Carbonation of fly ash concrete: laboratory and field data

2010 ◽  
Vol 37 (12) ◽  
pp. 1535-1549 ◽  
Author(s):  
N. Bouzoubaâ ◽  
A. Bilodeau ◽  
B. Tamtsia ◽  
S. Foo
Keyword(s):  
Fly Ash ◽  
Cementitious Materials ◽  
Natural Environments ◽  
Type I ◽  
Accelerated Carbonation ◽  
Fly Ash Concrete ◽  
Concrete Mixtures ◽  
Carbonation Resistance ◽  
American Society ◽  
Indoor And Outdoor

The present study consists of investigating the carbonation resistance of two series of concrete mixtures designed for three classes of concrete (25, 35, and 45 MPa compressive strength at 28 d) and using American Society for Testing and Materials (ASTM) type I Portland cement and two commercially used fly ashes meeting the ASTM standards at the level of 20%, 35%, and 50% of the total weight of cementitious materials. The carbonation resistance was determined on samples moist cured for 3, 7, and 10 d and exposed to a CO2-enriched environment (3% CO2 at 23 °C and 65% relative humidity) for 140 d to accelerate the carbonation; it was also determined on samples moist cured for 7 d and exposed to an indoor and outdoor natural environments for 4 years. A mathematical model allowing the prediction of the depth of accelerated carbonation of fly ash concrete mixtures is presented.

Studies about the Initial Curing Conditions on the Carbonation Resistance of Fly-Ash Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 920-924 ◽  
Author(s):  
En Li Lu ◽  
Guo Li ◽  
Ying Shu Yuan ◽  
Ou Geng ◽  
Jian Min Du
Keyword(s):  
Fly Ash ◽  
Curing Temperature ◽  
Accelerated Carbonation ◽  
Initial Water ◽  
Curing Conditions ◽  
Fly Ash Concrete ◽  
Concrete Carbonation ◽  
Carbonation Resistance ◽  
The Difference ◽  
C 30

Studies about the resistance of carbonation capability of fly-ash (FA) concrete at different initial curing regimes and exposure time through accelerated carbonation experiments were made. Firstly, 30% replacement ratio fly-ash concrete specimens were fabricated and cured in 20°C, 30°C and 40°C water for 3d, 7d, 14d and 28d respectively, and cured in a standard air environment (20±2°C, relative humidity ≥95% ) for 28d. As a comparison, ordinary Portland concrete (OPC) specimens were also made and cured in 30°C water for 7d, and standard curing for 28d. After the initial curing, all the specimens were taken out and placed indoor natural environment. When specimen age reach 30d, 60d and 120d, 2 weeks accelerated carbonation experiments were made and concrete carbonation depth were measured. In addition to this, hydration degrees of fly ash at different initial curing conditions were measured using the selective dissolve method. Results show that the initial curing conditions play an important role in the carbonation resistance of FA concrete. Initial water curing is beneficial to the development of carbonation resistance of FA and OPC concrete. Prolonging initial curing time and increasing curing temperature is beneficial for the carbonation resistance of FA concrete. For the same curing conditions, carbonation rate of FA concrete is usually higher than OPC concrete, but with the increase of initial curing temperature, the difference can be reduced.

Multiscale Model of Influence of Heat Curing on Fly-Ash Concrete Mixtures

2014 ◽  
Vol 1054 ◽  
pp. 162-167
Author(s):  
Tomáš Váchal ◽  
Rostislav Šulc ◽  
Pavel Svoboda
Keyword(s):  
Fly Ash ◽  
Mechanical Characteristics ◽  
Multiscale Model ◽  
Heat Energy ◽  
Correct Treatment ◽  
Fly Ash Concrete ◽  
Concrete Mixtures ◽  
Heat Curing ◽  
Time Period ◽  
Quantity Of Heat

This paper describes influence of time and temperature of heat curing on progress of mechanical characteristics of concrete mixtures based on alkali activated fly-ash (POPbeton). One of the major impacts for the correct treatment of alkaline activation is the quantity of heat energy in a given time period which is supplied during activation. The paper describes the dependence of progress of compressive strength of POPbeton on the time and temperature of heat curing. It was assembled a predictive model which describes the dependence of the supplied heat energy over time on the resulting properties of POPbeton. The result is a tool that can predict the resulting values of mechanical characteristics of test samples of POPbeton.

scholarly journals Experimental Study on Durability Improvement of Fly Ash Concrete with Durability Improving Admixture

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Hong-zhu Quan ◽  
Hideo Kasami
Keyword(s):  
Fly Ash ◽  
Experimental Studies ◽  
Drying Shrinkage ◽  
Replacement Ratio ◽  
Fly Ash Concrete ◽  
Air Content ◽  
Carbonation Resistance ◽  
Binder Ratio ◽  
Water Binder Ratio

In order to improve the durability of fly ash concrete, a series of experimental studies are carried out, where durability improving admixture is used to reduce drying shrinkage and improve freezing-thawing resistance. The effects of durability improving admixture, air content, water-binder ratio, and fly ash replacement ratio on the performance of fly ash concrete are discussed in this paper. The results show that by using durability improving admixture in nonair-entraining fly ash concrete, the compressive strength of fly ash concrete can be improved by 10%–20%, and the drying shrinkage is reduced by 60%. Carbonation resistance of concrete is roughly proportional to water-cement ratio regardless of water-binder ratio and fly ash replacement ratio. For the specimens cured in air for 2 weeks, the freezing-thawing resistance is improved. In addition, by making use of durability improving admixture, it is easier to control the air content and make fly ash concrete into nonair-entraining one. The quality of fly ash concrete is thereby optimized.

