High Strength Geopolymer Concrete Research Articles

Failure criterion and damage evolution of high-strength geopolymer concrete under compression-shear composite loading after high temperatures

Geopolymer concrete (GPC) holds significant potential for building fire safety design due to its green, low-carbon, and high-temperature resistant properties. In practical applications, concrete structures often face multiaxial composite loads. Therefore, investigating the composite stress performance of high-strength geopolymer concrete (HGPC) after exposure to high temperatures is crucial for assessing structural damage and enhancing fire prevention measures. This paper examines the compressive shear performance of HGPC at various temperatures T (20°C, 200°C, 400°C, 600°C) and stress ratios k (0.15, 0.3, 0.45, 0.6). The study analyzes failure patterns, shear load-displacement curves, shear strengths and their components, and peak shear deformation. Failure criteria are proposed to describe the damage patterns of HGPC under compressive shear loading after high temperatures. Additionally, the damage evolution process is evaluated using the energy method. The results show that HGPC damage surfaces penetrate the coarse aggregate at room temperature under compression-shear composite loading but shift to the aggregate-mortar interface at 600°C. Shear stiffness, peak shear strength, and residual strength increase with higher stress ratios but decrease with rising temperatures. Temperature affects peak shear strength by over 95 %, significantly more than the stress ratio. The shear strength decreases more slowly than compressive strength up to 400°C but more rapidly beyond 400°C. The cohesive strength of HGPC decreases with increasing stress ratio under different temperatures, while contact friction strength exceeds 50 % of peak shear strength. Shear dilation strength generally increases, then decreases, peaking at k = 0.45. The failure criterion based on the modified twin shear unified strength theory aligns best with experimental results. Furthermore, an increased stress ratio retarded the development of damage evolution, which was first accelerated and then slowed with rising temperature.

Utilization of waste phosphogypsum in high-strength geopolymer concrete: Performance optimization and mechanistic exploration

Utilization of waste phosphogypsum in high-strength geopolymer concrete: Performance optimization and mechanistic exploration

Mix proportion design and carbon emission assessment of high strength geopolymer concrete based on ternary solid waste

To achieve dual optimization of the mechanical properties and environmental impacts of geopolymer concrete (GPC), this study proposes a high-strength geopolymer concrete (HSGPC) without coarse aggregate. The mix proportion of HSGPC was optimized using the response surface methodology, targeting compressive strength and splitting tensile strength to determine the optimal mix. Additionally, the carbon emission impact of HSGPC was assessed and compared with ordinary Portland cement concrete, ultra-high-performance concrete, and reactive powder concrete. The results indicate that the optimal mix proportion for HSGPC includes 15% fly ash content, 10.30% silica fume content, alkali activator ratio of 2.5, and a NaOH molar concentration of 10 M. Simultaneously, the carbon emissions of HSGPC are reduced by about 30% compared to ordinary Portland cement concrete. Compared to ultra-high-performance concrete and reactive powder concrete of the same strength, the production of HSGPC respectively reduces carbon emissions by 59.87% and 68.24%. This study not only provides valuable technical support for the practical application of GPC in engineering but also holds significant implications for promoting sustainable development in the construction industry.

Influence of Steel and Poly Vinyl Alcohol Fibers on the Development of High-Strength Geopolymer Concrete

The present study focuses on the mechanical performance of steel and polyvinyl alcohol fibers embedded in the geopolymer matrix. A high-strength geopolymer concrete with fly ash, slag and silica fume as precursors and sodium hydroxide and sodium silicate solutions as activators has been tested for its strength in compression and flexure. The influence of fibers on flowability, long-term shrinkage and sulphuric acid attack on the geopolymer concrete has also been studied. The dosage of fibers was maintained at 1%, 2% and 3% by volume, and fibers of length 13 mm have been used in the study. Results indicate that slag with 3% steel fibers by volume had a predominant influence on the strength development of steel fiber-reinforced geopolymer concrete, yielding a compressive strength of 107 MPa after 28 days. Blast furnace slag resulted in increasing the shrinkage of concrete due to rapid gel formation owing to the presence of calcium ions, although the fibers helped reduce the shrinkage to some extent. The strength of steel fiber geopolymer concrete was superior to PVA fiber geopolymer concrete; however, after an acid attack, the strength of steel fiber geopolymer concrete was reduced more than PVA fiber geopolymer concrete due to the enhanced corrosion resistance of PVA fibers.

