scholarly journals EXPERIMENTAL STUDIES ON MECHANICAL PROPERTIES AND THE SALT PERMEABILITY OF CONCRETES FOR PRECAST CONCRETE MEMBERS CONTAINING FLY ASH OR BLAST FURNACE SLAG FINE POWDER AS ADMIXTURE

2015 ◽  
Vol 69 (1) ◽  
pp. 311-318
Author(s):  
Toshio URANO ◽  
Manabu MATSUDA ◽  
Yasushi MATSUMOTO ◽  
Toshifumi HISANO
Author(s):  
Hitoshi Owada ◽  
Tomoko Ishii ◽  
Mayumi Takazawa ◽  
Hiroyasu Kato ◽  
Hiroyuki Sakamoto ◽  
...  

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.


2019 ◽  
Vol 7 (1) ◽  
pp. 126-136
Author(s):  
Hakan Çağlar ◽  
Arzu Çağlar

In this study, it is aimed to make improvements on blended brick (1) which is the first building material has a history of at least 10,000 years. To the blended brick which is a traditional material was kept constant at 5% the addition of fly ash which is industrial waste. It was aim of determine of the effect on the physical and mechanical properties of the blended brick using different ratios (5%, 10%, 15% and 20%) blast furnace slag. In the first stage, the production of fly ash-based blast furnace slag doped sample of blended brick was performed. In the second stage, a variety of experiments were applied to determine the physical and mechanical properties of the blended brick sample. As a result; It has been determined that unit volume weight and compressive strength decreases with the use of industrial wastes in blended brick production. They have occured an increase in porosity and capillary water absorption values. The use of industrial wastes in the production of blended bricks will contribute both improve the properties of the bricks and   the reduction of wastes left to the environment.


2016 ◽  
Vol 851 ◽  
pp. 141-146
Author(s):  
Jan Koplík ◽  
Miroslava Smolková ◽  
Jakub Tkacz

The ability of alkali-activated materials (AAMs) to fix and immobilize heavy metals was investigated. Two raw materials were used to prepare alkali-activated matrices – high-temperature fly ash and blast furnace slag (BFS). NaOH served as an alkaline activator. Two heavy metals (Mn, Ni) were added in different amounts to find out the influence of dosage of heavy metal on the mechanical properties of the matrices and the leachability. Leachability was measured as concentration of heavy metals in leachates (ČSN EN 12457-4) by inductively coupled plasma/optical emission spectrometry (ICP/OES). Structure of prepared matrices was characterized by scanning electron microscopy (SEM). Increasing of addition of heavy metals led to decrease of mechanical properties of matrices. The leaching tests showed, that both matrices can immobilize Mn and Ni in dosages of 0.1 – 2,5%. Higher dosages caused deterioration of the matrices and increased the leachability. After alkali activation both heavy metals were transformed into the form of insoluble salts.


2013 ◽  
Vol 325-326 ◽  
pp. 67-70
Author(s):  
Yun Feng Li ◽  
Mi Xue Han ◽  
Li Xu

The mineral admixtures mixed into concrete have important effects on concrete performance. The workability and mechanical properties of the concrete are studied with different dosages of admixtures, such as steel slag powder, blast furnace slag powder and fly ash. The results show that fly ash has more advantages in improving the performance of the concrete. When steel slag powder, blast furnace slag powder and fly ash, respectively, replace the amount of cement to 30%, 30%, 20%, the mechanical properties of the concrete are improved significantly.


2017 ◽  
Vol 141 ◽  
pp. 111-117 ◽  
Author(s):  
Shukai Cheng ◽  
Zhonghe Shui ◽  
Tao Sun ◽  
Rui Yu ◽  
Guozhi Zhang ◽  
...  

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