Understanding formwork pressure generated by fresh concrete

Abstract: Correct prediction of the pressure on formwork from the fresh concrete to avoid under- or overestimating its value is vital in minimizing the cost of the formwork. Existing models for formwork pressure do not include the behaviour of the fresh concrete at rest, which is related to its consistency in terms of shear strength expressed as the slump value. With the introduction of self-compacting concrete (SCC), research efforts shifted to this material property at rest, i.e. the structural build-up. This chapter discusses existing models for conventional concrete, key parameters influencing formwork pressure and new models based on the structural behaviour of concrete at rest. Laboratory methods (more scientific) and industrial methods (more empirical) used to measure the static yield stress are presented.

[1]  Yannick Vanhove,et al.  Prediction of the lateral pressure exerted by self-compacting concrete on formwork , 2004 .

[2]  P. Billberg.  Form pressure generated by self-compacting concrete : influence of thixotropy and structural behaviour at rest , 2006 .

[3]  N. J. Gardner.  Pressure of Concrete on Formwork - A Review , 1985 .

[4]  Carl-Alexander Graubner,et al.  Formwork Pressure of Highly Workable Concrete – Experiments Focused on Setting, Vibration and Design Approach , 2010 .

[5]  Sofiane Amziane,et al.  SCC Formwork Pressure: Influence of Steel Rebars , 2009 .

[6]  Kamal H. Khayat,et al.  Effect of section width and casting rate on variations of formwork pressure of self-consolidating concrete , 2005 .

[7]  Sofiane Amziane,et al.  A novel settling and structural build-up measurement method , 2008 .

[8]  Sofiane Amziane,et al.  Lateral stress exerted by fresh cement paste on formwork: Laboratory experiments , 2008 .

[9]  Kamal H. Khayat,et al.  Field Validation of SCC Formwork Pressure Prediction Models , 2011 .

[10]  Nicolas Roussel,et al.  A Physical Model for the Prediction of Lateral Stress Exerted by Self-Compacting Concrete on Formwork , 2005 .

[11]  N. Roussel,et al.  Distinct-layer casting of SCC: The mechanical consequences of thixotropy , 2008 .

[12]  Matthew D. D'Ambrosia,et al.  Prediction of SCC Formwork Pressure in Full-Scale Elements , 2010 .

[13]  Philippe Coussot,et al.  Determination of yield stress fluid behaviour from inclined plane test , 1995 .

[14]  Ahmed F. Omran.  Formwork pressure exerted by self-consolidating concrete , 2009 .

[15]  Kamal H. Khayat,et al.  Assessment of Thixotropy of Flowable and Self-Consolidating Concrete , 2003 .

[16]  J. Mewis,et al.  Thixotropy - a general review , 1979 .

[17]  Kamal H. Khayat,et al.  Evaluation of SCC Formwork Pressure , 2010 .

[18]  Vincent Picandet,et al.  Measurement of yield stress for concentrated suspensions using a plate device , 2010 .