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The paper proposes a sustainability-oriented assessment through a case study based on the duplication project of one of the most critical federal highways for cargo transport in Southern Brazil, considering the most common pavement technologies used in the country. The framework consists of concatenating life cycle impacts determined through life cycle assessment, the corresponding social effects regarding the population's health and well-being, and the life cycle cost. Results show that while hot mix asphalt contributed 30% more to the damage of natural resources, the Portland cement concrete contributed 16% more to harming ecosystem quality and 27% to harming human health. The photochemical oxidation and climate change potential of Portland cement concrete was 33% and 68% higher than those of hot mix asphalt. The toxic substances potentially released in ecosystems were 27% (freshwater), 15% (marine), and 11% (terrestrial) higher for Portland cement concrete. In contrast, ozone layer depletion potential, cumulative energy demand, and net present value were 36%, 29%, and 89% higher for hot mix asphalt, and the acidification and eutrophication impacts surpassed those of Portland cement concrete by 10% and 8%. Maintenance services are the hotspots for both pavement technologies throughout the life cycle. The significance of the proposed framework relies on guiding local strategic initiatives at the government and agency levels, assisting decision-making processes, and designing business models that meet sustainability requirements for road infrastructure in emerging countries where sustainability-oriented practices are not yet consolidated.

The management of the açai palm, a species of the Euterpe genus, has grown in recent years mainly for the extraction of palm heart and the pulp of the fruit called açai. After the extraction of the’ pulp, there is a significant generation of residues, as the discarded seeds account for approximately 85% of the fruit. Therefore, this research aims to characterize the açai seed after fruit processing, as well as to evaluate the potential of thermally processed seed for use in soil-cement bricks. The seed morpho-anatomy tests were performed, including moisture content, loss of ignition, ash content, thermogravimetry, fluorescence, and X-ray diffraction of the ground seeds. Tests on thermally processed seeds included readings by X-ray diffraction and laser granulometry. After evaluating the properties of the ash, it was incorporated into soil-cement mixtures in proportions of 5%, 10%, 15%, and 20%, replacing the clinker content of LC3 (Limestone Calcined Clay Cement). Based on the results obtained, soil-cement bricks were produced with a composition of 90% soil and 10% LC3, with the LC3 cement clinker being replaced by 20% açai seed ash. The results indicate the potential for the application of açai seed ash in soil-cement bricks on a practical scale, demonstrating that the ash enhances soil stabilization and increases the compressive strength of the soil-cement matrix due to its smaller particle size compared to that of the soil grains. This not only reduces the amount of cement required for the matrix but also offers environmental sustainability through the utilization of seed waste. The study underscores the potential of applying açai seed ash in the context of environmentally significant alternative technologies and sustainable practices, emphasizing the promise of the properties found in discarded açai seeds.

Calcium carbonate limestone filler is used as a partial replacement for clinker in cements to reduce carbon dioxide emissions and fill the voids in the cement paste. However, concrete durability conditions depend on the composition and the water/cement ratio, one of the major origin of concrete´s porosity. The objective of this study was to evaluate physical and chemical effects of calcium carbonate limestone filler in mortar pastes subjected to accelerated carbonation. Composite formulations were elaborated with three proportions of filler substitution (15%, 25% and 35%) and three water/cement ratios (0.42, 0.50 and 0.58). Physical, chemical and mineral characterizations were performed on Portland cement PC V and calcium carbonate limestone. The resulting mortar paste formulations were evaluated with respect to mechanical strength and capillary water absorption both for samples without carbonation and with accelerated exposure conditions. In the latter, carbonation depth penetration was also ascertained. Carbonation effects were determined from X-ray diffraction and thermogravimetric analysis. Results on compression strength and water absorption determined that a 25% filler substitution achieved the best performance with 40.72 MPa and an absorption of up to 7% for the water/cement ratio of 0.42. The carbonation coefficient was primarily affected by the water/cement ratio rather than substitution level. Thermal and mineral analysis indicated that carbonation consumed portlandite and formed calcite. Further calcium carbonate polymorphs were identified after 28 days of accelerated carbonation as a result so far unreported in studies of Portland cement.

As an alternative for ordinary Portland cement, geopolymers are cost effective materials that can be prepared with relatively low energy consumption and substantial reduction of CO2 emissions. In the present study the characteristics of novel hybrid composite of geopolymer foam (GPF)/polylactic acid (PLA) and their efficiency in removing copper(II) and zinc(II) to treat high volumes of polluted water are investigated. Contrary to the conventional methods for removing heavy metals, the newly developed composites are ecological, low-cost, easily available, and economically viable alternatives providing good physical-chemical stability, ion-exchange properties, and a porous structure. Based on the sustainable advantage to produce geopolymers from recycled materials, GPFs were obtained from blast furnace slag (BFS) by reacting 20 ml of an 8 M alkaline solution of sodium metasilicate (Na2SiO3) with BFS particles and later addition of hydrogen peroxide. GPFs were produced with a stoichiometry of 1.4 and 1.6 g/L between BFS/alkali solution with a 1.6 ml solution of hydrogen peroxide 50% to develop porosity into the materials. Finally, the GPFs were coated with PLA. Specimens of GPF/PLA composites were characterized by X-ray fluorescence spectroscopy, Fourier transformed infrared spectroscopy, thermogravimetric analysis, dynamic mechanical analysis, and field emission gun scanning electron microscopy. Adsorption analysis of Cu(II) and Zn(II), as well as ion-exchanges from aqueous solution through the composite with 1.4 and 1.6 stoichiometry, were performed using deionized water containing 0.80% Cu(II) or Zn(II). The test resulted in high performance for retaining Cu(II) and Zn(II). Under CO2 pressure at 50 bar, the gas permeation tests confirmed porous formations into the geopolymer foams coated with molten PLA.

