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The main aim of the work is to study the effect of different fibres (steel, glass and basalt) on resistance of blast furnace slag-based alkali-activated mortar in acidic environment. The alkaliactivated slag mortars were exposed to 5% sulfuric and acetic acid solutions for 30 days. Mass change, compressive strength and microstructural changes were evaluated. In plain mortar, it was observed that 70% of the strength was retained in acetic acid environment whereas only 20% of residual strength remains in sulphuric acid environment. FTIR spectroscopy shows the degradation of the matrix, which implies the alkali-activated mortar was more vulnerable in sulphuric acid environment due to its aggressive nature compared to acetic acid. Decalcification and formation of calcium acetate also hinders the further progress of damage in acetic acid attack. Fibres helped in improving the performance of the mortar by holding the matrix together when the degradation occurred in acidic environment. Compared to plain mortar, incorporation of steel fibres exhibited a maximum strength retention of 19% in acetic acid and 7% in sulphuric acid, followed by glass and basalt fibres. SEM images clearly show the debonding of fibres and disintegration of matrix in acidic environment, which resulted in strength loss.

Alkali-activated magnesium aluminosilicate binders using only soapstone have been found to develop low strength and unacceptable durability properties. One of the effective solutions to enhance mechanical and durability properties of these binders could be using cobinders. Since cobinders are rich in different chemical components, the addition of different cobinders has different impacts on the mechanical performance and durability. This study investigates the influences of replacing 20% (in wt.%) of soapstone by different cobinders (metakaolin, lime, stone wool, and silica fume) on the mechanical strength (compressive and flexural strength), drying shrinkage, and durability (acid attack, high temperature, carbonation, water absorption by immersion, and capillary action). Moreover, the impacts of this replacement were analyzed by thermogravimetry analysis and X-ray diffraction. The results showed that the type of used cobinder has a great impact on the mechanical and durability performances of alkali-activated soapstone binders. In general, the lowest performance in the hardened-state properties resulted from the addition of lime as a cobinder, while each of the other cobinders had the best performance in one aspect of hardened-state properties.

Alkali-activated materials (AAMs), and geopolymers as their subgroup, are a valuable addition to the building materials with lower carbon footprints. Porous AAMs have promising performance, unique properties, and their carbon emissions are low due to the use of industrial wastes as raw materials. Porous AAMs can be prepared by several different methods such as direct foaming, sacrificial filler method, and 3D printing. Pore size plays a major role in defining, for instance, mechanical, thermal insulation, acoustic, and permeability properties. Strength improvement with a high-temperature exposure of the AAM makes it an excellent material for fireproofing and refractory linings compared to the conventional foam concrete made of Portland cement. The low thermal conductivity and high sound absorption capacity of the porous material is utilized for its application in insulation purposes. AAMs are now quickly progressing in the construction and environmental applications of the civil engineering sector. The development of foam with precise properties to satisfy the requirement for this specific application will open new market opportunities. This chapter covers the different preparation methods of porous AAMs, their characterization techniques, properties and functional relations, and applications in civil engineering.

Geopolymers resemble conventional ceramics but can be manufactured at near-ambient temperatures. In this work, geopolymer–bentonite composite foam with silver nanoparticles was prepared and applied for water disinfection, inspired by point-of-use ceramic water filters. The inactivation efficiency against Escherichia coli and intestinal enterococci bacteria was found to be promising (0.6–2.4 and 0.3–1.4 log₁₀ reductions, respectively) for ∼1 d. However, the inactivation efficiency against somatic coliphage viruses was poor (

Micropollutants escaping conventional wastewater treatment processes pose a threat to biota and the environment. Amongst micropollutants, small and ionizable organic compounds are particularly challenging, since their removal depends significantly on prevailing conditions. In this study, anionic cellulose nanofibrils (CNFs) were shown to perform as promising adsorbents for an ionizable pharmaceutical, salbutamol. The adsorbents were produced from wood cellulose through succinylation pretreatment in urea-LiCl deep eutectic solvent (DES), followed by a nanofibrillation procedure. The impact of pH, contact time, salbutamol concentration, and adsorbent dose on salbutamol uptake were investigated in batch adsorption studies. Based on the results, the chemical modification of cellulose significantly enhanced the adsorption of salbutamol. The adsorption efficiency was mainly dependent on the charge and colloidal stability of the anionic nanofibril suspension rather than the charge of salbutamol, because the adsorption was considerably improved at pH > 7 due to the deprotonation of the cellulose carboxyl groups. The experimental maximum adsorption capacity was 196 mg/g. This study highlights the potential of cellulose nanomaterial adsorbents and the importance of controlling the charge of the adsorbent material when developing solutions for ionizable micropollutant removal.

