High Strength Geopolymer Concrete Research Articles

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 Fiber 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.

Development of High-Strength Geopolymer Concrete Incorporating High-Volume Copper Slag and Micro Silica

The present work investigates the mechanical and chemical characteristics and durability of high-strength geopolymer concrete (HSGPC) developed using high-volume copper slag and micro silica. The objective of the study was to explore the feasibility of deploying high-volume copper slag as a replacement for river sand in the fabrication of high-strength geopolymer concrete. In total, 11 different trials were cast by varying copper slag up to 100% as a potential alternative for the river sand. The mixture of alkaline activators for the preparation of the geopolymer concrete (GPC), such as sodium silicate (Na2SiO3) and sodium hydroxide (12 M NaOH), was used in the ratio 2.5:1. The optimum mix was selected from different copper slag dosages based on the characteristics of the HSGPC, such as mechanical strength and workability. For the selected optimized mix, micro silica was added up to 5% by volume of the binder (i.e., 1%, 2%, 3%, 4% and 5%) to improve the particle packing density of the developed HSGPC mix which in turn further enhances the strength and durability properties. Two different curing methods, including (a) ambient curing and (b) steam curing at 80 °C, were deployed for achieving the polymerization reaction (i.e., the formation of Na-Al-Si-H gel). Experimental outcomes reveal a maximum compressive strength of 79.0 MPa when 2% micro silica was added to the optimized GPC mix. In addition to the mechanical tests, the quality of the developed HSGPC was assessed using the ultrasonic pulse velocity (UPV) tests, water-absorption tests, sorptivity tests and microstructural analyses.

Behavior evaluation of sustainable high strength geopolymer concrete based on fly ash, metakaolin, and slag

The environmental challenge such as high energy demand, consuming raw materials, large CO2 emissions, and many other reasons associated with ordinary Portland cement manufacturing-led us to search for alternatives such as green concrete or geopolymer concrete. In this paper industrial wastes like fly ash, metakaolin, and granulated blast furnace slag were used as a base for high strength geopolymer concrete (HSGC). Four high strength concrete (HSC) mixes with Portland cement were produced for comparison with fifteen different geopolymer concrete mixes. All mixes were cast, cured, and tested. Slump and air content were measured as fresh properties for both HSC and HSGC mixes. Compressive strength at 3, 7, 28, and 91 days, splitting tensile strength, flexural strength, and modulus of elasticity were also measured and analyzed as mechanical properties. Durability properties like water permeability coefficient, drying shrinkage at 3, 7, 14, 21, 28, 56, and 91 days and temperature studies from 100 ° to 700 ° were investigated. Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy analysis of cement and geopolymer concrete mixes were conducted. Regarding fresh properties results showed that the geopolymer concrete based on slag with 500 kg/m3 showed 225 mm slump, while in hardened properties, the mix contained 200 kg of metakaolin with 300 kg of slag had the greatest compressive strength in both early and late age 63.3, 82.6 MPa, respectively, also had the greatest splitting tensile strength 6.2 MPa, flexural strength reached 9.2 MPa and modulus of elasticity was 37.68 GPa. Also, the coefficient of permeability decreases as the granulated blast furnace slag increases. The mineral additives contributed to reducing the dry shrinkage of geopolymer concrete. SEM images exhibited that the geopolymer matrix contained more dispersed small-sized pores which indicate a higher compressive strength absolutely than other experimental mixes.

Study on the bond behavior of high-strength geopolymer concrete

Study on the bond behavior of high-strength geopolymer concrete

Mechanical Properties Prediction of Normal and High Strength Geopolymer Concrete

The production process of cement is the main binder material in concrete usually accompanied by carbon dioxide emission. Therefore, geopolymer concrete (GPC) an alternative binder material was developed as a replacement for cement. In order to make this promising material more common in constructions and applicable for different design purposes further investigations for GPC mechanical properties were needed. This work aims to predicate the splitting tensile strength, modulus of elasticity and flexural strength for normal and high strength GPC by deriving new equations covering a wide range of compressive strength based on data available from previous work. Equations behavior along the changes in compressive strength from normal to high is adopted in comparisons as illustrated. The results show that the proposed equations, as compared with other equations established by previous works, provide a steady behavior for the various values of compressive strength especially for high strength. The coefficient of variation (COV) used as additional comparison criteria, and shows that the proposed equations provide better estimation of GPC mechanical properties.

Influence of Using Various Percentages of Slag on Mechanical Properties of Fly Ash-based Geopolymer Concrete

In order to implement the concept of sustainability in the field of construction, it is necessary to find an alternative to the materials that cause pollution by manufacturing, the most important of which is cement. Because factory wastes provide siliceous and aluminous materials and contain calcium such as fly ash and slag that are used in the production of high-strength geopolymer concrete with specifications similar to ordinary concrete, it was necessary for developing this type of concrete that is helping to reduce CO2 (dioxide carbon) in the atmosphere. Therefore, the aim of this study was to study the influence of incorporating various percentages of slag as a replacement for fly ash and the effect of slag on mechanical properties. This paper showed the details of the experimental work that has been undertaken to search and make tests the strength of geopolymer mixtures made of fly ash and then replaced fly ash with slag in different percentages. The geopolymer mixes were prepared using a ground granulated blast-furnace slag (GGBFS) blend and low calcium fly ash class F activated by an alkaline solution. The mixture compositions of fly ash to slag were (0.75:0.25, 0.65:0.35, 0.55:0.45) by weight of cementitious materials respectively and compared with reference mix of conventional concrete with mix proportion 1:1.5:3 (cement: sand: coarse agg.), respectively. The copper fiber was used as recycled material from electricity devices wastes such as (machines, motors, wires, and electronic devices) to enhance the mechanical properties of geopolymer concrete. The heat curing system at 40 oC temperature was used. The results revealed that the mix proportion of 0.45 blast furnace slag and 0.55 fly ash produced the best strength results. It also showed that this mix ratio could provide a solution for the need for heat curing for fly ash-based geopolymer.

Ultra high performance and high strength geopolymer concrete

Ultra high performance and high strength geopolymer concrete