa to 3.05 MPa. X-ray diffraction (XRD) analyses were performed on raw materials and mixtures containing 70% soil and 30% waste to assess changes in mineralogical compositions due to waste incorporation. The results confirmed the potential of alkali activation for stabilizing mixtures of soil and RM for sustainable construction.

This was a study on the mechanical behavior of hot asphalt mixtures with regard to permanent deformation, considering static creep tests and the parameters derived from the Superpave compaction curve. For the asphalt mixture production, mineral aggregates and two types of asphalt binder (CAP 50/70 and AMP 60/85) were used. These mixtures were designed using the Superpave methodology and compacted in the content and number of gyrations according to the design. For the design condition, asphalt mixtures using the conventional CAP 50/70 asphalt binder showed better workability and lower deformation than asphalt mixtures with the AMP 60/85 polymer binder. Furthermore, the influence of asphalt binder content on the behavior of asphalt mixtures in relation to permanent deformation and compaction indices was studied, considering the maximum number of gyrations in the design. Regarding this investigation, asphalt mixtures with higher asphalt binder content tend to show higher permanent deformation and better workability. Complementarily, the compaction curve indices (Construction Densification Index, CDI; modified Traffic Densification Index, TDIm and Locking Point, LP) were correlated with parameters obtained from static creep tests (total deformation after the recovery period, Dt; creep modulus, CM and curve inclination, Icurve) through curves obtained by the correlation between these indices. Based on this analysis, a good correlation was found between the results of static creep tests and compaction indices, showing the potential of these indices for predicting the mechanical behavior of the analyzed mixtures in relation to the development of permanent deformations.