scholarly journals Properties of Alkali-Activated Slag Paste Using New Colloidal Nano-Silica Mixing Method

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1571 ◽  
Author(s):  
Taewan Kim ◽  
Jae Hong Kim ◽  
Yubin Jun
Keyword(s):  
Substitution Rate ◽  
Setting Time ◽  
High Strength ◽  
Nano Silica ◽  
Replacement Rate ◽  
Substitution Method ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Mixing Water ◽  
Alkali Activated

Previous studies of alkali-activated slag cement (AASC) using nano-silica have mentioned mostly powdered nano-silica and binder weight replacement methods, which have a rapid decrease in fluidity, a short setting time and a low nano-silica replacement rate (< 5%). In this study, colloidal nano-silica (CNS) was used and the mixing-water weight substitution method was applied. The substitution method was newly applied to improve the dispersibility of nano-silica and to increase the substitution rate. In the experiment, the CNS was replaced by 0, 10, 20, 30, 40, and 50% of the mixing-water weight. As a result, as the substitution rate of CNS increased, the fluidity decreased, and the setting time decreased. High compressive strength values and increased rates were also observed, and the diameter and volume of pores decreased rapidly. In particular, the increase of CNS replacement rate had the greatest effect on decrease of medium capillary pores (50–10 nm) and increase of gel pores (< 10 nm). The new displacement method was able to replace up to 50% of the mixing water. As shown in the experimental results, despite the high substitution rate of 50%, the minimum fluidity of the mixture was secured, and a high-strength and compact matrix could be formed.

scholarly journals Influence of Na2O Content and Ms (SiO2/Na2O) of Alkaline Activator on Workability and Setting of Alkali-Activated Slag Paste

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2072 ◽  
Author(s):  
Sung Choi ◽  
Kwang-Myong Lee
Keyword(s):  
Setting Time ◽  
High Strength ◽  
Abrupt Decrease ◽  
Na2o Content ◽  
Alkali Activated Slag ◽  
Granulated Blast Furnace Slag ◽  
Type Composition ◽  
Activated Slag ◽  
Binary Alkaline ◽  
Alkali Activated

The performance of alkali-activated slag (AAS) paste using activators of strong alkali components is affected by the type, composition, and dosage of the alkaline activators. Promoting the reaction of ground granulated blast furnace slag (GGBFS) by alkaline activators can produce high-strength AAS concrete, but the workability might be drastically reduced. This study is aimed to experimentally investigate the heat release, workability, and setting time of AAS pastes and the compressive strength of AAS mortars considering the Na2O content and the ratio of Na2O to SiO2 (Ms) of binary alkaline activators blended with sodium hydroxide and sodium silicate. The test results indicated that the AAS mortars exhibited a high strength of 25 MPa at 24 h, even at ambient temperature, even though the pastes with an Na2O content of ≥6% and an Ms of ≥1.0 exhibited an abrupt decrease in flowability and rapid setting.

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 Reuse of volcanic mud to controlled low-strength materials with cement and alkali-activated slag binders

2019 ◽  
Vol 107 ◽  
pp. 01008
Author(s):  
Chung-Ho Huang ◽  
Hao-Yu Fang
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Sodium Oxide ◽  
Engineering Properties ◽  
Fine Aggregate ◽  
Replacement Rate ◽  
Alkali Activated Slag ◽  
Low Strength ◽  
Activated Slag ◽  
Alkali Activated

This paper aims to evaluate the applicability of volcanic mud as the fine aggregate for controlled low-strength material (CLSM) by the experimental method. Two types of binder were selected, including cement and alkali-activated slag binders (without cement). The study mainly explored the effects of different addition rates of volcanic mud and different concentrations of alkaline agents (sodium hydroxide) on the engineering properties of CLSM. The test results show that the CLSMs with cement and volcanic mud have better workability and less water bleeding. However, the compressive strength of CLSM decreases as the replacement rate of volcanic mud increases, and the setting time also increases. The replacement rate of volcanic mud is recommended to be 20%. The volcanic mud mixed with the alkali-activated slag binder (without cement) can be successfully made into CLSM. When the concentration of sodium oxide in CLSM is 5%, although the compressive strength is highest at 7 days or 28 days, it cannot be hardened at the early age (before four days) and without compressive strength. CLSM with 20% sodium oxide concentration has poor workability. Its compressive strength is slightly lower than that of the 10% group. Therefore, the amount of calcium hydroxide recommended is 10%.

Experimental Study on Alkali-Activated Slag-Lithium Slag-Fly Ash Environmental Concrete

2011 ◽  
Vol 287-290 ◽  
pp. 1237-1240
Author(s):  
Lan Fang Zhang ◽  
Rui Yan Wang
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Fly Ash ◽  
Setting Time ◽  
Alkali Activated Slag ◽  
Percent Increase ◽  
Compressive Strength Of Concrete ◽  
Activated Slag ◽  
Lithium Slag ◽  
Alkali Activated

The aim of this paper is to study the influence of lithium-slag and fly ash on the workability , setting time and compressive strength of alkali-activated slag concrete. The results indicate that lithium-slag and fly-ash can ameliorate the workability, setting time and improve the compressive strength of alkali-activated slag concrete，and when 40% or 60% slag was replaced by lithium-slag or fly-ash, above 10 percent increase in 28-day compressive strength of concrete were obtained.

Effect of nano-silica on hydration, microstructure of alkali-activated slag

2019 ◽  
Vol 220 ◽  
pp. 110-118 ◽  
Author(s):  
Jinbang Wang ◽  
Peng Du ◽  
Zonghui Zhou ◽  
Dongyu Xu ◽  
Ning Xie ◽  
...  
Keyword(s):  
Nano Silica ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated
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