Alkali-activated Slag Research Articles

Effect of pre-wetting treatment for waste waterglass foundry sand on the properties of alkali-activated slag

Waste waterglass foundry sand (WwFS) is a solid waste generated by the foundry industries that is commonly discarded in landfills and has urgent needs for disposal and recycling. Accordingly, this study suggests using WwFS as aggregates source for the preparation of alkali-activated slag mortars (AASM). Two different pre-wetting methods (24 h pre-wetting at 20°C and 1~6 h pre-wetting at 70°C) were used to treat WwFS and compared their performances with adding quartz sand and dried WwFS mortars. Compared to WwFS mortars without pre-wetting treatment, the compressive strengths of WwFS mortars containing WwFS pre-wetting in water at 70°C at 28d were increased by 1.3~10.0%, and the C-(A)-S-H average elastic modulus was increased by 16%. This study confirmed the feasibility of using hot water pre-wetted WwFS as the single aggregate source for AASM, which is important for the large-scale utilization of WwFS.

Enhancing mechanical strength and microstructural properties of alkali-activated systems through nano graphene oxide dispersion and polycarboxylate ether admixture

The dispersion of graphene oxide (GO) nanoparticles in alkali-activated concrete with / without superplasticizers can help in understanding the effect it has on its mechanical strength and microstructural properties. The dispersion of GO in alkali activator fluid of 10(M) and 12(M) with / without polycarboxylate ether (PCE) admixture has been explored in this study. The alkali activator solution of 10(M) NaOH solution with PCE shows better dispersion than 12(M) NaOH solution, as higher alkalinity leads to agglomeration of GO. The study investigated the effect of incorporating PCE in GO-based alkali-activated slag (AAS) mortar with 8(M), 10(M) and 12(M) of alkaline activator solution. The mechanical strength and microstructural characteristics of conventional AAS (without both GO and PCE), GO-based AAS (without PCE) and GO-based AAS with PCE of the respective molar concentration of activator fluid are analysed. The mechanical strength of the AAS mortars has been evaluated using compressive, flexural, and splitting tensile strength testing. The micro-structural and mineralogical characteristics of the binders are evaluated using Field Emission Scanning Electron Microscopy (FESEM with EDS), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The addition of only GO (0.06 % of binder w/w) and the addition of both GO and PCE in AAS have shown up to 30 % and 40 % mechanical strength improvement with respect to conventional AAS, respectively. The effectiveness of PCE and percentages of strength improvement are higher with a lower molarity of activator fluid, and vice versa. Adding GO and PCE to the AAS system improves its hydration rate and denser microstructure, enhancing its strength.

Mechanical properties and sulfate resistance of basalt fiber-reinforced alkali-activated fly ash-slag-based coal gangue pervious concrete

To address the strength deficiencies and enhance the durability of coal gangue pervious concrete while promoting the resource utilization of coal gangue, this study employs alkali-activated fly ash and slag as binding materials, partially replacing natural coarse aggregates with coal gangue to prepare alkali-activated fly ash-slag-based coal gangue pervious concrete (AFSGPC). Basalt fibers are introduced to examine the effects of varying fiber lengths and volume fractions on the mechanical properties, permeability, and sulfate resistance of AFSGPC. Results indicate that incorporating an appropriate amount of basalt fibers improves the mechanical properties and sulfate resistance of AFSGPC, attributed to the high strength characteristics of the alkali-activated fly ash-slag binder and the crack-bridging and toughening effects of the basalt fibers, although it may slightly reduce permeability. When the fiber length is 12mm and the volume fraction is 0.1%, the compressive strength at 28 days reaches 24.12MPa, and the splitting tensile strength is 2.95MPa, reflecting increases of 10.48% and 32.89%, respectively. The permeability coefficient is measured at 2.07mm/s, meeting the standards for pervious concrete in road applications. After undergoing 60 cycles of sulfate wet-dry erosion, the corrosion resistance coefficient of AFSGPC increases by 20.02%. To meet the stringent strength requirements for pervious pavements, it is recommended that basalt fibers with a length of 12mm and a volume fraction of 0.1% be utilized in AFSGPC. In regions characterized by high precipitation, the application of basalt fibers shorter than 12mm, with a volume fraction not exceeding 0.15%, is advisable to minimize the obstruction of interconnected pores. These findings provide valuable insights for the preparation and engineering application of basalt fiber-modified AFSGPC.

