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.

scholarly journals Characterization and Comparison Research on Composite of Alluvial Clayey Soil Modified with Fine Aggregates of Construction Waste and Fly Ash

2021 ◽  
Vol 28 (1) ◽  
pp. 83-95
Author(s):  
Qu Jili ◽  
Wang Junfeng ◽  
Batugin Andrian ◽  
Zhu Hao
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Clayey Soil ◽  
Dry Density ◽  
Maximum Dry Density ◽  
Construction Waste ◽  
Comparison Research ◽  
Fine Aggregates ◽  
Optimum Water Content

Abstract Fine aggregates of construction waste and fly ash were selected as additives to modify the characteristics of Shanghai clayey soil as a composite. The laboratory tests on consistency index, maximum dry density, and unconfined compressive strength were carried out mainly for the purpose of comparing the modifying effect on the composite from fine aggregates of construction waste with that from fly ash. It is mainly concluded from test results that the liquid and plastic limit of the composites increase with the content of two additives. But their maximum dry density all decreases with the additive content. However, fine aggregates of construction waste can increase the optimum water content of the composites, while fly ash on the contrary. Finally, although the two additive all can increase the unconfined compressive strength of composites, fly ash has better effect. The current conclusions are also compared with previous studies, which indicates that the current research results are not completely the same as those from other researchers.

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.

Available Alkalis in Fly Ash

1985 ◽  
Vol 65 ◽  
Author(s):  
Chau Lee ◽  
Scott Schlorholtz ◽  
Turgut Demirel
Keyword(s):  
Fly Ash ◽  
Calcium Hydroxide ◽  
Fly Ashes ◽  
Class C ◽  
Time Required ◽  
Class F

ABSTRACTThe available alkalis of six Iowa fly ashes, four Class C and two Class F, have been studied as outlined by the procedures listed in ASTM C 311. The purposes of the study were to: (1) assess the significance of the test when it is used to analyze different fly ashes; (2) to investigate the possibility of decreasing the time required to complete the test (it currently requires 28 days for curing). When cured for 28 days at 38 C, the available alkalis were found to be about 60% and 30% of the total equivalent alkalis (equivalent alkalis = %Na20 + 0.658 × %K20) for Class C and Class F fly ashes, respectively. However, more than 85% and more than 40% of the total equivalent alkalis for the Class C and Class F fly ashes, respectively, were mobilized after 5 to 6 months of curing at 38 C. It was concluded that the available alkali test described in ASTM C 311 tends to underestimate the amount of equivalent alkalis present in Class C fly ash-calcium hydroxide mixtures after long periods of time.

scholarly journals Strength and Pore Structure Development of High-Plasticity Clay Treated with MK-Blended Cement

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Qian Guo ◽  
Mingli Wei ◽  
Haochen Xue ◽  
Changhui Gao ◽  
Guangyin Du
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Unconfined Compressive Strength ◽  
Structure Refinement ◽  
Structure Evolution ◽  
Strength Development ◽  
High Plasticity ◽  
Soil Mixture ◽  
Treated Soil ◽  
High Plasticity Clay

This paper focuses on the strength development and pore structure evolution of high-plasticity clay mixtures treated with metakaolin- (MK-) blended ordinary Portland cement (OPC). The unconfined compressive strength (fcu) of treated soil mixtures is measured to study the effect of MK replacement. The microstructural study is carried out by mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results showed that the MK replacement led to the decrease of unconfined compressive strength of OPC-treated soil mixture cured for 28 days, but the influence on 7 days strength was negligible. However, the MK addition also enhanced the unconfined compressive strength significantly. The MK addition provided more cementitious products by secondary hydration and pozzolanic reaction, which would give rise to a notable filling effect by turning the large pores (1 to 10 μm) into smaller ones (0.1 to 1 μm). However, the MK replacement led to a decrease of cementitious products due to the lack of calcium hydroxide (CH) in soil mixture, and thus the effect on pore structure refinement was reduced. Nevertheless, the presence of MK enhanced the unconfined compressive strength cured for 7 days, due to the high reactivity of MK with CH.

scholarly journals State-of-the-Art Report on Alkali Silica Reactivity Mitigation Effectiveness Using Different Types of Fly Ashes

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Enamur R. Latifee
Keyword(s):  
Fly Ash ◽  
State Of The Art ◽  
Oxide Content ◽  
Fly Ashes ◽  
Linear Effect ◽  
Alkali Silica Reactivity ◽  
Rapid Effect ◽  
Different Types ◽  
Class C ◽  
Class F

Use of fly ash by percent replacement of cement is considered as one of the most economical and effective methods for mitigating alkali-silica reaction (ASR) related distress in the concrete. However, fly ash has been proven to be somewhat variable in its effectiveness in inhibiting alkali-silica reactivity, principally because its composition depends on the coal properties from which it is derived. Typically class C fly ashes are not as efficient as class F ashes due to their higher calcium oxide content. Nevertheless, it is important to find out whether the lime content in the fly ash has linear effect on ASR distress mitigation and if the dosage of fly ash is more influential than type of fly ash. This research conducted extensive testing with nine different types of fly ashes with three in each category of fly ashes, class C, class F, and intermediate class. The results indicated that the effect of increased dosage of fly ash on ASR mitigation is linear for both low-lime and high-lime fly ashes and the dosage effect is more significant with rapid effect with high-lime fly ashes compared to low-lime fly ashes.

