The Effect of the Carbon Nanotubes on the Mechanical Fracture Properties of Alkali Activated Slag Mortars

2014 ◽  
Vol 617 ◽  
pp. 243-246 ◽  
Author(s):  
Libor Topolář ◽  
Hana Šimonová ◽  
Pavel Rovnaník ◽  
Pavel Schmid
Keyword(s):  
Carbon Nanotubes ◽  
Building Materials ◽  
Mechanical Performance ◽  
Drying Shrinkage ◽  
Mechanical Fracture ◽  
Fracture Properties ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
High Level ◽  
Alkali Activated

New nanomaterials such as carbon nanotubes and nanofibres considerably improve performance of current building materials and they can contribute to new application facilities. Alkali activated slag is a material having a great potential to be used in practice. The main drawback of this material is a high level of autogenous and especially drying shrinkage, which causes a deterioration of the mechanical fracture properties. The aim of this paper is introduce the effect of carbon nanotubes admixture on the microstucture and mechanical performance of alkali activated slag mortars. The three-point bending tests of specimens with central edge notch were performed. Method of acoustic emission was used during this testing.

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.

Effect of Spontaneous Drying on Mechanical Parameters of Alkali-Activated Slag Mortar

2014 ◽  
Vol 969 ◽  
pp. 144-147
Author(s):  
Pavel Rovnaník ◽  
Libor Topolář ◽  
Pavel Schmid ◽  
Zbyněk Keršner
Keyword(s):  
Drying Shrinkage ◽  
Industrial Applications ◽  
Fracture Parameter ◽  
Lower Strength ◽  
Mechanical Fracture ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
High Level ◽  
Parameter Values ◽  
Alkali Activated

Alkali-activated slag is a material which has great potential for use in industrial applications. The main drawback of this material is the high level of autogenous and especially drying shrinkage that affects it, causing the deterioration of its mechanical properties. Mechanical and mechanical fracture parameter values show that an alkali-activated slag composite which is saturated with water is more brittle and exhibits lower strength in comparison with the same material after being surface-dried. These results are essential for the adjustment of testing conditions in order to obtain accurate and reproducible results.

The Influence of Curing and Process of Hydration to Damping Coefficient of Alkali Activated Slag Mortars

2015 ◽  
Vol 1100 ◽  
pp. 21-24
Author(s):  
Kristýna Timcakova ◽  
Libor Topolář ◽  
Peter Rypák
Keyword(s):  
Acoustic Analysis ◽  
Drying Shrinkage ◽  
Analysis Method ◽  
Impact Echo ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
High Level ◽  
Non Destructive ◽  
Impact Echo Method ◽  
Alkali Activated

Non-destructive acoustic analysis method Impact-echo method as a traditional for civil engineering was used for experiment. This paper reports the experiment during hardening and drying of specimens of alkali activated slag mortars. Alkali activated slag is a material having a great potential to be used in practice. The main drawback of this material is a high level of autogenous and especially drying shrinkage, which causes a deterioration of the mechanical properties. The aim of this paper is introduce the effect of method curing of mortars and time curing on the microstructure of alkali activated slag mortars. An understanding of microstructure performance relationships is the key to true understanding of material behaviours.

Non-Destructive Testing during the Hardening of Alkali-Activated Slag

2015 ◽  
Vol 732 ◽  
pp. 329-332
Author(s):  
Libor Topolář ◽  
Peter Rypák ◽  
Kristýna Šamárková ◽  
Pavel Rovnaník
Keyword(s):  
Acoustic Analysis ◽  
Drying Shrinkage ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Impact Echo ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
High Level ◽  
Non Destructive ◽  
Alkali Activated

Non-destructive acoustic analysis methods, Impact-echo method as a traditional and the Acoustic Emission method as nontraditional method for civil engineering, were used for experiment. This paper reports the experiment during hardening and drying of specimens of alkali activated slag mortars. Alkali activated slag is a material having a great potential to be used in practice. The main drawback of this material is a high level of autogenous and especially drying shrinkage, which causes a deterioration of the mechanical properties. The aim of this paper is introduce the effect of method used and time curing on the microstructure of alkali activated slag mortars. An understanding of microstructure–performance relationships is the key to true understanding of material behaviours.

scholarly journals Mechanical Fracture Properties of Alkali-Activated Slag with Graphite Filler

2017 ◽  
Vol 190 ◽  
pp. 43-48 ◽  
Author(s):  
Pavel Rovnaník ◽  
Hana Šimonová ◽  
Libor Topolář ◽  
Zbyněk Keršner
Keyword(s):  
Mechanical Fracture ◽  
Fracture Properties ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated

scholarly journals Pottery Sand as Fine Aggregate for Preparing Alkali-Activated Slag Mortar