Development and field validation of pumpable alkali-activated ground granulated blast furnace slag binder-based concrete using sodium gluconate as a retarder

Development and field validation of pumpable alkali-activated ground granulated blast furnace slag binder-based concrete using sodium gluconate as a retarder

Performance optimisation of alkali-activated slag ultra-low carbon concrete (AAS-ULCC) for shield tunnel segments by steel fibres

Performance optimisation of alkali-activated slag ultra-low carbon concrete (AAS-ULCC) for shield tunnel segments by steel fibres

The formation of CaCO3-based binder by carbonating high-dosage Ca(OH)2 + slag + NaHCO3 (HCHSN) cement paste

Normally, carbonation can cause the decalcification of C-(A)-S-H gel of alkali-activated cement and the degradation of mechanical properties. While, we propose another possibility to form CaCO3-based binder by carbonating the alkali-activated slag cement of high-dosage Ca(OH)2 (30%) + slag (70%) + NaHCO3 (5.11% by weight of Ca(OH)2 and slag) (HCHSN) in this study. The results supported that the compressive strength and volume stability of HCHSN cement paste can be improved by the carbonation curing and the carbonated HCHSN cement paste could reach a maximum compressive strength of 32.4MPa. According to the micro-analysis of XRD, TGA, FTIR, 1H NMR, BSE and SEM, the carbonated HCHSN cement paste was developed into a CaCO3-based binder with a CaCO3 content approaching 60% (based on the mass of the samples heated to 800℃). NaHCO3 played a key role in the formation of the CaCO3-based binder, which not only accelerated the carbonation rate, but also promoted the carbonation of slag. The eco-efficiency assessment showed that compared to the production of 12.5kg CO2 /MPa/t from carbonated ordinary Portland cement, the carbonated HCHSN cement paste only produced 3.5kg CO2 /MPa/t, making it a very green CaCO3-based cementitious materials.

A novel all-solid-waste binder prepared by salt-alkali synergistic activation system constructed from phosphogypsum, soda residue and calcium carbide slag

Conventional alkali-activated slag materials apply strong industrial alkalis with high cost and potential corrosion risk. Alternatively, this study utilized industrial solid waste phosphogypsum, soda residue, and calcium carbide slag to construct a salt-alkali synergistic activated system. A new salt-alkali synergistic activation effect was formed by the SO42- introduced by PG together with the Cl- and OH- provided by SR and CS, which promoted the hydration reaction. AFt, Friedel's salt, C-(A)-S-H, and other hydration products were generated and congregated, and a new all-solid-waste binder was created with 3d/28d strengths of 17.9/43.9 MPa, meeting the P·O 42.5 cement strength standard requirements. By conducting compressive strength and drying shrinkage tests on mortar and paste specimens with varying ratios, and employing XRD, TG-DTG, FTIR, and SEM-EDS analyses, the mechanical attributes of the binder were systematically assessed, and its hydration process was elucidated.

Study on Impact Resistance of Alkali-Activated Slag Cementitious Material with Steel Fiber

Alkali-activated slag cementitious materials (AASCMs) use alkaline activators to activate blast furnace slag and waste slag to replace traditional Portland cement, which can reduce CO2 emissions. An impact resistance test and scanning electron microscopy (SEM) microscopic performance analysis of alkali-activated slag cementitious material specimens with four different steel-fiber contents are performed. The effects of steel-fiber volume content and strain rate on the dynamic elastic modulus Ed, dynamic compressive strength σd, dynamic peak compressive strain εc, and energy absorption of the AASCM-SS are studied. The results indicate that the dynamic elastic modulus Ed, dynamic compressive strength σd, and energy absorption of the AASCM-SS increase with the increase of strain rate, and the dynamic peak compressive strain εc decreases with the increase of strain rate. The dynamic elastic modulus Ed, dynamic compressive strength σd, and dynamic peak compressive strain εc of the SS-AASCM increase first and then decrease with the increase of steel-fiber content. When the steel-fiber content is 0.5%, the σd and εc of the AASCM-SS are the highest, increased by 9.9% and 19.3%. The energy absorption of AASCM-SS increases with the increase of steel-fiber content. A dynamic constitutive model of the FR-AASCM considering the influence of damage, strain rate, and steel-fiber volume fraction is established. The proposed constitutive model is in acceptable agreement with the experimental AASCM-SS dynamic stress–strain curve, and the correlation coefficient is 0.91.

