A study of fly ash concrete in curb and gutter construction under various laboratory and field curing regimes

1987 ◽  
Vol 14 (5) ◽  
pp. 614-620 ◽  
Author(s):  
P. M. Gifford ◽  
B. W. Langan ◽  
R. L. Day ◽  
R. C. Joshi ◽  
M. A. Ward
Keyword(s):  
Fly Ash ◽  
Field Tests ◽  
Moisture Loss ◽  
Strength Development ◽  
Freezing And Thawing ◽  
Fly Ash Concrete ◽  
Dry Out ◽  
Air Void ◽  
Curing Regimes ◽  
Scaling Resistance

It has been assumed that cement – fly ash systems only work efficiently given full curing; low temperatures and (or) moisture loss may lead to poor (slow) strenght development and concomitant reduced freezing and thawing cycling and scaling performance.The aim of the present study, undertaken by the Calgary Fly Ash Research Group, was to examine the validity of the above assumption. Strength development and freezing and thawing durability characteristics of fly ash concretes subjected to a range of environmental variables are reported; laboratory and field tests were performed. The field study involved a coring and laboratory testing programme on three ready-mixed concretes, which were used to machine place 200 m of standard curb and gutter on a major roadway. In the laboratory programme the field concretes and an additional high fly ash mixture were cast; specimens were demoulded at the age of 4 h and were either sealed at the time of casting or allowed to dry out while curing at room temperature or at 5 °C. Strength development, freezing and thawing effects, and scaling resistance as well as air-void parameters were determined; a comparison between the field and laboratory tests is presented. Also reported are measurements of internal concrete temperature and moisture loss versus time for the different curing regimes of the laboratory specimens. Key words: concrete, fly ash, strength, durability, field trial.

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

Influence de la température minimale du cycle de gel–dégel sur la détérioration du béton par écaillage en présence de sels fondants

1996 ◽  
Vol 23 (3) ◽  
pp. 595-601
Author(s):  
J. Marchand ◽  
M. Pigeon ◽  
L. Boisvert
Keyword(s):  
Test Procedure ◽  
Air Entrainment ◽  
Freezing Temperature ◽  
Freezing And Thawing ◽  
Concrete Mixtures ◽  
Conditioning Period ◽  
Binder Ratio ◽  
Freezing Cycle ◽  
Air Void ◽  
Scaling Resistance

Eight different concrete mixtures were prepared to investigate the influence of the minimum temperature of the freezing and thawing cycle on scaling deterioration due to deicer salt. In addition to the two minimum temperatures studied (−18 and −9 °C), test variables included the type of binder (with or without silica fume), the water/binder ratio (0.35 or 0.45), the characteristics of the air-void network (with or without air entrainment), and the drying temperature during the conditioning period prior to the scaling test (20, 40, or 110 °C). The scaling resistance to deicer salt of all concrete mixtures was assessed according to the prescriptions of the ASTM C672 test procedure using a 3 % NaCl solution. Test results indicate that a reduction of the minimal temperature from −9 to −18 °C significantly increases the scaling deterioration of concrete due to deicer salt. Key words: freezing cycle, scaling resistance, minimal freezing temperature, deicer salts.

Research on Durability of High Volume Fly Ash Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 380-383 ◽  
Author(s):  
Hong Zhu Quan
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Experimental Studies ◽  
High Volume ◽  
Portland Cement Concrete ◽  
Freezing And Thawing ◽  
Replacement Ratio ◽  
Rapid Reduction ◽  
Fly Ash Concrete

The paper presents the results of series of experimental studies on effects of the type and replacement ratio of fly ash to portland cement on durability of concrete. Specimens made from 28 mixes of fly ash concrete with water binder ratio of 38% to 60% and with replacement ratio of fly ash of 25% to 70% and 5 mixes of portland cement concrete with water cement ratio of 38% to 75% were tested for compressive strengths, drying shrinkage, carbonation and resistance to freezing and thawing. As a results, drying shringkage decreased with fly ash addition regardless of type and replacement ratio of fly ash. Carbonation increased with fly ash replacement ratio, and type 1 fly ash showed higher carbonation. Type 1 and tpye 2 fly ashes showed practically no change in durability factor after 300 cycles of freezing and thawing up to 55% replacement, while type 4 fly ash showed rapid reduction in durability factor up to 40% replacement ratio.

Fly-Ash Concretes of 50% of the Replacement Ratio to Reduce the Cracking in Concrete Structures

2013 ◽  
Vol 405-408 ◽  
pp. 2665-2670 ◽  
Author(s):  
Ming Jie Mao ◽  
Qiu Ning Yang ◽  
Wen Bo Zhang ◽  
Isamu Yoshitake
Keyword(s):  
Fly Ash ◽  
Concrete Structures ◽  
High Volume ◽  
Pozzolanic Reaction ◽  
Strength Development ◽  
Early Age ◽  
Replacement Ratio ◽  
Fly Ash Concrete ◽  
Massive Concrete ◽  
Normal Strength