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Zhenzhen Jiao ◽  
Ying Wang ◽  
Wenzhong Zheng ◽  
Wenxuan Huang
Keyword(s):  
Compressive Strength ◽  
Mechanical Performance ◽  
Setting Time ◽  
Drying Shrinkage ◽  
Sodium Oxide ◽  
Oxide Content ◽  
Fine Aggregate ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated

Alkali-activated slag (AAS) mortars were prepared using pottery sand as a fine aggregate in a ratio of 1 : 1.75 using a blend of sodium silicate and NaOH as an alkaline activator at room temperature. The effects of sodium oxide content and silicate moduli on the setting time, fluidity, consistency, compressive strength, and drying shrinkage of different AAS mortars were determined. These results revealed that sodium oxide content and silicate modulus had little effect on the setting time and workability of the mortar; however, they did have a significant effect on their mechanical performance and drying shrinkage levels. All the AAS mortars exhibited faster setting times, better workability, and higher early and late compressive strength compared to traditional mortars. Optimum compressive strength was achieved at 93 and 123 MPa after 1 d and 28 d, respectively, using a silicate modulus of 1.2 and Na2O content of 8%. The microstructures of mortars were characterized using scanning electron microscopy with energy dispersive spectrometric (SEM/EDS) and mercury intrusion porosimetry (MIP). These results reveal that AAS mortars containing pottery sand as a fine aggregate may represent a promising building material with improved properties for use in the construction industry.

Influence of Chemical Admixtures on Properties of Alkali-Activated Slag-Based Mortars

2015 ◽  
Vol 1124 ◽  
pp. 37-42 ◽  
Author(s):  
Vlastimil Bílek Jr. ◽  
Lukáš Kalina ◽  
Jan Koplík ◽  
Radoslav Novotný ◽  
Miroslava Hajdúchová ◽  
...  
Keyword(s):  
Ordinary Portland Cement ◽  
Chemical Resistance ◽  
Mechanical Performance ◽  
Drying Shrinkage ◽  
The Other ◽  
Alkali Activated Slag ◽  
Chemical Admixtures ◽  
Shrinkage Reducing Admixture ◽  
Activated Slag ◽  
Alkali Activated

Alkali-activated slag (AAS) based binders can have similar or even better properties in terms of mechanical performance, durability and chemical resistance than ordinary Portland cement (PC), but AAS binders also show some drawbacks, especially high shrinkage and poor rheology. Improvement of these features in the case of PC binder is well established, but a lot of conventional admixtures like superplasticizers do not work in AAS. The influence of shrinkage reducing admixture (SRA) and airentraining admixture (AEA) on mechanical properties, workability and shrinkage was investigated in this study. These admixtures were used in the different dosages in the range of 0–2.0% (by mass of slag). With increasing content of both admixtures compressive and flexural strength decreased. Similar effect was observed for workability. On the other hand, promising results in respect of shrinkage reduction were obtained particularly for SRA, where its 1.0% dose reduced drying shrinkage of the reference mortar by more than 70%. Only slight shrinkage reduction was observed for 0.50% of AEA.

scholarly journals Investigation of Graphene Derivatives on Electrical Properties of Alkali Activated Slag Composites

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4374
Author(s):  
Wu-Jian Long ◽  
Xuanhan Zhang ◽  
Biqin Dong ◽  
Yuan Fang ◽  
Tao-Hua Ye ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Electrical Properties ◽  
Mechanical Performance ◽  
Structural Defects ◽  
Alkali Activated Slag ◽  
Mechanical And Electrical Properties ◽  
Reduced Graphene ◽  
Graphene Derivatives ◽  
Activated Slag ◽  
Alkali Activated

Reduced graphene oxide (rGO) has been widely used to modify the mechanical performance of alkali activated slag composites (AASC); however, the mechanism is still unclear and the electrical properties of rGO reinforced AASC are unknown. Here, the rheological, mechanical, and electrical properties of the AASC containing rGO nanosheets (0, 0.1, 0.2, and 0.3 wt.%) are investigated. Results showed that rGO nanosheets addition can significantly improve the yield stress, plastic viscosity, thixotropy, and compressive strength of the AASC. The addition of 0.3 wt.% rGO nanosheets increased the stress, viscosity, thixotropy, and strength by 186.77 times, 3.68 times, 15.15 times, and 21.02%, respectively. As for electrical properties, the impedance of the AASC increased when the rGO content was less than 0.2 wt.% but decreased with the increasing dosage. In contrast, the dielectric constant and electrical conductivity of the AASC containing rGO nanosheets decreased and then increased, which can be attributed to the abundant interlayer water and the increasing structural defects as the storage sites for charge carriers, respectively. In addition, the effect of graphene oxide (GO) on the AASC is also studied and the results indicated that the agglomeration of GO nanosheets largely inhibited the application of it in the AASC, even with a small dosage.

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