Slag Based Geopolymer Concrete Research Articles

The confinement effect of basalt fibers for reinforced geopolymer composites: Flexural, shear and torsion capability for ductility and failure

Geopolymer concrete is a promising candidate to replace conventional concrete (CC), as geopolymer concrete is based on alkali-activated binders instead of Portland cement. The elimination of cement in the mix leads to a reduction in the release of greenhouse gases. It is known from the literature that the microscale properties of geopolymer concrete are similar to those of its counterparts. However, the structural performance of geopolymer elements should be investigated in detail. Therefore, in this study, the effect of basalt fiber ratio (%0 and %1), geopolymer mix type and stirrup (with and without stirrup) on flexural (four-point test), shear (overhanging test) and torsional (pure torsion test) behavior of RC beam were investigated. In these experiments, slag based geopolymer concrete with waste marble, geopolymer concrete with fly ash and geopolymer concrete with quartz powder were used in order to manufactured to the RC beams. The mechanical performances of RC beams were assessed by using load-deflection curves, stiffness, ductility, failure mode and crack propagations. Test results revealed that the use of basalt fiber tolerated the decrease in strength, although the shear, flexural and torsion capacity decreased if stirrups were not used in the beams. The use of fly ash in the mixture was more effective on the strength than other materials in terms of the aluminate and silicate it contained.

Impact of variations in the molarity of sodium hydroxide on metakaolin-ground granular blast-furnace slag-based geopolymer concrete

Impact of variations in the molarity of sodium hydroxide on metakaolin-ground granular blast-furnace slag-based geopolymer concrete

Estimation of Compressive Strength of Rubberised Slag Based Geopolymer Concrete Using Various Machine Learning Techniques Based Models

Estimation of Compressive Strength of Rubberised Slag Based Geopolymer Concrete Using Various Machine Learning Techniques Based Models

Flexural performance and damage of reinforced fly ash and slag-based geopolymer concrete after coupling effect of freeze-thaw cycles and sustained loading

To better represent field conditions, the bending performance of reinforced geopolymer concrete (GPC) beams after the coupling effect of freeze-thaw cycling and sustained flexural load was investigated. Two types of GPC (G10 and G50) with different content of fly ash and slag were included and compared with ordinary Portland cement concrete (OPC). The mechanical strength of concrete and bond strength of rebars in concrete before and after freeze-thaw cycles were measured. It was found that the frost resistance of G10 was the weakest followed by OPC and G50. Three scenarios of bending tests on reinforced concrete beams were included: (1) control (without freeze-thaw damage); (2) individual freeze-thaw cycling; (3) coupling effect before bending. Rebound tests were conducted to evaluate frost damages at different areas of the beams as the base to analyze bending behaviors of the beams. The failure mode, load-displacement(strain) relationship, ultimate flexural strength, and bending stiffness of beams from bending tests are analyzed. All beams in scenario (1) were dominant in flexural failure. For scenario (2), G10 and G50 failed in debonding failure due to significant reduction in bond strength, while OPC failed in diagonal tension failure as OPC could sustain bond stiffness, thus preventing debonding failure. For scenario (3), damages in GPC were exacerbated, while damages in OPC were limited.

Development of Sustainable Slag-based Geopolymer Concrete Using Different Types of Chemical Admixtures

Geopolymer concrete (GPC) has achieved a wide popularity since innovating it as an alternative to conventional concrete because of its superior mechanical characteristics and durability, in addition to being a green concrete due to its low negative impact on the environment. However, GPC still suffers from the problem of its poor workability which suppresses its spread in construction applications. This study investigated the most effective parameters on the workability of GPC including GGBFS content, water to binder ratio, and dosage of different types of chemical admixtures, Naphthalene-Based Admixture (NPA) and Polycarboxylate-Based Admixture (PCA), using Taguchi approach and Analysis of Variance (ANOVA) analysis considering the compressive strength at the different concrete ages. It was observed that NPA, in the geopolymer concrete, improved the compressive strength compared to PCA. The NPA-based mixes achieved the highest 28-day compressive strength, 69 MPa, with about 27.8% more than the highest 28-day compressive strength achieved by the PCA-based mixes, 54 MPa. The obtained results revealed that the NPA has achieved the best improvement for both the workability, in terms of initial slump value and slump loss rate, and the compressive strength of GPC mixes compared to PCA.

