scholarly journals Curing Time and Temperature Effect on the Resistance to Wet-Dry Cycles of Fly Ash Added Pumice Based Geopolymer

2020 ◽  
Vol 1 (2) ◽  
pp. 19-25
Author(s):  
Engin Yener
Keyword(s):  
Fly Ash ◽  
Structural Changes ◽  
Raw Material ◽  
Liquid Sodium ◽  
Ftir Analysis ◽  
Curing Time ◽  
Reaction Products ◽  
Curing Conditions ◽  
Curing Regimes ◽  
Soluble Carbonate

The effects of curing regimes varying combinations of temperatures (ambient, 60 °C, 75 °C, 90 °C, 105 °C) and durations (4h, 8h, 24h, 48h, 96h, 168h) on the performance of fly ash added pumice based geopolymer pastes were investigated in this study. The precursor raw material consists of 70% pumice dust and 30% fly ash (FA). Alkali activator was prepared by mixing 10M sodium hydroxide (SH) solution and liquid sodium silicate (SS) in the ratio of SS/SH=2. Activator to precursor ratio was fixed as 0.45. Compressive strengths were determined at the 28 days of age as well as after exposure 5 wetting-drying (w-d) cycles. In addition, Fourier Transform Infrared Spectroscopy (FTIR) tests were conducted on the fresh and hardened geopolymer pastes in order to examine the effect of curing conditions to the structural changes and reaction products. The results show that in the case of 60 °C and 75 °C, the strength of the w-d conditioned samples increased steadily as the curing time increased. However, longer curing times of more than 24 hours are not beneficial for high curing temperatures (90 °C and 105 °C). The maximum strength after the w-d cycles is obtained for the curing conditions of 60°C/168h (74.4 MPa). Also, FTIR analysis confirmed that the hardened geopolymer paste transformed into a more coordinated structure and soluble carbonate compounds were reduced at 60 °C and 168 hours curing condition.

The Effect of Curing Time on the Properties of Fly Ash-Based Geopolymer Bricks

2012 ◽  
Vol 626 ◽  
pp. 937-941 ◽  
Author(s):  
W.I. Wan Mastura ◽  
H. Kamarudin ◽  
I. Khairul Nizar ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
H. Mohammed
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Water Absorption ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Experimental Work ◽  
Base Material ◽  
Curing Time ◽  
Curing Conditions ◽  
Alkaline Activator

This paper reports the results of an experimental work conducted to investigate the effect of curing conditions on the properties of fly ash-based geopolymer bricks prepared by using fly ash as base material and combination of sodium hydroxide and sodium silicate as alkaline activator. The experiments were conducted by varying the curing time in the range of 1-24 hours respectively. The specimens cured for a period of 24 hours have presented the highest compressive strength for all ratio of fly ash to sand. For increasing curing time improve compressive strength and decreasing water absorption.

scholarly journals Compressive Strength Performance of Alkali Activated Concretes under Different Curing Conditions

2021 ◽  
Author(s):  
Anıl Niş ◽  
İlhan Altındal
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Strength Performance ◽  
Curing Conditions ◽  
Standardization Process ◽  
Water Curing ◽  
Curing Regimes ◽  
Alkali Activated Concrete ◽  
Alkali Activated ◽  
Ambient Curing

This study investigated the influence of different curing conditions on the compressive strength (CS) of the different alkali activated concrete (AAC) specimens at the ages of 2, 28, and 90 days for the structural utilization and standardization process of AAC instead of OPC concrete. For this aim, 100% slag (S100), 75% slag and 25% fly ash (S75FA25), and 50% slag and 50% fly ash based (S50FA50) AAC specimens were produced. Based on the oven-curing (O), water-curing (W), and ambient-curing (A) methods, the influence of 2O for 2 days, 26A2O, 2O26A, 28A, 28W, 26W2O, and 2O26W for 28 days, and 88A2O, 2O88A, 90A, 88W2O, 2O88W, 90W for 90 days on the CS of the AAC were examined in details. In addition, the influence of delayed oven-curing conditions on CS development was also investigated. The results indicated that curing conditions significantly affected on the CS and the water-curing condition could provide a better CS for those of AAC at 90 days. Although, the oven-curing enhanced CS of the S100 specimens at initial ages (first oven-curing applied), delayed oven-curing (oven-curing applied later) was found significant for S75FA25 and S50FA50 specimens. The delayed oven-curing affected more on the CS of the AAC when fly ash content increased. The most of AAC specimens with oven-curing had significantly enhanced the CS at 28 days, but S50FA50 at the age of 90 days decreased. Different curing regimes were proposed for the superior compressive strength values for each AAC specimens at the ages of 28 and 90 days.

scholarly journals Effect of Curing Conditions on Microstructure and Pore-Structure of Brown Coal Fly Ash Geopolymers

