SELF-HEALING CONCRETE USING FLY ASH

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Yoshitaka Ishikawa
Keyword(s):  
Fly Ash ◽  
Strength Test ◽  
Self Healing ◽  
Test Results ◽  
Freezing Damage ◽  
Replacement Ratio ◽  
Concrete Deterioration ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Dry Shrinkage

In recent studies, it has been recognized that concrete deterioration is accelerated by growth of the fine cracks of a few micron meter wide which was induced by dry shrinkage and/or freezing damage. Research of the concrete which carries out self-healing of these fine cracks has been abundantly expected. To confirm the ability of fly ash on self-healing, we conducted fundamental test of mortar using fly ash (replacement ratio: 20%) which was deteriorated by accelerated freeze-thaw cycle until the relative dynamic modulus of elasticity reduced to 80% and 60%. The mortar specimens were then cured in water at 40°C and 20°C. We have evaluated the self-healing degree of the cured mortar specimens by strength test, some durability tests, and concrete structure observations. From the test results, it was confirmed that fly ash functioned effectively as a self-healing material of concrete.

Experimental Study on Freeze-Thaw Resistance Durablilty of High Performance Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 393-397 ◽  
Author(s):  
Jun Fang Huo ◽  
Xiao Xia Ji ◽  
Hui Yang
Keyword(s):  
Fly Ash ◽  
Large Volume ◽  
High Performance ◽  
High Performance Concrete ◽  
Test Results ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Resistance Performance ◽  
Maximum Weight Loss

Freeze-thaw cycle experiments on high performance concrete were carried out while cement was respectively replaced by fly ash for 30%～50%. The test results showed that maximum weight loss rate of concrete was 1.78% and minimum relative dynamic elastic modulus was 94.08% after 300 freeze-thaw cycles for high performance concrete based on low water-cement ratio, efficient air-water-reducing agent and large quantities of industrial waste fly ash. The test data were far less than limits of 5% and 60% in specification. Freeze-thaw resistance performance of high performance concrete with large volume fly ash was excellent according to test results. The high performance concrete with large volume fly ash can meet the requirements of frost resistance performance of concrete in the cold regions. Particularly, it can be fit for the railway concrete engineering.

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.

Study on the Influence of Mix Design Parameters on the Properties of Self-Compacting Concrete

2013 ◽  
Vol 857 ◽  
pp. 10-19
Author(s):  
Ji Liang Wang ◽  
Xiang Qian Wen ◽  
Jun Hong Shan ◽  
Ying Liu
Keyword(s):  
Fly Ash ◽  
Volume Content ◽  
Coarse Aggregate ◽  
Mineral Admixture ◽  
Design Parameters ◽  
Fine Aggregate ◽  
Test Results ◽  
Self Compacting Concrete ◽  
Volume Stability ◽  
Dry Shrinkage

the influence of mixing amount of mineral admixture, volume content of fine and coarse aggregate have been systematical studied on the workability, mechanical properties and volume stability of self-compacting concrete. Test results showed that with the fly ash content increased, the workability of self-compacting concrete improved significantly, early compressive strength decreased, but increase rate of later strength improved remarkably, and the mixing amount of fly ash inhibited significantly the dry shrinkage of self-compacting concrete; with the volume content of coarse aggregate increased, the workability of self-compacting concrete decreased significantly, but the volume stability of self-compacting concrete improved obviously, thus the optimum volume content of coarse aggregate of self-compacting concrete was range from 0.30 to 0.34; when the volume content of fine aggregate varied at the range of 0.40~0.50, there may be little effects on the workability of self-compacting concrete, but the increase self-compacting concretes volume content could reduce obviously the dry shrinkage of self-compacting concrete. Moreover, the variation in the volume content of coarse and fine aggregate should have slight influence on the early strength of self-compacting concrete, and the influence of the volume content variety on the later strength of self-compacting concrete could be neglected eventually.