Predictive modelling of compressive strength of fly ash and ground granulated blast furnace slag based geopolymer concrete using machine learning techniques

Ordinary Portland cement (OPC) is proving to be hazardous to the environment. To replace the OPC, geopolymers (GPs) are introduced. However, to fully replace the OPC by GPs extensive laboratory tests are required to assess the long-term and short-term properties of GPs in different scenarios. Given the shortage of time for performing such extensive testing, artificial intelligence (AI) is used to analyze the properties of GPs. In this study, different AI techniques such as artificial neuro network (ANN), adaptive neuro-fuzzy inference system (ANFIS), and gene expression programming (GEP) are used to obtain the predictive models for estimating the compressive strength of fly ash and ground granulated blast furnace slag-based GP concrete. Different statistical parameters are used to evaluate the performance of predictive models. Similarly, sensitivity and parametric analysis are also conducted on the input parameters. Additionally, multiple linear regression was also performed on the whole database. After comparing all the results, it was concluded that GEP is the best AI technique to predict the compressive strength of GP-based concrete.

Research on the Carbonation Resistance and Carbonation Depth Prediction Model of Fly Ash- and Slag-Based Geopolymer Concrete

Research on the Carbonation Resistance and Carbonation Depth Prediction Model of Fly Ash- and Slag-Based Geopolymer Concrete

Experimenting the influence of corncob ash on the mechanical strength of slag-based geopolymer concrete

Abstract The construction sector has been under growing public attention recently as one of the leading causes of climate change and its detrimental effects on local communities. In this regard, geopolymer concrete (GPC) has been proposed as a replacement for conventional concrete. Predicting the concrete’s strength before pouring is, therefore, quite useful. The mechanical strength of slag and corncob ash (SCA–GPC), a GPC made from slag and corncob ash, was predicted utilizing multi-expression programming (MEP). Modeling parameters’ relative importance was determined using sensitivity analysis. When estimating the compressive, flexural, and split tensile strengths of SCA–GPC with MEP, 0.95, 0.93, and 0.92 R 2-values were noted between the target and predicted results. The developed models were validated using statistical tests for error and efficiency. The sensitivity analysis revealed that within the mix proportions, the slag quantity (65%), curing age (25%), and fine aggregate (3.30%) quantity significantly influenced the mechanical strength of SCA–GPC. The MEP models result in distinct empirical equations for the strength characteristics of SCA–GPC, unlike Python-based models, which might aid industry and researchers worldwide in determining optimal mix design proportions, thus eliminating unneeded test repetitions in the laboratory.

Mechanical properties and mesoscopic damage characteristics of basalt fibre-reinforced seawater sea-sand slag-based geopolymer concrete

This study aims to investigate the macroscopic mechanical properties and mesoscopic damage mechanisms of basalt fibre-reinforced seawater sea-sand slag-based geopolymer concrete (SS-SGC). At the macroscopic level, the influences of different volumes and lengths of basalt fibre (BF) on the workability, compressive strength, and splitting tensile strength of SS-SGC were analyzed. The optimum BF length was identified as 12 mm, with an optimal volume fraction of 0.6 %. This combination resulted in 9 % improvement in compressive strength and a 7 % enhancement in splitting tensile strength compared to the control group. Compared to Ordinary Portland Cement (OPC), SS-SGC exhibited a remarkable reduction of 79.6 %, 60.2 %, and 21 % in carbon emissions, energy consumption, and cost, respectively. At the microscopic level, scanning electron microscopy (SEM) was employed to analyze fibre distribution characteristics and the ITZ microstructure between the two aggregates and the matrix. The fibre bridging and aggregate synergistic mechanisms were proposed, highlighting the role of the high-density far-field ITZ of coral coarse aggregate (CCA) in altering the crack propagation trend and confining microscopic damage within the highly ductile matrix, thereby improving the mechanical properties of the concrete. At the mesoscopic level, a six-phase numerical model was established, considering different aggregates and their ITZ characteristics, to systematically analyze the mesoscopic damage evolution, as well as the macroscopic strength and stress-strain behavior of SS-SGC. The research outcomes serve as a reference for future multiscale studies on SS-SGC and its practical engineering applications.

