scholarly journals Corrosion Evaluation of Geopolymer Concrete Made with Fly Ash and Bottom Ash

2021 ◽  
Vol 13 (1) ◽  
pp. 398
Author(s):  
Priyanka Morla ◽  
Rishi Gupta ◽  
Peiman Azarsa ◽  
Ashutosh Sharma
Keyword(s):  
Fly Ash ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Bottom Ash ◽  
High Rate ◽  
Geopolymer Concrete ◽  
Cell Potential ◽  
Accelerated Corrosion ◽  
Corrosion Evaluation ◽  
Alumino Silicate

Environmental pollution caused by CO2 releasing from the production of cement is a great challenge for the construction industry and has triggered exploration into more sustainable alternatives. Geopolymer Concrete (GPC) is a potential sustainable solution that does not involve the use of cement as a binder. GPC is produced by mixing the alumino-silicate source materials such as fly-ash with alkali activators such as potassium hydroxide (KOH) and potassium silicate (K2SiO3). Unlike Ordinary Portland Concrete (OPC), the characteristics of GPC depend on the precursor materials and therefore vary for different mixes. Consequently, corrosion behavior needs to be evaluated separately for individual mixes. This has narrowed the scope of existing published work on corrosion behavior of GPC. In this study, GPC and OPC specimens were prepared and exposed to accelerated corrosion exposure. Half-cell potential and linear polarization resistance were used to evaluate the corrosion rate in GPC and OPC. Under accelerated conditions, the corrosion rate of the GPC specimens was between 10 µm/year and 20 µm/year exhibiting a moderate to high rate of corrosion. Meanwhile, the corrosion rate of the OPC specimens was between 40 µm/year and 60 µm/year indicating a very high corrosion activity. It can be concluded that GPC has a higher resistance to chloride-induced corrosion; with a low corrosion rate and lower mass loss percentage, compared to OPC.

Microstructure and Mechanical Properties of Ambiently-Cured Blended Coal Ash-Based Geopolymer Concrete

2016 ◽  
Vol 857 ◽  
pp. 400-404
Author(s):  
Tian Yu Xie ◽  
Togay Ozbakkaloglu
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Compressive Strength ◽  
Fly Ash ◽  
Bottom Ash ◽  
Coal Ash ◽  
Geopolymer Concrete ◽  
Mass Ratio ◽  
Blended Coal ◽  
Microstructure And Mechanical Properties

This paper presents the results of an experimental study on the behavior of fly ash-, bottom ash-, and blended fly and bottom ash-based geopolymer concrete (GPC) cured at ambient temperature. Four bathes of GPC were manufactured to investigate the influence of the fly ash-to-bottom ash mass ratio on the microstructure, compressive strength and elastic modulus of GPC. All the results indicate that the mass ratio of fly ash-to-bottom ash significantly affects the microstructure and mechanical properties of GPCs

Corrosion Behavior of Steel Reinforcement in Simulated Concrete Pore Solutions with Various pH and Chloride Contents

2014 ◽  
Vol 629-630 ◽  
pp. 168-172
Author(s):  
Shao Heng Hsieh ◽  
Ran Huang ◽  
Mao Chieh Chi ◽  
Pokuei Liang
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Pore Solution ◽  
Chloride Content ◽  
Chloride Ions ◽  
Test Results ◽  
Weight Loss Measurement ◽  
Half Cell ◽  
Cell Potential ◽  
Significant Factors

Corrosion of rebar in reinforced concrete is a major problem affecting the integrity and loading capacity of the structures. Usually concrete pore solution provides high alkaline environment to protect steel from corrosion. However, the ingress of chloride ions or carbon dioxide would reduce the alkalinity and destroy the stable oxide film which could accelerate the corrosion process of rebar. This study was aimed to evaluate the combined effect of pH and chloride contents on corrosion behavior of rebar using simulated concrete pore solutions. Weight-loss measurement were performed to obtain the corrosion rate. Meanwhile, explore the effect of carbonation and chloride contents to Half-cell potential value on mortar and concrete. Test results show that both pH and chloride content are significant factors influencing the corrosion behavior of rebar. Higher corrosion rate was found in the rebar immersed in the solutions with smaller pH and higher chloride content.