Research on Factors Affecting Reinforced Concrete Durability

2014 ◽  
Vol 898 ◽  
pp. 403-406 ◽  
Author(s):  
Fu Yuan Chong ◽  
Ya Nan An ◽  
Peng Wang
Keyword(s):  
Reinforced Concrete ◽  
Life Cycle Cost ◽  
Concrete Durability ◽  
Building Structures ◽  
Factors Affecting ◽  
Concrete Deterioration ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
The Cost ◽  
Corrosion Of Steel

Reinforced concrete is widely used in building structures. However, due to its corrosion, deterioration loss is more and more outstanding. Therefore, besides building material mechanical properties and the cost, the structural designer also need to focus on the durability of reinforced concrete. Effects of reinforced concrete durability factors mainly include corrosion of steel in reinforced concrete, freeze-thaw cycle, soft water, high temperature and chemical erosion. Understanding the influencing factors will help control the concrete deterioration, reduce the structural reparation and maintenance costs, and thereby reduce the life cycle cost of structure.

scholarly journals Equation for the Degradation of Uniaxial Compression Stress of Concrete due to Freeze-Thaw Damage

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Xiaolin Yang ◽  
Genhui Wang ◽  
Shiwu Gao ◽  
Min Song ◽  
Anqi Wang
Keyword(s):  
Concrete Strength ◽  
Damage Variable ◽  
Curved Surface ◽  
Large Temperature ◽  
Test Results ◽  
Stress Strain ◽  
Cycle Number ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

To study the freeze-thaw damage characteristics of concrete, the uniaxial compressive tests of concrete under different number of freeze-thaw cycles were conducted, and the damage variable of freeze-thaw was obtained. The test results showed that the stress was a function of strain and freeze-thaw damage variable, and it can describe the degradation of concrete strength. Meanwhile, the equation for the stress-strain curved surface about strain and freeze-thaw damage variable was also proposed in this paper. The derivative function of the stress-strain curved surface equation with respect to strain presented the change of elastic modulus with the increase of freeze-thaw cycle number. Equation proposed in this paper can be used for predicting the concrete lifetime effectively in cold and large temperature difference regions.

Study on the Freezing Resistance of HFCC

2011 ◽  
Vol 308-310 ◽  
pp. 2555-2559
Author(s):  
Hong Mei Ai ◽  
Pu Guang Lu ◽  
Jun Ying Bai ◽  
Jing Jing Wei
Keyword(s):  
Fly Ash ◽  
Compression Strength ◽  
Ash Content ◽  
Freezing Resistance ◽  
Cycle Times ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Binder Ratio ◽  
Water Binder Ratio

To the High fly-ash content concrete(abbreviated HFCC) whose fly-ash adding amount is 50%~70%, the influence of actual water-binder ratio, fly-ash content, quality of fly-ash and compression strength on the freezing resistance of HFCC were studied; The critical freeze-thaw cycle times in this paper involved with mass loss rate Wn=5% and relative dynamic elastic modulus P=60%, the relationship between the critical freeze-thaw cycle times and the 28d compression strength of HFCC was analyzed; To HFCC without air-entraining agent, the experiment results showed that the freezing resistance decreased with the increase of actual water-binder ratio, the increase of fly-ash content and the reduce of fly-ash quality. The freeze-thaw damage of HFCC dues to the freeze-thaw degradation results from surface denudation.

scholarly journals Damage and Degradation of Concrete under Coupling Action of Freeze-Thaw Cycle and Sulfate Attack

2020 ◽  
Vol 2020 ◽  
pp. 1-17 ◽  
Author(s):  
Wei Tian ◽  
Fangfang Gao
Keyword(s):  
Fly Ash ◽  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Sodium Sulfate Solution ◽  
Failure Characteristics ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Two Stages

In this study, the mechanical behaviors, failure characteristics, and microstructure of concrete containing fly ash (FA) against combined freeze-thaw cycles and sulfate attack were studied compared with normal concrete, and the formation rates of corrosion products during coupling cycles were investigated. Results showed that, during the coupling action of freeze-thaw cycles and sodium sulfate solution, concrete containing 10% fly ash exposed in 5% sodium sulfate solution exhibited better freeze-thaw resistance. Meanwhile, the variation of compressive strength of concrete during the coupling cycles could be divided into two stages, including the strength enhancement stage and the strength reduction stage. Moreover, the proportion of micropores and capillary pores decreased obviously during combined freeze-thaw cycles and sulfate attack, and excessive concentration of sodium sulfate solution led to more macropores after high-frequency freeze-thaw cycles.