Constitutive behavior of CFRP-confined normal- and high-strength geopolymer concrete: Experiments and modelling

The constitutive behavior of geopolymer concrete (GPC), which is essential to the design of GPC structures, has not been well explored, especially in multi-axial stress state. This study therefore performs an investigation on the constitutive behavior of normal- and high-strength GPC confined by carbon fiber-reinforced polymer (CFRP) jacket. A total of 36 CFRP-confined GPC specimens are fabricated, which cover six GPC mixtures and three thickness of CFRP jacket. A dataset comprising of 24 specimens is employed to develop the models for ultimate condition and axial stress-strain curve. Two testing datasets, one consisting of the rest 12 specimens and the other composed of six specimens collected from the literature, are exploited to test the models. A linear function of actual confinement ratio is competent for modelling the compressive strength, whereas a nonlinear function is capable of characterizing the ultimate axial strain. The average absolute error of predicted compressive strengths and ultimate axial strains is less than 8.0 % and 15.0 % for both testing datasets. A single four-parameter function originally proposed for OPCC can be extended to represent the axial stress-strain curve of CFRP-confined GPC by formulating expressions for the parameters. The correlation coefficient between predicted and measured curves is more than 0.96.

High-strength steel fibre-reinforced geopolymer concrete utilising recycled granite waste and rice husk ash

A limited number of research studies have managed to attain high-strength geopolymer concrete, especially by utilising waste materials. In this study, granite waste (GW) from the mining industry, which contaminates the surrounding environment and causes air pollution, and rice husk ash (RHA) from agricultural waste were used to produce high-strength steel fibre-reinforced geopolymer concrete (HSFRGC). To reduce natural sand consumption, GW was utilised as a fine aggregate. RHA was added at 0%, 1%, 3%, and 5% by weight of coal fly ash to enhance the properties of HSFRGC. In addition, hooked-end steel fibres were employed as reinforcement at 0%, 0.5%, and 1% by volume of the concrete. The objective of this study is to investigate the effect of incorporating GW and RHA into HSFRGC, examining properties such as workability, strength, durability, and microstructure. Additionally, an assessment was conducted on the environmental impact and cost-effectiveness of the HSFRGC system with additives to determine its feasibility for practical scenarios. The results showed that the addition of 1% RHA as an additive in the geopolymer system, which led to microstructural homogeneity in the geopolymer matrix, could effectively enhance the mechanical properties and durability. Moreover, the addition of hooked-end steel fibres along with 1% RHA further improved the mechanical performance compared to samples without steel fibres, increasing both compressive strength by 25% and flexural response by 70%. Meanwhile, incorporating 1% RHA in mixtures could assist in mitigating chloride migration by approximately 10% due to the filler effect occurring in the geopolymer matrix. Regarding to environmental impact and cost-effectiveness, the incorporation of 1% RHA and 0.5% steel fibre demonstrated a suitable balance, exhibiting eco-strength efficiency with an increase of 15% compared to plain geopolymer concrete, making it a reasonable choice for both environmental concerns and cost efficiency.

Experimental investigation on bond behaviour of the GFRP bars with normal and high strength geopolymer concrete

The study presents the experimental investigation of bond performance of normal and high-strength geopolymer concrete and Glass Fibre Reinforced Polymer (GFRP) bars. The effects of bar diameters, embedment lengths, and concrete grades on maximum pullout load and failure characteristics are investigated. When the adhesive and residual strengths of GFRP bond specimens were compared to steel specimens, the former demonstrated remarkable performance despite having differing surface properties. An energy-based equivalent bond strength approach is proposed to examine pre-peak bond performance, which demonstrating that the decreasing rate of strength is faster for higher diameter and embedment, showing a drop in bond performance. Pullout failure was noted in smaller diameter bond specimens, where the shear strength between the ribs and the GFRP bar controlled the bond strength. Concrete split failure occurs for 12 mm specimens with embedment lengths greater than 5d in both GPC40 and GPC60. Specimens with 16 mm, excluding G-16-5d-60, demonstrated concrete split failure for all embedment lengths and concrete grades; bond strength is determined by the concrete shear strength. Enhancing the concrete’s compressive strength has a beneficial impact on the bond strength as it increases ranging, from 14.57 to 32.12%. Analytical models such as mBPE and CMR were employed to derive the mathematical expression for the bond stress versus slip curve. It was found that the curves of CMR model were typically closer to experimental curves than the mBPE model.