The aim of this study was the valorization of paper sludge waste from paper industry in designing one-part geopolymer cement using ground granulated blast furnace slag as main precursor. The effects of increasing the amount of paper sludge pretreated with a constant amount of sodium hydroxide (2% of slag) on mechanical strength, heat evolution, setting time and durability were analyzed. The reaction products were characterized using X-ray diffraction and thermogravimetric analysis. The findings showed that paper sludge can successfully be used as a secondary source of calcium carbonate in the one-part (“just add water”) geopolymer. The compressive strength of the cured geopolymer increased with increasing the amount of paper sludge, and the non-reacted sludge acted as a filler. The maximum strength (42 MPa, 28 d) was reached at 18 wt-% paper sludge addition. The main reaction products were calcium aluminate silicate hydrate and hydrotalcite-like cementitious gels. From the perspective of its blast-furnace slag content, strength properties, water absorption and setting time, the one-part geopolymer cement could be classified as a CEM IIIC and Type 32.5N class cement under the European standard EN-197.

In the present experimental/numerical study, a combination of ceramic waste and ground-granulated blast furnace slag were used in the preparation of one-part alkali-activated binders. Moreover, the effect of fiber type and content on hardened-state properties and shrinkage was studied under two different curing conditions. In the first stage of this study water absorption, compressive strength, and flexural strength were assessed. Subsequently, the flexural performance of fiber-reinforced binders was simulated and predicted using finite element models under concentrated and distributed flexural loading, respectively. The experimental results showed that fibers improved mechanical properties, and enhancement was governed by fiber type and curing conditions. Moreover, the numerical results indicated that the developed fiber-reinforced binders offer a flexural load-carrying capacity in the range of 10–40 kN/m2 and permissible service loads were well below the ultimate capacity.

Alkali-activated materials (AAM) are recognized as potential alternatives to ordinary Portland cement (OPC) in order to limit CO2 emissions as well as beneficiate several wastes into useful products. However, the alkali activation process involves concentrated aqueous alkali solutions, which are corrosive, viscous, and, as such, difficult to handle and not user friendly. Consequently, the development of so-called one-part or “just add water” AAM may have greater potential than the conventional two-part AAM, especially in cast-in-situ applications. One-part AAM involves a dry mix that consists of a solid aluminosilicate precursor, a solid alkali source, and possible admixtures to which water is added, similar to the preparation of OPC. The dry mix can be prepared at elevated temperatures to facilitate the reactivity of certain raw materials. This review discusses current studies of one-part AAMs in terms of raw materials, activators, additives, mechanical and physical properties, curing mechanisms, hydration products, and environmental impacts.

Geopolymers are functional materials that can be used in various environmental applications such as adsorbents in pollutant removal from wastewaters. Metakaolin geopolymer (MK-GP) has been proven to be especially suitable for ammonium (NH4 +) removal. In this research, the optimal reagent and raw material ratios in the preparation of MK-GP in terms of NH4 + adsorption capacity were investigated. The response surface methodology based on the face-centered central composite design was used to optimize the levels of three factors: the amounts of hydroxide, silicate, and metakaolin. In addition, the effect of Na or K as the charge-balancing cation was studied. Empirical models were fitted to the experimental data using multiple linear regression. The significance of the models was confirmed by means of analysis of variance. Optimal NH4 + removal efficiency was achieved when the amounts of hydroxide and silicate were maximized, the amount of metakaolin was minimized, and Na-based reagents were used. These trends are most likely a result of optimized conversion of metakaolin into MK-GP.

