• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.11a
• /
• pp.127-128
• /
• 2022

In order to realize carbon neutrality in the international society, research on supplementary cementitious materials(SCMs) has been actively conducted as a way to reduce carbon dioxide emissions in the cement industry. However, the use of SCMs causes problems of initial hydration delay and strength reduction due to the reduction of tricalcium silicate(C3S) in the cement clinker. Therefore, in this study, the initial hydration and basic characteristics of cement mortar were confirmed by adding a C-S-H based hardening acceleration to blended cement mixed with Portland cement, blast furnace slag, fly ash, and limestone power. As a result of the heat of hydration and compressive strength test, it was confirmed that when hardening acceleration was added, the initial reactivity was high, so the heat of hydration was promoted, and the initial strength was increased. It is considered to be due to C-S-H seeding effect. Therefore, it is judged that the use of C-S-H based hardening acceleration can supplement the problem of initial hydration delay of blended cement in Korea.

• Journal of the Korean Ceramic Society
• /
• v.35 no.2
• /
• pp.185-195
• /
• 1998

This experiment carried out in order to investigate the effect of the chemical activators for acceleration of hydration the system of Fly ash-Cao The paste was consisted of 80wt% Fly ash and 20wt% CaO with 1. 3. 5wt% of 4 activators(N{{{{ alpha _2 }}S{{{{ OMICRON _4 }}, CaC{{{{ {l }_{2 } }}, NaOH, Ca(N{{{{ OMICRON _3 {)}_{2 } }} and W/S ratio of 0.42 After curing for 1, 3, 7, 14, 28 days the paste hydration was characterized by the measurement of compressive strength XRD analysis SEM observation the combined water and the reaction amount of Ca(OH)2 determination. As a result of this ex-periment all of the system which involved Na2SO4 or NaOH had a god compressive strength. In the case of 7 days curing a system which added CaCl2 showed the highest compressive strength among all especially NaOH system showed a high increase in strength as a dosage of it increased. Hydration products were different according to activatores added. Only C-S-H was observed in NaOH system. As the reaction amount of Ca(OH)2 and combined water were increased the compressive strength increased. There were few differences in the comparision of strength between ignited loss 3.1% and loss 9.3% of fly ash.

• Journal of the Korea Concrete Institute
• /
• v.27 no.1
• /
• pp.3-9
• /
• 2015

In this study, hydration properties of ordinary Portland cement were examined, shown from a limestone and blast furnace slag alone or their mixture up to 10% as a minor mineral additives. As of setting time, it was identified that final setting became faster as the amount of limestone mixture increased, which showed limestone accelerated early hydration faster than blast furnace slag. This is because limestone did accelerate the hydration of alite. At the age of 3 days, limestone 5%-blast furnace slag 5% mixture had the highest compressive strength of mortar. It is because hydration acceleration of alite by limestone, and $Ca(OH)_2$ that was additionally formed by hydration acceleration of alite reacted with blast furnace slag, and as a result, additionally created C-S-H hydrate. Regarding the hydration properties by the age of 7 and 28 days, limestone 3%-blast furnace slag 7% of composited mixture showed the largest compressive strength, and in comparison with the 3 days in curing age. This period is when hydration reaction of blast furnace slag is active and the amount of hydrate depends on the amount of blast furnace slag mixture more than that of the limestone mixture. And in order to vitalize hydration reaction of blast furnace slag the amount of $Ca(OH)_2$ created has to increase, and thus, a small amount of limestone is necessary that can accelerate the hydration of alite. Therefore, after the age of 7 days, the fact that there were a large amount of blast furnace slag mixture and small amount of limestone mixture was effective to the strength development of ordinary Portland cement.

• Journal of the Korea Institute of Building Construction
• /
• v.12 no.4
• /
• pp.369-376
• /
• 2012

In this study, to reduce the hydration heat velocity (HHV) of high-strength mass concrete at early ages, phase change materials (PCM) that could absorb hydration heat were applied, and the changes in autogenous shrinkage were investigated, as well as the relationship between the hydration temperature and autogenous shrinkage. The acceleration of the cement hydration process by the PCM leads to an early setting and a higher development of the compressive strength and elastic modulus of concrete at very early ages. The function of PCM could be worked below the original melting point due to the eutectic effect, while the hydration temperature and HHV of high-strength mass concrete can be decreased through the use of the PCM. A close relationship was found between the hydration temperature and autogenous shrinkage: the higher the HHV, the greater the ultimate autogenous shrinkage.