Biaxial compressive failure criteria and constitutive model of high-strength geopolymer concrete after high temperature

This paper studies the effect of high temperatures (20℃, 200℃, 400℃, and 600℃) and stress ratios (σ2/σ3) (0.15, 0.3, 0.45, and 0.60) on biaxial compressive strength and strain development patterns of high-strength geopolymer concrete (HGPC). Experimental observations indicate that HGPC exhibits laminar damage similar to ordinary Portland concrete (OPC) before and after exposure to high temperatures, under biaxial compression. Unlike OPC, damage in HGPC initially passes through coarse aggregates at room temperature but shifts predominantly to the aggregate-mortar interface at 600℃. The biaxial compressive strength envelope of HGPC expands with rising temperatures. The increased multiple of biaxial compressive strength (σ3/fm) for HGPC at room temperature rises and then falls with increasing stress ratios, peaking at a stress ratio of 0.45 and surpassing the values for OPC and high-strength concrete (HSC). Before high temperature, the modulus of elasticity of HGPC is higher than that of OPC and decreases with increasing temperature, decreasing by about 45–60% for every 200°C increase, and the reduction is greater than that of OPC. The existing failure criterion is not suitable for HGPC after high temperature, this paper develops a new biaxial compression failure criterion for HGPC before and after high temperature based on Kupfer's criterion, taking into account the effect of temperature. The proposed failure criterion calculation results are well in agreement with the experimental data. A damage constitutive model for HGPC considering the effect of temperature and lateral pressure is also proposed, combining the Weibull distribution model for the ascending branch and a modified empirical model for the descending branch. This combined model effectively predicts the stress-strain relationship of HGPC under various temperature conditions.

Effect of olive waste ash on the properties of high‐strength geopolymer concrete

AbstractThis study examines the effect of incorporating olive waste ash (OWA) into high‐strength geopolymer concrete (HSGC) by partially replacing fly ash (FA) and/or granulated blast furnace slag (GBFS) in the presence of rice husk ash (RHA). A total of 18 different mixtures were prepared and divided into three groups: (1) Utilizing OWA as a partial replacement for FA at a weight ratio of 10%–50%. (2) Incorporating OWA as a partial substitute for GBFS, with a weight ratio of 10%–50%. (3) Incorporate OWA as a partial substitute for FA and GBFS, with a recommended weight ratio of 10%–50%. The slump flow test was used to analyze the fresh properties of the HSGC. The hardening properties were examined by measuring the compressive strength, tensile strength, flexural strength, and modulus of elasticity. Furthermore, an analysis was conducted on the water absorbency, sulfate attack, and chloride penetration depth. A scanning electron microscope was used for the microstructural analysis. The inclusion of OWA in HSGC mixtures resulted in a significant enhancement of the compressive strength. Specifically, adding 20% OWA to FA increased the compressive strength by 8.9% at 28 days. Similarly, 30% OWA for GGBS and 30% OWA for GGBS + FA led to compressive strength improvements of 20% and 17.8%, respectively. OWA application resulted in an enhanced microstructure density of the HSGC samples. The ideal substitution ratio varied between 20% and 30% based on weight.

Proposed Mixture Design Method for High-Strength Geopolymer Concrete

Proposed Mixture Design Method for High-Strength Geopolymer Concrete

Durability, Microstructure, and Optimization of High-Strength Geopolymer Concrete Incorporating Construction and Demolition Waste