The urgent need to find green alternatives to cement concrete in order to reduce the consumption of fossil fuels and non-renewable resources that are used to produce cement. This research aims to study the possibility of using volcanic pumice dust (VPD) waste with cement kiln dust (CKD) or Ordinary Portland cement (OPC) to produce alkaline activated green concrete (HAC). VPD was used to improve the mechanical performance, strength, and engineering properties of HAC. CKD and OPC were used as a partial replacement for VPD in different proportions of 0, 5%, 10%, 20%, and 30% by weight. Na2SiO3 and NaOH were used as alkaline activator solutions to realize the alkaline reaction process in geopolymer paste. Workability, compressive strength, and engineering properties, such as bulk density, porosity, and water absorption, were studied. Results of this research indicated that increasing the replacement rates of CKD or OPC decreased slump flow but increased the strength of HAC and enhanced the values of its engineering properties. Geopolymer concrete with OPC and CKD as partial replacement of 30% by weight of VPD achieved an increase of 23% and 8%, respectively, in compressive strength at a test age of 90 days. Meanwhile, 20% VPD replacement by CKD achieved 11% higher compressive strength for the VPD–CKD samples compared with the control mixture. In addition, water absorption rate decreased by 25% and 20%, respectively, compared with the control samples.

Geopolymer concrete (GCC) is a high-performance concrete, where a geopolymer mass serves to bond coarse aggregates, steel fiber and any non-reactive materials. The development of this concrete is an important step for the production of ecologically correct concrete. Indeed, in addition to reducing CO2, a common fact in cement industries, it also uses waste. The fatigue behavior of GCC reinforced with steel fiber was evaluated by dynamically cycled tensile tests and compared with ordinary Portland concrete (OPCC). In both types of concrete, the effects of different cement aging time (1, 7 and 28 days) and ratio of minimum applied stress level (R = σmin/ σflex) with quasi-static flexural strength (0.07, 0.20 and 0.40) as well as the volume fraction of added steel fiber (0.5 and 1.0 vol%) were disclosed. The GCC fatigue resistance associated with the number of cycle to rupture was, in average, higher than that of OPCC and, in particular 96% superior after 7 days of aging. As for the minimum applied stress ratio, the results showed a better performance of the GCC with unchanged mean values 50% higher than those of OPCC. Regarding the addition of steel fibers, comparable values were found for both GCC and OPCC within the standard deviation. These values are significantly higher, more than 4 times, than those of unreinforced concretes. The GCC SEM fractographs revealed a better cement matrix interfacial adhesion with both aggregates and steel fibers, as compared with OPCC. This was attributed to fibrous crystalline phase formation at the GCC cement interfaces.

The cement industry is responsible for a considerable part of the emission of gases that cause the greenhouse effect. In this context, geopolymer materials have been the subject of extensive studies, as they are an ecologically sustainable viable alternative to Portland cement. The geopolymer consists of a part rich in silica and alumina and another alkaline activating fraction, not having burning steps in its production chain, which consequently reduces the emission of CO2. Geopolymers also allow the incorporation of specific residues in its precursor part, such as calcined clays. The specimens for this study were produced by the molding process, using commercial metakaolin as the basis for the precursor fraction. After demolding, the test cups were subjected to ambient curing at 25 °C and thermal curing at 80 °C, for periods of 7, 14 and 28 days. The objective of this work was to analyze the behavior of geopolymers specimens against the variation of several parameters such as percentage of calcined clay (CC) incorporation into metakaolin in 10% and 20%, its granulometry in 100 and 200 Mesh, the molar ratio of SiO2/Al2O3, type and period of cure to evaluate technological properties such as resistance to bending, open porosity, water absorption, linear shrinkage and bulk density, aiming for future applications in the production of ceramic bricks. The results showed that an increase in the percentage of CC incorporation contributes to an improvement in the flexural strength, reaching 4.88 MPa to 20%. The molar SiO2/Al2O3 ratio of 3.0 was the most ideal. The importance of this study is linked to the evaluation of several parameters for the incorporation of calcined clay, in order to obtain properties required for future applications in ceramic bricks.

