Effect of Admixture Dosage and Specimens Age on Mechanical Fracture Parameters of Lime Mortars Enhanced by Burnt Clays

2014 ◽  
Vol 1000 ◽  
pp. 356-359
Author(s):  
Hana Šimonová ◽  
Ivana Havlíková ◽  
Eva Navrátilová ◽  
Pavel Schmid ◽  
Pavla Rovnaníková ◽  
...  
Keyword(s):  
Hydrated Lime ◽  
Mechanical Fracture ◽  
Lime Mortar ◽  
Three Point Bending ◽  
Historical Materials ◽  
Brick Powder ◽  
Lime Mortars ◽  
Fracture Tests ◽  
Bending Fracture ◽  
Reference Mixture

In the restoration of historic buildings with priorities of historic preservation there exists an effort to modify the mortars by admixtures which are in compliance with historical materials and techniques. Therefore the specimens were made from lime mortar modified by brick powder or metakaolin. The reference mixture used only hydrated lime while the other mixtures were enhanced by brick powder or metakaolin in the amounts of 25, 50 and 100 % of the weight of hydrated lime. This paper presents the results of three-point bending fracture tests obtained by using double-K fracture model. The specimen’s age was 90 and 150 days.

Mechanical Fracture Parameters of Mortars Modified by Burnt Clays

2014 ◽  
Vol 969 ◽  
pp. 241-244
Author(s):  
Eva Navrátilová ◽  
Hana Šimonová ◽  
Barbara Kucharczyková ◽  
Ivana Havlíková ◽  
Jan Bedáň ◽  
...  
Keyword(s):  
Hydrated Lime ◽  
The Other ◽  
Mechanical Fracture ◽  
Lime Mortar ◽  
Three Point Bending ◽  
Fracture Parameters ◽  
Brick Powder ◽  
Fracture Tests ◽  
Bending Fracture ◽  
Reference Mixture

This paper presents the results of three-point bending fracture tests. Specimens were made from lime mortar modified by brick powder or metakaolin. The first, reference mixture only used hydrated lime, while the other mixtures were enhanced by brick powder or metakaolin in amounts of 25, 50 and 100 % of the weight of hydrated lime.

Fracture Response of Fine-Grained Cement-Based Composite Specimens with Special Inclusions

2019 ◽  
Vol 292 ◽  
pp. 63-68 ◽  
Author(s):  
Michal Vyhlídal ◽  
Iva Rozsypalová ◽  
Tomáš Majda ◽  
Petr Daněk ◽  
Hana Šimonová ◽  
...  
Keyword(s):  
Transition Zone ◽  
Interfacial Transition Zone ◽  
Mechanical Fracture ◽  
Three Point Bending ◽  
Fine Grained ◽  
Fracture Parameters ◽  
Edge Notch ◽  
Fracture Tests ◽  
Materials Used ◽  
Bending Fracture

This paper concerns research into the importance of the interfacial transition zone around inclusions of selected materials in fine-grained cement-based composite. Tests were performed on eight sets of prismatic test specimens. The sets differed in the inclusion materials used, which were placed at midspan above the initial central edge notch. The first was a reference set without any inclusion, the second contained a steel inclusion, four more contained different types of rock inclusion, the seventh contained an inclusion of extruded polystyrene, and the last contained a space of the same dimensions as that occupied by the inclusions in sets 2 to 7. The test specimens were subjected to three-point bending fracture tests at the age of (usually) 28 days. The fracture response was analysed by means of fracture mechanics theory, and apparent mechanical fracture parameters (modulus of elasticity, fracture toughness and fracture energy) were evaluated. The conclusion shows that a possible relationship exists between the differences in the mechanical fracture parameters of specimens with/without an inclusion and the existence of the interfacial transition zone.

Mechanical Fracture Properties of Cement Mortars with Diatomite in Relation to their Microstructure

2015 ◽  
Vol 1124 ◽  
pp. 57-62
Author(s):  
Pavla Rovnaníková ◽  
Hana Šimonová ◽  
Pavel Schmid ◽  
Jana Zahálková ◽  
Patrik Bayer ◽  
...  
Keyword(s):  
Elasticity Modulus ◽  
Hardened Cement ◽  
Mechanical Fracture ◽  
Fracture Properties ◽  
Three Point Bending ◽  
Cement Mortars ◽  
Edge Notch ◽  
Fracture Tests ◽  
Specific Fracture ◽  
Bending Fracture

The paper is focused on the mechanical fracture properties of hardened cement mortars in which Portland cement is partially replaced by reactive admixtures. These properties are evaluated in relation to the mortars’ microstructure through the size and content of pores. The cement in the mortars was partially replaced by a diatomite that contains amorphous SiO2. The three-point bending fracture tests were performed on beams with a central edge notch. The investigated mechanical fracture properties of the aforementioned cement-based composites included flexural strength, compressive strength, elasticity modulus, effective fracture toughness and specific fracture energy.