The incorporation of construction and demolition (C&D) waste in concrete production has gained great importance toward sustainability, especially in geopolymer concrete. In this study, ground granulated blast-furnace slag (GGBFS) and fine aggregate of normal geopolymer concrete were partially replaced by clay brick powder (CBP) and fine clay brick (FCB) derived from C&D waste, respectively, aiming to produce high-strength geopolymer concrete (HSGC). Fly ash (FA) was also used as a partial replacement for GGBFS in normal geopolymer concrete. Twenty HSGC mixtures were designed using the response surface methodology with three variables, including CBP (0–25%), FA (0–25%), and FCB (0–50%). The performance of the proposed HSGC mixtures was assessed by measuring several mechanical and durability properties. In addition, a variety of physicochemical methods, including X-ray fluorescence spectroscopy, X-ray diffraction, and scanning electron microscopy, were used to examine the mineralogical and microstructural characteristics of the control and the developed mixtures. The findings revealed that the compressive, splitting tensile, and flexural strengths of the HSGC made with C&D waste ranged from 38.0 to 70.3 MPa, 4.1 to 8.2 MPa, and 5.2 to 10.0 MPa, respectively. The results also indicated that the incorporation of FA is an essential parameter to eliminate the negative impacts of C&D waste addition on concrete workability. The optimal proportions for the HSGC were 5% for CBP, 5% for FA, and 40% for FCB, which were determined to generate the optimized HSGC with the highest mechanical performance, according to the verified models and optimization findings. The physicochemical analyses showed that the thick amorphous geopolymeric gel predominated the nonporous structure of the optimized HSGC, which had good mechanical characteristics. Furthermore, the anti-carbonation performance and freezing resistance of the optimal HSGC increased by 17.7% and 14.6%, respectively, while the apparent porosity decreased by 8.4%.

Mechanical and Microstructural Characteristics of Manufactured Sand-Based High-Strength Geopolymer Concrete and Its Environmental Impact

Mechanical and Microstructural Characteristics of Manufactured Sand-Based High-Strength Geopolymer Concrete and Its Environmental Impact

Mechanical and durability properties of standard and high strength geopolymer concrete using particle packing theory

Aggregate packing significantly affects the characteristics of fresh and hardened concrete; aggregates having higher packing density (PD) improve these characteristics. There is a lack of research on how the PD affects the properties of geopolymer concrete (GPC). Hence, the present study includes the effect of the PD on the mechanical and durability properties of the standard and high-strength GPC. The study parameters are the binder content, the concentration of NaOH, and the fly ash to ground granulated blast furnace slag (GGBS) ratio. Six aggregate groups (like 12.5–10 mm, 10–4.75 mm, 4.75–2.36 mm, 2.36-1.18 mm, 1.18–0.6, and 0.6–0.15 mm) were investigated for the particle packing experiment, and the blended coarse:fine aggregate ratio of 55:45 which produced the highest packing density of 0.702, were used in the GPC mixes. A total of 120 cubes of size 100 mm, 30 cylinders of size 100 × 200 mm, and 30 prisms of size 100 × 100 × 500 mm were cast for 10 different mixes in the study. Sorptivity and water absorption are the tests performed for the durability studies. The result shows that GPC mixes with Particle packing theory significantly improved the compressive strength, and durability, and showed better workability. The workability of the GPC reduces by increasing the GGBS and concentration of the NaOH solution. As the GGBS proportion and the concentration of the NaOH solution increases, the concrete compressive, split, and flexural strength increases. As the binder content increases, the strength increases at first, then reduces. Increasing the GGBS content, binder content, and molarity of the NaOH accomplishes a reduction of the sorptivity coefficient and water absorption of the GPC.

Mixture Design of High-Strength Geopolymer Concrete

In the present day, the primary issue associated with the use of Ordinary Portland Cement-based concrete is the emission of CO2. This type of concrete has a significant adverse environmental effect due to the substantial release of carbon dioxide during the calcination of limestone and the combustion of associated fuels. These processes are responsible for approximately 6–9% of the global anthropogenic greenhouse gas emissions.Geopolymer concrete serves as a viable substitute for traditional Portland cement-based concrete, as it is created through the interaction of aluminosilicate-rich source materials with highly alkaline solutions. By utilizing geopolymer concrete made from pulverized fuel-ash and ground granulated blast furnace slag (GGBFS), it becomes possible to decrease the carbon footprint and, consequently, mitigate the greenhouse effect.The main objective of this study is to develop high-strength geopolymer concrete suitable for road pavements. The materials used for this purpose includes fly ash, Ground Granulated Blast Furnace Slag, coarse and fine aggregates and alkaline solutions. Specifically, sodium hydroxide (NaOH) with a molarity of 12 and sodium silicate (Na2SiO3) in a 1:2 ratio are the chosen alkaline liquids for the geopolymerization process. Water is also incorporated, and a poly-carboxylate ether-based superplasticizer is employed to enhance the workability of fresh fly-ash-based geopolymer concrete. The compressive strength targeted in this research is M60 for the high-strength geopolymer concrete.