Mechanical and fracture properties of slag/steel slag-based geopolymer fully recycled aggregate concrete

Blast furnace /steel slag-based geopolymer and recycled aggregate (RA) as green alternatives to cement and natural aggregate (NA), respectively, are attracting increasing attention. This study investigated the influence of four different aggregate systems (i.e., full-NA, full-recycled coarse aggregate, full-recycled fine aggregate, and full-RA) and three different replacement ratios of steel slag (i.e., 0%, 25%, and 50% of the precursor) on the mechanical properties (compressive and splitting tensile strength) and fracture properties (fracture energy and fracture toughness) of one-part slag/steel slag-based geopolymer concrete, aiming to promote its utilization in structural engineering. The experimental results indicate that substituting ordinary Portland cement with slag-based one-part geopolymer significantly enhanced the compressive and splitting tensile strength of geopolymer natural aggregate concrete (GNAC), although it leaded to a decrease in fracture properties. The incorporation of RA in GNAC resulted in deteriorated properties, with the 28-day compressive strength being reduced by up to 5%− 19.4% and fracture energy being reduced by up to 16.8%− 43.8%. Moreover, incorporating an appropriate amount of steel slag (approximately 25%) in geopolymer fully recycled aggregate concrete (GFRAC) had minimal impact on mechanical properties, while it enhanced the fracture energy values by up to approximately 16.6%. Nevertheless, a higher content of steel slag adversely affected the relevant properties due to its lower cementitious activity compared to slag. To mitigate the drawbacks associated with steel slag, less than 25% of steel slag content is recommended considering the mechanical and fracture properties of GFRAC.

Durability studies on conventional concrete and slag-based geopolymer concrete in aggressive sulphate environment

Durability studies on conventional concrete and slag-based geopolymer concrete in aggressive sulphate environment

Durability and Mechanical Properties of Granulated Blast Furnace Slag Based Geopolymer Concrete Containing Polyolefin Fibers and Nano Silica

In the current study, the improvement of granulated blast furnace slag (GBFS) based geopolymer concrete (GPC) applying 0 – 2% polyolefin fibers (POFs) and 0 – 8% nano-silica (NS) is investigated. After curing the specimens, they are subjected to compressive strength, tensile strength, elastic modulus, Ultrasonic Pulse Velocity (UPV), and impact resistance tests to evaluate their mechanical properties and durability. Moreover, the permeability of specimens is also assessed using water absorption. The compressive strength, tensile strength, and elastic modulus of the concrete increase by up to 22%, 14%, and 24%, respectively. The addition of the POFs to the GPC significantly increases the tensile strength (by up to 9%) and the absorbed energy due to the impact. By adding NS to the GPC composition, the results of the permeability and water capillary absorption test were improved. These results are evaluated through microstructure analysis, along with ultrasonic, X-Ray diffraction (XRD), X-Ray fluorescence (XRF), and scanning electron microscope (SEM) tests.

Phosphorous slag-based geopolymer cement incorporate with mullite for 3D printing application

In successful 3D printing, the primary key is the proper binder and correct formulation, which leads to the printable mortar. In this work an attempt has been made to fabricate a 3D printable phosphorous slag-based geopolymer concrete with the incorporation of mullite and precisely determined liquid-based activator. The results showed that with the increase of Si/Na from 0.2 to 0.6 increases initial setting time and open time. Presence of mullite resulted in more orientation of Al(IV)-O vibration band in the produced geopolymer matrix so that the maximum compressive strength has achieved in the sample incorporated with mullite and with Si/Na of 0.4 in the activator. The designed geopolymer paste is following the Herschel-Buckley model and show thixotropic behavior, which is useful rheological property for 3D printing applications especially for continuous extrusion and having a desirable layer-by-layer printing.

Durability characteristics of slag based geopolymer concrete modified with crumb rubber

Today, due to the increasing demand in the building sector, the interest of researchers in sustainable building materials is increasing. Geopolymer concretes especially come to the forefront due to energy saving and recycling of waste materials. In this paper, slag based geopolymer concretes were produced by substituting crumb rubber (CR) in different proportions instead of fine aggregate. In the samples using 12 M potassium hydroxide (KOH) as alkali activator, river aggregate was used as aggregate. The 28-day compressive strengths of the samples were between 25.95 MPa and 38.17 MPa, between 9.8 MPa and 11.95 MPa at the end of 300F-T cycles, and between 40.65 MPa and 35.70 MPa in sulfate solutions at the end of 12 weeks. Sulfate (5% Na2SO4 and 5% MgSO4) and freeze–thaw (F-T) (100, 200 and 300 cycles) resistances of the samples cured in the laboratory were determined. As a result of durability tests, the compressive strength, weight changes, sorptivity, water absorption, visual and microstructure analysis of the samples were examined. While the compressive strength of the samples kept in sulfate solutions increased, the compressive strength of the samples exposed to F-T cycles decreased. Sodium sulfate solution caused more strength increase in the samples compared to magnesium sulfate solution. After 300F-T, the strength losses in the samples were over 60%. In general, although the CR slightly reduced the mechanical properties of the control samples, it reduced the permeability of the samples, which increased their durability.

