Tesis doctoral de Victor Fernandez Altable
This research aims at contributing to better understand the action of superplasticisers in cementitious systems. The temperature dependence, over a range of 5 to 45 ºc, of the rheological behaviour of concentrated superplasticised cement-based pastes (w/c = 0.33) is studied under a wide range of variables of preparation of the mixes, including dosage, type and moment of addition of superplasticiser, time of mixing, and presence or absence of mineral additives, such as fly ash and/or microsilica. this thesis comprises three parts. The first one is a comprehensive introduction to the two topics that occur in this investigation. Thus, chapter 2 is devoted to rheology in the frame of cementitious materials, including concepts from colloid science underlying interparticle interaction phenomena in aqueous suspensions. Description of the traditional methods used in civil engineering for evaluation of flow behaviour of cementitious materials, and their theoretical modelling for determination of actual rheological parameters, is also included. On the other hand, a state-of-the-art on superplasticisers is presented in chapter 3. the second part of this thesis is devoted to the experimental work. A methodology based on the application of a thixotropic loop by means of a coaxial cylinders viscometer is developed for rheological evaluation (chapter 4). The characterisation is made in terms of yield stresses and apparent viscosities for each of the two flow curves obtained (upwards and downwards), providing a criterion that allows precise comparison between the wide range of samples tested. Additionally, the area enclosed between both flow curves is also reported as a relative measure of thixotropy. A first series of 6 experimental campaigns is carried out with ordinary portland cement (opc) mixes that are admixtured with commercial superplasticisers based on polycarboxylates (pc), on sulphonated polynaphthalene (pns), and on sulphonated polymelamine (pms). Each admixture
Datos académicos de la tesis doctoral «Rheological performance of superplasticisers in cement-based pastes«
- Título de la tesis: Rheological performance of superplasticisers in cement-based pastes
- Autor: Victor Fernandez Altable
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 19/04/2007
Dirección y tribunal
- Director de la tesis
- Ignasi Casanova Hormaechea
- Tribunal
- Presidente del tribunal: marc Barraco serra
- francisca Puertas maroto (vocal)
- robert Johann flatt (vocal)
- yolanda De Miguel (vocal)