scholarly journals EFFECT OF FLY-ASH ON THE STRENGTH DEVELOPMENT OF COASTAL SOILS-A CASE STUDY FOR THE SOUTHERN COASTAL ZONE OF BANGLADESH

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
O.C. Debanath ◽  
M.A Rahman ◽  
S. A. Chowdhury ◽  
R.U. Ahmed ◽  
S.N. Hassan ◽  
...  
Keyword(s):  
Fly Ash ◽  
Threshold Value ◽  
Ash Content ◽  
Performance Criteria ◽  
Strength Development ◽  
Deep Foundation ◽  
Environmental Threat ◽  
Residential Demand ◽  
Ground Stability

The rapid demand for urbanization expands the requirements of infrastructures and owing to the scarcity of available firm land; people are now built structures on soft soils. However, the application of a deep foundation for a low-rise structure may not be economically feasible for developing countries. The economic, as well as safe foundation, can be ensured by adopting traditional ground stability approaches. However, replacement of the industrial by-product, which possess minimum environmental threat may be a plausible option for ground stability. Therefore, an attempt is taken in this research to study the improvement of soft coastal soil by replacing with eco-friendly fly ash. The eastern bank of the river Karnaphuli, which has increasing industrial and residential demand is taken as a case study in this research. A series of experimental set-ups have been conducted to evaluate the strength development with different fly ash contents. It is found that the strength of fly ash treated soils increases with fly ash content up to a threshold value, and beyond that, the strength decreases. In addition, compaction and plasticity characteristics are also investigated through experimental observations and show better performance criteria with increasing fly ash contents. In a nutshell, this approach of replacing fly ash is suitable for coastal soil, and the experimental investigation reveals that an optimum 20% of fly ash content is justified.

scholarly journals Study on Rheological and Mechanical Properties of Aeolian Sand-Fly Ash-Based Filling Slurry

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1266
Author(s):  
Xiaoping Shao ◽  
Long Wang ◽  
Xin Li ◽  
Zhiyu Fang ◽  
Bingchao Zhao ◽  
...  
Keyword(s):  
Fly Ash ◽  
Rheological Properties ◽  
Economic Benefits ◽  
Ash Content ◽  
Sand Fly ◽  
Strength Development ◽  
Hydration Reaction ◽  
Aeolian Sand ◽  
Delayed Reaction ◽  
Uniaxial Test

Backfill mining is the most environmentally friendly mining method at present, which can effectively control the surface subsidence, improve the recovery rate, and has good social and economic benefits. The purpose of this study is to solve the environmental problems caused by solid waste, combined with the rich geographical advantages of aeolian sand in the Yushenfu mining area of China. The rheological properties of the aeolian sand-fly ash-based filling slurry with different fly ash content are studied by experiments, and the strength development law of the filling body under different age and fly ash content are studied from the macroscopic and microscopic points of view. The rheological experiments showed that the increase of the amount of fly ash has a significant effect on the thixotropy, plastic viscosity, and yield stress of the filling slurry. Additionally, rheological properties of aeolian sand-fly ash-based filling slurry conform to the Bingham model. With the increase of the amount of fly ash, the performance of the filling slurry has been significantly improved. Uniaxial test and scanning electron microscope observation showed that the influence of fly ash on the strength of the filling body was mainly reflected in the late stage of maintenance, but was not obvious in the middle stage. Fly ash particles mainly bear the role of “water reduction” and a physical filling effect, which makes the filling slurry thicker and the internal structure more closely spaced. The volcanic ash reaction of fly ash is lagging behind the hydration reaction of cement; the secondary product of the delayed reaction is filled in the pores of cement hydrates, which can greatly reduce the porosity of the backfill body and increase the later strength of the backfill body. It provides a guarantee for the safe replacement of coal pillars in the working face.

