scholarly journals Acoustic Emissions in Compression of Building Materials: Q-Statistics Enables the Anticipation of the Breakdown Point

2019 ◽  
Author(s):  
A. Greco ◽  
Constantino Tsallis ◽  
Andrea Rapisarda ◽  
A. Pluchino ◽  
G. Fichera ◽  
...  
Keyword(s):  
Building Materials ◽  
Probability Distributions ◽  
Failure Process ◽  
Acoustic Emissions ◽  
Breakdown Point ◽  
Warning Signs ◽  
Compression Tests ◽  
Existing Structures ◽  
Event Times ◽  
Linear Alignment

In this paper we present experimental results concerning Acoustic Emission (AE) recorded during cyclic compression tests on two different kinds of brittle building materials, namely concrete and basalt. The AE inter-event times were investigated through a non-extensive statistical mechanics analysis which shows that their decumulative probability distributions follow q-exponential laws. The entropic index q and the relaxation parameter q 1=Tq, obtained by fitting the experimental data, exhibit systematic changes during the various stages of the failure process, namely (q; Tq) linearly align. The Tq = 0 point corresponds to the macroscopic breakdown of the material. The slope, including its sign, of the linear alignment appears to depend on the chemical and mechanical properties of the sample. These results provide an insight on the warning signs of the incipient failure of building materials and could therefore be used in monitoring the health of existing structures such as buildings and bridges.

Acoustic emissions in compression of building materials: q-statistics enables the anticipation of the breakdown point

2020 ◽  
Vol 229 (5) ◽  
pp. 841-849 ◽  
Author(s):  
Annalisa Greco ◽  
Constantino Tsallis ◽  
Andrea Rapisarda ◽  
Alessandro Pluchino ◽  
Gabriele Fichera ◽  
...  
Keyword(s):  
Building Materials ◽  
Acoustic Emissions ◽  
Breakdown Point

Failure Process of Rock Sample Observed by AE Source Locating Technique under Uniaxial Compression

2006 ◽  
Vol 324-325 ◽  
pp. 567-570
Author(s):  
Yuan Hui Li ◽  
Rui Fu Yuan ◽  
Xing Dong Zhao
Keyword(s):  
Uniaxial Compression ◽  
High Speed ◽  
Failure Process ◽  
Compression Tests ◽  
Temporal And Spatial Distribution ◽  
Primary Stage ◽  
Brewing Process ◽  
Ae Signal ◽  
Failure Location ◽  
Low Amplitude

A series of uniaxial-compression tests were conducted on some representative brittle rock specimens, such as granite, marble and dolerite. A multi-channel, high-speed AE signal acquiring and analyzing system was employed to acquire and record the characteristics of AE events and demonstrate the temporal and spatial distribution of these events during the rupture-brewing process. The test result showed that in the primary stage, many low amplitude AE events were developed rapidly and distributed randomly throughout the entire specimens. In the second stage, the number of AE increased much slower than that in the first stage, while the amplitude of most AE events became greater. Contrarily to the primary stage, AE events clustered in the middle area of the specimen and distributed vertically conformed to the orientation of compression. The most distinct characteristic of this stage was a vacant gap formed approximately in the central part of the specimen. In the last stage, the number of AE events increased sharply and their magnitude increased accordingly. The final failure location coincidently inhabited the aforementioned gap. The main conclusion is that most macrocracks are developed from the surrounding microcracks existed earlier and their positions occupy the earlier formed gaps, and the AE activity usually becomes quite acute before the main rupture occurs.

scholarly journals THE MICROSTRUCTURAL PROPERTIES OF PLASTER COMPOSITE PRODUCED DURING PRE-REPUBLIC AND EARLY REPUBLIC PERIODS IN DEMIRCI

2020 ◽  
Vol 4 (12) ◽  
pp. 8-12
Author(s):  
SadıkAlper Yıldızel
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Early Republic ◽  
Building Materials ◽  
Optical Microscope ◽  
Microstructural Properties ◽  
Micro Structure ◽  
Existing Structures ◽  
Composite Production ◽  
Scanning Electron

Structural plaster properties of the residence type buildings that were constructed during prerepublic and early republic periods in Demirci were investigated within the scope of this study. Samples taken from the existing structures were dried in laboratory conditions and made ready for micro-structure examination. Proper samples were examined with scanning electron microscopy (SEM) with the sensitivity of 5 nm and a magnification of 20.000 times, and the optical microscope (magnification: 250 x). In the light of obtained results, it has been determined that the microstructure of the composite used in the Demirci county in the preRepublican period and early republic period is similar to the resultant of mixes produced with the modern fiber added composite production technology. It is thought that this study will contribute to the study of the production of the related building materials to be improved in the future within the limits of the district.