Evaluation of Three-Point Bending Fracture Tests of Selected Concrete: Mechanical Fracture Parameters

2017 ◽  
Vol 259 ◽  
pp. 64-69
Author(s):  
Hana Šimonová ◽  
Petr Daněk ◽  
David Lehký ◽  
Zbyněk Keršner ◽  
Lubos Pazdera
Keyword(s):  
Fracture Energy ◽  
Modulus Of Elasticity ◽  
Crack Model ◽  
Mechanical Fracture ◽  
Three Point Bending ◽  
Fracture Parameters ◽  
Fracture Tests ◽  
Specific Fracture ◽  
Bending Fracture ◽  
Work Of Fracture

In this paper, authors focus attention on mechanical fracture parameters obtained from records of three-point bending fracture tests on concrete specimens with initial notch. Total eight sets of specimens were tested. Three specimens at the age of 28 days were tested in each set. Concrete was different in dosage of Portland cement CEM I 42.5 R and amount of used superplasticizer. The Effective Crack Model (ECM) was used to evaluate the load vs deflection diagrams to obtain modulus of elasticity and effective fracture toughness; specific fracture energy was determined using work-of-fracture method. Modulus of elasticity, tensile strength and fracture energy were also subject of identification via inverse analysis based on artificial neural network, which aim is to transfer the input data obtained from the fracture test to the desired material parameters.

Detailed Determination of Mechanical Fracture Parameters of Concrete after Fire Experiments

2018 ◽  
Vol 272 ◽  
pp. 220-225 ◽  
Author(s):  
Hana Šimonová ◽  
Tomáš Trčka ◽  
Michal Bejček ◽  
Iva Rozsypalová ◽  
Petr Daněk ◽  
...  
Keyword(s):  
Statistical Dependence ◽  
Crack Model ◽  
Mechanical Fracture ◽  
Three Point Bending ◽  
Fracture Parameters ◽  
Fracture Tests ◽  
Detailed Determination ◽  
Bending Fracture ◽  
Fire Experiments

The aim of this paper is to describe the procedure of determining the mechanical fracture parameters of selected concrete specimens taken from panels after the fire experiments. The records (in form load vs displacement diagrams) of three-point bending fracture tests of these specimens with initial stress concentrators was first advanced corrected and subsequently evaluated using the Effective Crack Model and the work-of-fracture method. The increasing temperatures during the fire experiments ranging between 550 to 1000 °C led to a decrease of modulus of elasticity and fracture toughness values and to the increase of fracture energy value. The 2D laser profile scanner was used to estimate the degree of complexity of fracture surfaces; its statistical dependence on the mechanical fracture parameters proved to be moderate – the absolute value of the correlation coefficient was about 0.5°[–].

Effect of Concrete Mixture Composition on Acoustic Emission and Fracture Parameters Obtained from Three-Point Bending Test

2015 ◽  
Vol 1100 ◽  
pp. 152-155
Author(s):  
Libor Topolář ◽  
Hana Šimonová ◽  
Petr Misák
Keyword(s):  
Acoustic Emission ◽  
Bending Test ◽  
Mixture Composition ◽  
Three Point Bending ◽  
Concrete Mixtures ◽  
Fracture Parameters ◽  
Fracture Tests ◽  
Stress Behaviour ◽  
Bending Fracture ◽  
Fracture Processes

This paper reports the analysis of acoustic emission signals captured during three-point bending fracture tests of concrete specimens with different mixture composition. Acoustic emission is an experimental tool well suited for monitoring fracture processes in material. The typical acoustic emission patterns were identified in the acoustic emission records for three different concrete mixtures to further describe the under-the-stress behaviour and failure development. An understanding of microstructure–performance relationships is the key to true understanding of material behaviour. The acoustic emission results are accompanied by fracture parameters determined via evaluation of load versus deflection diagrams recorded during three-point bending fracture tests.

