Influence of calcium and sodium nitrate on the strength and reaction products of the CaO-activated GGBFS system

Yum, Woo Sung; Suh, Jung-Il; Sim, Sungwon; Yoon, Seyoon; Jun, Yubin

doi:10.1016/j.conbuildmat.2019.04.240

Cited by 24 publications

(8 citation statements)

References 29 publications

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“…The gravitational mass change was recorded over time. Yum et al [ 38 , 39 , 40 ] discovered that thermogravitational characteristics can be analyzed more accurately by differentiating the data from TG (e.g., mass over temperature), which is known as differential thermogravimetry (DTG). Therefore, both TG and DTG were employed in this study (i.e., TG/DTG).…”

Section: Methodsmentioning

confidence: 99%

Use of Bacteria to Activate Ground-Granulated Blast-Furnace Slag (GGBFS) as Cementless Binder

Yum¹,

2022

Materials

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Ground-granulated blast-furnace slag (GGBFS) can be used as a cementless binder after activation. Recent approaches to activate GGBFS have focused on chemical methods that use NaOH, KOH, and CaO. This study introduces the use of bacteria to activate GGBFS as a biological approach. The presence of bacteria (volumetric ratio), curing temperature (23 °C and 60 °C), and number of curing days (3, 7, and 28 d) are investigated. The use of urea is considered owing to the possibility of calcium carbonate formation. The activated GGBFS is evaluated in the form of a cube (5 cm × 5 cm × 5 cm) for its strength, mineral identification, and pore size distribution. A brick (19 cm × 9 cm × 5.7 cm) is prefabricated to see the feasibility of commercializing bacteria-activated GGBFS based on water absorption and strength measurements. All results are compared with those of water-activated GGBFS. The results indicate that the use of urea inhibits the strength improvement of bacteria-activated GGBFS. Bacterial suspension enhances the GGBFS strength at a curing temperature of 60 °C. Mineral identification tests show that the strength increase is primarily due to the formation of calcite. The compressive strength satisfies the commercial standard of concrete bricks; however, the water absorption rate must be resolved.

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Section: Methodsmentioning

confidence: 99%

Use of Bacteria to Activate Ground-Granulated Blast-Furnace Slag (GGBFS) as Cementless Binder

Yum¹,

2022

Materials

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“…The other binders (C-, F-, and N-binders) were CaO-activated GGBFS binders, which used CaO as a primary activator for activating GGBFS while included different additives. The C-binder, F-binder, and N-binder used CaCl 2 , Ca(HCOO) 2 , and Ca(NO 3 ) 2 , respectively, as additives, and their material proportions were determined via previous studies [ 21 , 24 , 25 ]. Note that F-binder and N-binder additionally used five weight percentages of CaSO 4 to enhance the early compressive strength of the binders.…”

Section: Methodsmentioning

confidence: 99%

“…On the other hand, the CaO-activated binder system [ 21 , 22 ] relatively overcame the disadvantages mentioned above of alkali-activated binders. Kim et al [ 23 ] studied CaO-activated GGBFS binder, and Yum et al [ 21 , 24 , 25 ] enhanced mechanical properties of CaO-activated GGBFS binders by adding different types of additional activators. In addition, there are studies to develop cementless binders by activating fly ash using CaO and other chemical additives [ 22 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

Mechanical and Durability Properties of Cementless Concretes Made Using Three Types of CaO-Activated GGBFS Binders

Yum

Jeon

et al. 2021

Materials

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This study examined the mechanical and durability properties of CaO-activated ground-granulated blast-furnace slag (GGBFS) concretes made with three different additives (CaCl2, Ca(HCOO)2, and Ca(NO3)2) and compared their properties to the concrete made with 100% Ordinary Portland Cement (OPC). All concrete mixtures satisfied targeted air content and slump ranges but exhibited significantly different mechanical and durability properties. The CaO-activated GGBFS concretes showed different strength levels, depending on the type of additive. The added CaCl2 was the most effective, but Ca(NO3)2 was the least effective at increasing mechanical strength in the CaO-activated GGBFS system. The OPC concrete showed the most excellent freezing–thawing resistance in the durability test, but only the CaO-activated GGBFS concrete with CaCl2 exhibited relatively similar resistance. In addition, the chemical resistance was significantly dependent on the type of acid solution and the type of binder. The OPC concrete had the best resistance in the HCl solution, while all CaO-activated GGBFS concretes had relatively low resistances. However, in the H2SO4 solution, all CaO-activated GGBFS concretes had better resistance than the OPC concrete. All concrete with sulfate ions had ettringite before immersion. However, when they were immersed in HCl solution, ettringite tended to decrease, and gypsum was generated. Meanwhile, the CaO-activated GGBFS concrete with CaCl2 did not change the type of reaction product, possibly due to the absence of ettringite and Ca(OH)2. When immersed in an H2SO4 solution, ettringite decreased, and gypsum increased in all concrete. In addition, the CaO-activated concrete with CaCl2 had a considerable amount of gypsum; it seemed that the dissolved C-S-H and calcite, due to the low pH, likely produced Ca2+ ions, and gypsum formed from the reaction between Ca2+ and H2SO4.

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“…Some chemicals have been used as accelerators in the recent years. Especially, inorganic salts containing ions with lower activity such as Ca(NO2)2, Ca(NO3)2 are used as accelerators [6,7]. However, for these chemicals to be used, appropriate mixing ratios must be obtained by experiment.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the type of concrete that gains early strength is extremely important for the prefabricated industry. There are many studies on early strength gain of concrete [4][5][6][7]. The early-strength concrete should be able to meet the minimum requirements of concrete in terms of mechanical and durability.…”

Section: Introductionmentioning

confidence: 99%

Priz Hızlandırıcı Katkılı Betonun Mekanik ve Dayanıklılık Özelliklerinin Taguchi Optimizasyonu

Çöğürcü

Uzun

2022

Politeknik Dergisi

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Influence of calcium and sodium nitrate on the strength and reaction products of the CaO-activated GGBFS system

Cited by 24 publications

References 29 publications

Use of Bacteria to Activate Ground-Granulated Blast-Furnace Slag (GGBFS) as Cementless Binder

Use of Bacteria to Activate Ground-Granulated Blast-Furnace Slag (GGBFS) as Cementless Binder

Mechanical and Durability Properties of Cementless Concretes Made Using Three Types of CaO-Activated GGBFS Binders

Priz Hızlandırıcı Katkılı Betonun Mekanik ve Dayanıklılık Özelliklerinin Taguchi Optimizasyonu

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