Evaluation of strength and set behavior of mortar containing shotcrete set accelerators

2008 ◽  
Vol 35 (4) ◽  
pp. 400-407 ◽  
Author(s):  
Jincheol Kim ◽  
Jonghyun Ryu ◽  
R. D. Hooton
Keyword(s):  
Compressive Strength ◽  
Calcium Aluminate ◽  
Setting Time ◽  
Strength Loss ◽  
Test Methods ◽  
Calcium Aluminate Cement ◽  
Cement Matrix ◽  
Early Age ◽  
Rapid Setting ◽  
Aluminate Cement

The influence of rapid-set accelerating admixtures on the setting behavior and early-age strength of a cement matrix was investigated to evaluate the appropriateness of the specification and test methods for shotcrete set accelerators. The results verified two different rapid setting behaviors according to the types of accelerator. The aluminate-base and the calcium aluminate cement-base accelerators facilitate hydration by formation of a calcium aluminate solid solution, whereas the alkali-free set accelerating agents present rapid setting time by the formation of ettringite. It was also found that the Vicat test was more desirable than the Gillmore test as the standard for setting time evaluation. Additionally, the cement mortar mixed with the aluminate-base and the calcium aluminate cement-base accelerators exhibited very fast development of early-age compressive strength. However, most of the set accelerators, except for alkali-free accelerators, failed to satisfy the specification because of greater than 40% compressive strength loss at 28 d.

scholarly journals Development of Strength for Calcium Aluminate Cement Mortars Blended with GGBS

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Hee Jun Yang ◽  
Ki Yong Ann ◽  
Min Sun Jung
Keyword(s):  
Calcium Aluminate ◽  
Setting Time ◽  
Isothermal Condition ◽  
Microscopic Analysis ◽  
Calcium Aluminate Cement ◽  
Cement Matrix ◽  
Strength Development ◽  
Hydration Kinetics ◽  
Calorimetric Analysis ◽  
Aluminate Cement

In the present study, the development of strength in different calcium aluminate cement (CAC) mixture mortars with granulated ground blast-furnace slag (GGBS) was investigated. The substitution of GGBS levels was 0, 20, 40, and 60% weight of binder, of which the CAC used in this study naturally contained C2AS clinker as a secondary phase. To activate a hydraulic nature of the phase, in addition to the mineral additive, all specimens were cured at 35 ± 2°C for the first 24 hours and then stored in a 95% humidity chamber at 25 ± 2°C. The penetration resistance of fresh mortar was measured immediately after pouring, and the mortar compressive strength was monitored for 365 days. Simultaneously, to evaluate the hydration kinetics at early ages, in terms of heat evolution, the calorimetric analysis was performed at the isothermal condition (35°C) for 24 hours. The hydration behavior in the long term was characterized by X-ray diffraction, which was supported by microscopic observation using scanning electron microscopy with energy dispersive spectroscopy. Furthermore, an examination of the pore structure was accompanied to quantify the porosity. As a result, it was found that an increase in the GGBS content in the mixture resulted in an increased setting time, as well as total heat evolved for 24 hours in normalized calorimetry curves. In addition, the strength development of mortar showed a continuous increased value up to 365 days, accounting 43.8–57.5 MPa for the mixtures, due to a formation of stratlingite, which was identified at the pastes cured for 365 days using chemical and microscopic analysis. However, GGBS replacement did not affect on the pore size distribution in the cement matrix, except for total intrusion volume.

Application of ultrasonic testing to describe the hydration of calcium aluminate cement at the early age

2001 ◽  
Vol 31 (3) ◽  
pp. 405-412 ◽  
Author(s):  
T Chotard ◽  
N Gimet-Breart ◽  
A Smith ◽  
D Fargeot ◽  
J.P Bonnet ◽  
...  
Keyword(s):  
Calcium Aluminate ◽  
Ultrasonic Testing ◽  
Calcium Aluminate Cement ◽  
Early Age ◽  
Aluminate Cement