Investigating the impact of foundry by-product sand as an activator on workability improvement and strength development in alkali-activated blast furnace slag mortar

The substitution of alkali-activated furnace slag significantly reduces the necessity of cement manufacture and mitigates the continuous growth of carbon emissions. In addition, it shows superior mechanical properties compared to traditional concrete materials. However, rapid setting issues hinder its widespread applications. This study investigated the innovative use of zero-carbon waste sodium silicate-bonded sand as a substitute for the fine aggregate and sodium silicate in traditional alkali-activated blast furnace slag mortar. The primary objective is to analyze the impact of waste sodium silicate-bonded sand on the workability and mechanical properties of the mortar. The key properties such as flowability, setting time, temperature measurement, compressive strength, and microstructural were analyzed to determine the improvement in workability and the strength development of alkali-activated blast furnace slag mortar resulting from the use of waste sodium silicate-bonded sand. The research showed the integration of waste sodium silicate-bonded sand results in an eco-friendly and cost-effective material, which addresses limitations in traditional activated blast furnace slag mortars. The finding revealed that substituting fine aggregate and sodium silicate with waste sodium silicate-bonded sand significantly improved the mechanical and workability properties of alkali-activated mortars. Notably, the compressive strength of mortars incorporating waste sodium silicate-bonded sand exceeded that of traditional Portland cement and effectively mitigated rapid setting issues. In addition, this approach led to an environmentally friendly mortar with satisfactory workability. The research emphasizes the practical benefits of utilizing waste sodium silicate-bonded sand and offers new insights into its effects on mortar performance. This has provided more details for future exploration and refinement in the field of alkali-activated materials.

Probing the dual mechanism of load damage and flowing solution on sulfate attack resistance of alkali-activated slag concrete

Alkali-activated slag concrete (AASC) is a representative low-carbon green building material. To effectively characterize the sulfate attack resistance of AASC in complex environments, a self-designed simulation device for complex corrosion environments was used to study the sulfate attack mechanism and property deterioration law of AASC under the loads and flowing corrosion solutions. The results indicated that both load-induced damage and dissolution accelerated the transport of sulfate ions into the AASC. On the one hand, the load-induced damage and dissolution resulted in a decrease in the proportion of gel pores, reducing the electrostatic interaction between ions and the gel pore wall as well as the gel pore wall thinning effect. On the other hand, the load-induced damage and dissolution decreased the pH of the pore solutions in AASC, causing easier decalcification or dealumination of C-A-S-H gel under sulfate ion attack. This further accelerated the sulfate ion attack and deterioration of AASC.

Mechanisms of efflorescence of alkali-activated slag

Efflorescence presents not only as a cosmetic concern but also as a structural issue, which impacts the performance of alkali-activated materials (AAMs). In this study, the mechanisms of efflorescence of alkali-activated slag (AAS) pastes are investigated. First, the efflorescence of AAS pastes with different alkali dosages (3 %, 5 % and 7 %), activator types (sodium hydroxide (NH) and sodium silicate (NS)), exposure atmospheres (ambient, N2 and 0.2 vol% CO2), and relative humidities (40 %, 60 % and 80 %) was observed. Subsequently, leaching tests were performed and the impacts of efflorescence on AAS pastes at different heights were studied. It was found that a lower relative humidity facilitated more rapid and severe efflorescence. The positioning of efflorescence products was dependent on the porosity of the matrix. Compared to NH pastes, NS pastes subjected to semi-contact water conditions were more vulnerable to cracking problems, which turned out to be exacerbated by the formation of efflorescence products. A new method to quantify efflorescence was developed and it corresponded well with both efflorescence observations and leaching experiments. Furthermore, a competitive reaction between Ca and Na in the presence of carbonate ions was identified. CaCO3, a representative product of natural carbonation, was rarely found in the regions where efflorescence products (sodium carbonate) formed. Regarding compressive strength, NS pastes were more adversely affected by efflorescence than NH pastes.

