scholarly journals EFFECT OF CALCIUM NITRITE ON HYDRATION REACTION OF BLAST FURNACE SLAG

2020 ◽  
Vol 73 (1) ◽  
pp. 44-51
Author(s):  
Shuya OSAKI ◽  
Daiki ATARASHI ◽  
Hyeonjin SONG ◽  
Yuhji SUDOH
2021 ◽  
Vol 8 ◽  
Author(s):  
Fusheng Niu ◽  
Yukun An ◽  
Jinxia Zhang ◽  
Wen Chen ◽  
Shengtao He

In this study, the influence of steel slag (SS) content on the strength of the cementitious materials was investigated. The quaternary active cementitious material (CaO-SiO2-Al2O3-SO3) was prepared using various proportions of steel slag (SS), granulated blast furnace slag (BFS), and desulfurized gypsum (DG). The mechanism of synergistic excitation hydration of the cementitious materials was examined using various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). The strength of the mortar test block was initially increased and decreased later with the increase of the SS content. Mortar test block with 20% steel slag, 65% granulated blast furnace slag, and 15% desulfurized gypsum with 0.35 water-binder ratio showed the highest compressive strength of 57.3 MPa on 28 days. The free calcium oxide (f-CaO) in the SS reacted with water and produced calcium hydroxide (Ca(OH)2) which created an alkaline environment. Under the alkaline environment, the alkali-activated reaction occurred with BFS. In the early stage of hydration reaction, calcium silicate hydrate (C-S-H) gel and fibrous hydration product ettringite (AFt) crystals were formed, which provided early strength to the cementitious materials. As the hydration reaction progressed, the interlocked growth of C-S-H gel and AFt crystals continued and promoted the increase of the strength of the cementitious system.


2010 ◽  
Vol 64 (1) ◽  
pp. 48-53
Author(s):  
Takeshi ANSAI ◽  
Makoto NISHIKAWA ◽  
Yosaku IKEO ◽  
Etsuo SAKAI

2009 ◽  
Vol 63 (1) ◽  
pp. 22-27 ◽  
Author(s):  
Takeshi ANSAI ◽  
Makoto NISHIKAWA ◽  
Yosaku IKEO ◽  
Etsuo SAKAI

2008 ◽  
Vol 385-387 ◽  
pp. 625-628
Author(s):  
Sang Hyun Lee ◽  
Han Seung Lee

Life span of structures made with concrete was shortened by carbonation. This phenomenon makes pH in concrete lower. If pH value in concrete become below 10, rebar in concrete begin to be corroded. This pH value was effected by quantity of Ca(OH)2 that depends on cement types, hydration reaction and carbonation time. In this study, pH value and quantity of Ca(OH)2 in mortar which has blast furnace slag were tested according to hydration and carbonation time. As a test result, the more cement has blast furnace slag (BFS) and the longer carbonation time last, the lower pH value in mortar has. And using this quantitative analysis result of pH and Ca(OH)2, it may be used effectively when service life considering carbonation is predicted using FEMA.


Author(s):  
Hiyori Ishizuka ◽  
Hiromi Fujiwara ◽  
Masanori Maruoka ◽  
Tao Wang ◽  
Shintaro Tanaka

In recent years, deterioration of concrete structures of sewerage facilities due to sulfuric acid attacks has been progressing. Therefore, it can be concluded that the demand for sulfur-acid resistant concrete is extremely high. In addition, concerning recent global warming countermeasures, research and development is underway on low-carbon concrete that reduced cement, which emits a large amount of carbon dioxide during the manufacturing process. The purpose of this study is to develop low carbon concrete with high sulfur-acid resistance by replacing cement with large amounts of blast furnace slag and various admixtures. As a result, it was found that the sulfur-acid resistance was improved when using blast furnace slag fine powder and fly-ash. In particular, when cement content was 20% of binder by mass, it was confirmed that the sulfur-acid resistance was excellent. What is more, there was no loss in compressive strength. It was considered that almost Ca(OH) produced by hydration reaction of cement reacted with blast furnace slag and fly-ash, so the reaction of sulfur-acid and calcium hydroxide was suppressed.


2021 ◽  
Vol 74 (1) ◽  
pp. 349-356
Author(s):  
Takumi INO ◽  
Tsuyoshi SAITO ◽  
Kazuho SUZUKI ◽  
Tatsuhiko SAEKI

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1371 ◽  
Author(s):  
Jin-Young Lee ◽  
Jin-Seok Choi ◽  
Tian-Feng Yuan ◽  
Young-Soo Yoon ◽  
Denis Mitchell

For sustainable development in the construction industry, blast furnace slag has been used as a substitute for cement in concrete. In contrast, steel-making slag, the second largest by-product in the steel industry, is mostly used as a filler material in embankment construction. This is because steel-making slag has relatively low hydraulicity and a problem with volumetric expansion. However, as the quenching process of slag has improved recently and the steel making process is specifically separated, the properties of steel-making slag has also improved. In this context, there is a need to find a method for recycling steel-making slag as a more highly valued material, such as its potential use as an admixture in concrete. Therefore, in order to confirm the possibility of using electric arc furnace (EAF) oxidizing slag as a binder, a comparative assessment of the mechanical properties of concrete containing electric arc furnace oxidizing slag, steel-making slag, and granulated blast furnace (GBF) slag was performed. The initial and final setting, shrinkage, compressive and split-cylinder tensile strength of the slag concretes were measured. It was found that replacing cement with EAF oxidizing slag delayed the hydration reaction at early ages, with no significant problems in setting time, shrinkage or strength development found.


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