Case study of the application of pervious fly ash geopolymer concrete for neutralization of acidic wastewater

There have been a few attempts to develop prediction models of splitting tensile strength and reinforcement-concrete bond strength of FAGC (low-calcium fly ash geopolymer concrete), however, no model can be used as a design equation. Therefore, this paper aimed to provide practical prediction models. Using 115 test results for splitting tensile strength and 147 test results for bond strength from experiments and previous literature, considering the effect of size and shape on strength and structural factors on bond strength, this paper developed and verified updated prediction models and the 90% prediction intervals by regression analysis. The models can be used as design equations and applied for estimating the cracking behaviors and calculating the design anchorage length of reinforced FAGC beams. The strength models of PCC (Portland cement concrete) overestimate the splitting tensile strength and reinforcement-concrete bond strength of FAGC, so PCC’s models are not recommended as the design equations.

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Influence of red mud on performance enhancement of fly ash-based geopolymer concrete

Innovative Infrastructure Solutions ◽

10.1007/s41062-021-00578-x ◽

2021 ◽

Vol 6 (4) ◽

Author(s):

Ramamohana Reddy Bellum ◽

Chava Venkatesh ◽

Sri Rama Chand Madduru

Keyword(s):

Fly Ash ◽

Red Mud ◽

Performance Enhancement ◽

Geopolymer Concrete

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Micro-level studies of fly ash and GGBS—based geopolymer concrete using SEM and XRD

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/1130/1/012062 ◽

2021 ◽

Vol 1130 (1) ◽

pp. 012062

Author(s):

B. Rajini ◽

A.V. Narasimha Rao ◽

C. Sashidhar

Keyword(s):

Fly Ash ◽

Geopolymer Concrete ◽

Micro Level

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Behavior of Quarry Rock Dust, Fly Ash and Slag Based Geopolymer Concrete Columns Reinforced with Steel Fibers under Eccentric Loading

Applied Sciences ◽

10.3390/app11156740 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6740

Author(s):

Rana Muhammad Waqas ◽

Faheem Butt

Keyword(s):

Fly Ash ◽

Concrete Cover ◽

Steel Fibers ◽

Structural Behavior ◽

Partial Replacement ◽

Geopolymer Concrete ◽

Fiber Reinforced ◽

Conventional Concrete ◽

Source Materials ◽

Rock Dust

Geopolymer concrete, also known as an earth-friendly concrete, has been under continuous study due to its environmental benefits and a sustainable alternative to conventional concrete construction. The supplies of many source materials, such as fly ash (FA) or slag (SG), to produce geopolymer concrete (GPC) may be limited; however, quarry rock dust (QRD) wastes (limestone, dolomite, or silica powders) formed by crushing rocks appear virtually endless. Although significant experimental research has been carried out on GPC, with a major focus on the mix design development, rheological, durability, and mechanical properties of the GPC mixes; still the information available on the structural behavior of GPC is rather limited. This has implications in extending GPC application from a laboratory-based technology to an at-site product. This study investigates the structural behavior of quarry-rock-dust-incorporated fiber-reinforced GPC columns under concentric and eccentric loading. In this study, a total of 20 columns with 200 mm square cross-section and 1000 mm height were tested. The FA and SG were used as source materials to produce GPC mixtures. The QRD was incorporated as a partial replacement (20%) of SG. The conventional concrete (CC) columns were prepared as the reference specimens. The effect of incorporating quarry rock dust as a replacement of SG, steel fibers, and loading conditions (concentric and eccentric loading) on the structural behavior of GPC columns were studied. The test results revealed that quarry rock dust is an adequate material that can be used as a source material in GPC to manufacture structural concrete members with satisfactory performance. The general performance of the GPC columns incorporating QRD (20%) is observed to be similar to that of GPC columns (without QRD) and CC columns. The addition of steel fibers considerably improves the loading capacity, ductility, and axial load–displacement behavior of the tested columns. The load capacities of fiber-reinforced GPC columns were about 5–7% greater in comparison to the CC columns. The spalling of concrete cover at failure was detected in all plain GPC columns, whereas the failure mode of all fiber-reinforced GPC columns is characterized with surface cracking leading to disintegration of concrete cover.