The effect of copper slag as a precursor on the mechanical properties, shrinkage and pore structure of alkali-activated slag-copper slag mortar

Copper slag, an industrial by-product produced in large quantities during copper smelting and refining, has the potential to be used as an alternative precursor for alkali-activated materials. This approach not only reduces the environmental impact of copper slag but also addresses the growing scarcity of conventional precursors, such as ground granulated blast furnace slag. In this research, copper slag was used as an alternative precursor for alkali-activated slag-copper slag mortars. Sodium hydroxide and water glass served as the activators. The workability, mechanical properties, autogenous shrinkage and drying shrinkage were investigated to evaluate the influence of copper slag content. Furthermore, the reaction products and pore structure of hardened mortar were analysed to gain deeper insights into its performance. The results show that the incorporation of copper slag effectively prolongs the setting time and increases the fluidity. Copper slag reduces the autogenous shrinkage, but it also results in an undesirable increase in drying shrinkage. While copper slag delays strength development and reduces the strength, incorporating copper slag at a 50 % ratio still results in strength comparable to that of mortars utilizing 100 % ground granulated blast furnace slag as the precursor. The incorporation of copper slag alters the composition of calcium aluminosilicate hydrate and promotes the formation of ferro-silicate. Although it reduces the proportion of macropores in the total pore volume, it simultaneously increases the amount of capillary pores. Copper slag alters pore solution, and although heavy metal leaching remains minimal, risks in complex environments require further study.

Fracture toughness of alkali-activated concrete subjected to aggressive environment

This study investigates the fracture toughness of alkali-activated granulated blast-furnace slag (GBFS)-based geopolymer concrete (GPC), non-activated slag cement concrete, and ordinary Portland cement (OPC) concrete in acidic, alkaline, and chloride solutions over six months. A total of 580 centrally straight-notched Brazilian disc (CSNBD) specimens were cast to assess pure mode-I (0°), pure mode-II (28.7°), and mixed-mode (15° and 45°) fractures under these conditions. Microstructural analyses (SEM) were performed to evaluate microstructural changes after six months of exposure. Results showed that GPC exhibited the lowest initial fracture toughness but the smallest reduction (7 %-11 % depending on the mode) across all environments, with slag cement concrete and OPC experiencing reductions of 11 %-14 % and 14 %-21 %, respectively, in acidic conditions. In alkaline environments, GPC showed a 3 %-6 % decrease in fracture toughness, while OPC and slag cement concrete showed reductions of 6 %-13 %. The gradient boosting regressor accurately predicted the failure load of CSNBD specimens, achieving an R² score of 0.948. Finally, SHAP sensitivity analysis identified concrete type, exposure time, and environment as critical input features, consistent with experimental results.

A Review on Research Progress of Corrosion Resistance of Alkali-Activated Slag Cement Concrete.

China is the largest producer and user of Ordinary Silicate Cement (OPC), and rapid infrastructure development requires more sustainable building materials for concrete structures. Portland cement emits large amounts of CO2 in production. Given proposals for "carbon peaking and carbon neutralization", it is extremely important to study alternative low-carbon cementitious materials to reduce emissions. Alkali-activated slag (AAS) cement, a new green cementitious material, has high application potential. The chemical corrosion resistance of AAS concrete is important for ensuring durability and prolonging service life. This paper reviews the hydration mechanism of AAS concrete and discusses the composition of hydration products on this basis, examines the corrosion mechanism of AAS concrete in acid, sulfate, and seawater environments, and reviews the impact of its performance due to the corrosion of AAS concrete in different solutions. Further in-depth understanding of its impact on the performance of concrete can provide an important theoretical basis for its use in different environments and provides an important theoretical basis for the application of AAS concrete, so that we can have a certain understanding of the durability of AAS concrete.

The Effects of Ester and Ether Polycarboxylate Superplasticizers on the Fluidity and Setting Behavior of Alkali-Activated Slag Paste.

