scholarly journals An Empirical Model for Geopolymer Reactions Involving Fly Ash and GGBS

2022 ◽  
Vol 2022 ◽  
pp. 1-13
Author(s):  
Beulah M ◽  
MR Sudhir ◽  
Shenen Chen ◽  
Sasha Rai ◽  
Deekshith Jain
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Linear Regression Analysis ◽  
Correlation Coefficients ◽  
Multiple Linear Regression Analysis ◽  
Alkali Concentration ◽  
Strength Development ◽  
Individual Values ◽  
Dependent Parameter ◽  
Compressive Strength Development

Numerous works are reported in literature regarding the enhancement of compressive strength of fly ash-GGBS geopolymer combinations with addition of alkali activators of varying concentrations. However, a limited study has been chronicled, revealing the specific role of alkali or alkaline earth contributed by the fly ash-GGBS combinations on the compressive strength development. It is well known that the strength of a geopolymer is dependent on gel formation from Al/Si ratio, Ca/Si ratio, and Ca/(Si + Al) ratio but their exact role when cured for various extended periods is unknown as yet. In the present study, alkali concentration in a fly ash-GGBS geopolymer combination was varied from 6 M to 12 M with increments of two mol in six different fly ash-GGBS combinations with a minimum of 20 percent and a maximum of 70 percent GGBS. The correlation coefficients between compressive strength and Al/Si, Ca/Si, and Ca/(Si + Al) ratios exhibited values higher than 0.95 taken individually. Multiple linear regression analysis with compressive strength (as dependent parameter) and individual values of Al/Si, Ca/Si, and Ca/(Si + Al) ratios (as independent parameters) was effectuated. It was observed that, depending on the composition, the compressive strength circumstantiated a changeover from Ca/Si to Ca/(Si + Al) ratio in the intermediate composition range. Such a detailed analysis is considered supportive of developing a suitable composition which will provide the optimum compressive strength of the combination.

Model for compressive strength development of OPC concrete and fly ash concrete with time

2018 ◽  
Vol 70 (11) ◽  
pp. 541-557 ◽  
Author(s):  
Gollapalli S. Vijaya Bhaskara ◽  
Kanchi Balaji Rao ◽  
Madambikkattil B. Anoop
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Strength Development ◽  
Fly Ash Concrete ◽  
Compressive Strength Development

scholarly journals Influence of Mechanical and Mineralogical Activation of Biomass Fly Ash on the Compressive Strength Development of Cement Mortars

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6654
Author(s):  
Jakub Popławski ◽  
Małgorzata Lelusz
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Cement Mortar ◽  
Setting Time ◽  
Green Energy ◽  
Biomass Combustion ◽  
Strength Development ◽  
Compressive Strength Development ◽  
Biomass Fly Ash

Biomass combustion is a significant new source of green energy in the European Union. The adequate utilization of byproducts created during that process is a growing challenge for the energy industry. Biomass fly ash could be used in cement composite production after appropriate activation of that material. This study had been conducted to assess the usefulness of mechanical and physical activation methods (grinding and sieving), as well as activation through the addition of active silica in the form of silica fume, as potential methods with which to activate biomass fly ash. Setting time, compressive strength, water absorption and bulk density tests were performed on fresh and hardened mortar. While all activation methods influenced the compressive strength development of cement mortar with fly ash, sieving of the biomass fly ash enhanced the early compressive strength of cement mortar. The use of active silica in the form of silica fume ensured higher compressive strength results than those of control specimens throughout the entire measurement period.

scholarly journals Compressive Strength Development of High-Volume Fly Ash Ultra-High-Performance Concrete under Heat Curing Condition with Time

2020 ◽  
Vol 10 (20) ◽  
pp. 7107
Author(s):  
Pham Sy Dong ◽  
Nguyen Van Tuan ◽  
Le Trung Thanh ◽  
Nguyen Cong Thang ◽  
Viet Hung Cu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
High Volume ◽  
Strength Development ◽  
Ultra High Performance Concrete ◽  
Heat Curing ◽  
Compressive Strength Development ◽  
Curing Condition