PGA Fiber Reinforced Calcium Aluminate Cement for Orthopaedic Application

2016 ◽  
Vol 852 ◽  
pp. 1188-1193
Author(s):  
Yan Ni Tan ◽  
Liu Yong ◽  
Xiang He ◽  
Wen Wang ◽  
Dong Duan ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Calcium Aluminate ◽  
Fiber Composite ◽  
Calcium Aluminate Cement ◽  
Lower Strength ◽  
Crystalline Phases ◽  
Oxide Hydrate ◽  
In Vitro Biocompatibility ◽  
Aluminate Cement

Calcium aluminate cement (CAC) is a penitential candidate for bone replacements with good bioactivity but relative lower strength. In this study, biodegradable PGA fiber was incorporated into the CAC paste in order to improve the strength of the material. And MC3T3 cells were seeded on the surface of CAC and CAC/fiber to study their in vitro biocompatibility. The results indicate that the PGA fiber can improve the compressive strength of CAC without changing the crystalline phases and micromorphology. Calcium aluminate oxide hydrate, katoite and Gibbsite crystals were detected by XRD. Plate-like crystals can be observed under FESEM. The MC3T3 cells were attached well on both CAC and CAC/fiber composite, indicating their good in vitro biocompatibility. In summary, fiber reinforcement can be an effective way to improve the properties of calcium aluminate cement for orthopaedic application.

Different Chlorides Attack on the Hydration of Calcium Aluminate Cement at 5~40°C

2021 ◽  
Vol 1036 ◽  
pp. 247-254
Author(s):  
Zhong Ping Wang ◽  
Yu Ting Chen ◽  
Xiang Peng ◽  
Ling Lin Xu
Keyword(s):  
Compressive Strength ◽  
Calcium Aluminate ◽  
Physical Adsorption ◽  
Calcium Aluminate Cement ◽  
Binding Ability ◽  
Cement Pastes ◽  
Thermal Analyzer ◽  
Chloride Attack ◽  
Different Temperatures ◽  
Aluminate Cement

Calcium aluminate cement (CAC) has excellent resistance to seawater erosion, but the mechanism remains to be explored. Effects of NaCl and CaCl2 on the hydration of CAC at 5, 20 and 40°C were investigated in this paper by X-ray diffraction(XRD), thermal analyzer(TG-DSC), scanning electron microscopy(SEM), acoustic and electroacoustic spectrometer. Results show that the varieties of chlorides have great impacts on the chloride binding ability, mechanical properties and microstructure of cement pastes at different temperatures. At 5°C and 20°C, the formation of C2AH8 is suppressed by chloride attack. Though the addition of NaCl promotes the formation of CAH10, CaCl2 leads to a denser microstructure and the improvement in compressive strength. At 40°C, C2AH8 disappears by chloride attack, while C3AH6 and Friedel’s salt increase. Comparing with the attack of CaCl2, NaCl contributes to the formation of C3AH6. Therefore, it results in a the retraction in compressive strength, ascribing to a coarser structure. In addition, although NaCl is superior in chemical binding ability, CaCl2 has better physical adsorption ability which dominants the binding process, and thus leading to greater amount of bonded chloride than that with NaCl. This research provides the oretical basis for the application of CAC in marine environment.

Monitoring of Calcium Aluminate Cement Setting at the Early Age by Acoustic Emission Technique

2001 ◽  
Vol 206-213 ◽  
pp. 1851-1854
Author(s):  
Thierry J. Chotard ◽  
A. Smith ◽  
N. Gimet-Bréard ◽  
Marc Huger ◽  
D. Fargeot ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Calcium Aluminate ◽  
Calcium Aluminate Cement ◽  
Early Age ◽  
Acoustic Emission Technique ◽  
Aluminate Cement ◽  
Cement Setting

Effect of wollastonite and a bioactive glass-ceramic on the in vitro bioactivity and compressive strength of a calcium aluminate cement

2018 ◽  
Vol 44 (16) ◽  
pp. 19077-19083
Author(s):  
G. García-Álvarez ◽  
J.C. Escobedo-Bocardo ◽  
D.A. Cortés-Hernández ◽  
J.M. Almanza-Robles ◽  
B.A. Sánchez-Escobedo
Keyword(s):  
Compressive Strength ◽  
Bioactive Glass ◽  
Calcium Aluminate ◽  
Glass Ceramic ◽  
Calcium Aluminate Cement ◽  
In Vitro Bioactivity ◽  
Aluminate Cement
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