Application of Desalination to Concrete Admixing Fly Ash or Blast-Farnace Slag

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1452-1457 ◽  
Author(s):  
Kenji Nagao ◽  
Takao Ueda ◽  
Masanobu Ashida ◽  
Toyoaki Miyagawa
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Exposed Surface ◽  
Carbonation Depth ◽  
Total Chloride ◽  
Cover Concrete ◽  
Chloride Attack ◽  
Chloride Removal ◽  
Furnace Slag

This paper mainly describes corrosion behavior of the steel bars in concrete specimens using fly ash or blast-furnace slag, deteriorated by chloride attack, carbonation of concrete, or complex of both mechanisms. Furthermore, chloride removal effect due to applying desalination to such deteriorated specimens is investigated. Results obtained from this study can be summarized as follows: (1) Carbonation depth of concrete using fly ash or blast-furnace slag was larger than that of normal concrete and the larger replacement rate of them became, the more carbonation depth of concrete increased. (2) As the result of measurement of Cl- content in concrete before desalination, in the case of carbonated specimens, soluble chloride percentage to total chloride near the exposed surface was increased with the influence of carbonation of concrete. (3) Chloride removal percentage due to applying desalination to non-carbonated specimens was 15-30% as a whole cover concrete. On the other hand, in the case of carbonated specimens, Cl- ion near the exposed surface was decreased by desalination and chloride removal percentage reached 50-80%.

The Influence of Size Effect on High-Volume Fly-Ash Concrete’s Carbonation Resistance Performance

2011 ◽  
Vol 368-373 ◽  
pp. 1121-1124
Author(s):  
Li Fang Liu ◽  
Xiao Xia Niu ◽  
Wang Yu ◽  
Xiao Man Liu
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Size Effect ◽  
Blast Furnace Slag ◽  
High Volume ◽  
Carbonation Depth ◽  
Granulated Blast Furnace Slag ◽  
High Volume Fly Ash ◽  
Carbonation Resistance ◽  
Furnace Slag

using fixed concrete slump method,the carbonation resistance of concretes with high-volume fly-ash and ground granulated blast-furnace slag had been studied, and make an approach to size- effect .The results show that the more fly-ash joined in,the more carbonation depth is deeper . The carbonation resistance of concretes with high-volume fly-ash and ggbs is better than only with high-volume fly-ash’s. Size effect on carbonation depth of concretes is also important . Carbonation depth will become deeper as soon as the block size improving .and the early improvement is bigger than the late .The more concretes with high-volume fly-ash and ground granulated blast-furnace slag,the size-effect on carbonation depth of concretes will be more evident.

Resistance Performance of Concrete Using both Blast Furnace Slag Cement and Fly Ash against Chloride Attack and Carbonation

2015 ◽  
Vol 1110 ◽  
pp. 271-276
Author(s):  
Kenta Miura ◽  
Takao Ueda ◽  
Masayuki Tsukagoshi
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Pore Structure ◽  
Blast Furnace Slag ◽  
Chloride Ions ◽  
Slag Cement ◽  
Fly Ash Concrete ◽  
Chloride Attack ◽  
Resistance Performance ◽  
Furnace Slag

From the viewpoint of effective utilization of industrial wastes and reduction of CO2 emission, the use of concrete mixed with blast furnace slag and fly ash has been promoted. However, the durability of fly ash concrete using blast furnace slag cement has not been clarified enough. About chloride attack, the resistance against the penetration of chloride ions could be improved due to the dense pore structure formed by the synegetic effect of mixing both ground granulated blast-furnace slag and fly ash into concrete. In this study, resistance performance of concrete using both blast furnace slag cement and fly ash against chloride attack and carbonation was experimentally investigated. The relationship between such resistance performance and pore structure of the concrete was also examined. As a result, the combination of blast furnace slag cement and fly ash type II resulted in the decrease of pore volume over 50 nm in the diameter and reduction of the apparent diffusion coefficient of chloride ion, but the resistance performance against carbonation of the concrete was lower than the case of the normal fly ash concrete.

scholarly journals Effect of Mineral Admixtures on the Performance of Low-Quality Recycled Aggregate Concrete

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 596
Author(s):  
Yasuhiro Dosho
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mineral Admixtures ◽  
Structural Concrete ◽  
Aggregate Concrete ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

To improve the application of low-quality aggregates in structural concrete, this study investigated the effect of multi-purpose mineral admixtures, such as fly ash and ground granulated blast-furnace slag, on the performance of concrete. Accordingly, the primary performance of low-quality recycled aggregate concrete could be improved by varying the replacement ratio of the recycled aggregate and using appropriate mineral admixtures such as fly ash and ground granulated blast-furnace slag. The results show the potential for the use of low-quality aggregate in structural concrete.