Water Penetration Resistance of Fly Ash Concrete Incorporating with Quarry Wastes

2017 ◽  
Vol 886 ◽  
pp. 159-163 ◽  
Author(s):  
Suppachai Sinthaworn
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Strength ◽  
Cementitious Materials ◽  
Fine Aggregate ◽  
Water Penetration ◽  
Strength Concrete ◽  
Fly Ash Concrete ◽  
Suitable Amount ◽  
Normal Strength

Slump of fresh concrete, compressive strength and water penetration depth under pressure of fly ash concrete incorporate with quarry waste as fine aggregate were investigated. The cementitious materials of the concrete includes ordinary Portland cement 80% and fly ash 20% by weight of cementitious. The mix proportions of the concrete were set into two classes of compressive strength. The results show that fly ash enhances workability of both concretes (normal concrete and concrete incorporate with quarry waste). Increasing the percentage of quarry dusts as fine aggregate in concrete seem negligible effect on the compressive strength whereas adding fly ash shows a slightly improve the compressive strength in the case of cohesive concrete mixture. Besides, adding the suitable amount of fly ash could improve the permeability of concrete. Therefore, fly ash could be a good admixture to improve the water resistant of normal strength concrete and also could be a supplemental material to improve the compressive strength of normal high strength concrete.

Variation of Carbonation Coefficient of Pumping Concrete with Moist-Curing Time at early Ages and Fly-Ash Content

2011 ◽  
Vol 287-290 ◽  
pp. 899-905
Author(s):  
Qing Ye ◽  
Zhi Wei Song ◽  
Guo Rong Yu
Keyword(s):  
Fly Ash ◽  
Concrete Cover ◽  
Ash Content ◽  
Curing Time ◽  
Accelerated Carbonation ◽  
Carbonation Depth ◽  
Carbonation Resistance

Based on accelerated carbonation test, the variation of carbonation resistance of pumping concrete (C40 grade) with moist-curing time at early ages and fly-ash content was studied. Results indicate that the carbonation coefficient and the accelerated carbonation depth of the concrete increased obviously with a reduction in the moist-curing time at early ages and with an increase in the fly-ash content. For example, in conditions of curing schedules with 28, 7, 3, 2 and 1 d moist-curing at 20 0C with above 95% RH at early ages and then 0, 21, 25, 26 and 27 d air curing at 20 0C with 60% RH, respectively, carbonation coefficients of the concrete incorporated with 30% fly-ash were 2.04, 2.49, 3.16, 3.86 and 5.42 mm/a0.5 respectively, and thus it can be seen that the calculated times when concrete cover (25 mm) was completely carbonated naturally in now atmosphere (0.04% CO2) were 164, 104, 66, 44 and 21 years respectively. The results suggest that for the carbonation resistance of the C40 concrete incorporated with up to 30% fly-ash, the moist-curing time of 7 days at early ages should be necessary.

Effects of stress and high temperature on the carbonation resistance of fly ash concrete

2017 ◽  
Vol 138 ◽  
pp. 486-495 ◽  
Author(s):  
Wei Wang ◽  
Caifeng Lu ◽  
Yunxia Li ◽  
Guanglin Yuan ◽  
Qingtao Li
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
Fly Ash Concrete ◽  
Carbonation Resistance ◽  
Effects Of Stress

scholarly journals A Study on the Carbonation Characteristics of Fly Ash Concrete by Accelerated Carbonation Test

2009 ◽  
Vol 21 (4) ◽  
pp. 449-455 ◽  
Author(s):  
Sung Choi ◽  
Kwang-Myong Lee ◽  
Sang-Hwa Jung ◽  
Joo-Hyung Kim
Keyword(s):  
Fly Ash ◽  
Accelerated Carbonation ◽  
Fly Ash Concrete

scholarly journals Sustainable cementitious materials: The effect of fly ash percentage as a part replacement of portland cement composite (PCC) and curing temperature on the early age strength of fly ash concrete

2019 ◽  
Vol 258 ◽  
pp. 01001
Author(s):  
Gidion Turuallo ◽  
Harun Mallisa
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Cement Composite ◽  
Cementitious Materials ◽  
Curing Temperature ◽  
Early Age ◽  
Water Tank ◽  
Lower Strength ◽  
Fly Ash Concrete ◽  
Lower Temperature

This research aims to determine the effect of fly ash percentage as a part replacement of Portland cement and curing temperatures to the early age strength of concrete. The percentages of fly ash used were 0, 10 and 15% by cement weight. The cured temperatures were 25, 30 dan 50°C. The concrete specimens were cubes of 150 x 150 x 150 mm3. The cubes, which were cured at 25°C, placed in water tank, while those cured at 30 and 50°C cured in oven until 7 days and then continued in water. The testing was conducted at ages 3, 7, 14 dan 28 days. The results showed that at early ages, the strength of concrete without fly ash cured at 25°C were higher than that of fly ash concrete. The higher level replacement of cement with fly ash, the lower strength of concrete obtained. The higher the curing temperature at earlier age resulted the higher the strength of concrete. The strength of concretes with 10% of fly ash cured at 25, 30 and 50°C at age three days were 15.111, 15.481 and 16.296 MPa respectively. Conversely, the strength of concrete that of cured at higher temperatures at ages 28 days, were lower than that of concretes cured at lower temperature. The results of this research also showed that fly ash could improve the workability of concrete.

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