This study aims to investigate the comparative performance of ester- and ether-based polycarboxylate superplasticizers in maintaining the fluidity and controlling the setting time of alkali-activated slag (AAS) paste. The experiments employed rheological tests, mini-slump tests, ultrasonic pulse velocity (UPV) measurements, and gel permeation chromatography (GPC) analysis. The results indicate that ether-based superplasticizers maintain fluidity approximately 25% longer than their ester-based counterparts and extend the setting time by about 30%. The enhanced performance of ether-based superplasticizers is attributed to their superior molecular stability in highly alkaline environments, which mitigates early polymer degradation. Additionally, the Na2O/SiO2 ratio was maintained at 1:1 throughout the experiments to ensure consistency in the activation process. The relationship between fluidity loss and the onset of setting occurs more rapidly in AAS paste than in conventional cement-based systems. These findings provide valuable insights for the development of environmentally friendly construction materials by optimizing the use of superplasticizers in alkali-activated systems.

Using acetic acid as a preconditioner to optimize rheology of alkali-activated coal gasification slag based backfill pastes

The workability of alkali-activated coal gasification slag (CGS) based backfill materials is critical parameter in transportation processes, while the high water demand of CGS hinders its application due to its high specific surface area. This study utilizes acetic acid (AA) as a preconditioner to modify the surface characteristics of CGS, aiming to optimize the rheology of alkali-activated CGS backfill pastes (AAC). The shear stress, viscosity, thixotropic property, and zeta potential of AAC, and mineral composition and surface morphology of AA-modified CGS at various AA dosages were systematically investigated. It is found that the yield stress, plastic viscosity, and hysteresis loop area of AAC reaches the lowest value at 4 wt% AA dosage on the basis of the CGS, owing to AA reacts with the minerals on the surface of CGS particles, and then the AA is adsorbed on the CGS particles and acts as a surfactant, which increases the static electricity between CGS particles. However, the yield stress of AAC increases significantly when the AA dosage exceeds 4 wt%, attributing to the smaller particle size resulting from AA modification, which raises water demand. This investigation proposes a novel approach for optimizing the rheology of CGS based AAC and provides theoretical guidance for employing modified CGS as backfill materials.

Influence of mixing protocols on flow retention of one-part alkali activated slag systems

Poor workability and rapid flowability loss are among several challenges hindering the wider acceptance of alkali-activated slag (AAS) (i.e. shrinkage, efflorescence). Several attempts were made to solve this issue, focusing more on selected ingredients, proportions, type and dosage of admixtures, and addition sequence. This study shifted the focus to mixing protocol, highlighting its potential and effects on AAS flow retention considering mixing duration, sequence, and relaxation time. Various one-part AAS mixtures activated by 6 %, 8 %, and 10 % sodium metasilicate were tested. Mixing protocols were applied for 10–90 min, mixing with and without relaxation time. Mini-slump, flowability-loss rate, setting time, the heat of hydration, rheological properties, and compressive strength were evaluated. Changes in hydration products were also examined by XRD, FTIR and TGA. Pearson correlation coefficient and ANOVA were applied to identify the dominant factors. Results reveal the dependency of the optimum mixing protocol on the used activator dosage. A long mixing period with r intervals was more effective for high activator dosages due to the continuous breakdown of formed hydration products' links. Modifying the mixing protocol did not alter the amount of formed hydration products, regardless of the activator dosage. These findings pave the way to understanding the role played by the mixing protocol in mineral hydration for wider in-situ implementation of AAS and the flourishing potential of the ready-mix AAS market.

Non-sintered ceramsite from alkali-activated gasification slag for adsorption through the regulation of physical properties and pore structure

With the development of the coal gasification industry, the comprehensive utilization of coal gasification fine slag (CGFS) has become increasingly important. This study explored the potential of producing non-sintered ceramsite by combining CGFS with blast furnace slag (BFS). The impacts of the alkali activator modulus, dosage, and BFS-CGFS ratio on the ceramsite's cylinder compressive strength, bulk density, apparent density, water adsorption ratio, hydration products, microstructure, and adsorption capacity were investigated. Moreover, the leaching behavior of heavy metals in acidic environments and the production costs were evaluated. The results indicated that the modulus and dosage of the alkali activator, along with the BFS-CGFS ratio, significantly affected the properties of the ceramsite. The cylinder compressive strength, bulk density, and apparent density of the ceramsite increased with the increase in the alkali activator dosage and modulus, but decreased as the BFS-CGFS ratio decreased. The water absorption rate behaved oppositely. With increasing alkali activator modulus and dosage, the ceramsite's adsorption capacity for iodine, CODCr, and methylene blue first increased and then decreased, peaking at a modulus of 1.4 and a dosage of 12%, respectively. A reduced BFS-CGFS ratio increased the adsorption capacity of the ceramsite for iodine and CODCr. Considering both mechanical and adsorption properties, the optimal composition for the ceramsite was found to be an alkali activator modulus of 1.4, a dosage of 12%, and a CGFS content of 70%. With this ratio, the use of ceramsite would not result in secondary environmental pollution. This study not only provided a new approach to enhance the utilization of CGFS but also avoided the use of calcination processes in producing ceramsite, demonstrating its potential in reducing environmental impact.