Effect of Thermal Environment at Early Age on Hydration Phases Composition and Strength Development of Concrete Containing Fly Ash

2010 ◽  
Vol 168-170 ◽  
pp. 582-588
Author(s):  
Feng Chen Zhang ◽  
De Jian Shen ◽  
Ji Kai Zhou ◽  
Zhong Hua Li
Keyword(s):  
Tensile Strength ◽  
Fly Ash ◽  
Thermal Environment ◽  
Ash Content ◽  
Splitting Tensile Strength ◽  
Curing Temperature ◽  
Strength Development ◽  
Early Age ◽  
Mass Concrete ◽  
Hydration Phases

Cement hydration at early age is sometimes in a certain thermal environment probably caused by hydration heat of mass concrete as well as cement productions curing at high temperature. And phases composition and strength development in thermal environment are commonly different from those in normal curing conditions. Phases composition and strength development of concrete containing different fly ash content curing in different thermal environment are studied in this paper. Experimental results show that compressive strengths of concrete with 0.3 water to binder ratio increase with the increase of curing temperature. Splitting tensile strength of concrete not containing any fly ash curing at about 50 is the highest among those curing at temperature between 40 and 80 . For concrete with different fly ash content, splitting tensile strengths increase approximately with the increse of curing temperature. Dehydration of ettringite and formation of monosulfate solid solution and AFm at higher temperature perhaps relate to the development of concrete splitting tensile strength along with different curing temperature. Adding fly ash to binder, curing temperature at which hydration phases change occurs is raised, which helps to explain that splitting tensile strengths of concrete with different fly ash content decrease little with the increase of curing temperature between 60 and 80 .

scholarly journals Study on the Heat of Hydration and Strength Development of Cast-In-Situ Foamed Concrete

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Wenhui Zhao ◽  
Qian Su ◽  
Feng Han ◽  
Wubin Wang
Keyword(s):  
Fly Ash ◽  
Ash Content ◽  
Heat Of Hydration ◽  
Maximum Temperature ◽  
Strength Development ◽  
Maximum Temperature Difference ◽  
Curing Conditions ◽  
Temperature Change Rate ◽  
Foamed Concrete

This study aims to investigate the relationship between the heat of hydration and the strength development of cast-in-situ foamed concrete. First, indoor model tests are conducted to determine the effects of the casting density and the fly ash content on the hydration heat of foamed concrete in semiadiabatic conditions. Second, compression tests are carried out to evaluate the development of the compressive strength with the curing time under standard curing conditions and temperature matched curing conditions. Third, the hydration heat development of the foamed concrete is tested in four projects. The results showed that the peak temperature, the maximum temperature change rate, and the maximum temperature difference increased with the increase in the casting density at different positions in the foamed concrete. For the same casting density of the foamed concrete, the peak temperature, the maximum temperature change rate, and the maximum temperature difference decreased with the increase in the fly ash content. For the foamed concrete without the admixture, the early strength was significantly higher under temperature matched curing conditions than under standard curing conditions, but the temperature matched curing conditions had a clear inhibitory effect on the strength of the foamed concrete. The strengths during the early stage and the later stage were both improved under temperature matched curing conditions after adding the fly ash, and the greater the fly ash content, the larger the effect. The maximum temperature increments were higher in the indoor model test than in the field tests for the same casting density. Reasonable cooling measures and the addition of fly ash decreased the maximum temperature increments and increased the corresponding casting times.

Strength development of inadequately cured high fly ash content and structural concretes

1986 ◽  
Vol 16 (3) ◽  
pp. 363-372 ◽  
Author(s):  
M.N. Haque ◽  
M.K. Goplan ◽  
R.C. Joshi ◽  
M.A. Ward
Keyword(s):  
Fly Ash ◽  
Ash Content ◽  
Strength Development

scholarly journals Effect of molarity of sodium hydroxide and molar ratio of alkaline activator solution on the strength development of geopolymer concrete

2021 ◽  
Vol 309 ◽  
pp. 01058
Author(s):  
V Srinivasa Reddy ◽  
Karnati Vamsi Krishna ◽  
M V Seshagiri Rao ◽  
S Shrihari
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Ash Content ◽  
Mix Design ◽  
Molar Ratio ◽  
Strength Development ◽  
Geopolymer Concrete ◽  
Synergic Effect ◽  
Alkaline Activator