The use of activated alkali cements (AAC) as a replacement for Ordinary Portland cement (OPC) has become a viable alternative. This is due to the advantages of these materials, such as the possibility of using wastes or industrial by-products in their composition, contributing to environmental sustainability, in addition to the mechanical properties’ superior to OPC. The objective of this work was to evaluate the mechanical, physical and durability properties of an AAC based on blast furnace slag. The production of specimens was carried out in the proportion 1:2:0.45 (binder: aggregate: water), varying the sodium content in the alkaline solution between 2.5% and 15% and varying the age of thermal cure at 65ºC in 7 and 28 days. Compressive strength tests, calorimetry, diametrical compressive strength, density, electrical resistivity, capillary water absorption, water absorption and determination of porosity were carried out. It was observed that the compressive strength values for the 10% sodium composition were 22.12 MPa at 7 days and 41.07 MPa at 28 days. OPC, on the other hand, showed strength of 7.85 and 16.25 MPa, at 7 and 28 days in thermal cure at 65ºC, respectively. In addition, the performance of activated alkali cement-based mortar was superior to cement-based mortar in the other parameters evaluated. Thus, it is concluded that the use of blast furnace slag is a viable alternative for the production of AAC, a potential substitute for OPC, a material whose production is extremely polluting.

This article proposes a dosing procedure for interlocking concrete pavements that incorporate ornamental rock waste, with a view to meeting mechanical and molding criteria and ensuring the sustainability of the mineral industry, an economically important sector in Brazil despite environmental issues surrounding its waste generation. The procedure involves evaluating the packing density of the sand, coarse aggregate and waste fines via the minimum void ratio. A simplex lattice experimental design and the theoretical particle size distribution (Alfred) model were used, followed by a 22 factorial with a center point to determine the influence of the factors (proportions) and different water-cement (w/c) ratios (levels). The full cubic model obtained a 95.62 % adjustment index for optimal particle size of the aggregates and waste fines, and the lowest MVR (1.961 103kg/m³). This trend was confirmed by the theoretical Alfred model, with a coefficient of 0.29, and the factorial experiment, with an adjustment index of 97.50 %. Dosing indicated an ideal cement content of 20 %, 15.2 % for sand, 44.8 % for the coarse aggregate and waste fine incorporation of 20 % of the total mass (25 % of the aggregate mass), achieving compressive strength of 36.70 MPa for w/c and water/aggregate ratios of 0.5 and 0.123, respectively, and a carboxylate superplasticizer content of 6% of cement consumption, as well as adequate molding and demolding conditions. An ecotoxicological assessment was conducted, which found that waste fine incorporation posed no risk to the environment. Scanning electron microscopy (SEM) demonstrated that this mixture exhibited the best mechanical performance, with adequate aggregate particle size distribution and paste coverage, as well as waste fine stability in the cement matrix.

This paper investigates the application of Water Treatment Sludge (WTS), the main waste generated by water potabilization activities, for the development of a Supplementary Cementitious Material (SCM). The waste has been processed by calcining at a temperature range of 600 °C–800 °C for one hour. Chemical, mineralogical, physical, and morphological characterization has been performed to identify the potential pozzolanic activity of the calcined WTS and validate the application as SCM. Compressive strength tests have been performed in cement mortars with 14%, 35%, and 50% replacement of Portland cement by WTS. The WTS is a non-hazardous and non-inert waste, composed of SiO2, Al2O3, Fe2O3 and contains essentially quartz and kaolinite. Results confirmed the transformation of kaolinite into reactive amorphous phase by calcining. WTS calcined at 600 °C shows great potential to the production of SCM, confirmed by the chemical and physical analysis and the evidence of pozzolanic activity. The mechanical properties of mortars produced with 14% and 35% WTS calcined at 600 °C suggests a promising application in the production of blended and pozzolanic Portland cement.

This paper aims to investigate the influence of design strategies on the economic and environmental performance of 30-storey residential reinforced concrete (RC) building located in the Southern Brazil, through a case study. Four design options are simulated for the same building, including structural design as rigid frame system or hinged frame system with second order/P delta effects. In both cases buildings were designed with concrete strength class 25 MPa (C25) applied in all the structural elements or a concrete strength class range of 50 MPa to 25 MPa (C25–C50) applied in columns, varying along the building height. Environmental impacts were quantified through Life Cycle Assessment (LCA) based on measurements of environmental loads of processes and products, from cradle to grave. Results show reduction of environmental impacts, embodied energy and construction costs when a decrease in the amount of steel is combined with the increase in the concrete compressive strength of columns, which is more representative for the building designed as hinged frame system. The production of materials phase showed to be the major contributor to environmental impacts with steel and concrete being the most relevant impact producers. Concrete represents important impacts for stratospheric ozone depletion and climate change while steel dominates the ecotoxicity-related indicators. Results highlight the importance of design strategies to increase the sustainability potential of a RC structure and contribute to consolidate contemporary approaches that suggest the need to incorporate the degree of environmental impacts in design methods. Keywords: Concrete, Life cycle assessment, Compressive strength, Structural design