Fracture behavior of slag & fly ash-based geopolymer concrete in comparison with opc-based conventional concrete, including the effect of steel and hybrid fibers

The study presents an experimental investigation of the fracture behavior of hardened slag and fly ash-based alkali-activated normal and high-strength geopolymer concrete compared with conventional Ordinary Portland Cement (O.P.C.) based concrete with steel and hybrid fibers. The fracture parameters considered in the experimental investigation include fracture energy, stress intensity factor, energy release rate, and characteristic length. The study concludes that the observed differences in conventional and geopolymer concrete's fracture and mechanical performance agree with the microstructural differences between these concrete systems reported in past literature. The slag-based geopolymer concrete is marginally inferior to the O.P.C.-based concrete, with similar compressive strength in fracture performance. Also, hybrid fiber reinforcement improves the fracture performance of geopolymer concrete more than steel fiber alone. Contrary to geopolymer concrete, steel fiber reinforced conventional concrete is superior to hybrid fiber reinforced conventional concrete in terms of fracture behavior.

Innovative use of micronized biomass silica-GGBS as agro-industrial by-products for the production of a sustainable high-strength geopolymer concrete

Micronized biomass silica (MBS) and ground granulated blast furnace slag (GGBS) are agro-industrial byproducts generated by incinerating of rice husk (grinding in jar mill) and blast furnaces that used produce iron, respectively. MBS accounts for 20% of the world's total paddy output of 590 million tons. These by-products (MBS and GGBS) have a high concentration of amorphous silica, which is utilized as a mineral additive in concrete. This amorphous silica interacts with hydration products, resulting in the formation of additional CSH gel. This improves concrete's strength and durability properties. Therefore, it is proven that inclusion of agro-industrial by-products in concrete helps to promote sustainable and greener development, which in turn reduces carbon footprints and waste that must be disposed of in landfills. There have been few investigations on concrete using MBS and demonstrated the great potential of employing MBS as a cement substitute or additive in normal concrete. Also, the utilization of MBS as partial replace to GGBS in geopolymer concrete (GPC) with different molarity is a novel aspect of this study. However, this study has the aim and limit to develop a high-strength eco-friendly GPC with agro-industrial byproducts (MBS and GGBS) for use in sustainable construction. The impact of incorporating MBS as a partial replacement of GGBS on compressive and split tensile strengths, sorptivity, and chloride permeability was tested up to the age of 28 days. MBS was used to replace GGBS in varying percentages in the preparation of concretes. MBS were used in concrete at 0%, 10%, 20%, and 30% replacement by weight. It was discovered that a GPC combination containing MBS 20% and the balance GGBS as the binder had the best performance in terms of its strength and durability. The compressive strengths of all GPC mixtures exceeded the intended design strength. The main findings of this study demonstrated clearly that MBS may be employed as a binder in the production of GPC.

High-strength geopolymer concrete based on coal washing waste

In recent years, geopolymers have gained significant attention as an environmental-friendly alternative to Ordinary Portland Cement (OPC). Geo-Polymer Concrete (GPC) can be made using different aluminosilicate sources but using waste aluminosilicate sources not only helps to reduce environmental pollution, also leads to efficient waste management. Coal Washing Waste (CWW) refers to the waste that remains after coal washing process in the purification plants. CWW (if properly activated) can be used as a high potential aluminosilicate source to produce GPC or a supplementary cementitious material in the production of Blended Cement (BC). Hence, this study aims to investigate the use of CWW as a waste aluminosilicate source for manufacturing GPC. In this regard, CWW subjected to various methods of thermal activation and the obtained ash was used to produce GPC specimens. Thereafter, the mechanical and physical properties of CWW based-GPC were studied and also compared with conventional concrete. Furthermore, CWW ash was used as an OPC partial replacement (15 %) for BC production. The obtained results indicated that thermal activation conditions of CWW have a significant effect on the properties of the obtained CWW ash. Rapid and abrupt cooling of ash after heat treatment resulted in higher pozzolanic reactivity and thus higher compressive strength. Moreover, CWW ash-based GPC offers higher mechanical strengths, as well as excellent resistance to acidic conditions and low water absorption capacity. Furthermore, CWW ash-based GPC provides proper resistance to evaluated temperatures so that it is almost stable up to 800 °C.