Correlation between Parameters of Acoustic Emission and Fracture Characteristics Obtained from Three-Point Bending Test

2015 ◽  
Vol 1124 ◽  
pp. 231-236
Author(s):  
Libor Topolář ◽  
Luboš Pazdera
Keyword(s):  
Acoustic Emission ◽  
Bending Test ◽  
Emission Method ◽  
Fracture Characteristics ◽  
Three Point Bending ◽  
Experimental Tool ◽  
Fracture Tests ◽  
Stress Behaviour ◽  
Bending Fracture ◽  
Fracture Processes

This paper reports the analysis of acoustic emission signals captured during three-point bending fracture tests of concrete specimens with different mixture composition. Acoustic emission method is an experimental tool well suited for monitoring fracture processes in material. The typical acoustic emission patterns were identified in the acoustic emission records for three different mixtures to further describe the under-the-stress behaviour and failure development. An understanding of microstructure–performance relationships is the key to true understanding of material behaviour. The acoustic emission results are accompanied by fracture parameters determined via evaluation of load versus deflection diagrams recorded during three-point bending fracture tests.

Alkali Activated Binders Based Concrete Specimens: Length Change and Fracture Tests

2016 ◽  
Vol 258 ◽  
pp. 623-626 ◽  
Author(s):  
Vlastimil Bílek Jr. ◽  
Hana Šimonová ◽  
Ivana Havlíková ◽  
Libor Topolář ◽  
Barbara Kucharczyková ◽  
...  
Keyword(s):  
Stress Concentrator ◽  
Length Change ◽  
Bending Test ◽  
Crack Model ◽  
Mechanical Fracture ◽  
Three Point Bending ◽  
Fracture Tests ◽  
Alkali Activated Binders ◽  
Work Of Fracture ◽  
Alkali Activated

The aim of this paper is to quantify mechanical fracture and length change parameters of the two types of concrete with alkali activated binder. The six beam specimens (75 × 75 × 295 mm) were made from each mixture. After demolding specimens were placed in air storage for 28 days. During this period length change (shrinkage) were recorded in accordance with ASTM C490 (2011). After that the three-point bending test was performed on these specimens with initial stress concentrator at the age of 28 days to obtain the mechanical fracture parameters. Records of fracture tests in form load versus deflection (F–d) diagrams were evaluated using effective crack model and work of fracture method.

Mechanical Fracture Parameters of Extruded Polystyrene

2018 ◽  
Vol 776 ◽  
pp. 160-163 ◽  
Author(s):  
Hana Šimonová ◽  
Barbara Kucharczyková ◽  
Zbyněk Keršner
Keyword(s):  
Mechanical Fracture ◽  
Mean Values ◽  
Three Point Bending ◽  
Fracture Parameters ◽  
Coefficients Of Variation ◽  
Specimen Height ◽  
Edge Notch ◽  
Bottom Side ◽  
Fracture Tests ◽  
Specific Fracture

Extruded polystyrene (XPS) is a material with applications in the building industry, where it is typically used as thermal insulation. Fracture experiments in the three-point bending configuration were conducted on XPS beam specimens with an initial stress concentrator made before testing. The nominal dimensions of the beams were 40 × 40 × 160 mm. The depth of the initial edge notch on the bottom side of the specimen was approximately 1/3 of specimen height. The span length was 120 mm. Load vs. displacement diagrams were recorded during fracture tests, and subsequently the modulus of elasticity (E), effective fracture toughness (KIce) and specific fracture energy (GF) of the XPS were determined. The mean values obtained for the mechanical fracture parameters and coefficients of variation (number of specimens) were the following: E = 10.7 MPa, 9.2 % (7); KIce = 0.0547 MPa∙m1/2, 16.7 % (3); GF = 183.2 J∙m–2, 34.3 % (3).

The Effect of Concrete Quality on the Acoustic Emission Parameters during Three-Point Bending Fracture Test

2014 ◽  
Vol 897 ◽  
pp. 149-152 ◽  
Author(s):  
Michal Matysík ◽  
Libor Topolář ◽  
Petr Daněk ◽  
Tomáš Vymazal ◽  
Iveta Plšková
Keyword(s):  
Acoustic Emission ◽  
Large Scale ◽  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Fracture Test ◽  
Opening Displacement ◽  
Three Point Bending ◽  
Fracture Tests ◽  
Stress Behaviour ◽  
Bending Fracture

Acoustic emission is an experimental tool well suited for monitoring fracture processes. The paper presents experiment focused on analysing acoustic emission signals captured during three-point bending fracture test of specimens of concrete. Quantitative acoustic emission techniques were used to measure micro fracture properties. For three different concrete mixtures typical acoustic emission patterns were identified in the acoustic emission records to further describe the under-the-stress behaviour and failure development. If we have a better understanding of the relationships between micro structural events and macroscopic behaviour we can better formulate predictive models for large-scale structural performance and reliability. An understanding of microstructureperformance relationships is the key to true understanding of material behaviours. Three-point bending fracture tests were conducted on these specimens and load versus crack mouth opening displacement (Load-CMOD) diagrams were recorded during the testing.

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