Acoustic Emission in Protected and Non-Protected Concrete During the First 24 Hours

Abstract

Concrete is a composite construction material frequently used in civil engineering. We know that concrete is as a man – when concrete is made it is as a baby, then it ages and its properties change in accordance to its baby life. That means it is better to monitor and change its properties when it is young as soon as possible. However, using the methods immediately after concrete birth (making the mixture) is difficult. Article describes monitoring concrete structure during the first 24 hours from their making. Acoustic Emission Method and the measurement temperature were used for monitoring both samples.

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

“…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]. Literature offers a number of approaches to determine the value of cement-based composite shrinkage [12][13][14].…”

“…In recent years, the method of acoustic emission (AE) has also been widely used as supplemental measurement in the nondestructive monitoring of changes in a specimen's internal structure during static and dynamic loading tests as well as for the monitoring of the behaviour of composite materials during setting and hardening [11,25,26]. The AE method is considered to be a "passive" nondestructive technique because it usually identifies defects as they develop during the test [27] and allows the monitoring of changes in the behaviour of materials over a long period of time without moving any of their components.…”

Influence of Superplasticizer Quantity on Formation of Micro-Cracks during Setting and Hardening of Concretes by Acoustic Emission Method

“…3). Acoustic emission signals were taken by measuring equipment DAKEL XEDO with six acoustic emission sensors MTPA-15 with preamplifier 35 dB [9]. The specimens were inserted to bath water for 27 days after demoulding.…”

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

“…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]. However, these methods mostly determine separate components of early-age shrinkage-e.g., methods for determining plastic or autogenous shrinkage [8,9,12,[15][16][17][18][19] and methods for determining shrinkage due to drying (defined mainly in the standards of various countries).…”