Alkali-activated binders have received substantial attention due to their excellent potential in enabling the reuse and recycling of industrial solid wastes and by-products. One-part or just-add-water alkali-activated binders are an approach to reduce the negative aspects of using an alkali solution during the preparation of traditional two-part alkali-activated binders. The work aims to utilize the maximum content of ceramic wastes in alkali-activated blast-furnace slag/ceramic binders. The ground granulated blast-furnace slag was partially replaced [10%, 20%, and 30% in weight (wt.)%] by two types of ceramic wastes (porcelain and raw; i.e., fired and unfired). Moreover, the coarse particle size of porcelain ceramic waste was used as recycled aggregate. The specimens were cured under two different curing regimes: (1) sealing with plastic; and (2) using thermal curing conditions for 3 h in 60°C after demolding and then sealing until the test day. Mechanical testing and microstructural analysis were used to characterize the effects of different curing regimes and different ceramic sources. The results showed that replacing ground granulated blast-furnace slag with all types of ceramic wastes reduced the compressive strength; this reduction was mainly caused by reduction of the calcium content. This strength loss was also governed by the ceramic waste type, curing regime type, and curing duration. The microstructural analysis indicated that some cracks formed between the ceramic waste particles and the matrix. Moreover, the microscopic analysis indicated the use of preheating could eliminate cracking.

Soapstone is a soft, magnesium-rich mineral widely used in the production of carved objects and architectural elements, for instance. The processing of soapstone causes the formation of significant amounts of waste powder, which is largely landfilled at the moment. The aim of the present study is to evaluate the suitability of soapstone waste as the main binder for the alkali-activation process using sodium silicate and hydroxide solutions as activators. The results demonstrate that soapstone alone reacts to some extent (compressive strength of 13 MPa at 28 day age), but mechanical properties are improved significantly after replacing 20% of soapstone by metakaolin (compressive strength of 31 MPa at 28 d age). The obtained mechanical properties are closely similar to those of virgin soapstone. Durability properties of the developed alkali-activated binders were similar or better than typical Portland cement-based binders in terms of high temperature, acid, and freeze-thaw resistance, and sorptivity. The material costs alkali-activated soapstone mortar were estimated as approximately 70 €/t. Thus, the results enable utilizing currently underexploited soapstone waste in a sustainable and economically interesting way.

Alkali-activated materials are a low-CO2 alternative for Portland cement in construction. However, one major issue in their use is the poor or varying functionality of the currently available commercial superplasticizers. Especially for one-part (‘just add water’) alkali-activated materials, the number of studies is limited. In this study, one-part alkali-activated mortar was prepared from blast furnace slag by using solid sodium hydroxide as an activator and microsilica as an additional silica source. Comparison of commonly used superplasticizer types revealed that lignosulfonate, melamine, and naphthalene-based superplasticizers are more efficient than the currently most used polyacrylate and polycarboxylate-superplasticizers. Lignosulfonate-based superplasticizer was overall best-performing: it improved significantly the workability (+41% spread, −51% yield stress, −27% viscosity), setting time (+70%), and compressive strength (+19%) at a 0.5 wt% dose. When the amount of water and superplasticizer were optimized, compressive strength of mortar could be doubled (from 19 to 40 MPa at 28 d).

Peracids have gained interest in the water treatment over the last few decades. Peracetic acid (CH3CO3H) has already become an accepted alternative disinfectant in wastewater disinfection whereas p...

Blast-furnace slag and metakaolin were geopolymerised, modified with barium or treated with a combination of these methods in order to obtain an efficient SO4(2-) sorbent for mine water treatment. Of prepared materials, barium-modified blast-furnace slag geopolymer (Ba-BFS-GP) exhibited the highest SO4(2-) maximum sorption capacity (up to 119mgg(-1)) and it compared also favourably to materials reported in the literature. Therefore, Ba-BFS-GP was selected for further studies and the factors affecting to the sorption efficiency were assessed. Several isotherms were applied to describe the experimental results of Ba-BFS-GP and the Sips model showed the best fit. Kinetic studies showed that the sorption process follows the pseudo-second-order kinetics. In the dynamic removal experiments with columns, total SO4(2-) removal was observed initially when treating mine effluent. The novel modification method of geopolymer material proved to be technically suitable in achieving extremely low concentrations of SO4(2-) (

