DISPERSING EFFECTIVENESS OF ROTATIONAL SHEAR TO DISPERSE CONCENTRATED CEMENT SUSPENSION

Author(s): Ahmed M. Mostafa, Paco Diederich and prof. Ammar Yahia
Paper category: Proceeding
Book title: Design, Performance and Use of Self-Consolidating Concrete
Editor(s): Caijun Shi, Zhihua Ou and Kamal Henri Khayat
Print-ISBN: 978-2-35158-143-8
e-ISBN: 978-2-35158-144-5
Publisher: RILEM Publications SARL
Publication year: 2014
Pages: 142
Total Pages : 1
Language : English

Abstract: Build-up of cement suspensions has a great impact on their structural behaviour after casting. The build-up is governed by the colloidal interactions and chemical linkages formed between cement particles during hydration. Cement-based suspensions differ considerably in their build-up kinetics at rest because of the mix design parameters, type, fineness and reactivity of cement, presence of admixture, and dispersion state of the suspension. Due to the complexity of build-up phenomenon of cement suspensions, good understanding of the mechanisms affecting this phenomenon relies on the dispersion state of suspension before measurements. The dispersing effectiveness of rotational shear to achieve the most dispersed state is evaluated. Various disruptive shear rates were employed to disperse cement paste proportioned with low water-to-cement ratio (w/c) of 0.35. The storage modulus and the shear stress before and after applying disruptive shear rate were measured using small-amplitude oscillatory shear (SAOS). Test results indicated that increasing the disruptive shear rate value enhances suspension dispersion (i.e. breakdown) till a critical value, beyond which shear thickening effects dominate and flocculation takes place. This critical shear rate can be easily identified from the flow curve.

Online publication: 2017
Publication type: full_text
Public price (Euros): 0.00