Role of demoulding agents during self-compacting concrete casting in formwork

• Published in: Materials and structures Vol. 35; no. 252; pp. 470 - 476
• Main Authors: DJELAL, C, VANHOVE, Y, DE CARO, P, MAGNIN, A
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01.10.2002
• Subjects: Admixtures for concrete, mortar and grouts; Applied sciences; Buildings. Public works; Concretes. Mortars. Grouts; Exact sciences and technology; Materials; Properties and performance of fresh concrete; Strength of materials (elasticity, plasticity, buckling, etc.); Structural analysis. Stresses; Form stripping agent; Shear; Friction; Material engineering; Test method; Mould release agent; Grain size distribution; Self compacting concrete; Interface; Strength of materials; Aggregate(materials); Tribology
• ISSN: 1359-5997; 1871-6873
• DOI: 10.1617/12670

The use of 'super-plasticisers' to obtain concretes that are highly workable, easy to place in formwork and require no vibration has spread throughout Europe in the last few years. The placing process for fresh so-called Self-Compacting Concrete (SCC) is linked to the friction that occurs at the concrete/wall interface. A rectilinear movement tribometer has been developed. Tests performed with certain modifications of the interface conditions show that friction is governed by the characteristics (viscosity, tensioactivity, etc.) of the demoulding agents used. The interface appears to undergo two types of phenomena: - shear stress in the thick lubricating layer, which entails low shear stresses, - granular behaviour. The shear stress is higher in the second case.