Geopolymers are aluminosilicate compounds that are amorphous analogues of zeolites, and thus possess similar cation-exchange properties. Geopolymers have been successfully applied to remove toxic metals and organic dyes from aqueous solutions. In this study, geopolymer was synthesized from metakaolin and applied to remove ammonium (NH 4 + ) from model solutions and landfill leachate. Geopolymerization increased the ammonium removal capacity, surface area and average pore width and changed the chemical structure of metakaolin. The maximum NH 4 + removal capacity of the geopolymer was 21.07 mg g − 1 which was 46% higher than the capacity of the reference clinoptilolite–heulandite zeolite (14.42 mg g − 1 ). The adsorption data of the geopolymer and zeolite fitted best to the Langmuir–Freundlich isotherm and the removal kinetics followed the pseudo-second order kinetic equation. The spent geopolymer adsorbent was regenerated efficiently using 0.2 M NaCl and 0.1 M NaOH as a regenerant. A small-scale continuous field experiment with landfill leachate was performed and further indicated that the metakaolin-based geopolymer could be a feasible NH 4 + removal adsorbent.

Sodium silicate powders with different SiO2/Na2O (silica modulus) were characterized by solubility rate, pH, and chemical structure (by 29Si MAS-NMR) and compared in the preparation of one-part (or dry-mix) alkali-activated blast furnace slag mortar. The low SiO2/Na2O indicated the beneficial presence of less-polymerized silica (Q1 and Q2 Si environments) and thus faster dissolution. Consequently, using sodium silicates with SiO2/Na2O of 0.9, 2.1, and 3.4 resulted 28 d compressive strengths of 103, 80, and 2 MPa, respectively, with increasing setting time and decreasing heat release in isothermal calorimetry. Adjustment of activator SiO2/Na2O from 2.1 or 3.4 to 0.9 by adding NaOH powder resulted increased or decreased mechanical properties of mortar, respectively, depending on the initial silica modulus. These properties were not, however, similar to those obtained with sodium silicate having SiO2/Na2O of 0.9 originally. Depending on the case, the added NaOH can be consumed for dissolving sodium silicate activator, slag, or the forming (C,N)-(A)-S-H gel.

Sulfate (SO₄²⁻) is a ubiquitous anion in natural waters. It is not considered toxic, but it may be detrimental to freshwater species at elevated concentrations. Mining activities are one significant source of anthropogenic sulfate into natural waters, mainly due to the exposure of sulfide mineral ores to weathering. There are several strategies for mitigating sulfate release, starting from preventing sulfate formation in the first place and ending at several end-of-pipe treatment options. Currently, the most widely used sulfate-removal process is precipitation as gypsum (CaSO₄·2H₂O). However, the lowest reachable concentration is theoretically 1500 mg L⁻¹ SO₄²⁻ due to gypsum’s solubility. At the same time, several mines worldwide have significantly more stringent sulfate discharge limits. The purpose of this review is to examine the process options to reach low sulfate levels (< 1500 mg L⁻¹) in mine effluents. Examples of such processes include alternative chemical precipitation methods, membrane technology, biological treatment, ion exchange, and adsorption. In addition, aqueous chemistry and current effluent standards concerning sulfate together with concentrate treatment and sulfur recovery are discussed.

The high CO₂ emissions of ordinary Portland cement (OPC) production have led to increasing the efforts on developing eco-efficient alternative binders. Geopolymers are inorganic binders proposed as an alternative to OPC, which are mainly based on aluminosilicate by-products and alkali activators. Higher utilization of industrial waste materials, such as ceramic manufacturing waste, could be enabled by geopolymers. In ceramic industry, around 30% of raw materials end up in waste streams, and therefore, an attempt is made to recycle these materials. The ceramic wastes are rich in silicate and aluminate and have therefore high potential to be used in the geopolymeric concrete. In the present paper, the porcelain ceramic waste was used as 10% of total binder weight in substituting ground-granulated blast-furnace slag (GGBFS). The results showed that the resulting binders have comparatively high compressive strength (≥60 MPa) and show brittle behavior, which is typical to inorganic binders with no fiber reinforcement. Microsteel fibers were used to improve the flexural performance of these binders at three different fibers by mass of binder (0.5%, 1%, and 1.5%). After curing, mechanical performances were investigated by measuring the compressive and flexural strength. The results showed that the addition of steel fibers significantly improved the flexural behavior. In addition, it was revealed that these fiber-reinforced binders had a deflection hardening behavior due to the bridging action of steel fibers.

