Compaction and unconfined compressive strength of sand modified by class F fly ash

2015 ◽  
Vol 9 (2) ◽  
pp. 261-273
Author(s):  
Ashis K. Bera ◽  
Sourav Chakraborty
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Class F Fly Ash ◽  
Class F

scholarly journals Influence of the Nature and Rate of Alkaline Activator on the Physicochemical Properties of Fly Ash-Based Geopolymers

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Marouane EL Alouani ◽  
Saliha Alehyen ◽  
Mohammed EL Achouri ◽  
Abdelowahed Hajjaji ◽  
Chouaib Ennawaoui ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Physicochemical Properties ◽  
Fire Resistance ◽  
Electrical Performance ◽  
Infrared Spectrometry ◽  
X Ray ◽  
Alkaline Activator ◽  
Class F Fly Ash ◽  
Class F

The influence of alkali cations on mix design of geopolymers is essential for their mechanical, thermal, and electrical performance. This research investigated the influence of alkali cation type on microscale characteristics and mechanical, dielectric, and thermal properties of fly ash-based geopolymer matrices. The geopolymers were elaborated via class F fly ash from the thermal plant Jorf Lasfar, El Jadida (Morocco), and several alkaline solutions. Morphological, structural, mechanical, dielectric, and thermal characteristics of materials synthesized via fly ash with different proportions of KOH and NaOH aged 28 days were evaluated. The physicochemical properties of class F fly ash-based geopolymers were assessed using X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FTIR), and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) analyses. Based on readings of the results obtained, XRD and FTIR analysis detected the creation of semicrystalline potassium/sodium aluminate-silicate hydrate (KASH/NASH) gel in the elaborated matrices after the geopolymerization reaction. The SEM analysis proved the formation of alkali alumina-silicate hydrate gel in the raw material particles after the polycondensation stage. Experimental compressive strength data indicated that the highest compressive strength (39 MPa) was produced by the alkaline activator (75% KOH/25% NaOH). The dielectric parameters values of the elaborated materials changed depending of the mass ratios KOH/NaOH. Dielectric findings demonstrated that geopolymers containing 100% NaOH have better dielectric performances. The fire resistance study revealed that the geopolymer binders induced by KOH are stable up to 600°C. Based on these results, it can be deduced that the formulated geopolymer concrete possesses good mechanical, dielectric, and fire resistance properties.

scholarly journals A Comparative Study on the Effect of Class C and Class F Fly Ashes on Geotechnical Properties of High-Plasticity Clay

CivilEng ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 1009-1018
Author(s):  
Salar Shirkhanloo ◽  
Mohammad Najafi ◽  
Vinayak Kaushal ◽  
Mehrdad Rajabi
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Geotechnical Properties ◽  
Dry Density ◽  
High Plasticity ◽  
Fly Ashes ◽  
High Plasticity Clay ◽  
Class C ◽  
Class F

Clays generally have a low strength and capacity, and additives are usually used to stabilize them. In recent years, using fly ash to stabilize soil has decreased environmental pollution while also having an economic benefit. The objective of this study is to perform a comparative investigation on the effect of class C and class F fly ashes on geotechnical properties of high-plasticity clay using the Atterberg’s limit, compaction, California Bearing Ratio (CBR), and unconfined compressive strength tests. The results showed that with an increase in the amount of fly ash, there was a decrease in the maximum dry density and an increase in the optimum moisture content. Moreover, an addition of fly ashes of up to 25% caused a reduction of the liquid limit and plasticity index, and an increase in the maximum unconfined compressive strength and CBR. Lengthening the curing time had a positive impact on the unconfined compressive strength of the soil. The soil samples with class C fly ash were seen to possess more efficient geotechnical properties as compared to class F fly ash.

Hydroceramic-Concrete Designed for a Project Material of Soil Stabilization

2012 ◽  
Vol 450-451 ◽  
pp. 756-763
Author(s):  
Ri Gao Chen ◽  
Yi Lan Chen ◽  
Xin Yue Zhao ◽  
Michael W Grutzeck
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Room Temperature ◽  
Soil Stabilization ◽  
Coagulation Time ◽  
Conventional Concrete ◽  
Good For ◽  
Class F Fly Ash ◽  
Cementing Material ◽  
Class F

As the traditional material commonly used, cement has its own limitation such as limited solidifying objects, bad stability in water, high cost and uneasy adjustment in coagulation time, not good for solidifying the waste etc.. The succeed in developing a hydroceramic-concrete for soil stabilization can take place of traditional cementing material such as conventional concrete applying and avoid the shortage of them. Here we show that a mixture of Class F fly ash, metakaolin and 8M NaOH (hydroceramic) will harden at room temperature, attaining 9.2 MPa compressive strength at 90 days, It is suggested that a hydroceramic-concrete may be used as a project material of soil stabilization as it has similar or even better compressive strength than conventional concrete.

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 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.

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