scholarly journals Experimental Study on Axial Compression Behavior of Masonry Columns’ Strengthening with Bamboo Scrimber Bar Mesh Mortar Layer

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Hongyao Liu ◽  
Min Lei ◽  
Bowang Chen
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
Axial Compression ◽  
Failure Process ◽  
Engineering Application ◽  
Compression Tests ◽  
Compression Behavior ◽  
Bamboo Scrimber ◽  
Calculation Results ◽  
Strengthening Method

We propose a new method to strengthen structural masonry. To study on the axial compression behavior of masonry columns’ strengthening with a bamboo scrimber bar mesh mortar layer, axial compression tests of twelve masonry columns have been completed: nine strengthened columns and three unstrengthened columns. The failure process, bearing capacity, and failure mode are carried out. The strengthening method of bamboo scrimber bar mesh mortar layer permits the upgrade of the columns’ bearing capacity. The effects of bamboo bar ratio and mortar strengthening ratio on bearing capacity of the reinforced columns are compared. We propose the method for calculating the axial bearing capacity of such a reinforced column. The calculation results agree well with the experimental results, and the research results are available for engineering application.

scholarly journals Rebound Hammer Test: An Investigation into Its Reliability in Applications on Concrete Structures

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Antonio Brencich ◽  
Rossella Bovolenta ◽  
Valeria Ghiggi ◽  
Davide Pera ◽  
Paolo Redaelli
Keyword(s):  
Building Materials ◽  
Concrete Strength ◽  
Research Work ◽  
Third Party ◽  
Test Reliability ◽  
Surface Finishing ◽  
Engineering Practice ◽  
Rebound Hammer ◽  
Existing Structures ◽  
Concrete Maturity

The issue of concrete strength often arises in civil engineering practice, either due to quality control of new constructions or due to the assessment of existing structures. To this aim, one of the most widely spread techniques is the rebound hammer (Schmidt hammer) test, for which calibration is still related to the original Schmidt curve dating back to the early 50’s. In spite of the large amount of research work performed in the last decades, the uncertainties of the rebound test are still not clearly quantified and open to further insight. This paper presents and discusses a wide research campaign on laboratory specimens and on third-party specimens delivered to the Laboratory for Building Materials of the University of Genoa, Italy, for standard quality controls. While it is well known that moisture content, surface finishing, and concrete maturity strongly affect the test result, the effect of the stress state has not yet been studied and is found in this research to be a further parameter affecting the test reliability. The final outcome of all the uncertainties is variability in estimated concrete strength as large as ±70%; additionally, some issues are discussed on the intrinsic uncertainty of this test. As already demonstrated by many authors, the results of this research also show that a universal calibration curve to be used for any concrete, in any condition, conceptually does not exist.

Constitutive model to simulate full deformation and failure process for rocks considering initial compression and residual strength behaviors

2019 ◽  
Vol 56 (5) ◽  
pp. 649-661 ◽  
Author(s):  
Wengui Cao ◽  
Xin Tan ◽  
Chao Zhang ◽  
Min He
Keyword(s):  
Constitutive Model ◽  
Residual Strength ◽  
Triaxial Compression ◽  
Failure Process ◽  
Deformation Model ◽  
Good Prediction ◽  
Compression Tests ◽  
Deformation And Failure ◽  
Macroscopic Deformation ◽  
Triaxial Compression Tests

A constitutive model with capacity to simulate the full deformation and failure process for rocks considering initial compression and residual strength behaviors is discussed in this paper. The rock was assumed to consist of the initial voids portion and the solid skeleton portion. The full deformation model of rocks can be established by the consideration of the macroscopic deformation of rocks and the microscopic deformations of the two different portions based on the statistical damage theory. Comparisons between the experimental data from triaxial compression tests and calculated results show that the proposed constitutive model provided a good prediction of the full deformation and failure process, including the effects of initial void compression, stiffness degradation, strain hardening–softening, and residual strength.

Dynamic Compression Test of CFRP Laminates Using SHPB Technique

2014 ◽  
Vol 566 ◽  
pp. 122-127
Author(s):  
Takayuki Kusaka ◽  
Takanori Kono ◽  
Yasutoshi Nomura ◽  
Hiroki Wakabayashi
Keyword(s):  
Compressive Strength ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Failure Process ◽  
Compression Tests ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Cfrp Laminates ◽  
Split Hopkinson ◽  
Pressure Bar

A novel experimental method was proposed for characterizing the compressive properties of composite materials under impact loading. Split Hopkinson pressure bar system was employed to carry out the dynamic compression tests. The dynamic stress-strain relations could be precisely estimated by the proposed method, where the ramped input, generated by the plastic deformation of a zinc buffer, was effective to reduce the oscillation of the stress field in the specimen. The longitudinal strain of gage area could be estimated from the nominal deformation of gage area, and consequently the failure process could be grasped in detail from the stress-strain relation. The dynamic compressive strength of the material was slightly higher than the static compressive strength. In addition, the validity of the proposed method was confirmed by the computational and experimental results.