In the current study, effect of SiO2/Na2O ratio in Sodium silicate (Na2SiO3) solution, Na2SiO3/NaOH ratio and molarity of NaOH on the compressive strength of geopolymer concrete. A geopolymer mix design is formulated with various mixes are casted with alkali activator solution (AAS) / fly ash (FA) =0.5 and constant fly ash content. The molar ratio of SiO2/Na2O in Na2SiO3 solution is altered from 1.50 to 3.00 for different ratios of Na2SiO3/NaOH (2.0, 2.5 and 3.0) and also for various molarities of NaOH (8M,10M,12M,14M,16M and 18M) are studied for their synergic effect on the compressive strength of geopolymer concrete. Results highlighted that the 16M NaOH yields high compressive strength when SiO2/Na2O in Na2SiO3 solution is around 2.00 to 2.40 and Na2SiO3/NaOH=2.5.

A novel method for the determination of linting propensity of paper

TAPPI Journal ◽  
2012 ◽  
Vol 11 (10) ◽  
pp. 9-17
Author(s):  
ALESSANDRA GERLI ◽  
LEENDERT C. EIGENBROOD
Keyword(s):  
Ash Content ◽  
The Novel ◽  
Offset Printing ◽  
Excellent Correlation ◽  
End Conditions ◽  
Bottom Side ◽  
Novel Method ◽  
Total Fraction

A novel method was developed for the determination of linting propensity of paper based on printing with an IGT printability tester and image analysis of the printed strips. On average, the total fraction of the surface removed as lint during printing is 0.01%-0.1%. This value is lower than those reported in most laboratory printing tests, and more representative of commercial offset printing applications. Newsprint paper produced on a roll/blade former machine was evaluated for linting propensity using the novel method and also printed on a commercial coldset offset press. Laboratory and commercial printing results matched well, showing that linting was higher for the bottom side of paper than for the top side, and that linting could be reduced on both sides by application of a dry-strength additive. In a second case study, varying wet-end conditions were used on a hybrid former machine to produce four paper reels, with the goal of matching the low linting propensity of the paper produced on a machine with gap former configuration. We found that the retention program, by improving fiber fines retention, substantially reduced the linting propensity of the paper produced on the hybrid former machine. The papers were also printed on a commercial coldset offset press. An excellent correlation was found between the total lint area removed from the bottom side of the paper samples during laboratory printing and lint collected on halftone areas of the first upper printing unit after 45000 copies. Finally, the method was applied to determine the linting propensity of highly filled supercalendered paper produced on a hybrid former machine. In this case, the linting propensity of the bottom side of paper correlated with its ash content.

Study on Strength Development of High Strength Concrete Containing Alccofine and Fly-Ash

2012 ◽  
Vol 2 (3) ◽  
pp. 102-104 ◽  
Author(s):  
Suthar Sunil B ◽  
◽  
Dr. (Smt.) B. K. Shah Dr. (Smt.) B. K. Shah
Keyword(s):  
Fly Ash ◽  
High Strength Concrete ◽  
High Strength ◽  
Strength Development ◽  
Strength Concrete

The Influence of the Ash Addition from Thermal Power Plant on the Mechanical, Thermal and Dielectric Characteristics of Mortars

2018 ◽  
Vol 69 (8) ◽  
pp. 2040-2044
Author(s):  
Georgeta Velciu ◽  
Virgil Marinescu ◽  
Adriana Moanta ◽  
Ladislau Radermacher ◽  
Adriana Mariana Bors
Keyword(s):  
Thermal Conductivity ◽  
Fly Ash ◽  
Power Plant ◽  
Cement Mortar ◽  
Thermal Power ◽  
Total Content ◽  
Ash Content ◽  
Dielectric Losses ◽  
Dielectric Characteristics ◽  
Cement Mortars

The influence of fly ash adittion (90 % fraction [ 100 mm) on the cement mortar characteristics was studied. The XRD, XRF, SEM and FTIR determinations indicated that fly ash used has a hollow microstructure of microsphere and cenosphere whose total content in SiO2, Al2O3 and Fe2O3 is 88.63 % and that of CaO and MgO of 8.55 %. The mechanical, thermal and dielectric determinations made on mortar samples with content of fly ash in the 0-40 % range have highlighted fact that the mechanical strength of cement mortars is maximal at 20 %, the increase in fly ash content leads to a decrease in relative density and thermal conductivity as well as and to increased dielectric losses tgd.

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