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.

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.

scholarly journals Non-traditional non-destructive testing of the alkali-activated slag mortar during the hardening

2016 ◽  
Vol 50 (1) ◽  
pp. 7-10 ◽  
Author(s):  
Libor Topolář ◽  
Peter Rypák ◽  
Krýstina Timčaková-Šamárková ◽  
Luboš Pazdera ◽  
Pavel Rovnaník
Keyword(s):  
Non Destructive Testing ◽  
Destructive Testing ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Non Destructive ◽  
Alkali Activated

Impact-Echo Method for Non-Destructive Testing of High-Temperature-Degraded Cement-Based Composite

2015 ◽  
Vol 1124 ◽  
pp. 301-306
Author(s):  
Daniela Štefková ◽  
Kristýna Timcakova ◽  
Zdeněk Chobola
Keyword(s):  
High Temperature ◽  
Acoustic Analysis ◽  
Heat Exposure ◽  
Acoustic Method ◽  
High Temperature Treatment ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Impact Echo ◽  
Non Destructive ◽  
Impact Echo Method

Non-destructive acoustic analysis method Impact-echo method as a traditional method for civil engineering was used for this experiment. The paper deals with the applicability of Impactecho acoustic method to testing of cement-based composites prepared from a mix of cement mortar and quartz sand, which were intentionally degraded by high-temperature treatment (in the temperatures range from 200°C to 1200°C). The aim of this paper is introduce the effect of high-temperature degradation. An understanding of microstructure performance relationships is the key to true understanding of material behaviors. The results of non-destructive testing confirmed the different structure of mortar specimens. The subjected to high-temperatures led to absorption of lower frequencies as compared to the reference specimens. A significant decrease of the absorbed frequencies was observed, depending on temperature. The largest decrease occurred after the specimens exposure at 400-600 °C. The effect of heat exposure to the decrease of frequencies was mitigated to the temperature degradation 1200 °C.

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 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.

Estimation of Thickness of Concrete Slab Members Using Impact Echo Method

2014 ◽  
Vol 605 ◽  
pp. 139-142
Author(s):  
Seong Uk Hong ◽  
Yong Taeg Lee ◽  
Seung Hun Kim ◽  
J.H. Na
Keyword(s):  
Concrete Slab ◽  
Hardness Test ◽  
Pulse Velocity ◽  
Non Destructive Testing ◽  
Testing Methods ◽  
Destructive Testing ◽  
Impact Echo ◽  
Maintenance And Repair ◽  
Non Destructive ◽  
Impact Echo Method

Recently, the interest in maintenance and repair of existing concrete structures have increased, and it is typical to use non-destructive testing methods such as rebound hardness test or ultrasonic pulse velocity method to execute maintenance and repair of structures efficiently. Many non-destructive testing methods are being used in practice such as at construction sites, but verification for site applications are quite inadequate. Thus, this study intends to evaluate the applicability of Impact Echo Method which is one of the non-destructive testing methods using stress wave. Total of four specimens were planned and produced. The thickness of concrete slab members was estimated using I.E(OLSENs Freedom Data PC with Win.TFS Software Version 2.5.2). The estimated materials of concrete members by IE was found to be IE-1 specimen 178mm, IE-2 specimen 197mm, IE-3 specimen 191mm, and IE-4 specimen 263mm, and the error rate was found to be 4.22%~18.67% (average 9.6%), showing that they are relatively well in agreement. In this study, the experiments were executed with the objective of estimating the thickness of concrete slab members using Impact Echo Method. Through this study, the applicability of thickness estimation in concrete slab members using impact echo method could be confirmed.

scholarly journals Preliminary Research on Influence of Welding Parameters Strength at Welded Joints in Ribbed Reinforcing Steel

2020 ◽  
Vol 14 (3) ◽  
pp. 369-374
Author(s):  
Željko Bilić ◽  
Ivan Samardžić ◽  
Nedjeljko Mišina ◽  
Katarina Stoić
Keyword(s):  
Welded Joint ◽  
Welding Process ◽  
Welding Parameters ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Butt Welding ◽  
Control Interface ◽  
High Level ◽  
Non Destructive

As already known, no proper control or process control parameter which absolutely guarantees a high level quality of joints made by electro-resistive welding has been established so far, especially when all possible parameters are taken into account during the welding process. Due to the process of butt-welding being very short-lived, ensuring quality of the joints is a difficult and under-researched problem. The application of non-destructive testing methods to the control interface joints is also not reliable. Therefore, further research in this area should concentrate on studying the influence of basic welding parameters, and calculating their direct or indirect impact can serve to achieve a highquality welded joint with for practice sufficient accuracy.

scholarly journals Mitigating the Drying Shrinkage and Autogenous Shrinkage of Alkali-Activated Slag by NaAlO2

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3499
Author(s):  
Bin Chen ◽  
Jun Wang ◽  
Jinyou Zhao
Keyword(s):  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Nitrogen Adsorption ◽  
Partial Substitution ◽  
Hydration Reaction ◽  
X Ray Diffraction ◽  
Na2o Content ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated

The shrinkage of alkali-activated slag (AAS) is obviously higher than ordinary Portland cement, which limited its application in engineering. In this study, the effects of NaAlO2 in mitigating drying shrinkage and autogenous shrinkage of AAS were studied. To further understand the shrinkage mechanism, the hydration products and microstructures were studied by X-ray diffraction, scanning electron microscopy and nitrogen adsorption approaches. As the partial substitution rate of NaAlO2 for Na2SiO3 increased, the drying shrinkage and autogenous shrinkage reduced significantly. The addition of NaAlO2 could slow down the rate of hydration reaction and reduce the porosity, change the pore diameter and the composition of generated paste and cause more hydrotalcite and tetranatrolite generated—which contributed to reduced shrinkage. Additionally, raising the Na2O content rate caused obvious differences in drying shrinkage and autogenous shrinkage. As the Na2O content elevated, the drying shrinkage decreased and autogenous shrinkage increased. A high Na2O content would cause complete hydration reactions and provoke high autogenous shrinkage. However, incomplete hydration reactions left more water in the paste, and the evaporated water dramatically influenced drying shrinkage. The results indicate that addition of NaAlO2 could greatly mitigate the drying shrinkage and autogenous shrinkage of AAS.

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