Alkali-activated materials (AAMs) are one of the alternative low-CO2 binders. One-part AAMs, (that is, mixing a solid precursor with a solid alkali activator and adding water) have recently attracted increasing interest. The purpose of this study is to examine if fast-dissolving solid synthetic sodium metasilicate could be replaced by a combination of sodium hydroxide and slow-dissolving silica derived from rice husk ash or microsilica in the preparation of one-part alkali-activated blast furnace slag mortar. The replacement would improve the carbon footprint and the cost efficiency of the binder. The results demonstrate that silica availability significantly affects compressive strength development as a function of time or mixture composition. The highest compressive strength (107 MPa, 28 d) was obtained with fast-dissolving silica. Furthermore, setting times could be adjusted based on the mix composition, and the durability of mortar remained good after 120 freeze–thaw cycles. The results highlight the overall effect of silica availability on the fresh and hardened properties of one-part AAMs.

Ammonium (NH₄⁺) removal from municipal wastewater poses challenges with the commonly used biological processes. Especially at low wastewater temperatures, the process is frequently ineffective and difficult to control. One alternative is to use ion-exchange. In the present study, a novel NH4+ ion-exchanger, metakaolin geopolymer (MK-GP), was prepared, characterised, and tested. Batch experiments with powdered MK-GP indicated that the maximum exchange capacities were 31.79, 28.77, and 17.75 mg/g in synthetic, screened, and pre-sedimented municipal wastewater, respectively, according to the Sips isotherm (R² ≥ 0.91). Kinetics followed the pseudo-second-order rate equation in all cases (kp₂ = 0.04–0.24 g mg⁻¹ min⁻¹, R² ≥ 0.97) and the equilibrium was reached within 30–90 min. Granulated MK-GP proved to be suitable for a continuous column mode use. Granules were high-strength, porous at the surface and could be regenerated multiple times with NaCl/NaOH. A bench-scale pilot test further confirmed the feasibility of granulated MK-GP in practical conditions at a municipal wastewater treatment plant: consistently

Organic compounds decomposing in high temperature and pressure of a steam boiler plant water–steam cycle result in low molecular weight (LMW) organic acids and carbon dioxide. Subsequently a drop of pH value is observed in condensate which ultimately can cause corrosion. Organics may also contain for example chloride and release it to condensate. Thirdly decomposition products mask online cation conductivity measurements. This paper evaluates the use of activated carbon (AC) filtration as an option to remove the residues of organic compounds present in deionized make-up water. The experimental part was done using continuous flow bench scale AC filters (AC dry volume 3.75 l, flow rate 25 l/h, water temperature approximately 20 °C) at a steam boiler desalination plant. Four commercial ACs were tested and all proved equally efficient removing approximately 42–45% of total and 58–68% of dissolved organic carbon after 30 days of operation. The most efficiently removed organic fractions were LMW neutral compounds, decomposition products of humic substances and hydrophobic compounds. Biopolymers were not effectively removed. Coconut shell based ACs leached more Ca, Mg and Na ions compared to coal based while for silica there were no differences. Pre-acid washing of ACs was efficient in reducing the initial leaching of impurities. However, the differences between acid washed and non-acid washed AC diminished with time. A mixed bed (MB) ion exchanger as a polishing treatment after AC filters is required to control the leaching of impurities.

Mineral wools –a general term for stone wool and glass wool– are the most common building insulation materials in the world. The annual amount of mineral wool waste generated in Europe totaled 2.3 Mt in 2010 – including wastes from the mineral wool production and from the construction and demolition industry. Unfortunately, mineral wools are often considered unrecyclable due to their fibrous nature and low density. Thus, the utilisation of post-consumer mineral wool waste in different applications remains low. Mineral wools have a great potential as geopolymer precursors as they have suitable chemical and mineralogical compositions. As geopolymers can provide significant CO2 emission reductions compared to traditional Portland cement concretes, using mineral wool waste as geopolymer precursor would be an attractive utilisation path. Here, we show that mineral wool waste can be geopolymerised to form sustainable cements with good mechanical properties. Geopolymerisation of mineral wool waste therefore offers an attractive route for waste valorisation and production of low-CO2 cements.