• Journal of the Korean Ceramic Society
• /
• v.22 no.6
• /
• pp.15-20
• /
• 1985

In the course of cement hydration it was found that the addition of polyvinyl alcohol(contracted as PVA. here after) only in the cement paste could more influence on the set-retardation the depression of heat evol-ution rate than that of montmorillonit only or PVA-montmorillonie intercalation complex (PMIC) due to the effective adsorption of PVA on cement particles. The improved mechanical strength by addition of montmorillonite and PMIC was observed remarkably up to 0.05wt% due to the decrease of macro-pores caused by lowed viscosity or the acceleration of hydration reaction.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.12
• /
• pp.1327-1331
• /
• 2005

This study was to investigate the reduction of hydration heat by utilizing industrial by-products such as BFS(Blast Furnace Slag). DM(Dredged Mud) was used by parent soil and Ordinary portland cement was used by cementing material. Additive added to reduce the heat of hydration was BFS. From the results of experiment, hydration heat was decreased in accordance with the addition of BFS. The reason was that surface of BFS coated with aluminosulfate. Initial uniaxial strength was low, neither was not long term uniaxial strength. It was concluded that silica rich layer($H_2SiO_4^{4-}$) in solid phase early in the reaction of hydration was difficultly moved in liquid phase due to the increase of ZP(Zeta Potential). However, the ZP in the later hydration was decreased due to the acceleration of mobility of silica rich layer($H_2SiO_4^{4-}$). Therefore, long term physical properties such as uniaxial strength revealed.

• Korean Journal of Materials Research
• /
• v.12 no.7
• /
• pp.540-544
• /
• 2002

Hydration treatments were performed on the pure aluminum substrate at $100^{\circ}C$ followed by anodizing and heat treatments on the layers. The transformation behaviors of the oxide layers according to the hydration treatment were studied using TEM, XRD, RBS etc. Above $90^{\circ}C$ the hydrous oxide film could be formed, which were turned out to be hydrous oxides(AlOOH $nH_2$O). The anodization on the hydrous oxide film was more effective for the transition of amorphous anodic oxides to the crystalline $\Upsilon-Al_2$ $O_3$ comparing with the case for anodizing on the aluminum substrate without hydration treatment And additional heat treatments were also helpful for the acceleration of the transformation of the hydrous oxide to $\Upsilon-Al_2$ $O_3$. During the heat treatment the interface between $\Upsilon-Al_2$ $O_3$and the hydrous oxide layers migrated to the outer side of hydrous layer.

• Applied Chemistry for Engineering
• /
• v.22 no.4
• /
• pp.423-428
• /
• 2011

Hydration characteristics of cement containing zeolite mined at Daepo in Gyeongbuk province were studied for use as a mineral admixture. The cement paste containing zeolite was characterized by the measurement of heat evolution, XRD, EDS, nitrogen adsorption and mercury intrusion porosimetry. The cement paste containing zeolite exhibited tendencies toward acceleration of paste setting and promotion of cement hydration with the increase of zeolite content. The flow of mortar containing zeolite strongly reduced with increase of zeolite content. Compressive strength of the mortar containing zeolite increased very rapidly at an early age in comparison with plain mortar. These results would be related to aluminum species escaped from zeolite particles during the alkali dealumination of zeolite by the hydration process of cement.

• Applied Chemistry for Engineering
• /
• v.10 no.8
• /
• pp.1124-1128
• /
• 1999

In this study the effect of organic additive, triethanolamine(TEA), and temperature change of accelerator for shotcrete was studied. Then the amount of accelerator, temperature and W/C were experimentally investigated. Effects of hydration time and hydration heat of concrete on organic additive amount were analysed by DSC, SEM and XRD. We found that the hydration heat was increased and hydration time was decreased with TEA(<5 wt %). The order of hydration rate of potassium accelerator was PA < PC-3 < PC-5 < PC-8.

• Journal of the Korean Ceramic Society
• /
• v.25 no.1
• /
• pp.15-20
• /
• 1988

In this study, the specimens of cement clinker minerals such as 80C3-S-15C4AF-5C3A added various blending materials were immersed in artificial seawater. In order to ascertain the effect of SO3 and blending materials on seawater resistance of the specimens, the acceleration experiment in the artificial seawater was carried out by repeating of immersion and drying operation periodically. As inner part of the specimen immersed in artificial seawater, Friedel's salt was produced by reaction with Cl ion. In outer part of the specimen, gypsum and ettringite were mainly formed. With the increase of SO3 content in the specimen the formation of ettringite was increased and Frieldel's salt in inner part was decreased. Total pore volume of the specimens was increased according to the amount of Cl ion penetrated and Mg(OH)2 leached in the solution.