Investigation on engineering properties and micro-structure characteristics of low strength and high strength geopolymer composites subjected to standard temperature exposure

Fire accidents are common and one among the serious hazards faced by civil infrastructures; therefore, appropriate measures have to be taken while designing the buildings and structures to ensure the safety of the residents. Reducing the damage caused by fire and the collapse of structural elements are the primary significance in designing concrete structures. An experimental study was conducted to examine the mechanical properties of temperature exposed concrete specimens following ISO 834 standard fire curve. Present investigation examines the performance of Geopolymer concrete (GPC) after exposed to temperature exposure. Two types of concrete namely, low and high strength GPC were cured under two curing regimes viz, room temperature curing and oven curing was adopted in this study. The GPC specimens were heated to 821 °C, 925 °C, 986 °C and 1029 °C, following the rate of heating was in accordance with ISO 834. Influence of elevated temperature on GPC specimens were examined by visual inspection, weight loss, strength loss and micro-level studies including Scanning Electron Microscope (SEM). Results from the study reveals that, the strength of high strength concrete was more prone to temperature exposure. Room temperature cured GPC specimens possessed higher residual strength than oven cured specimens for all the heating durations (marginal variation less than 5%). Crushing Index (CI) of 8.1% was regarded as optimal value for coarse aggregates (CA) to sustain its strength at a temperature of 821 °C. The phase change and dehydration of geopolymeric gel were observed in SEM analysis, and strength loss of CA are considered as the influencing parameters for degradation of concrete at higher temperature exposure. High strength concrete is more prone to strength loss than low strength concretes.

Performance evaluation on engineering properties and sustainability analysis of high strength geopolymer concrete

This research presents an investigation that aims to optimize the mix proportion of the High Strength Alkali Activated Concrete (HSAAC) developed using the Taguchi Method (TM). Since Alkali Activated Concrete (AAC) contains a wide range of mix ingredients than conventional cement-based concrete, several trials are required to optimize the strength requirement of HSAAC. In this paper, the influence of binder (slag content), the concentration of sodium hydroxide, alkaline activator (AA) ratio, and curing condition on the strength of HSAAC is discussed. Eighteen trial mixes were designed based on the Taguchi analysis and evaluated experimentally. Based on the analysis of the results from TM, the mix design of HSAAC is evaluated. The experimental investigation on mechanical properties such as compressive, tensile, and flexural strengths of HSAAC is carried out. In addition to the mechanical properties, the workability of HSAAC is evaluated. The study reports that with the binder content of 500 kg/m3, AA ratio of 2, Activator to Binder (A/B) ratio of 0.5, and 12 M concentration of sodium hydroxide under ambient curing conditions attains the maximum compressive strength of 63.37 MPa. In addition, the sustainability performance of HSAAC in terms of cost-efficiency, carbon efficiency, and energy efficiency was evaluated and compared with the existing conventional cement-based concrete.

Flexural behavior evaluation of repaired high strength geopolymer concrete

CO2 is released during the manufacture of ordinary Portland cement (OPC). The utilization of wastes and byproducts in concrete can lead to new sustainable constructions. To replace OPC in high-strength Portland cement concrete (HSPC), ground granulated blast furnace slag (GGBS) is utilized. GGBS is a by-product of the blast furnace used for iron manufacturing. It has a high silicate gel content and is used to produce good concrete. This paper investigates the load-deformation behavior of high-strength reinforced geopolymer concrete (HSGC) beams that were tested in flexure after being repaired. Six beams were placed using HSGC and HSPC. The original beams were tested, and deflections were measured. Specimens were tested under static stresses, then repaired with epoxy resin injection and re-tested for flexural strength. For both the original and repaired beams, load versus deflection graphs were recorded. Maximum deflection, ultimate load, cracking load, and crack pattern were all determined. The findings suggest that the restored HSGC beams' strength is equivalent to that of the original beams. The strength of the beam has been recovered. The cracks do not re-open after retesting, instead, new nearby cracks developed. The repaired beams showed superior flexural behavior and greater ductility than the original beams.