Shrinkage of Fine-Grained Composites Based on Alkali-Activated Slag

2018 ◽  
Vol 761 ◽  
pp. 7-10 ◽  
Author(s):  
Barbara Kucharczyková ◽  
Vlastimil Bílek Jr. ◽  
Dalibor Kocáb ◽  
Ondřej Karel
Keyword(s):  
Experimental Investigation ◽  
Experimental Determination ◽  
Alkali Activated Slag ◽  
Fine Grained ◽  
Shrinkage Reducing Admixture ◽  
Activated Slag ◽  
Alkali Activated

The paper deals with the experimental determination of shrinkage development of the composites based on the alkali-activated slag (AAS). The main aim of the experimental investigation was to verify the effect of the addition of shrinkage-reducing admixture (SRA) on the overall process of shrinkage properties during AAS composites ageing.

scholarly journals Experimental and numerical analysis of the fracture response of alkali-activated slag-based materials

2020 ◽  
Vol 323 ◽  
pp. 01006
Author(s):  
Martin Lipowczan ◽  
David Lehký ◽  
Hana Šimonová ◽  
Barbara Kucharczyková
Keyword(s):  
Crack Model ◽  
Fracture Test ◽  
Mechanical Fracture ◽  
Alkali Activated Slag ◽  
Fine Grained ◽  
Shrinkage Reducing Admixture ◽  
Edge Notch ◽  
Fracture Tests ◽  
Activated Slag ◽  
Alkali Activated

The paper deals with the experimental and numerical determination of mechanical fracture parameters of fine-grained composites based on the alkali-activated slag (AAS) at different ages of hardening. Two AAS composites, which differed only in the presence of shrinkage reducing admixture, were studied. The prismatic specimens with the nominal dimensions of 40 × 40 × 160 mm and initial central edge notch were subjected to fracture tests in a three-point bending configuration. The results of the fracture tests in the form load F versus deflection d diagrams were used as input data for the identification of parameters via the inverse analysis based on the artificial neural network whose aim is to transfer the fracture test response data to the desired material parameters. The modulus of elasticity, tensile strength, and fracture energy values were identified and subsequently compared with values obtained based on the direct fracture test evaluation using the effective crack model and work-of-fracture method.

Experimental Determination of Early Shrinkage of Alkali-Activated Slag

2019 ◽  
Vol 292 ◽  
pp. 114-119
Author(s):  
Martin Alexa ◽  
Dalibor Kocáb ◽  
Barbara Kucharczyková ◽  
Jan Kotrla
Keyword(s):  
Autogenous Shrinkage ◽  
Volume Changes ◽  
Alkali Activated Slag ◽  
Detailed Evaluation ◽  
The Difference ◽  
Organic Admixture ◽  
Activated Slag ◽  
The Relationship ◽  
Alkali Activated

This paper deals with the relationship between chemical processes in the early stages of hydration of alkali-activated slag, volume changes and the development of the microstructure of this material. Two test pastes were produced for the purpose of the experiment - one with and the other without an organic admixture (isopropyl alcohol). The pastes were used to monitor autogenous shrinkage by measuring volume changes and at the same time the changes in the material during setting and early hardening using a modern ultrasonic instrument Vikasonic. The output of the described experiment is a detailed evaluation of the difference in the behaviour of the used alkali-activated paste with and without the addition of an organic admixture.

Experimental investigation of mix design for high-strength alkali-activated slag concrete

2021 ◽  
Vol 291 ◽  
pp. 123387
Author(s):  
Nilvan T. Araújo Júnior ◽  
Victor M.E. Lima ◽  
Sara M. Torres ◽  
Priscilla E.A. Basto ◽  
Antônio A. Melo Neto
Keyword(s):  
Experimental Investigation ◽  
High Strength ◽  
Mix Design ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated

Shrinkage-Reducing Admixture Efficiency in Alkali-Activated Slag across the Different Doses of Activator

2018 ◽  
Vol 761 ◽  
pp. 19-22 ◽  
Author(s):  
Vlastimil Bílek Jr. ◽  
Lukáš Kalina ◽  
Ondřej Fojtík
Keyword(s):  
Compressive Strength ◽  
Drying Shrinkage ◽  
Strength Development ◽  
Alkali Activated Slag ◽  
Reducing Ability ◽  
Wide Range ◽  
Shrinkage Reducing Admixture ◽  
Negative Effect ◽  
Activated Slag ◽  
Alkali Activated