The mining industry is a major contributor of various toxic metals and metalloids to the aquatic environment. Efficient and economical water treatment methods are therefore of paramount importance. The application of natural or low-cost sorbents has attracted a great deal of interest due to the simplicity of its process and its potential effectiveness. Geopolymers represent an emerging group of sorbents. In this study, blast-furnace-slag and metakaolin geopolymers and their raw materials were tested for simultaneous removal of Ni(II), As(III) and Sb(III) from spiked mine effluent. Blast-furnace-slag geopolymer proved to be the most efficient of the studied materials: the experimental maximum sorption capacities for Ni, As and, Sb were 3.74 mg/g, 0.52 mg/g, and 0.34 mg/g, respectively. Although the capacities were relatively low due to the difficult water matrix, 90–100% removal of Ni, As, and Sb was achieved when the dose of sorbent was increased appropriately. Removal kinetics fitted well with the pseudo-second-order model. Our results indicate that geopolymer technology could offer a simple and effective way to turn blast-furnace slag to an effective sorbent with a specific utilization prospect in the mining industry.

The use of organic peracids in wastewater treatment is attracting increasing interest. The common beneficial features of peracids are effective anti-microbial properties, lack of harmful disinfection by-products and high oxidation power. In this study performic (PFA), peracetic (PAA) and perpropionic acids (PPA) were synthesized and compared in laboratory batch experiments for the inactivation of Escherichia coli and enterococci in tertiary wastewater, oxidation of bisphenol-A and for corrosive properties. Disinfection tests revealed PFA to be a more potent disinfectant than PAA or PPA. 1.5 mg L(-1) dose and 2 min of contact time already resulted in 3.0 log E. coli and 1.2 log enterococci reduction. Operational costs of disinfection were estimated to be 0.0114, 0.0261 and 0.0207 €/m(3) for PFA, PAA and PPA, respectively. Disinfection followed the first order kinetics (Hom model or S-model) with all studied peracids. However, in the bisphenol-A oxidation experiments involving Fenton-like conditions (pH = 3.5, Fe(2+) or Cu(2+) = 0.4 mM) peracids brought no additional improvement to traditionally used and lower cost hydrogen peroxide. Corrosion measurements showed peracids to cause only a negligible corrosion rate (

Peracetic acid (PAA) has been studied for wastewater disinfection applications for some 30 years and has been shown to be an effective disinfectant against many indicator microbes, including bacteria, viruses, and protozoa. One of the key advantages compared to, e.g., chlorine is the lack of harmful disinfection by-products. In this paper a pilot-scale study of PAA-based disinfection is presented. Indicator microbes (E. coli, total coliforms and coliphage viruses) as well as chemical parameters (pH, oxidation-reduction potential (ORP), chemical and biochemical oxygen demand (COD and BOD), and residual PAA and hydrogen peroxide) were studied. The main aim of this investigation was to study how these selected chemical parameters change during PAA treatment. Based on the results, disinfection was efficient at C·t values of 15 to 30 (mg·min)/l which equals to a PAA dose of 1.5 to 2 mg/l and a contact time of 10 to 15 min. In this concentration area changes in pH, COD and BOD were negligible. However, hydrogen peroxide residues may interfere with COD measurements and apparent COD can be higher than the calculated theoretical oxygen demand (ThOD). Additionally PAA or hydrogen peroxide residues interfere with the BOD test resulting in BOD values that are too low. Residual PAA and ORP were found to correlate with remaining amounts of bacteria. Keywords : tertiary wastewater disinfection, peracetic acid, total coliform, E. coli , coliphages

The growth of global construction has contributed to an inevitable increase in the amount of construction and demolition (C&D) waste, and the recycling of C&D waste as aggregates in concrete is receiving increased interest, resulting in less demand for normal aggregates and bringing a potential solution for the landfilling of wastes. Recently, several studies have focused on the use of C&D waste in alkali-activated concrete to move one step closer to sustainable concretes. This paper focuses on the main mechanisms of using C&D waste in the resulting physical, mechanical, and durability properties of alkali-activated concrete in fresh and hardened state properties. The main difficulties observed with recycled aggregates (RA) in concrete, such as high levels of water demand, porous structure, and low mechanical strength, occur in RA alkali-activated concretes. These are associated with the highly porous nature and defects of RA. However, the high calcium concentration of RA affects the binder gel products, accelerates the hardening rate of the concrete, and reduces the flowability of alkali-activated concretes. For this reason, several techniques have been investigated for modifying the water content and workability of the fresh matrix and for treating RA and RA/alkali-activated binder interactions to produce more sustainable alkali-activated concretes.