This research investigated the effect of fly ash content on the compressive strength development of ultra-high-performance concrete (UHPC) at different curing conditions, i.e., the standard curing condition and the heat curing. A total of 20 mixtures were prepared to cast specimens to measure the compressive strength at different ages from 3 days to 180 days. Additionally, 300 specimens were prepared to estimate the appropriate heat curing period at the early ages in terms of enhancing the 28-day compressive strength of UHPC with high content of fly ash (FA). From the regression analysis using test data, empirical equations were formulated to assess the compressive strength development of UHPC considering the FA content and maturity function. Test results revealed that the preference of the addition of FA for enhancing the compressive strength of UHPC requires the early heat curing procedure which can be recommended as at least 2 days under 90 °C. Moreover, the compressive strength of UHPC with FA under heat curing mostly reached its 28-day strength within 3 days. The proposed models based on the fib 2010 model can be a useful tool to reliably assess the compressive strength development of UHPC with high-volume fly ash (HVFA) (up to 70% fly ash content) under a heat curing condition that possesses a different performance from that of normal- and high-strength concrete. When 50% of the cement content was replaced by FA, the embodied CO2 emission for UHPC mixture reduced up to approximately 50%, which is comparable to the CO2 emission calculated from the conventional normal-strength concrete.

scholarly journals Compressive Strength Development of Geopolymer Mortar by Utilization Slag and Fly Ash Mixtures

2019 ◽  
Vol 9 (2) ◽  
pp. 4066-4069
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Solid Material ◽  
Solid Wastes ◽  
Strength Development ◽  
Solid Materials ◽  
Compressive Strength Development ◽  
Alkaline Activator ◽  
Materials Used ◽  
Made In

The paper displays the use of two base solid wastes materials to produce the alkaline-activated binder mortar to reduce the CO2 emission on climate change. The solid materials used in this research were slag and fly-ash to improve the compressive strength (CS) of alkaline activated mortar (AAM). The output AAM of 7 trial mixes were designed with different combinations of slag and fly ash. The mixes combinations were made in ratios of (100:0), (90:10), (80:20), (70:30), (50:50), (25:75), and (0:100), respectively. The combination of 10 M NaOH and Na2SiO3 was used as alkaline activator (AA). The wt. ratio of Na2SiO3 to NaOH = 2.5, and wt. ratio of AA to solid material = 0.52. The samples of AAM were cured at 75°C for 24 h. Among all the 7 trial mixtures, it was found that mixture with a combined ratio of slag:fly ash of 25:75 produce the maximum CS at 28 days of 88.87 MPa. Therefore, the alteration percentage of SiO2 and Al2O3 derived from fly ash in combination with CaO derived from slag contributed to significant CS improvement due to the formation of (N-A-S-H), (C-S-H) and (C-(A)-S-H) gels. The result observed of gel binder formation was confirmed by XRD and FESEM analyses.

Effects of Activators on Compressive Strength of Fly Ash-Based Geopolymers

2011 ◽  
Vol 197-198 ◽  
pp. 830-836
Author(s):  
Dong Min Wang ◽  
Pei Fu Cheng ◽  
Fan Fan ◽  
Yun Fen Hou ◽  
Liang Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Calcium Oxide ◽  
Water Glass ◽  
Solution Concentration ◽  
Solid Content ◽  
Strength Development ◽  
Obvious Effect ◽  
Compressive Strength Development ◽  
Visible Effect

The effects of different activators on compressive strength of fly ash-based geopolymers have been studied. It is discovered that, alkali solution doesn’t have obvious effect, while Na2SiO3 solution has visible effect, the strength of samples rise with the increase of Na2SiO3 solution concentration. The effect of K2SiO3 solution is more obvious than Na2SiO3 solution, the strength of samples tend to first increase and then decrease with the increase of K2SiO3 solution concentration. The K2SiO3 solution with concentration of 2 M is the best activator to prepare geopolymers, which has compressive strength of 28.8 MPa at 28 d. When water glass are used as activators, the best modulus and solid content for Na-water glass (Na2O•nSiO2) are 1.2 and 32%, respectively. On this condition the sample’s compressive strength at 28 d is 38.9 MPa. However crystal calcium oxide is harmful for the compressive strength development, which is different with the conclusion accepted abroad.

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