scholarly journals The Effects of Water to Solid Ratio, Activator to Binder Ratio, and Lime Proportion on the Compressive Strength of Ambient-Cured Geopolymer Concrete

2019 ◽  
Vol 5 (2) ◽  
pp. 161 ◽  
Author(s):  
Andi Arham Adam
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide Solution ◽  
Geopolymer Concrete ◽  
Solid Ratio ◽  
Slaked Lime ◽  
Binder Ratio ◽  
Class F Fly Ash ◽  
Good Workability ◽  
Class F

Low calcium fly ash based Geopolymer has been proven to be one of the potential alternatives substitutes to Portland Cement not only due to its high resistance to chemical attack but also because of the vast availability of class F fly ash for raw materials. However, one of the limitations of geopolymer as the alternative binders in concrete is that the strength develops slowly under ambient condition. This paper presented the investigation of water to solid ratio, activator to binder ratio, and lime proportion on the compressive strength of ambient-cured geopolymer concrete. To develop sufficient strength at an early age, class F fly ash and slaked lime (Ca (OH)2) were used as the binder with the proportion of lime to binder of 4%, 5%, 6%, and 7%. The blended binder was activated by sodium silicate and sodium hydroxide solution with the variation of activator to binder ratio of 0.45, 0.5, 0.55, and 0.6.  The water to solid ratio of 0.30, 0.31, 0.32, and 0.33 was chosen to facilitate good workability which was done by adding water to the mix. The compressive strength tests were conducted at 7, 14, and 28 days on the cylindrical concrete specimens with a dimension of 100 mm diameter and 200 mm height. The results show that the activator to binder ratio of 0.50 to 0.55, and the proportion of lime to the binder of 6% to 7% were the optimum range value. It was also found that the lower the water to cement ratio the higher the compressive strength and the water to solid ratio as low as 0.3 produced the highest compressive strength while still maintaining good workability.

scholarly journals Development of Sustainable Eco-friendly Geopolymer Composites for Construction Applications

2020 ◽  
Author(s):  
Mohamed Rabie ◽  
Mohammad Irshidat ◽  
Nasser Al-Nuaimi
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Power Plants ◽  
Sodium Hydroxide Solution ◽  
Testing Machine ◽  
Heat Curing ◽  
Alkali Solutions ◽  
Binder Ratio ◽  
Class F Fly Ash ◽  
Class F

Geopolymerization is a process where silica and alumina rich source materials turns into excellent binding materials by the aid of alkali solutions. Materials such as fly ash are by-products in energy power plants. Fly ash is classified based on its constituent materials. Fly ash class F mainly consists of alumina and silica. Compressive strength of class F fly ash geopolymer mortar is influenced by many factors such as the molarity of sodium hydroxide solution, fluid to binder ratio, Na2SiO3/NaOH ratio, curing duration and curing temperatures. The present study investigates the effect of these factors on the compressive strength of geopolymer mortar. For each combination, three cubes with dimensions of 50 x 50 x 50 mm were casted. After heat curing in the laboratory oven, the samples were tested on a universal testing machine for the compressive strength. The results showed very high early compressive strength of 63.9 MPa for samples cured at 80 °C and for a duration of 24 hr.

scholarly journals Experimental and Statistical Study on Mechanical Characteristics of Geopolymer Concrete

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1651 ◽  
Author(s):  
Yifei Cui ◽  
Kaikai Gao ◽  
Peng Zhang
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
Mechanical Characteristics ◽  
Statistical Hypothesis ◽  
Geopolymer Concrete ◽  
Empirical Equations ◽  
Class F Fly Ash ◽  
Class F

This paper studies the statistical correlation in mechanical characteristics of class F fly ash based geopolymer concrete (CFGPC). Experimentally measured values of the compressive strength, elastic modulus and indirect tensile strength of CFGPC specimens made from class F fly ash (CFA) were presented and analyzed. The results were compared with those of corresponding ordinary Portland cement concrete (OPCC) using statistical hypothesis tests. Results illustrated that when possessing similar compressive and tensile strength, the elastic modulus for CFGPC is significantly lower than that of OPCC. The corresponding expressions recommended by standards for the case of OPCC is proved to be inaccurate when applied in the case of CFGPC. Statistical regression was used to identify tendencies and correlations within the mechanical characteristics of CFGPC, as well as the empirical equations for predicting tensile strength and elastic modulus of CFGPC from its compressive strength values. In conclusion, CFGPC and OPCC has significant differences in terms of the correlations between mechanical properties. The empirical equations obtained in this study could provide relatively accurate predictions on the mechanical behavior of CFGPC.

