scholarly journals Effects of Light-Burnt Dolomite Incorporation on the Setting, Strength, and Drying Shrinkage of One-Part Alkali-Activated Slag Cement

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2874 ◽  
Author(s):  
In Kyu Jeon ◽  
Jae Suk Ryou ◽  
Sadam Hussain Jakhrani ◽  
Hong Gi Kim
Keyword(s):  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Setting Time ◽  
Drying Shrinkage ◽  
Slag System ◽  
Strength Development ◽  
Alkali Activated Slag ◽  
Granulated Blast Furnace Slag ◽  
Activated Slag ◽  
Alkali Activated

This study investigates the potential of light-burnt dolomite (LBD) as a supplementary cementitious material with ground granulated blast furnace slag (GGBFS) and Ordinary Portland cement (OPC). In this work, LBD was substituted for up to 20% of GGBFS in sodium sulfate-activated slag systems. The effects of LBD incorporation on the flow, setting time, compressive and flexural strength development, and drying shrinkage were explored with, X-ray diffraction and thermogravimetric analyses. LBD incorporation resulted in greater strength development of an alkali-activated slag system. The optimum LBD content for strength development was 10%, regardless of ordinary Portland cement content. In addition, LBD decreased the drying shrinkage, accelerated the hydration process, and induced hydrotalcite formation, which can be attributed to the reactive MgO inside LBD.

Effect of Alkali-Activators on the Strength Development and Drying Shrinkage of Alkali-Activated Binder

2012 ◽  
Vol 482-484 ◽  
pp. 1012-1016
Author(s):  
Mao Chieh Chi ◽  
Jiang Jhy Chang ◽  
Ran Huang ◽  
Zai Long Weng
Keyword(s):  
Ph Value ◽  
Setting Time ◽  
Drying Shrinkage ◽  
Strength Development ◽  
Modulus Ratio ◽  
Alkali Activated Slag ◽  
Key Factor ◽  
Activated Slag ◽  
Portland Cement Paste ◽  
Alkali Activated

The purpose of this study is to investigate the effect of various contents and modulus ratios of alkali activators on strength development and drying shrinkage of alkali-activated slag pastes. Experimental results show that the alkali-modulus ratio is the key factor influencing pH value and drying shrinkage. The lower the alkali-modulus ratio is, the higher the pH value is, and the lower the drying shrinkage is. In addition, the increase of the amount of alkali-activators decreases the initial and final setting time. The compressive strength of alkali-activated slag pastes is higher than that of Portland cement paste at all ages.

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.

A Review of Alkali-Activated Slag as Cement Replacement

2019 ◽  
Vol 803 ◽  
pp. 262-266
Author(s):  
Osama Ahmed Mohamed ◽  
Maadoum M. Mustafa
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Construction Industry ◽  
Ordinary Portland Cement ◽  
Environmental Footprint ◽  
Alkali Activated Slag ◽  
Cement Replacement ◽  
Activated Slag ◽  
Alkali Activated

Alkali activated slag (AAS) offers opportunities to the construction industry as an alternative to ordinary Portland cement (OPC). The production of OPC and its use contributes significantly to release of CO2 into the atmosphere while AAS is an industrial by-product that contributes much less to the environmental footprint that needs to be recycled if not landfilled. This paper outlines some of the key properties, merits and demerits of AAS when used as alternative to OPC. Competitive compressive strength of AAS concrete is amongst of the advantages of replacing cement with AAS while high shrinkage and carbonation levels are potential disadvantages.

scholarly journals A Review of Durability and Strength Characteristics of Alkali-Activated Slag Concrete

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1198 ◽  
Author(s):  
Osama Ahmed Mohamed
Keyword(s):  
Rapid Development ◽  
Setting Time ◽  
High Rate ◽  
Alkali Activation ◽  
Promising Alternative ◽  
Alkali Activated Slag ◽  
Granulated Blast Furnace Slag ◽  
High Alkalinity ◽  
Activated Slag ◽  
Alkali Activated

Alkali-activated slag (AAS) is a promising alternative to ordinary Portland cement (OPC) as sole binder for reinforced concrete structures. OPC is reportedly responsible for over 5% of the global CO2 emission. In addition, slag is an industrial by-product that must be land-filled if not re-used. Therefore, it has been studied by many investigators as environmentally friendly replacement of OPC. In addition to recycling, AAS offers favorable properties to concrete such as rapid development of compressive strength and high resistance to sulfate attack. Some of the potential shortcomings of AAS include high shrinkage, short setting time, and high rate of carbonation. Using ground granulated blast furnace slag (GGBS) as an alternative to OPC requires its activation with high alkalinity compounds such as sodium hydroxide (NaOH), sodium sulfate (Na2SO3), sodium carbonate (Na2CO3), or combination of these compounds such as NaOH and Na2SO3. The mechanism of alkali-activation is still not fully understood and further research is required. This paper overviews the properties, advantages, and potential shortcomings of AAS concrete.

scholarly journals Effect of Mixture Variables on Durability for Alkali-Activated Slag Cementitious

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2252 ◽  
Author(s):  
Chi-Che Hung ◽  
Yuan-Chieh Wu ◽  
Wei-Ting Lin ◽  
Jiang-Jhy Chang ◽  
Wei-Chung Yeih
Keyword(s):  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Chloride Permeability ◽  
Alkali Activated Slag ◽  
Binder Ratio ◽  
Activated Slag ◽  
Alkali Activated ◽  
Ordinary Portland Cement Concrete

In this study, the influence of three mixture variables named Sand/Aggregate ratio, Liquid/Binder ratio, and Paste/Aggregate ratio on the cementitious properties were studied. The durability of cementitious including absorption, absorption rate, resistivity, rapid chloride permeability index, and carbonation rate were examined. Results showed that the alkali-activated slag cementitious has superior durability. The trends of influences on the composites properties for these three mixture variables are similar to those for the ordinary Portland cement concrete. It means that the experiences for making the ordinary Portland cement concrete should be able to be used for the alkali-activated slag cementitious. This paper also provides a lot of data for the alkali-activated slag cementitious for future development of the mix design.

scholarly journals Understanding the Role of Metakaolin towards Mitigating the Shrinkage Behavior of Alkali-Activated Slag

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6962
Author(s):  
Bo Fu ◽  
Zhenyun Cheng ◽  
Jingyun Han ◽  
Ning Li
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Drying Shrinkage ◽  
Activator Concentration ◽  
Reaction Products ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated ◽  
Shrinkage Behavior

This research investigates the mechanism of metakaolin for mitigating the autogenous and drying shrinkages of alkali-activated slag with regard to the activator parameters, including concentration and modulus. The results indicate that the incorporation of metakaolin can decrease the initial viscosity and setting time. Increasing activator concentration can promote the reaction process and shorten the setting time. An increase in the metakaolin content induces a decrease in compressive strength due to reduced formation of reaction products. However, increasing activator dosage and modulus can improve the compressive strength of alkali-activated slag containing 30% metakaolin. The inclusion of metakaolin can mitigate the autogenous and drying shrinkage of alkali-activated slag by coarsening the pore structure. On the other hand, increases in activator concentration and modulus result in an increase in magnitude of the autogenous and drying shrinkage of alkali-activated slag containing metakaolin. The influence of the activator modulus on the shrinkage behavior of alkali-activated slag-metakaolin binary system should be further investigated.

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