scholarly journals Effect of various parameters on the workability and strength properties of geopolymer concrete

2021 ◽  
Vol 309 ◽  
pp. 01102
Author(s):  
Nutakki Sai Ketana ◽  
V Srinivasa Reddy ◽  
M V Seshagiri Rao ◽  
S Shrihari
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Strength Properties ◽  
Ash Content ◽  
Geopolymer Concrete ◽  
Alkaline Activator ◽  
Class C ◽  
Class F

In the present study, effect of various molarities of NaOH, various fly ash content and alkaline activator solution (AAS) / fly ash(FA) ratios on the workability of geopolymer concrete(GPC) are studied along with the effect of use of Na2SiO3/NaOH and K2SiO3/KOH as alkaline activator solutions and various fly ash contents on the compressive strength of geopolymer concrete mixes. Observations shows that both Na2SiO3/NaOH and K2SiO3/KOH gives better performance for different molar, AAS/FA and oxide ratios. Class C GPC has better performance than Class F GPC. It was found that the increase in molarity decreases workability of geopolymer concrete. Also, the workability increases with increase in fly ash (FA) content and AAS/FA ratio in geopolymer concrete. Compressive and split tensile strengths decrease with increase in fly ash content.

Phosphogypsum as a Component of Flowable Fill

1996 ◽  
Vol 1546 (1) ◽  
pp. 79-87
Author(s):  
S. Gandham ◽  
R. K. Seals ◽  
Paul T. Foxworthy
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Preliminary Test ◽  
Flowable Fill ◽  
Final Design ◽  
Potential Component ◽  
Class C ◽  
The Individual ◽  
Minimal Environmental Impact

Phosphogypsum (PG) is a by-product of the production of phosphoric acid, a key ingredient in the manufacture of fertilizers. Large amounts of PG have been stockpiled in Florida, Louisiana, and Texas, as well as other parts of the world. The means of using and disposing of this by-product with minimal environmental impact have been developed in research spanning almost 20 years. A study was conducted to investigate PG as a potential component of flowable fill materials along with Class C fly ash. Both Class F and Class C fly ashes have been used successfully to provide flowability and strength characteristics to flowable fill. A number of mix proportions of PG and fly ash were tested for flowability, time of setting, and unconfined compressive strength in a preliminary test series. Using the results of these preliminary tests, three final design mixtures were developed. These mixtures were then subjected to different physical and engineering property tests, including flowability, time of setting, unconfined compressive strength, flexural strength, dimensional stability, and permeability. Tests were also conducted to evaluate the environmental effects of the individual mixtures. These tests included the toxicity characteristic leaching procedure and radon emission testing. The results of this study indicated that PG can be used successfully as a component of flowable fill.

scholarly journals Black Cotton Soil Stabilization by Using Fly Ash - Kota Stone Slurry Mix

2021 ◽  
Vol 9 (11) ◽  
pp. 1699-1703
Author(s):  
Phoolwanti Nanda
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Soil Stabilization ◽  
Atterberg Limits ◽  
Black Cotton Soil ◽  
Strength Development ◽  
Dry Density ◽  
X Ray ◽  
Soil Stabilizer

Abstract: The usage of waste material for stabilizing black cotton soil has been a sustainable interest. Kota stone slurry is a waste from kota stone and fly ash is a waste from industries containing high amount of sodium and magnesium, was used as a soil stabilizer for blac cotton soil improvement in this study. This research investigated the effects of sizes and percentages of kota stone slurry mix and fly ash on the physical and strength properties, which included particle size distribution, Atterberg limits, compaction, and unconfined compressive strength (UCS) of blac cotton soil. Micro structural characterization, including the scanning electron microscopic, energy dispersive X-ray spectroscopy, and X-ray diffraction was conducted on both untreated and treated black cotton soil samples to examine the mechanism of strength development. The addition of kota stone slurry and fly ash reduced the water holding capacity, which then caused the reduction in soil plasticity (from 18 to 11%) and optimum water content (from 20 to 16%) along with the increase in peak dry density (from 1.66 to 1.74 Mg/m3). The strength of black cotton soil may increased from 50 to almost 220 kPa. The optimum kota stone slurry and fly ash contents, providing the highest UCS, were at 20 and 30% for 0.063 mm kota stone slurry and fly ash and 0.15 mm kota stone slurry and fly ash, respectively. The UCS improvement of treated marine clay is attributed to the formation of cementation compounds, mainly aluminum magnesium silicate hydrate (A–M–S–H). The outcome of this research will allow the use of RBT as a low-carbon soil stabilizer across civil engineering applications. Keywords: Stablization, Fly ash, kota stone slurry, Atterberg limits, Compaction, and unconfined compressive strength

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