scholarly journals Investigation into the gas adsorption-loading coupling damage constitutive model of coal rock

2021 ◽  
Author(s):  
Zhongzhong Liu ◽  
Hanpeng Wang ◽  
Su Wang ◽  
Yang Xue ◽  
Chong Zhang
Keyword(s):  
Gas Adsorption ◽  
Coupling Effect ◽  
Influencing Factor ◽  
Failure Process ◽  
Damage Model ◽  
Strain Curve ◽  
In Situ Stress ◽  
Compression Tests ◽  
Damage And Failure ◽  
Coal Rock

Abstract Coal and gas outburst is the result of comprehensive action of in-situ stress, gas and mechanical properties of coal rock. The coupling effect of loading and gas adsorption eventually leads to the coal rock failure. Based on the principle of strain equivalence and considering the coupling effect of gas adsorption and stress loading, an adsorption-loading coupling damage model is established which breaks through the bottleneck of only considering single influencing factor. Taking briquette samples with controllable properties as the research object, uniaxial compression tests of coal rock at different gas adsorption pressures are carried out, and the model is verified based on the test results. The results of model calculation and tests show that the meso damage stage of coal body can well correspond to the macroscopic deterioration phenomenon and it is in good agreement with the stress-strain curve. It is proved that the model has good applicability and can accurately describe the damage and failure process of coal rock.

Bio-Stabilised Earthen Blocks: A Critical Study on Compression Tests of Immersed Samples

2022 ◽  
Author(s):  
Simon Guihéneuf ◽  
Arnaud Perrot ◽  
Damien Rangeard ◽  
Mathilde Cocheteux
Keyword(s):  
Compressive Strength ◽  
Xanthan Gum ◽  
Building Materials ◽  
Linseed Oil ◽  
Water Diffusion ◽  
Critical Study ◽  
Capillary Absorption ◽  
Compression Tests ◽  
Positive Effects ◽  
Water Sensitivity

Currently, much consideration is given to earthen building materials regarding their highly sustainable properties. Numerous studies have highlighted their structural ability but their water sensitivity is still limiting a potentially more spread use. To limit this sensitivity several studies have recently brought out the positive effects of bio-stabilisers such as linseed oil or xanthan gum. These recent developments allow bio-stabilized earthen materials to be resistant to immersion in water. Also, a French experimental standard (XP P 13-901) for compressed earth blocks already asks for a minimal compressive strength after a two-hour immersion that is overly severe and is difficult to satisfy without the addition of high contents of hydraulic binders. In this paper, a critical study of this compressive test after immersion is conducted on bio-stabilized (linseed oil and xanthan gum) samples of different Breton earths. Some testing adjustments are suggested and the water-diffusion in the samples is followed and linked to previously obtained capillary absorption coefficients. It is shown that the effect of immersion on the mechanical strength depends on the sample size and that an equivalence between size and immersion time can be made based on an equivalent penetration depth. Linseed oil and xanthan gum help to significantly increase the compressive strength of the earthen materials after immersion and allow to avoid the addition of hydraulic binders in earthen blocks to obtained a strong water resistance. The water diffusion in the sample during the immersion can be linked to capillary absorption behaviour, thus a water content and a compressive strength after a given time of immersion could be easily predicted.

scholarly journals Terrestrial Laser Scanner as a Tool for Assessment of Saturation and Moisture Movement in Building Materials

2018 ◽  
Author(s):  
Czesław Suchocki ◽  
Jacek Katzer ◽  
Jacek Rapiński
Keyword(s):  
Structural Engineering ◽  
Building Materials ◽  
Laser Scanner ◽  
Research Programme ◽  
Terrestrial Laser Scanner ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Moisture Movement ◽  
Existing Structures ◽  
Non Destructive

Non Destructive Testing (NDT) is a key element of modern civil engineering. It is especially important in civil and structural engineering helping both in quality control of produced elements and technical assessments of existing structures. Existing NDT methods are being continuously improved and new methods are developed or adopted from different engineering fields. Terrestrial Laser Scanner (TLS) method which is commonly used for geodetic applications has a great potential to be successfully harnessed in civil and structural engineering. TLS can be used for remote sensing of saturation of building materials. A research programme was prepared in order to prove this concept. Specimens representing most popular European building materials were scanned using TLS. Tested specimens were in different saturation states including capillary rising saturation. The saturation assessment was based on differences of values of intensity. The concept proved to be feasible and technically realistic.

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