Compressive strength prediction of fly ash and blast furnace slag-based geopolymer concrete using convolutional neural network

Compressive strength prediction of fly ash and blast furnace slag-based geopolymer concrete using convolutional neural network

An investigation of micro-silica inclusion in slag-based geopolymer concrete with regression and cluster analysis

An investigation of micro-silica inclusion in slag-based geopolymer concrete with regression and cluster analysis

Comparison of the Beam Mechanical Properties between the CDG Based Geopolymer Concrete and OPC Concrete

This paper presents the results of an experimental investigation on the beam mechanical properties, based on the completely decomposed granite (CDG) & slag based geopolymer reinforced concrete, as well as the OPC reinforced concrete. The failure mode and bearing capacity of beam members were obtained. The load vs mid span deflection relationship and load vs displacement relationship were discussed. Furthermore, the results show the feasibility of the CDG & slag based geopolymer concrete in engineering application.

Experimental studies on strength and durability of alkali activated slag and coal bottom ash based geopolymer concrete

This thesis work describes the experimental evaluation of the durability and strength properties of nominally mixed conventional concrete of grade M35, Alkali Activated Slag Based Geopolymer Concrete. Research on Rapid Chloride Permeability Test (RCPT) durability properties has been conducted. Sodium hydroxide (NaOH) and sodium Chloride (NaCl) must be mixed in a 2.5:1 M ratio and at molarities of 12 and 16, respectively, in order to make alkali activators, with dry curing and open-air curing serving as distinct curing regimes. NaOH concentrations of 12 M and 16 M were used to make nine distinct mixes, one of which was designated as the control mix. Then, these mixtures were cured at room temperature in the open air. Prior to the testing day, they were maintained at room temperature after a 24-hour dry curing procedure at 90 °C in a hot air oven. Each of the nine mixes underwent split tensile and flexural strength and durability testing after 90 days. Compressive strength tests are conducted at 28, 56, and 90 days. The results show that tensile strength increases as NaOH solution concentration decreases, but compressive and flexural strength increase as NaOH solution concentration increases. However, it was discovered that the Geopolymer concrete made from Alkali Activated Slag and Coal Bottom Ash (CBA) did not perform well in tests of water fast chloride penetrability because surface cracking predominated. When compared to the results of the control mix, the Alkali Activated Slag and Coal Bottom Ash (CBA)-based geopolymer concrete mix shows a superior improvement in strength measures than standard concrete. At this time, it seems that making geopolymer concrete costs less than regular concrete.

Mechanical properties and bond behaviour of steel rebar and fly ash–slag based geopolymer concrete in pull-out test

Mechanical properties and bond behaviour of steel rebar and fly ash–slag based geopolymer concrete in pull-out test

Compound Effects of Sodium Chloride and Gypsum on the Compressive Strength and Sulfate Resistance of Slag-Based Geopolymer Concrete

Based on compressive strength, sulfate resistance, mass change, and relative dynamic elastic modulus tests, and XRD and SEM analysis, the effects of sodium chloride (NaCl) and gypsum on the mechanical properties and resistance to sulfate attack of slag-based geopolymer concrete activated by quicklime as well as the mechanism of action were studied. The results indicate that: (1) with appropriate dosages of NaCl or gypsum, the compressive strength of geopolymer concrete can be increased by 55.8% or 245.3% at 3 days and 23.9% or 82.3% at 28 days, respectively. When NaCl and gypsum are combined, Friedel’s salt, Kuzel’s salt, and NaOH are generated, and the strength is increased by 90.8% at 3 days, and 180.3% at 28 days. (2) With 2% NaCl alone, the mass loss is reduced from 5.29% to 2.44%, and the relative dynamic elastic modulus is increased from 0.37 to 0.41. When compounded with 7.5% gypsum, the mass is increased by 0.26%, and the relative dynamic elastic modulus is increased to 1.04. With a further increase of NaCl to 4%, the mass is increased by 0.27%, and the relative dynamic elastic modulus is increased to 1.09. The sulfate corrosion resistance coefficient of geopolymer concrete is increased from 0.64 to 1.02 when it is immersed with 7.5% gypsum alone for 90 days, and it can be further increased to 1.11 when compounded with 4% NaCl. (3) The geopolymer prepared with sodium chloride: gypsum: quicklime: slag = 4:7.5:13.5:75 can be used to replace 32.5 slag Portland cement in plain concrete. The cost and carbon emissions are reduced by 25% and 48%, respectively, and the sulfate corrosion resistance coefficient is higher by 38.8% than with slag Portland cement.