Effect of silica fume on durability of concrete composites containing fly ash

2013 ◽  
Vol 20 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Peng Zhang ◽  
Qing-fu Li
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Shrinkage Strain ◽  
Carbonation Depth ◽  
Freeze Thaw ◽  
Slump Flow ◽  
Carbonation Resistance ◽  
Dry Shrinkage ◽  
Shrinkage Property ◽  
Durability Of Concrete

AbstractIn this paper, the effect of silica fume on the workability and durability of concrete composites containing fly ash, including water impermeability, dry shrinkage property, carbonation resistance and freeze-thaw resistance, are presented. Four different silica fume contents (3%, 6%, 9% and 12%) were used. The results indicate that the addition of silica fume has greatly improved the durability of water impermeability, the carbonation resistance and the freeze-thaw resistance of the concrete composites containing fly ash. With the increase in silica fume content, the length of water permeability and the carbonation depth of the specimens decrease gradually, and the relative dynamic elastic modulus of the specimens has a tendency to increase. However, the addition of silica fume has a little adverse effect on the workability and dry shrinkage property of concrete composites containing fly ash. With the increase in silica fume content, both the slump and the slump flow decrease gradually, and the dry shrinkage strain increases gradually.

Effect of Silica Fume on Dry Shrinkage and Freezing-Thawing Durability of Concrete

2012 ◽  
Vol 238 ◽  
pp. 165-168 ◽  
Author(s):  
Feng Li ◽  
Zai Peng Cui
Keyword(s):  
Adverse Effect ◽  
Experimental Study ◽  
Silica Fume ◽  
Considerable Increase ◽  
Shrinkage Strain ◽  
Dry Shrinkage ◽  
Shrinkage Property ◽  
Durability Of Concrete

An experimental study has been conducted to investigate the effect of silica fume on shrinkage and freezing-thawing durability of concrete, a large number of tests have been carried out in this study. The results indicate that the addition of silica fume has adverse effect on the dry shrinkage property of concrete. The dry shrinkage strain of the concrete containing silica fume is more than that of the concrete without silica fume, and a considerable increase for the dry shrinkage strain of the concrete was observed by increasing the dosage of silica fume. However, the addition of silica fume can improve the freezing-thawing durability of the concrete evidently, and the freezing-thawing durability is becoming better and better as the silica fume content is increasing gradually.

Effect of Nano Materials on Durability of High Performance Concrete

2013 ◽  
Vol 742 ◽  
pp. 220-223 ◽  
Author(s):  
Yu Xi An
Keyword(s):  
Water Permeability ◽  
High Performance ◽  
High Performance Concrete ◽  
Shrinkage Strain ◽  
Nano Materials ◽  
Carbonation Depth ◽  
Shrinkage Cracking ◽  
Carbonation Resistance ◽  
Dry Shrinkage

The aim of this study was to study the effect of nanoSiO2 on durability of high performance concrete. Four different nanoSiO2 contents (1%, 2%, 3% and 4%) were used. The results indicate that the content of nanoSiO2 has great effect on the durability of high performance concrete. With the increase of nanoSiO2 content, both of the length of water permeability and the carbonation depth of concrete are decreasing gradually, and the water impermeability and the carbonation resistance of concrete are increasing gradually. However, with the increase of nanoSiO2 content, there is a tendency of increase on the dry shrinkage strain of 90 days of high performance concrete, and the anti-dry-shrinkage cracking property of concrete is decreasing.

scholarly journals Study of Durability of Concrete with Fly Ash as Fine Aggregate under Alternative Interactions of Freeze-Thaw and Carbonation

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Mingjie Mao ◽  
Dongsheng Zhang ◽  
Qiuning Yang ◽  
Wenbo Zhang
Keyword(s):  
Fly Ash ◽  
Concrete Strength ◽  
Microstructural Analysis ◽  
Fine Aggregate ◽  
X Ray Diffraction ◽  
Carbonation Depth ◽  
Freeze Thaw ◽  
Water To Cement Ratio ◽  
Deterioration Mechanism ◽  
Durability Of Concrete

To study the durability of concrete with fly ash as fine aggregate subjected to alternative attacks of freeze-thaw and carbonation, the appearance, mass loss, relative dynamic modulus of elasticity, relative compressive strength, and carbonation depth of the concrete are investigated using cyclic tests under single carbonation, single freeze-thaw, and alternation of freeze-thaw and carbonation. In addition, microstructural analysis techniques including scanning electron microscope and X-ray diffraction are adopted to reveal the deterioration mechanism of alternating freeze-thaw and carbonation. Results show that carbonation is beneficial for refining the pore structure and increasing concrete strength in the initial alternative cycle, which delays the damage from freeze-thaw cycles. Damage from freeze-thaw causes crack propagation in concrete, which leads to carbonation intensification. Compared with other test modes, concrete under alternative freeze-thaw and carbonation causes the greatest degree of deterioration during the initial freeze-thaw cycles. The carbonation depth under alternative freeze-thaw and carbonation is positively correlated with the carbonation time and the water-to-cement ratio. However, as the reactant is continuously consumed due to the expansion of crystalline ice and CaCO3, alternative cycles result in the appearance of many more new cracks in the concrete.