EVALUATION OF SHRINKAGE AND DURABILITY OF GEOPOLYMER CONCRETE USING F-CLASS COAL ASHES

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Gum Sung Ryu ◽  
Kyung Taek Koh ◽  
Gi Hong An ◽  
Jang Hwa Lee
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Bottom Ash ◽  
Drying Shrinkage ◽  
Geopolymer Concrete ◽  
Cement Concrete ◽  
Fly Ash Concrete ◽  
Coal Ashes

This paper evaluates the strength, shrinkage and durability characteristics of concrete using 100% fly ash and bottom ash as binder. It is seen that the compressive strength of activated fly ash and bottom ash concrete reaches respectively 25 MPa and 30 MPa, and that the change in strength is insignificant as per the content of bottom ash powder. Moreover, the total amount of shrinkage of the activated bottom ash concrete appears to be larger than that of the activated fly ash concrete. In addition, the drying shrinkage and durable performance of the activated ash geopolymer concrete is verified to be superior to that of ordinary cement concrete.

scholarly journals Long Term Corrosion Experiment of Steel Rebar in Fly Ash-Based Geopolymer Concrete in NaCl Solution

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Y. P. Asmara ◽  
J. P. Siregar ◽  
C. Tezara ◽  
Wan Nurlisa ◽  
J. Jamiluddin
Keyword(s):  
Fly Ash ◽  
Corrosion Rate ◽  
Corrosion Behaviour ◽  
Electrochemical Measurement ◽  
Corrosion Current ◽  
Electrochemical Process ◽  
Concrete Mixture ◽  
Nacl Solution ◽  
Polarization Diagram ◽  
Cell Potential

This research focuses on an experimental investigation to identify the effects of fly ash on the electrochemical process of concrete during the curing time. A rebar was analysed using potentiostat to measure the rest potential, polarization diagram, and corrosion rate. Water-to-cement ratio and amount of fly ash were varied. After being cured for 24 hours at a temperature of 65°C, the samples were immersed in 3.5% of NaCl solution for 365 days for electrochemical measurement. Measurements of the half-cell potential and corrosion current density indicated that the fly ash has significant effects on corrosion behaviour of concrete. Although fly ash tends to create passivity on anodic current, it increases corrosion rate. The corrosion potential of this concrete mixture decreases compared to concrete without fly ash. From the result, it can be summarized that concrete mixture with 70% of OPC (Ordinary Portland Cement) and 30% fly ash has shown the best corrosion resistance.

Development of Geopolymer Concrete from Fly Ash and Bottom Ash Mixture

2014 ◽  
Vol 73 (2) ◽  
pp. 143-148 ◽  
Author(s):  
Deependra Kumar Sinha ◽  
A. Kumar ◽  
Sanjay Kumar
Keyword(s):  
Fly Ash ◽  
Bottom Ash ◽  
Geopolymer Concrete

Fly Ash-Based Geopolymer: Green Material in Carbon-Constrained Society

2021 ◽  
Vol 321 ◽  
pp. 65-71
Author(s):  
Hoc Thang Nguyen ◽  
Phong Thanh Dang
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Thermal Power ◽  
Bottom Ash ◽  
Coal Ash ◽  
Raw Material ◽  
Engineering Properties ◽  
Gravimetric Analysis ◽  
Green Materials ◽  
Alumino Silicate

