4.5 Wave propagation by transmission: the case of the setting phenome-non in heterogeneous materials
Title: 4.5 Wave propagation by transmission: the case of the setting phenome-non in heterogeneous materials
Author(s): L. Arnaud, C. U. Grosse
Paper category : book
Book title: Advanced Testing of Cement-Based Materials during Setting and Hardening - Final Report of RILEM TC 185-ATC
Editor(s): H.W. Reinhardt and C.U. Grosse
Publisher: RILEM Publications SARL
Publication year: 2005
Pages: 191 - 237
Total Pages: 47
Nb references: 38
Abstract: This chapter presents some reflections on wave propagation by transmission. It is a summary of the works devoted to the rheological study of the setting phenomenon of different heterogeneous materials in Civil Engineering during the setting period. Examples of measurements are presented here for cellular concrete, mortar, concrete and cold bituminous mixes.
The setting phenomenon results from various processes (chemical, physical, and others) that bring the mixture from a fluid state that is favorable to easy placement, to that of a solid whose properties are important for the behavior of the material in service.
The terms setting and hardening are used to designate different instants in the evolution of the material, but their definitions are often imprecise. According to the description given by [Neville (1995)], in this document we will use the term setting to designate the period that precedes the moment when the solid particles become connected (either by means of a network of hydrates for cement-based materials, or by a network of bituminous bridges in the case of cold bituminous mixes).
Prior to this transition the mixture is a non-cohesive medium, and presents itself in the form of a fluid suspension [Arnaud et al. (1996a)]. At the moment of percolation of the hydrates between each other and with the other particles, or of the bridging of the aggregates with bituminous links, one attains the fluid-solid transition. After this transition, the structure of the skeleton progressively reinforces itself: this is the hardening phase.
This progressive change of state profoundly modifies the behavior of these media. The study of this phenomenon is complex, since these materials are highly heterogeneous (the size of the heterogeneities varies from several millimeters to centimeters). The evolution from the state of fluid to solid is very distinct in respect to the mechanical point of view, and in addition, these processes are very sensitive to thermodynamic conditions. For these reasons, and even since numerous studies have been devoted to the investigation of mechanical properties of civil engineering materials, there are very few measurements on materials during their setting and hardening. Moreover, the results are rarely linked to the mechanical properties of the materials.
Online publication: 2006-09-22
Publication type : full_text
Public price (Euros): 0.00
>> You must be connected to view the paper. You can register for free if you are not a member