Fly-ash concrete used in massive concrete structure has superior advantages to reduce hydration heat. On the other hand, the fly-ash concrete has negative property of low strength development at early age because pozzolanic reaction of fly-ash activates at mature age, such as after 28 days. To investigate these characteristics of fly-ash used in concrete, the present study discusses thermal cracking possibility of fly-ash concrete by using FE analysis software. The present study employs prediction formulae proposed by Zhang and Japanese design code in the simulations. The objects in this study are normal strength concrete mixed of fly-ash up to 50% of replacement ratio to cement. The comparative investigations show that temperature effect is more significant than strength development at early age. Based on the analytical study, high volume fly-ash concretes of 30-50% of the replacement ratio can be concluded as effective and useful materials to reduce the cracking possibility in massive concrete structures. Keywords-Fly-ash concrete; Early Age, Prediction Formulae for Strength; Thermal Stress Analysis

Prediction of the Strength Development of Fly Ash Concrete

2010 ◽  
Vol 150-151 ◽  
pp. 1026-1033 ◽  
Author(s):  
Ming Hui Liu ◽  
Yuan Feng Wang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Concrete Strength ◽  
Strength Development ◽  
Standard Temperature ◽  
Development Models ◽  
Fly Ash Concrete ◽  
Strength Tests ◽  
Maturity Method ◽  
Predicted Model

The effect of fly ash in improving the mechanical properties of concrete is investigated and the existing concrete strength development models are studied. Based on the chemic reactivity properties between fly ash and cement, an appropriate concrete strength model are chosen, and a new model for the fly ash strength factor combing Maturity method is built up and the factors are regressed by existing experimental datum. A total of 24 concretes, including two concretes were produced with two partial fly ash replacement ratios (23.7%, 32.7%). The cubic samples produced from ash fly concrete were demoulded after a day, and cured at standard temperature ( in GB/T 50081-2002) with 100% relative humidity until 28 days, then cured in water. The compressive strength tests were carried out on the cubic specimens at different ages. The compressive strength with time was evaluated by using the new predicted model. It was found that the calculated results by new method are fit the experimental data well.

Experiment and Micro-Mechanism Study on Mechanical Properties and Durability of High-Calcium Fly Ash Concrete

2011 ◽  
Vol 480-481 ◽  
pp. 59-65
Author(s):  
Shuang Xi Li ◽  
Tuan She Yang ◽  
Zhi Ming Wang ◽  
Quan Hu
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Frost Resistance ◽  
Strength Development ◽  
Hydration Reaction ◽  
Optimal Dosage ◽  
Fly Ash Concrete ◽  
Low Calcium ◽  
High Calcium ◽  
High Calcium Fly Ash

Low-calcium fly ash is paid much attention for its wide use in engineering, the research and application technology of it are very mature, but as to high-calcium fly ash concrete, the researches on stability, mechanical property and durability of it are very less , The existing researches are still inadequate for practice of engineering. As to this problem, using small shek kip hydropower project as example, the volume stability of high-calcium fly ash concretes with different fly ash dosages are tested, then the optimal dosage of the high-calcium fly ash is determined; based on this, the impacts of high-calcium fly ash on the performance of mechanical properties , impermeability and frost resistance of concrete are studied; Finally, macro performance is analyzed from a micro-mechanism point of view through taking the electron micrograph. As the study shows, the optimal dosage of high-calcium fly ash should be taken as 20% -25%; for the concrete with special requirements, the dosage can be relaxed to 30% when the high-calcium fly ash achieves high quality. The compressive strength of high-calcium fly ash concrete is higher than the low-calcium fly ash concrete. Strength development advantage of high-calcium fly ash concrete reflects at the early age, this advantage takes the trend of weakening as the development of age. Concrete mixed with high-calcium fly ash has good performance in impermeability. The high-calcium fly ash has high activity, the high-calcium fly ash and secondary hydration reaction products can be filled into the pore capillary and cracks of the concrete structure, improving the pore structure, thereby increasing the density of cement paste. High-calcium fly ash concrete has good performance in frost resistance. The destructive effects of freeze-thaw cycles on cement structure has connection with the microstructure of cement and impermeability , the improvement of impermeability avoids the water entering into the concrete, reduces the risk of destruction caused by frost heave.The study on micro-mechanism proves well the macro-phenomena above.

scholarly journals Influence of Concrete Sludge Addition in the Properties of Alkali-Activated and Non-Alkali-Activated Fly Ash-Based Mortars

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Fotini Kesikidou ◽  
Stavroula Konopisi ◽  
Eleftherios K. Anastasiou
Keyword(s):  
Fly Ash ◽  
Silicon Oxide ◽  
Strength Development ◽  
Alkali Activation ◽  
Early Age ◽  
Fly Ash Concrete ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Potential Synergy ◽  
Alkali Activated

This study investigated the use of concrete sludge, a by-product of the ready-mix concrete industry, in combination with high-calcium fly ash in binary cementless binders. Concrete sludge was used in substitution rates ranging from 0% to 60% in test fly ash-based mortars to determine potential synergy. The mortars were tested for fresh and hardened properties; workability, viscosity, strength development, open porosity, early-age shrinkage, and analytical tests were carried out. A mortar with 50% fly ash and 50% limestone filler as binders was used for comparison purposes. Furthermore, a series of mortars with fly ash and concrete sludge were alkali-activated in order to determine potential strength gain. In the activated mortars, two fractions of concrete sludge were used, under 75 μm and 200 μm, due to different silicon oxide contents, while one mortar was cured at 40°C to investigate the effect of heating on alkali activation. Results show that sludge contributes to the formation of C-S-H and strength development when used in combination with high-calcium fly ash even at high replacement rates. The alkali activation of fly ash-concrete sludge system contributed to early-age strength development and to early-age shrinkage reduction.

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