Climate change is recognized as a global problem and even the industrial and construction sectors are trying to reduce the green-house gas emissions, especially on CO2 emissions. In Vietnam, the coal-fired thermal power plants are discharging millions of tons of CO2 and coal ash annually. This coal ash is comprised of about 80% of fly ash and the rest is bottom ash. This study would like to introduce one of the potential solutions in a carbon-constrained society that would not only manage the fly ash but also utilized this as raw material for green materials through geopolymerization. The geopolymer-based material has lower energy consumption, minimal CO2 emissions and lower production cost as it valorizes industrial waste. The fly ash containing high alumino-silicate resources from a coal-fired power plant in Vietnam was mixed with sodium silicate and sodium hydroxide solutions to obtain the geopolymeric pastes. The pastes were molded in 10x10x20cm molds and then cured at room temperature for 28 days. The 28-day geopolymer specimens were carried out to test for engineering properties such as compressive strength (MPa), volumetric weight (kg/m3), and water absorption (kg/m3). The microstructure analysis was also conducted for this eco-friendly materials using X ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Differential Thermal Analysis - Thermal Gravimetric Analysis (DTA-TGA).

scholarly journals Comparative Study Involving Effect of Curing Regime on Elastic Modulus of Geopolymer Concrete

Buildings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 101 ◽  
Author(s):  
Peiman Azarsa ◽  
Rishi Gupta
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
Resonant Frequency ◽  
Construction Material ◽  
Bottom Ash ◽  
Geopolymer Concrete ◽  
Portland Cement Concrete ◽  
Steam Curing ◽  
Curing Regime

Geopolymer Concrete (GPC) as a cement-less construction material has attracted worldwide attention due to its lower carbon footprint. There are numerous studies reported on GPC made using different by-products including fly-ash. However, since the use of bottom-ash is comparatively limited, making potassium-based GPC using this waste can be an alternative to Portland Cement Concrete (PCC). In this study, two methods of accelerated curing were used to determine the influence of elevated temperature on the compressive strength of GPC, composed of 50% bottom-ash and 50% fly-ash. GPC specimens were cured using various temperatures including ambient, 30 °C, 45 °C, 60 °C, and 80 °C for 24 h, all followed by 28 days of ambient curing. The highest compressive strength was obtained with steam curing at a temperature of 80 °C for a duration of 24 h. It is of great significance to evaluate elastic modulus of the concrete mixture so that the short-term rigidity of structures subjected to elongation, bending, or compression can be predicted. In this study, a longitudinal Resonant Frequency Test (RFT) as a non-destructive test (NDT) was used to calculate the elastic modulus of both GPC and a comparative PCC mix. Based on the results, PCC had higher resonant frequency (by about 1000 Hz) compared to GPC. A review of empirical models for predicting GPC’s elastic modulus showed that all of the predicted elastic modulus values were lower than experimental values.

The Corrosion Behavior of Galvanized Steel in Alkaline Soil

2013 ◽  
Vol 331 ◽  
pp. 416-420 ◽  
Author(s):  
Feng Jie Yan ◽  
Xing Geng Li ◽  
Xue Gang Wang
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Corrosion Products ◽  
Galvanized Steel ◽  
Localized Corrosion ◽  
Alkaline Soil ◽  
Electrochemical Test ◽  
Accelerated Corrosion ◽  
Grounding Grid ◽  
Accelerated Corrosion Test

The grounding grid of some substation shows severely corrosion, which affects the safe running of power grid. Galvanized steel is widely used in grounding grid. However, the galvanized steel is easy to corrosion in alkaline soil. In this paper, the corrosion behavior of galvanized steel was studied through accelerated corrosion test of burying specimens in laboratory soils and the corrosion rate was measured by electrochemical test. The corrosion products and corrosion appearance were analyzed by means of SEM, and XRD. The results show that pitting corrosion and localized corrosion were observed on the surface of the galvanized steel, the corrosion products were rough and loose, indicating no protection, the corrosion products of galvanized steel were ZnO,FeO(OH),FeCl3,Zn3O(SO4)2,and ZnSO3·2.50H2O. Electrochemical test show that the corrosion rate of galvanized steel in the later corrosion stage is higher than in the initial corrosion stage.

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