scholarly journals The Effect of Activator to Binder Ratio on the Compressive Strength of Fly Ash Based Geopolymer Mortar in Sulphate Environment

2020 ◽  
Vol 331 ◽  
pp. 05002
Author(s):  
Andi Arham Adam ◽  
Suci Amalia Namira ◽  
Atur PN Siregar ◽  
Mustofa
Keyword(s):  
Compressive Strength ◽  
Sulfuric Acid ◽  
Fly Ash ◽  
Sample Volume ◽  
Strength Test ◽  
Acid Attack ◽  
Solid Ratio ◽  
Slaked Lime ◽  
Compressive Strength Test ◽  
Binder Ratio

One of the significant characteristic material needed to consider is durability. Sulphate ion contained in soil is one of aggressive agents that could cause degradation of concrete members which led to loss of compressive strength. The current research is to elaborate the effect of activator to binder ratio on the compressive strength of the fly ash based geopolymer mortar in the sulphate environment. Two different types of geopolymer mortar were casted i. e. mortar made of 100% fly ash and mortar contained 95% fly ash + 5% slaked lime. The fly ash used in this research is classified as F fly ash from the Mpanau power plant the variation of activator to binder ratio of 0. 40; 0. 50; and 0. 60, and water/solid ratio variations of 0. 32, 0. 34 and 0. 36. The composition of sulfuric acid was by 5% of the sample volume. Geopolymers mortar compressive strength test is conducted on the immersed samples in a solution of 5% sulfuric acid with age of 0, 7, 14, 28, 56, and 84 days, respectively. The compressive strength test results showed that the highest compressive strength of geopolymers mortar (resistant to sulfuric acid attack) was geopolymers mortar made from fly ash with activator to binder ratio 0. 60, water / solid ratio 0. 32, and percentage of lime to binder 5% at the age of 84 days.

Flexural Strength of Low Calcium Class F Fly Ash-Based Geopolymer Concrete in Long Term Performance

2016 ◽  
Vol 841 ◽  
pp. 104-110 ◽  
Author(s):  
Arie Wardhono ◽  
David W. Law ◽  
Thomas C.K. Molyneaux
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Pulse Velocity ◽  
Modulus Of Rupture ◽  
Geopolymer Concrete ◽  
Strength Performance ◽  
Low Calcium ◽  
Class F Fly Ash ◽  
Class F

This paper reports on experimental work that has been undertaken to investigate the flexural strength performance of fly ash-based geopolymer (FG) concrete. The FG concrete was prepared using low calcium class F fly ash with high silicate content. The flexural strength properties of FG were assessed using modulus of rupture test up to the age of 360 days. Compressive strength and Ultrasonic Pulse Velocity (UPV) tests were also performed to corroborate the flexural strength test results. The results showed that the FG concrete demonstrates a comparable compressive strength and velocity to OPC concrete. Hewever, the flexural strength of FG concrete exhibited a better performance compared to that OPC concrete. The measured flexural strength of FG concrete also exhibited a higher value compared to the predicted one using ACI 318M-08 standard. The relationship between flexural strength with compressive strength demonstrated a similarity behavior to that OPC concrete. Thus, it can be concluded that the use of the ACI standard can be applied conservatively to determine the flexural strength of fly ash-based geopolymer concrete.

scholarly journals Novel Analytical Method for Mix Design and Performance Prediction of High Calcium Fly Ash Geopolymer Concrete

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 900
Author(s):  
Chamila Gunasekara ◽  
Peter Atzarakis ◽  
Weena Lokuge ◽  
David W. Law ◽  
Sujeeva Setunge
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Gradient Algorithm ◽  
Geopolymer Concrete ◽  
Statistical Regression ◽  
Solid Ratio ◽  
Marquardt Algorithm ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Matlab Programming