Experimental Study of Slag Powder Fineness Effect on Concrete Performance

2013 ◽  
Vol 405-408 ◽  
pp. 2631-2634 ◽  
Author(s):  
Bin Li ◽  
Mei Yan Hang ◽  
Su Fen Dong
Keyword(s):  
Water Pressure ◽  
Mineral Admixture ◽  
Test Results ◽  
Application Process ◽  
Slag Powder ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Powder Fineness ◽  
Electric Flux ◽  
Strength And Durability

Slag powder can improve concrete compression strength and durability owing to the activity of volcano ash and powder filling effect when replacing cement as active mineral admixture. Test results show that the 28-day strength can reach to 74MPa if slag powder with the fineness 810 m2/kg is used to replace 60% cement when making C40 concrete. And at 4.0MPa water pressure, the seepage height can be only 12mm, the electric flux in 6 hours can drop by 72% than that didn't use slag powder, the ability of freeze-thaw cycle can reach F350. But attention should be paid to the grinding process impact on the economy of the massive practical application process.

scholarly journals Mechanical Properties and Durability of High-Performance Concretes Blended with Circulating Fluidized Bed Combustion Ash and Slag as Replacement for Ordinary Portland Cement

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhi Cheng ◽  
Lei He ◽  
Lan Liu ◽  
Zhijun Cheng ◽  
Xiaobo Pei ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Performance ◽  
Circulating Fluidized Bed ◽  
Strength Loss ◽  
Ash Content ◽  
Fluidized Bed Combustion ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Circulating Fluidized Bed Combustion

This study investigates the mechanical properties and durability of three families of high-performance concrete (HPC), in which the first was blended with fly ash, the second with circulating fluidized bed combustion (CFBC) ash, and the third with CFBC slag. In addition to each of the three mineral additives, silica fume and a superplasticizer were also incorporated into the HPC. Hence, three families of HPC, containing 10%, 20%, and 30% mineral admixtures and 9% silica fume of the binder mass, respectively, were produced. The microstructure and hydration products of the HPC families were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) to explore the influence of fly ash, CFBC ash, and CFBC slag on the compressive strength and frost resistance of HPC. The experimental results show that the compressive strength of HPC could reach 60 MPa at 28 d age. When the fly ash content was 30%, the compressive strength of HPC was 70.2 MPa at 28 d age; after the freeze-thaw cycle, the mass loss and strength loss of HPC were 0.63% and 8.9%, respectively. When the CFBC ash content was 20%, the compressive strength of HPC was 75 MPa at 28 d age. After the freeze-thaw cycle, the mass loss and strength loss of HPC were 0.17% and 0.81%, respectively.

A Model for Predicting the Carbonation Depth of SCC with Massive Fly Ash in the Loading State

2012 ◽  
Vol 446-449 ◽  
pp. 756-761
Author(s):  
Su Rong Luo ◽  
Li Pin Huang
Keyword(s):  
Fly Ash ◽  
Flexural Strength ◽  
Tensile Stress ◽  
Test Results ◽  
Accelerated Carbonation ◽  
Replacement Ratio ◽  
Carbonation Depth ◽  
Normal Concrete ◽  
Carbonation Resistance ◽  
Set Up

In this work, four series of SCC specimens which cement replacement ratio by fly ash was 30, 40, 50, and 60% , respectively, and one series of normal concrete comparative specimens were designed. For the same series specimens, the fly ash addition was fixed, but the loading value was 0.0, 0.2, 0.4, and 0.6 times of the 28 d concrete flexural strength, respectively. Using accelerated carbonation test, the effects of fly ash additions, tensile stress rates, and compressive stress rates on carbonation rate of SCC are studied. Based on the test results, a model considered both effects of fly ash addition and stress rate for predicting the carbonation depth of SCC under real environment conditions is set up. These results can provide a reference for carbonation resistance design of SCC.

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