Effects of Fly Ash and Granular Blast-Furnace Slag on Development Rate of Strength of Concrete

2014 ◽  
Vol 629-630 ◽  
pp. 371-375
Author(s):  
Ji Wei Cai ◽  
Si Jia Yan ◽  
Gong Lei Wei ◽  
Lu Wang ◽  
Jin Jin Zhou
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Development Rate ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Conventional Concrete ◽  
Enhancing Effect ◽  
Substitution Content ◽  
Furnace Slag

Fly ash (FA) and granular blast-furnace slag (GBFS) are usual mineral admixtures to conventional concrete, and their contents substituted for Portland cement definitely affect development rate of strength of concrete. C30 and C60 concrete samples with FA and/or GBFS were prepared to study the influence of substitution content of the mineral admixtures on 3 d, 7 d and 28 d strength. The results reveal that the development rate of strength in period from 3 d to 7 d gets slow with increasing content of mineral admixtures except for concrete with only GBFS less than 20%. In the case of substituting FA as the only mineral admixture for part of cement, the development rate of strength of C30 concrete in period from 7 d to 28 d keeps roughly constant even that of C60 concrete increases. When substituting mineral admixtures in the presence of GBFS for cement within experimental range, the development rate of strength in period from 7 d to 28 d gets fast with increasing substitution content. The enhancing effect of combining FA and GBFS occurs in period from 7 d to 28 d for both C30 and C60 concretes (FA+GBFS≤40%), even occurs in period from 3 d to 7 d for C60 concrete. Based on 7 d strength and the development rate, 28 d strength of concrete can be predicted accurately.

Optimization of Concrete Porous Mix Using Slag as Substitute Material for Cement and Aggregates

2017 ◽  
Vol 865 ◽  
pp. 282-288 ◽  
Author(s):  
Jul Endawati ◽  
Rochaeti ◽  
R. Utami
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Fly Ash ◽  
Silica Fume ◽  
Blast Furnace Slag ◽  
Environmental Effect ◽  
Substitution Effect ◽  
Main Concern ◽  
Binder Material ◽  
Furnace Slag

In recent years, sustainability and environmental effect of concrete became the main concern. Substituting cement with the other cementitious material without decreasing mechanical properties of a mixture could save energy, reduce greenhouse effect due to mining, calcination and limestone refining. Therefore, some industrial by-products such as fly ash, silica fume, and Ground Iron Blast Furnace Slag (GIBFS) would be used in this study to substitute cement and aggregate. This substitution would be applied on the porous concrete mixture to minimize the environmental effect. Slag performance will be optimized by trying out variations of fly ash, silica fume, and slag as cement substitution material in mortar mixture. The result is narrowed into two types of substitution. First, reviewed from the fly ash substitution effect on binder material, highest compressive strength 16.2 MPa was obtained from mixture composition 6% fly ash, 3% silica fume and 17% grinding granular blast-furnace slag. Second, reviewed from slag types as cement substitution and silica fume substitution, highest compressive strength 15.2 MPa was obtained from mortar specimens with air-cooled blast furnace slag. It composed with binder material 56% Portland composite cement, 15% fly ash, 3% silica fume and 26% air-cooled blast furnace slag. Considering the cement substitution, the latter mixture was chosen.

Modeling of Alteration Behavior on Blended Cementitious Materials

2011 ◽  
Author(s):  
Hitoshi Owada ◽  
Tomoko Ishii ◽  
Mayumi Takazawa ◽  
Hiroyasu Kato ◽  
Hiroyuki Sakamoto ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Chemical Composition ◽  
Mineral Composition ◽  
Blast Furnace Slag ◽  
Fine Powder ◽  
Cementitious Materials ◽  
Leaching Tests ◽  
Measured Concentration ◽  
Furnace Slag

A “realistic alteration model” is needed for various cementitious materials. Hypothetical settings of mineral composition calculated based on the chemical composition of cement, such as Atkins’s model, have been used to estimate the alteration of cementitious material. However, model estimates for the concentration of certain elements such as Al and S in leachate have been different from experimental values. In a previous study, we created settings for a mineralogical alteration model by taking the initial chemical composition of cementitious materials from analysis results in experiments and applying their ratios to certain hydrated cement minerals, then added settings for secondary generated minerals in order to account for Ca leaching. This study of alteration estimates for ordinary portland cement (OPC) in groundwater showed that the change in Al and S concentrations in simulated leachate approached values for actual leachate[1]. In the present study, we develop an appropriate mineral alteration model for blended cementitious materials and conduct batch-type leaching experiments that use crushed samples of blast furnace slag cement (BFSC), silica cement (SC), and fly ash cement (FAC). The cement blends in these experiments used OPC blended with blast furnace slag of 70 wt.%, silica cement consisting of an amorphous silica fine powder of 20 wt.%, and fly ash of 30 wt.%. De-ionized water was used as the leaching solution. The solid-liquid ratios in the leaching tests were varied in order to simulate the alteration process of cement hydrates. The compositions of leachate and minerals obtained from leaching tests were compared with those obtained from models using hypothetical settings of mineral composition. We also consider an alteration model that corresponds to the diversity of these materials. As a result of applying the conventional OPC model to blended cementitious materials, the estimated Al concentration in the aqueous solution was significantly different from the measured concentration. We therefore propose an improved model that takes better account of Al behavior by using a more reliable initial mineral model for Al concentration in the solution.

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