scholarly journals Alkali-Activated Slag cement: Alternative Adhesives for CFRP Sheets Bonded to Concrete at Elevated Temperatures

2020 ◽  
Vol 23 (3) ◽  
pp. 167-176
Author(s):  
Jing Zhu ◽  
Wenzhong Zheng ◽  
Lili Xie ◽  
Ning Ren ◽  
Yuxuan Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Heating Temperature ◽  
High Strength ◽  
Slag Cement ◽  
Alkali Activated Slag ◽  
Cfrp Sheets ◽  
Effects Of Temperature ◽  
Activated Slag ◽  
Alkali Activated

The properties and microstructures of alkali-activated slag cement (AASC) exposed to 20~1200°C were probed in this paper. The aim is to develop an eco-friendly fireproof high-strength adhesive with an optimum ratio and evaluate its usability for CFRP sheets bonded to concrete. The blast furnace slag and fly ash were employed as source materials (activated by potassium silicate, NaOH and Portland cement). The effects of slag content, activator nature and heating temperature on the compressive or bond properties were analyzed. The microstructures of the AASC exposed to different high temperatures were studied by two different techniques, including SEM and XRD analyses. The effects of temperature on the mechanical properties of AASC were first rising then descending, and the basic reason for the degradation of macro-mechanical properties is the deterioration of AASC microstructure. It is proved that AASC has comparable reinforcing effects as those of organic epoxy matrix.

The Characteristics of Alkali-Activated Slag Mortar containing Multi-Walled Carbon Nanotubes at Elevated Temperature

2021 ◽  
pp. 1-23
Author(s):  
Arash Sedaghatdoost ◽  
Kiachehr Behfarnia ◽  
Mohammad Bayati ◽  
Ali Hendi ◽  
Mohammad Sadegh Vaezi
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Mass Loss ◽  
Elevated Temperatures ◽  
Alkali Activated Slag ◽  
Ambient Temperatures ◽  
Multi Walled Carbon Nanotubes ◽  
Activated Slag ◽  
Walled Carbon Nanotubes ◽  
Alkali Activated

In the present paper, the effect of using multi-walled carbon nanotubes (MWCNTs) with different concentrations of 0, 0.05, 0.1, and 0.15 wt% on the mechanical properties and microstructure of alkali-activated slag (AAS) mortars at temperatures of 23, 200, 400, 600, and 800°C was investigated. In order to investigate the strength parameters of specimens, the mechanical strength and mass-loss of the specimens at ambient temperatures and after exposure to elevated temperatures were determined. Petrographic image analysis also was conducted to analyze the microstructures of the specimens. Moreover, the Image processing toolbox of Matlab software was used to calculate the pore area of the samples at room temperature. The results showed that the application of MWCNTs improved the mechanical properties of the AAS mortars at ambient and elevated temperatures. The addition of the MWCNTs improved the mechanical properties of the AAS mortars up to 69 and 85% for compressive and flexural strength, respectively. At 400°C, compressive strength increment of the specimens compensated the deterioration rate, which was about 3% mass-loss and this temperature should be considered the maximum tolerable degree for AAS mortars.

Research on Set Retarder of High and Super High Strength Alkali -Activated Slag Cement and Concrete

2011 ◽  
Vol 477 ◽  
pp. 164-169 ◽  
Author(s):  
Chang Hui Yang ◽  
Fang Wu ◽  
Ke Chen
Keyword(s):  
Setting Time ◽  
High Strength ◽  
Heat Evolution ◽  
Strength Development ◽  
Slag Cement ◽  
Alkali Activated Slag ◽  
Negative Effect ◽  
Cement And Concrete ◽  
Activated Slag ◽  
Alkali Activated

The set of alkali-activated slag cement (AASC) and concrete and the measures for set-retarding were reviewed. Due to the fast set of high and super high strength alkali-activated slag cement and concrete, an inorganic compound set retarder YP-3 was developed. The effect of the retarder on setting time and strength as well as heat evolution of AASC were tested, and the mechanism of the retarder was analysed. Results show that the retarder can regulate the initial set of high strength AASC in the range of 29hrs with little negative effect on its strength development. The retarder could react with silicate ions from liquid to rapidly form a compact film in early age of hydration of AASC, the film covered the surface of slag and obstructed R+ and OH- in contact with slag particle directly. Consequently the set of AAC was delayed.

scholarly journals The Effect of Different Types of Internal Curing Liquid on the Properties of Alkali-Activated Slag (AAS) Mortar

2021 ◽  
Vol 13 (4) ◽  
pp. 2407
Author(s):  
Guang-Zhu Zhang ◽  
Xiao-Yong Wang ◽  
Tae-Wan Kim ◽  
Jong-Yeon Lim ◽  
Yi Han
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Deionized Water ◽  
Internal Curing ◽  
Control Group ◽  
Alkali Activated Slag ◽  
Different Types ◽  
Naoh Solution ◽  
Activated Slag ◽  
Alkali Activated

This study shows the effect of different types of internal curing liquid on the properties of alkali-activated slag (AAS) mortar. NaOH solution and deionized water were used as the liquid internal curing agents and zeolite sand was the internal curing agent that replaced the standard sand at 15% and 30%, respectively. Experiments on the mechanical properties, hydration kinetics, autogenous shrinkage (AS), internal temperature, internal relative humidity, surface electrical resistivity, ultrasonic pulse velocity (UPV), and setting time were performed. The conclusions are as follows: (1) the setting times of AAS mortars with internal curing by water were longer than those of internal curing by NaOH solution. (2) NaOH solution more effectively reduces the AS of AAS mortars than water when used as an internal curing liquid. (3) The cumulative heat of the AAS mortar when using water for internal curing is substantially reduced compared to the control group. (4) For the AAS mortars with NaOH solution as an internal curing liquid, compared with the control specimen, the compressive strength results are increased. However, a decrease in compressive strength values occurs when water is used as an internal curing liquid in the AAS mortar. (5) The UPV decreases as the content of zeolite sand that replaces the standard sand increases. (6) When internal curing is carried out with water as the internal curing liquid, the surface resistivity values of the AAS mortar are higher than when the alkali solution is used as the internal curing liquid. To sum up, both NaOH and deionized water are effective as internal curing liquids, but the NaOH solution shows a better performance in terms of reducing shrinkage and improving mechanical properties than deionized water.

Influence of hydrated lime on mechanical and shrinkage properties of alkali-activated slag cement

2021 ◽  
Vol 289 ◽  
pp. 123201
Author(s):  
Juan He ◽  
Wenbin Bai ◽  
Weihao Zheng ◽  
Junhong He ◽  
Guochen Sang
Keyword(s):  
Hydrated Lime ◽  
Slag Cement ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated
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