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Assessment of the Rheological and Mechanical Properties of Geopolymer Concrete Comprising Fly Ash and Fluid Catalytic Cracking Residue as Aluminosilicate Precursor

Applied Sciences ◽

10.3390/app11073032 ◽

2021 ◽

Vol 11 (7) ◽

pp. 3032

Author(s):

Tuan Anh Le ◽

Sinh Hoang Le ◽

Thuy Ninh Nguyen ◽

Khoa Tan Nguyen

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Elastic Modulus ◽

Fly Ash ◽

Flexural Strength ◽

Catalytic Cracking ◽

Fluid Catalytic Cracking ◽

High Alumina ◽

Geopolymer Concrete ◽

Sem Images

The use of fluid catalytic cracking (FCC) by-products as aluminosilicate precursors in geopolymer binders has attracted significant interest from researchers in recent years owing to their high alumina and silica contents. Introduced in this study is the use of geopolymer concrete comprising FCC residue combined with fly ash as the requisite source of aluminosilicate. Fly ash was replaced with various FCC residue contents ranging from 0–100% by mass of binder. Results from standard testing methods showed that geopolymer concrete rheological properties such as yield stress and plastic viscosity as well as mechanical properties including compressive strength, flexural strength, and elastic modulus were affected significantly by the FCC residue content. With alkali liquid to geopolymer solid ratios (AL:GS) of 0.4 and 0.5, a reduction in compressive and flexural strength was observed in the case of geopolymer concrete with increasing FCC residue content. On the contrary, geopolymer concrete with increasing FCC residue content exhibited improved strength with an AL:GS ratio of 0.65. Relationships enabling estimation of geopolymer elastic modulus based on compressive strength were investigated. Scanning electron microscope (SEM) images and X-ray diffraction (XRD) patterns revealed that the final product from the geopolymerization process consisting of FCC residue was similar to fly ash-based geopolymer concrete. These observations highlight the potential of FCC residue as an aluminosilicate source for geopolymer products.

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Effect of Elevated Temperature on Mechanical Properties of High-Volume Fly Ash-Based Geopolymer Concrete, Mortar and Paste Cured at Room Temperature

Polymers ◽

10.3390/polym13091473 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1473

Author(s):

Jun Zhao ◽

Kang Wang ◽

Shuaibin Wang ◽

Zike Wang ◽

Zhaohui Yang ◽

...

Keyword(s):

Mechanical Properties ◽

Elevated Temperature ◽

Fly Ash ◽

Residual Strength ◽

Elevated Temperatures ◽

High Volume ◽

Sem Analysis ◽

Geopolymer Concrete ◽

Ordinary Concrete ◽

Exposure Temperature

This paper presents results from experimental work on mechanical properties of geopolymer concrete, mortar and paste prepared using fly ash and blended slag. Compressive strength, splitting tensile strength and flexural strength tests were conducted on large sets of geopolymer and ordinary concrete, mortar and paste after exposure to elevated temperatures. From Thermogravimetric analyzer (TGA), X-ray diffraction (XRD), Scanning electron microscope (SEM) test results, the geopolymer exhibits excellent resistance to elevated temperature. Compressive strengths of C30, C40 and C50 geopolymer concrete, mortar and paste show incremental improvement then followed by a gradual reduction, and finally reach a relatively consistent value with an increase in exposure temperature. The higher slag content in the geopolymer reduces residual strength and the lower exposure temperature corresponding to peak residual strength. Resistance to elevated temperature of C40 geopolymer concrete, mortar and paste is better than that of ordinary concrete, mortar and paste at the same grade. XRD, TGA and SEM analysis suggests that the heat resistance of C–S–H produced using slag is lower than that of sulphoaluminate gel (quartz and mullite, etc.) produced using fly ash. This facilitates degradation of C30, C40 and C50 geopolymer after exposure to elevated temperatures.

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