2019 ◽  
Vol 9 (15) ◽  
pp. 3138 ◽  
Author(s):  
Chamila Gunasekara ◽  
Rahmat Dirgantara ◽  
David W. Law ◽  
Sujeeva Setunge
Keyword(s):  
Fly Ash ◽  
Temperature Profile ◽  
Brown Coal ◽  
Structural Integrity ◽  
Coal Fly Ash ◽  
Curing Time ◽  
Curing Conditions ◽  
Heat Curing ◽  
Time Required ◽  
Class F Fly Ash

This study reports the effect of heat curing at 120 °C on the geopolymeric reaction and strength evolution in brown coal fly ash based geopolymer mortar and concrete. Moreover, an examination of this temperature profile of large size geopolymer concrete specimens is also reported. The specimen temperature and size were observed to influence the conversion from the glassy (amorphous) phases to the crystalline phases and the microstructure development of the geopolymer. The temperature profile could be divided into three principal stages which correlated well with the proposed reaction mechanism for class F fly ash geopolymers. The geopolymerisation progressed more rapidly for the mortar specimens than the concrete specimens with 12 to 14 h providing an optimum curing time for the 50 mm mortar cubes and 24 h being the optimum time for the 100 mm concrete cubes. The 50 mm and 100 mm concrete specimens’ compressive strengths in excess of 30 MPa could be obtained at 7 days. The structural integrity was not achieved at the center of 200 mm and 300 mm concrete specimens following 24 h curing at 120 °C. Hence, the optimal curing time required to achieve the best compressive strength for brown coal geopolymer was identified as being dependent on the specimen size.

scholarly journals Role of Curing Conditions and Precursor on the Microstructure and Phase Chemistry of Alkali-Activated Fly Ash and Slag Pastes

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1918
Author(s):  
Marija Nedeljković ◽  
Bahman Ghiassi ◽  
Guang Ye
Keyword(s):  
Fly Ash ◽  
Analytical Techniques ◽  
Limited Information ◽  
Reaction Products ◽  
Curing Conditions ◽  
X Ray ◽  
Phase Recognition ◽  
Phase Chemistry ◽  
Alkali Activated

Understanding the role of curing conditions on the microstructure and phase chemistry of alkali-activated materials (AAMs) is essential for the evaluation of the long-term performance as well as the optimization of the processing methods for achieving more durable AAMs-based concretes. However, this information cannot be obtained with the common material characterization techniques as they often deliver limited information on the chemical domains and proportions of reaction products. This paper presents the use of PhAse Recognition and Characterization (PARC) software to overcome this obstacle for the first time. A single precursor (ground granulated blast-furnace slag (GBFS)) and a binary precursor (50% GBFS–50% fly ash) alkali-activated paste are investigated. The pastes are prepared and then cured in sealed and unsealed conditions for up to one year. The development of the microstructure and phase chemistry are investigated with PARC, and the obtained results are compared with independent bulk analytical techniques X-ray Powder Fluorescence and X-ray Powder Diffraction. PARC allowed the determination of the type of reaction products and GBFS and FA’s spatial distribution and degree of reaction at different curing ages and conditions. The results showed that the pastes react at different rates with the dominant reaction products of Mg-rich gel around GBFS particles, i.e., Ca-Mg-Na-Al-Si, and with Ca-Na-Al-Si gel, in the bulk paste. The microstructure evolution was significantly affected in the unsealed curing conditions due to the Na+ loss. The effect of the curing conditions was more pronounced in the binary system.

The Influence of Curing Conditions on the Physical and Mechanical Properties of Magnesia Phosphate Cements

2008 ◽  
Vol 59 (2) ◽  
pp. 135-139 ◽  
Author(s):  
Jenica Paceagiu ◽  
Maria Georgescu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Variable Temperature ◽  
Physical And Mechanical Properties ◽  
Reaction Products ◽  
Phosphate Binding ◽  
Curing Conditions ◽  
Weight Variation ◽  
Chemical Solutions

The paper brings information on the influence of curing conditions such as humidity, variable temperature and chemical solutions, on the compressive strength and weight variation of the magnesia phosphate binding materials, obtained from magnesite, mono-ammonia phosphate, borax and sand having a granulation ranging between 0.1-1 mm, with or without fly ash addition. The XRD and SEM�EDX analysis were made for obtaining information concerning the reaction products formed in phosphate magnesia binding materials cured in conditions of variable humidity.

scholarly journals Optimization of Alkaline Activator Mixing and Curing Conditions for A fly Ash-Based Geopolymer Paste System

2015 ◽  
Vol 9 (12) ◽  
pp. 61 ◽  
Author(s):  
Omar A. Abdulkareem ◽  
Mahyuddin Ramli
Keyword(s):  
Fly Ash ◽  
High Strength ◽  
Liquid Sodium ◽  
Strength Development ◽  
Curing Conditions ◽  
Microstructure Characteristics ◽  
Naoh Solution ◽  
Alkaline Activator ◽  
Curing Regime ◽  
Optimal Strength