Study on the Influence of Freeze-Thaw on the Carbonation Property of Fly Ash Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 939-943 ◽  
Author(s):  
Jian Gang Niu ◽  
Liang Yan ◽  
Hai Tao Zhai
Keyword(s):  
Fly Ash ◽  
Laboratory Simulation ◽  
Influence Coefficient ◽  
Carbonation Depth ◽  
Freeze Thaw ◽  
Fly Ash Concrete ◽  
Concrete Carbonation ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

Based on the coupling testing program of freeze-thaw and carbonation, the laboratory simulation test is carried out. The laws of carbonation depth of the fly ash concrete suffered the freeze-thaw cycle in different test modes and the influence of fly ash dosage on concrete carbonation depth after the freeze-thaw cycle are studied. Defining the influence coefficient of the freeze-thaw cycles on carbonation depth of concrete, the mechanism of coupling of freeze-thaw and carbonation is analyzed,and the role of freeze-thaw and carbonation in the coupling process are obtained.

scholarly journals Freeze-Thaw Resistance of Normal and High Strength Concretes Produced with Fly Ash and Silica Fume

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Cenk Karakurt ◽  
Yıldırım Bayazıt
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
High Strength ◽  
Unit Surface Area ◽  
Normal Strength Concrete ◽  
Freeze Thaw ◽  
Strength Concrete ◽  
Thaw Cycle ◽  
Surface Scaling ◽  
Normal Strength

This study is based on determination of the freeze-thaw resistance of air-entrained and non-air-entrained normal strength concrete (NC) and high strength concrete (HSC) produced with fly ash and silica fume according to surface scaling. The procedure allows us to measure the amount of scaling per unit surface area due to a number of well defined freezing and thawing cycles in the presence of deicing salt. The weight loss, surface scaling, moisture uptake, and internal damage were measured after 0 and after every 4th freeze-thaw cycle. The test results showed that the freeze-thaw resistance is influenced directly by the compressive strength property of the concrete. Silica fume significantly reduced the resistance of normal strength concrete against freeze-thaw effect without plasticizing agent. The surface scaling of silica fume concrete without admixture was 22% higher than reference normal 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.

Comparative Investigations of some Properties of Lightweight Cement Concretes Containing Siliceous Fly Ash

2016 ◽  
Vol 677 ◽  
pp. 67-74
Author(s):  
Wojciech Kubissa
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Fly Ash ◽  
Chloride Ion ◽  
Lightweight Aggregate ◽  
Cement Concrete ◽  
Carbonation Depth ◽  
Ion Migration ◽  
Durability Of Concrete ◽  
Class F

In the article the possibility of lightweight cement concrete manufacturing has been presented with use of binder in which part of cement was replaced with siliceous fly ash Class F. It was used lightweight aggregate Pollytag and Keramzyt. Total amount of binder was 400 kg/m3 with w/b=0.5. Mechanical properties has been tested as well as properties affecting durability of concrete. Replacing part of cement with fly ash improved concrete resistance on chloride ion migration, reduced compressive and tensile strength of concrete and increased carbonation depth.

Experimental Study on Carbonation Resistance of Ready-Mixed Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 152-158 ◽  
Author(s):  
Jing Song Zhu ◽  
Ya Li Sun ◽  
Yue Feng Zhu ◽  
Dan Fei Chen
Keyword(s):  
Fly Ash ◽  
Service Life ◽  
Early Stage ◽  
Ash Content ◽  
Design Criteria ◽  
Carbonation Depth ◽  
Curing Conditions ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Carbonation Resistance

By means of accelerated carbonation tests, the carbonation resistance of concrete in relation to the variation of water-cement ratio, fly ash content and curing conditions is studied in this article. The results show that under the standard curing conditions, with the fly ash content of 20%, in response to different water-cement ratio, the carbonation depth of concrete and the water-cement ratio are presented more or less in a linear relationship. At the water-cement ratio of 0.40, there is hardly any carbonation effect onto the concrete. However, at the ratio of bigger than 0.60, the carbonation depth of concrete increases in a speedy way. Under the standard curing conditions, at the water-cement ratio of 0.55, with the fly ash content of lower than or equal to 30%, the carbonation resistance of concrete is good enough to fulfill the design criteria of 50~100 years for service life of important and general buildings, while the compressive strength declines by less than 10%. But under the condition of 1d curing with retention of moisture followed by curing in the air until 28d, with no fly ash content, the carbonation depth of concrete has reached 35mm, which fails to fulfill the design criteria of 50 years for service life of general buildings. It is therefore concluded that the control of water-cement ratio, the control of fly ash content, and the sufficient curing with retention of moisture in early stage are all the essential factors to ensure the durability against carbonation for the concrete with fly ash content.

Sign in / Sign up

Export Citation Format

Share Document