Approach to Design Sustainable Alkali-Activated Slag Recycled Aggregate Concrete: Mechanical and Microstructural Characterization

There is a steep increase in demand for concrete as the need for infrastructure is increasing with a rapid increase in urbanization. Consequently, there has been a surging demand for cement across the globe. By using alkaline concrete activated with ground granulated blast furnace slag (GGBS), cement usage can be eliminated in concrete, which addresses the issue of CO2 emissions concerned with the cement manufacturing process and promotes the use of industrial by-products as sustainable building materials. The current study focuses on proposing a methodology to design sustainable GGBS-based alkali-activated concrete incorporated with 100% coarse recycled coarse aggregates (RCA) recovered from construction and demolition (C&D), for various strengths by optimizing the mix proportions and verifying the same through experiments. From the current study, it is evident that this mix design procedure can be adopted to design alkali-activated slag recycled aggregate concrete (AASRAC) mixes for strengths ranging from 44MPa to 85MPa. The optimum values of alkalinity factor (λ) and NaOH concentration (M) i.e., 1.5 and 12, have a significant role in the development of high strengths which is attributed to the formation of hydrotalcite. Micrographs captured using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) studies reveal that the alkaline binders promote the development of a denser and stronger interfacial transition zone (ITZ) that enhances the strength of lower AA/B concretes at the microstructural level as Ca/Si ratio is higher for lower AA/B concretes. Global warming potential (GWP) analysis reveals that the alkali-activated concretes have significantly lower GWP compared to conventional OPC-based concrete by approximately 2.5 times. The mix-design chart proposed in this study may pave the way to designing structural grade AASRAC with enhanced performance for the desired strength, which may find its application in fast-track construction and manufacturing of prefabricated elements.

РОЛЬ САСО3 У ФОРМУВАННІ МІЦНІСНИХ І ДЕКОРАТИВНИХ ВЛАСТИВОСТЕЙ ПОРОШКОВОГО ЛУЖНО-АКТИВОВАНОГО ШЛАКОПОРТЛАНДЦЕМЕНТНОГО БЕТОНУ

The article discusses approaches to the formation of compositions of alkali-activated decorative Portland slag cements containing Portland cement type CEM1 5...45% with high performance and decorative properties. The optimization of the compositions of decorative alkali-activated Portland slag cements was carried out using statistical methods for designing experiments. Finely dispersed TiO2 and CaCO3 additives with a whiteness of 90% were used as bleaching components. The alkaline component is sodium metasilicate in the form of a non-hygroscopic powder. The research carried out made it possible to obtain decorative Portland slag cements with a whiteness of 45...77%, which allows them to be used to produce colored cements with a wide range of colors from white to black. It has been established that alkali-active decorative Portland slag cements have an activity of 37...59 MPa at the age of 28 days. All compositions have good hardening dynamics and, based on the strength at the age of 2 days  22...36.6 MPa, they can be classified as fast-hardening. Based on them, it is possible to produce dry construction mixtures. All mortar compositions based on alkali-active decorative Portland slag cements demonstrate fairly high frost resistance  F200. This allows them to be used for the manufacture of products and solutions both for indoor use and when exposed to atmospheric influences without loss of design characteristics and decorative appeal. The inherent shrinkage strains of decorative alkali-activated Portland slag cements are 0.51...0.61 mm/m, which eliminates cracking and premature destruction of products. The use of the CaCO3 additive is especially effective for controlling the shrinkage deformations. Thus, the CaCO3 additive performs the functions of not only a decorative component, but also a structure-forming component. Concrete and mortar mixtures can be used to produce decorative products using the traditional method, extrusion, 3D printing on construction printers, etc. And not too long setting times and a rapid increase in strength make it possible to produce products without thermal treatment or with minimal consumption of thermal energy.