<p class="zhengwen"><span lang="EN-GB">This article reports the strength development and microstructure characteristics of a fly ash (FA) geopolymer system prepared with an alkaline activator consisting of sodium hydroxide (NaOH) solution and liquid sodium silicate (Na<sub>2</sub>SiO<sub>3</sub>). The effect of Na<sub>2</sub>SiO<sub>3</sub>/NaOH mass mixing ratio on the compressive strength and microstructure characteristics of hardened FA geopolymers at different ages was investigated. The influence of different curing conditions on the strength development of the FA geopolymer was also explored. The experimental results revealed that the alkaline activator prepared with Na<sub>2</sub>SiO<sub>3</sub>/NaOH ratio of 1.00 provides sufficient alkalinity to promote the geopolymerization reaction and development of high-strength FA geopolymer material. The </span><span lang="EN-GB">scanning electron microscopy (SEM) results showed that the dissolution rates of the FA extremely affected by the content of NaOH solution in the liquid activator. </span><span lang="EN-GB">Also, the most effective curing regime was 70 °C for 24 h to produce geopolymers with optimal strength at different aging periods. </span></p>

Effect of Curing Time on the Performance of Fly Ash Geopolymer-Stabilized RAP Bases

2021 ◽  
Vol 33 (3) ◽  
pp. 04021001
Author(s):  
Maheshbabu Jallu ◽  
Sireesh Saride ◽  
Arul Arulrajah ◽  
Subrahmanyam Challapalli ◽  
Robert Evans
Keyword(s):  
Fly Ash ◽  
Curing Time

FLY ASH FROM THERMAL POWER PLANT, RAW MATERIAL FOR GLASS-CERAMIC

2013 ◽  
Vol 12 (2) ◽  
pp. 337-342 ◽  
Author(s):  
Firuta Goga ◽  
Roxana Dudric ◽  
Calin Cormos ◽  
Florica Imre ◽  
Liliana Bizo ◽  
...  
Keyword(s):  
Fly Ash ◽  
Power Plant ◽  
Glass Ceramic ◽  
Thermal Power Plant ◽  
Thermal Power ◽  
Raw Material ◽  
Plant Raw Material

Pyrolysis of unsubstituted bicyclic hydrocarbons and gas oil

1982 ◽  
Vol 47 (7) ◽  
pp. 1838-1847 ◽  
Author(s):  
Martin Bajus ◽  
Jozef Baxa
Keyword(s):  
Stainless Steel ◽  
Elemental Sulphur ◽  
Raw Material ◽  
Gas Oil ◽  
Mass Ratio ◽  
Reaction Products ◽  
Pyrolysis Products ◽  
Reactor Material ◽  
Tubular Reactors ◽  
Stainless Steel Reactor

Pyrolysis of tetraline, decaline, 1,1'-bicyclohexane, cyclohexylbenzene and gas oil was studied in stainless steel and quartz flow tubular reactors at 780 and 800 °C, residence time 0.08 to 0.5 s and at the mass ratio of steam to the raw material changing from 0.5 to 1.5. The effect of reaction temperature, the mass ratio of steam to the raw material, reactor material and of the added elemental sulphur on the yields of individual reaction products is reported. Of bicyclic hydrocarbons, condensed hydrocarbons are more stable than those with noncondensed rings, cyclanoaromates being more stable than bicyclanes. Pyrolysis of gas oil in the stainless steel reactor yields greater amounts of ethylene, propylene, butadiene and smaller amounts of methane and ethane, compared to the pyrolysis carried out under identical conditions in the quartz reactor. Elemental sulphur increases the conversion of gas oil into gaseous pyrolysis products.

scholarly journals Study of the Physical Behavior of a New Composite Material Based on Fly Ash from the Combustion of Coal in an Ultra-Supercritical Thermal Power Plant

2021 ◽  
Vol 5 (6) ◽  
pp. 151
Author(s):  
Mustapha El Kanzaoui ◽  
Chouaib Ennawaoui ◽  
Saleh Eladaoui ◽  
Abdelowahed Hajjaji ◽  
Abdellah Guenbour ◽  
...  
Keyword(s):  
Composite Material ◽  
Fly Ash ◽  
Power Plant ◽  
High Performance ◽  
Thermal Power ◽  
Recovery Process ◽  
Industrial Wastes ◽  
Raw Material ◽  
Polymerization Reaction ◽  
High Performance Composite

Given the amount of industrial waste produced and collected in the world today, a recycling and recovery process is needed. The study carried out on this subject focuses on the valorization of one of these industrial wastes, namely the fly ash produced by an ultra-supercritical coal power plant. This paper describes the use and recovery of fly ash as a high percentage reinforcement for the development of a new high-performance composite material for use in various fields. The raw material, fly ash, comes from the staged combustion of coal, which occurs in the furnace of an ultra-supercritical boiler of a coal-fired power plant. Mechanical compression, thermal conductivity, and erosion tests are used to study the mechanical, thermal, and erosion behavior of this new composite material. The mineralogical and textural analyses of samples were characterized using Scanning Electron Microscopy (SEM). SEM confirmed the formation of a new composite by a polymerization reaction. The results obtained are very remarkable, with a high Young’s modulus and a criterion of insulation, which approves the presence of a potential to be exploited in the different fields of materials. In conclusion, the composite material presented in this study has great potential for building material and could represent interesting candidates for the smart city.

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