Despite extensive in-depth research into high calcium fly ash geopolymer concretes and a number of proposed methods to calculate the mix proportions, no universally applicable method to determine the mix proportions has been developed. This paper uses an artificial neural network (ANN) machine learning toolbox in a MATLAB programming environment together with a Bayesian regularization algorithm, the Levenberg-Marquardt algorithm and a scaled conjugate gradient algorithm to attain a specified target compressive strength at 28 days. The relationship between the four key parameters, namely water/solid ratio, alkaline activator/binder ratio, Na2SiO3/NaOH ratio and NaOH molarity, and the compressive strength of geopolymer concrete is determined. The geopolymer concrete mix proportions based on the ANN algorithm model and contour plots developed were experimentally validated. Thus, the proposed method can be used to determine mix designs for high calcium fly ash geopolymer concrete in the range 25–45 MPa at 28 days. In addition, the design equations developed using the statistical regression model provide an insight to predict tensile strength and elastic modulus for a given compressive strength.

Freeze-thaw resistance of Class F fly ash-based geopolymer concrete

2019 ◽  
Vol 222 ◽  
pp. 474-483 ◽  
Author(s):  
Renda Zhao ◽  
Yuan Yuan ◽  
Zhengqing Cheng ◽  
Tian Wen ◽  
Jian Li ◽  
...  
Keyword(s):  
Fly Ash ◽  
Geopolymer Concrete ◽  
Freeze Thaw ◽  
Class F Fly Ash ◽  
Class F

Effect of Partial Replacement of Fly Ash by Metakaolin on Strength Development of Fly Ash Based Geopolymer Mortar

2017 ◽  
Vol 744 ◽  
pp. 131-135 ◽  
Author(s):  
Muhammad Zahid ◽  
Nasir Shafiq ◽  
Mohd Fadhil Nuruddin ◽  
Ehsan Nikbakht ◽  
Asif Jalal
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide Solution ◽  
Base Material ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Partial Replacement ◽  
Strength Development ◽  
Class C ◽  
Class F

This article aims to investigate the compressive strength variation by the addition of metakaolin as a substitute of fly ash in the fly ash based geopolymer mortar. Five, ten and fifteen percent by weight of fly ash was replaced by highly reactive metakaolin. Two type of fly ashes namely, ASTM class F and ASTM class C were used as a base material for the synthesis of geopolymer mortar. Eight molar sodium hydroxide solution mixed with sodium silicate solution was used as alkaline activator. For optimum geopolymerization, mortar was cured at sixty degree Celsius for twenty four hours duration. Results show different behavior of metakaolin replacement on compressive strength for two different types of fly ash based geopolymer mortar. Improvement in compressive strength was seen by addition of metakaolin in ASTM class F fly ash based geopolymer. On the other hand compressive strength was decreased abruptly in fly ash class C based geopolymer up to certain replacement level.

scholarly journals Compressive Strength and Thermal Conductivity of Fly Ash Geopolymer Concrete Incorporated with Lightweight Aggregate, Expanded Clay Aggregate and Foaming Agent

2019 ◽  
Vol 70 (11) ◽  
pp. 4021-4028 ◽  
Author(s):  
Liew Yun Ming ◽  
Andrei Victor Sandu ◽  
Heah Cheng Yong ◽  
Yuyun Tajunnisa ◽  
Siti Fatimah Azzahran ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide Solution ◽  
Density Ratio ◽  
Lightweight Aggregate ◽  
Alkali Activation ◽  
Geopolymer Concrete ◽  
River Sand ◽  
Foaming Agent

This paper investigates the effect of incorporation of lightweight aggregate and foam in the preparation of lightweight aggregate geopolymer concrete (LWAGC) and lightweight aggregate foamed geopolymer concrete (LWAFGC). The geopolymer paste was formed by alkali activation of Class F fly ash in mixture of sodium silicate and sodium hydroxide solution. LWAGC was incorporated with expanded clay lightweight aggregate and river sand while hydrogen peroxide was added as foaming agent for LWAFGC. Results showed that LWAGC and LWAFGC achieved an excellent 28-day compressive strength of 60 MPa and 20 MPa, respectively. The bulk densities were 1815 kg/m3 for LWAGC and 1593 kg/m3 for LWAFGC. Even so, low thermal conductivity of 0.12 W/mK and 0.09 W/mK were reported. It was concluded that the joint effect of lightweight aggregate and foam produced geopolymer concrete with good mechanical strength while having excellent thermal insulating properties. The geopolymer concretes possessed high strength-to-density ratio to be regarded as lightweight high-performance structures.

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