Applying Method of Acoustic Emission for Monitoring of Different Concrete Mixture during Setting and Hardening

Abstract

Non Destructive Testing is a powerful tool for determination of properties, durability and lifetime of concrete structures. Acoustic Emission Method is an unusual technique which describes only active defects or changes into structure arising as a consequence dangerous tension into structure. The method is appropriate to be used in homogenous structures as metal structures when cracks are highly active (generates sound). Its application in civil engineering is not so much used because building structures are inhomogeneous. This article shows possible application of Acoustic Emission Method for monitoring of concrete structure changes during its lifetime. The main aim of the article is to show the application of Acoustic Emission Method during the early age to 28 days after mixing. It is believed that early age of concrete structure is very important for its quality. Common concrete cube specimens have been tested after the production by Acoustic Emission Method with using waveguides. The results of acoustic emission method will be compared to classical parameters of fresh concrete e.g. the value water-cement ratio, air void content measured by different methods (pressure methods, AVA) and similar. In the results will be compared four mixtures when two mixtures were aerated and two mixtures were without aeration.

Comprehensive Testing Techniques for the Measurement of Shrinkage and Structural Changes of Fine-Grained Cement-Based Composites during Ageing

“…Controlling the variables that affect volume change can minimize high stresses and cracking [4,6,7]. Recent measurements suggest the necessity of assessing the magnitude of shrinkage in two consecutive stages of a composite's ageing, at an early age and at later ages [7][8][9][10]. Early-age measurements reveal differences in the development of volume changes as well as differences in the initiation and propagation of cracks which cannot normally be identified with traditional 2 Advances in Materials Science and Engineering measurement made after specimens have been removed from moulds (typically after 24 hours) [11].…”

“…An acoustic waveguide is a physical structure for guiding sound waves, that is, a soundpropagation duct that behaves like a transmission line. The duct contains some sound-propagation medium [8].…”

Degradation of Materials Based on Alkali-Activated Blast-Furnace Slag after Exposure to Aggressive Environments

“…Alkali-activated materials usually exhibit higher shrinkage than materials based on Portland cement, which can result in microcracks [8], and generally have a higher occurrence of efflorescence due to the reaction of alkali metal ions with CO2 in the air. On the other hand their exhibit superior durability in terms of thermal loading [9] or the durability under the acid conditions [10,11].…”

Using Acoustic Emission Methods to Monitor Cement Composites during Setting and Hardening

“…Controlling the variables that affect the volume change can minimize high stresses and cracking [7,9,10]. Recent measurements suggest the necessity of assessing the magnitude of shrinkage in two consecutive stages of composite aging-at an early age and at later ages [10][11][12][13]. The modern cementitious materials, such as high-performance concrete (HPC), show advantageous properties compared to conventional concretes, for example, good workability of the fresh concrete and high strength after hardening.…”

“…Controlling the variables that affect the volume change can minimize high stresses and cracking [7,9,10]. Recent measurements suggest the necessity of assessing the magnitude of shrinkage in two consecutive stages of composite aging-at an early age and at later ages [10][11][12][13]. Early-age measurements reveal differences in the development of volume changes, as well as differences in the initiation and propagation of cracks which cannot normally be identified by traditional methods applied after specimens have been removed from moulds (typically after 24 h) [14].…”