scholarly journals Experimental Investigation of Neutralisation of Concrete with Fly Ash as Fine Aggregate in Freeze-Thaw Environment

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Dongsheng Zhang ◽  
Mingjie Mao ◽  
Qiuning Yang ◽  
Wenbo Zhang ◽  
Pengfei Han
Keyword(s):  
Fly Ash ◽  
Mathematical Expression ◽  
Influence Coefficient ◽  
Fine Aggregate ◽  
Concrete Durability ◽  
Freeze Thaw ◽  
Composite Damage ◽  
Variation Characteristics ◽  
Deterioration Mechanism ◽  
Highly Correlated

To study the durability of concrete with fly ash as fine aggregate under alternate freeze-thaw and carbonation, freeze-thaw and carbonation cyclic tests are conducted to explore variation characteristics such as relative dynamic modulus of elasticity and neutralisation depth. The influence coefficient (λC) of carbonation on concrete freeze-thaw damage and the influence coefficient (λF) of freeze-thaw on concrete neutralisation are introduced. In addition, scanning electron microscopy is performed to reveal the deterioration mechanism of the alternating effect. Finally, through a regression analysis of test data, the mathematical expression of the composite damage coefficient kF under alternate freeze-thaw and carbonation is obtained. Based on these findings, a prediction model of the neutralisation depth of concrete is established with number of freeze-thaw cycles and water-cement ratio as parameters. The values calculated through this model and the values measured in the tests are highly correlated. This provides a theoretical reference and basis for the analysis of concrete durability in a multifactor environment.

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.

Estimating the Importance Degree of Influence Factors on Concrete Durability Based on Rough Set Theory

2014 ◽  
Vol 988 ◽  
pp. 191-194
Author(s):  
Xiao Ping Su ◽  
Hao Yue Sun
Keyword(s):  
Fly Ash ◽  
Set Theory ◽  
Rough Set ◽  
Loss Rate ◽  
Elasticity Modulus ◽  
Rough Set Theory ◽  
Ash Content ◽  
Concrete Durability ◽  
Freeze Thaw ◽  
Air Content

Under the saline soil environment in the western area of Jilin Province, the concrete durability is affected by a lot of factors, which include wet-dry cycles, freeze-thaw cycles, wet-dry and freeze-thaw cycles, salt soaking time, salts concentration, fly-ash content, air content. These factors impact on the durability of concrete is uncertain, and there may be a problem of duplicate action, with some roughness characteristics. In this article, the rough set theory is used to analyze the degree that these seven factors affect the concrete durability, and to calculate weights. In this article, the loss rate of dynamic elasticity modulus is looked as the evaluation index of concrete durability. The results show that: the importance degrees of 7 factors influencing the loss rate of concrete dynamic elasticity modulus in order are: wet-dry and freeze-thaw cycles > wet-dry cycle > freeze-thaw cycles > multiple salts concentration > air content > long-term soak > fly-ash content.

scholarly journals A Comparative Study for the Prediction of the Compressive Strength of Self-Compacting Concrete Modified with Fly Ash

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4934 ◽  
Author(s):  
Furqan Farooq ◽  
Slawomir Czarnecki ◽  
Pawel Niewiadomski ◽  
Fahid Aslam ◽  
Hisham Alabduljabbar ◽  
...  
Keyword(s):  
Machine Learning ◽  
Fly Ash ◽  
Gene Expression Programming ◽  
Empirical Relation ◽  
Mathematical Expression ◽  
Coefficient Of Determination ◽  
Support Vector ◽  
Fine Aggregate ◽  
Learning Approaches ◽  
Self Compacting Concrete

Artificial intelligence and machine learning are employed in creating functions for the prediction of self-compacting concrete (SCC) strength based on input variables proportion as cement replacement. SCC incorporating waste material has been used in learning approaches. Artificial neural network (ANN) support vector machine (SVM) and gene expression programming (GEP) consisting of 300 datasets have been utilized in the model to foresee the mechanical property of SCC. Data used in modeling consist of several input parameters such as cement, water–binder ratio, coarse aggregate, fine aggregate, and fly ash (FA) in combination with the superplasticizer. The best predictive models were selected based on the coefficient of determination (R2) results and model validation. Empirical relation with mathematical expression has been proposed using ANN, SVM, and GEP. The efficiency of the models is assessed by permutation features importance, statistical analysis, and comparison between regression models. The results reveal that the proposed machine learning models achieved adamant accuracy and has elucidated performance in the prediction aspect.

Research of the Uniaxial Compressive Property of the Concrete Mixed with High-Content Fly Ash in Seawater

2016 ◽  
Vol 723 ◽  
pp. 760-763
Author(s):  
Li Kun Qin ◽  
Hong Wei Song ◽  
Shu Han Yang
Keyword(s):  
Mechanical Property ◽  
Fly Ash ◽  
Frost Resistance ◽  
Mathematical Expression ◽  
Compressive Property ◽  
The Real ◽  
Freeze Thaw ◽  
Fly Ash Concrete ◽  
Seawater Environment ◽  
Uniaxial Strength

This paper studies on the frost resistance of high-content fly ash concrete which content 52 fly ash in seawater. The uniaxial compressive property test was carried out after the fast freeze-thaw test with 0, 100, 200, 300 and 400 cycles. The research analyzed the influence of the uniaxial strength of the concrete mixed with high-content fly ash after freeze-thaw cycles in seawater. Then established a mathematical expression in a simple way. In the real project, the concrete mixed with fly ash can improve the frost resistance. The dosage of fly ash will directly influence the frost resistance and mechanical property. However, there is less study on frost resistance of concrete mixed with fly ash, especially the test under the seawater environment.

scholarly journals Freeze–Thaw Resistance and Air-Void Analysis of Concrete with Recycled Glass–Pozzolan Using X-ray Micro-Tomography

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 154
Author(s):  
Marija Krstic ◽  
Julio F. Davalos ◽  
Emanuele Rossi ◽  
Stefan C. Figueiredo ◽  
Oguzhan Copuroglu
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
The United States ◽  
Adsorption Method ◽  
X Ray ◽  
Freeze Thaw ◽  
Void System ◽  
Spatial Parameters ◽  
Micro Tomography ◽  
Air Void

Recent studies have shown promising potential for using Glass Pozzolan (GP) as an alternative supplementary cementitious material (SCM) due to the scarcity of fly ash and slag in the United States. However, comprehensive studies on the freeze–thaw (FT) resistance and air void system of mixtures containing GP are lacking. Therefore, this study aimed to evaluate GP’s effect on FT resistance and characterize mixtures with different GP contents, both macro- and microscopically. In this study, six concrete mixes were considered: Three mixes with 20%, 30% and 40% GP as cement replacements and two other comparable mixes with 30% fly ash and 40% slag, as well as a mix with 100% Ordinary Portland cement (OPC) as a reference. Concrete samples were prepared, cured and tested according to the ASTM standards for accelerated FT resistance for 1000 cycles and corresponding dynamic modulus of elasticity (Ed). All the samples showed minimal deterioration and scaling and high F/T resistance with a durability factor of over 90%. The relationships among FT resistance parameters, air-pressured method measurements of fresh concretes and air void analysis parameters of hardened concretes were examined in this study. X-ray micro-tomography (micro-CT scan) was used to evaluate micro-cracks development after 1000 freeze–thaw cycles and to determine spatial parameters of air voids in the concretes. Pore structure properties obtained from mercury intrusion porosimetry (MIP) and N2 adsorption method showed refined pore structure for higher cement replacement with GP, indicating more gel formation (C-S-H) which was verified by thermogravimetric analysis (TGA).

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