One of the largest obstacles for the wider use of alkali-activated slag (AAS) in a building industry is its severe drying shrinkage. According to some studies shrinkage-reducing admixtures (SRAs) could be a solution of this problem, but they were also reported to have a fatal impact on AAS hydration resulting in a serious strength development slowdown. The aim of this paper was to investigate this phenomenon in a wide range of the waterglass doses (4–12% Na2O of the slag mass). Mortars without and with 2% of SRA based on hexylene glycol were prepared and their shrinkage and compressive strength development was tested. By far the highest shrinkage reduction was observed for the lowest doses of waterglass, but these were also the cases of the highest compressive strength decrease. However, it is possible to suppress the negative effect of SRA on AAS strength development through the activator dose increase with certainly decreased shrinkage reducing ability of SRA.

scholarly journals THE INFLUENCE OF A SHRINKAGE REDUCING ADMIXTURE ON THE LONG-TERM DEVELOPMENT OF DYNAMIC PROPERTIES IN ALKALI-ACTIVATED SLAG

2019 ◽  
Vol 22 ◽  
pp. 1-6
Author(s):  
Martin Alexa ◽  
Dalibor Kocáb ◽  
Barbara Kucharczyková ◽  
Jan Kotrla
Keyword(s):  
Dynamic Properties ◽  
Resonance Method ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Alkali Activated Slag ◽  
Shrinkage Reducing Admixture ◽  
Activated Slag ◽  
Alkali Activated

The paper investigates the way a shrinkage-reducing admixture affects the long-term development of dynamic properties in mortars made with alkali-activated slag (AAS). Two AAS mortars were tested - one contained a shrinkage-reducing admixture, the other did not. The specimens (prisms of 40 × 40 × 160mm) were observed for changes in the dynamic modulus of elasticity at ages of 3 days through 2 years using the ultrasonic pulse velocity test and the resonance method. Even though the statistical analysis of the results gave no proof that the shrinkage-reducing admixture affected the final values, the development of the elastic modulus appeared to follow a very interesting trend which is completely different from trends commonly observed in cement-based composites.

Influence of Polymer Additives on Mechanical Fracture Properties and on Shrinkage of Alkali Activated Slag Mortars

2018 ◽  
Vol 761 ◽  
pp. 39-44
Author(s):  
Olesia Mikhailova ◽  
Hana Šimonová ◽  
Libor Topolář ◽  
Pavel Rovnaník
Keyword(s):  
Drying Shrinkage ◽  
Polypropylene Glycol ◽  
Mechanical Fracture ◽  
Fracture Properties ◽  
Alkali Activated Slag ◽  
Shrinkage Reducing Admixture ◽  
Emission Activity ◽  
Polyethylene Glycol 1000 ◽  
Activated Slag ◽  
Alkali Activated

Alkali-activated slags represent an alternative to ordinary Portland cement due to reducing the environmental impact of the building industry. In spite of the numerous advantages of alkali activated slag mortars, alkali-activated aluminosilicates have big disadvantage – high value of shrinkage followed by formation of microcracks. This effect is caused by both autogenous and drying shrinkage and it finally results in volume contraction, microcracking and deterioration of the mechanical fracture properties. Therefore, using various types of polymer admixtures can overcome these problems. The aim of this paper is to present the effect of shrinkage-reducing admixture Peramin® SRA 40, polymer polyethylene glycol 1000 and polypropylene glycol on shrinkage and mechanical fracture characteristics of alkali-activated slag mortars. These admixtures were used in amount 0–2.0% weight of slag. The results showed that with increasing content of admixtures compressive and flexural strength decreased. Fracture tests with acoustic emission activity during this testing were carried out. Addition of 2% Peramin® SRA decreased shrinkage by 55%, but with 1% of Peramin® SRA the shrinkage was reduced only by 10%. Specimen with 1% of Peramin® is the most durable material, but more brittle compared to specimens with 1 and 2% of polypropylene glycol.

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