scope:

The objective of this report is to provide detailed information to concrete professionals, including concrete suppliers and formwork contractors, with respect to the main SCC mixture characteristics and casting parameters that influence form pressure. This report also presents the most prevalent models to estimate form pressure available to assess form pressure exerted by SCC, and the accuracy of these models are evaluated based on measurements collected from two round-robin field studies.

The development of factors of safety for use in formwork design, incuding those used for allowable stress design (ASD) and load and resistance factor design (LRFD) methodologies, is outside the scope of this report. The correction factors or safety factors will be dependent upon the capability of the ready mixed concrete producer to control the rheological parameters of the SCC mixture.    

Additionally, test procedures for measuring thixotropy and other parameters needed for determining form pressure using these models are discussed. Details regarding the instrumentation needed for field measurement of form pressure and major round-robin field studies conducted to validate these models are presented.

Chapter 2 presents notation and definitions specific to this document. Chapter 3 describes the thixotropy of cement-based materials, test methods, and the effect of thixotropy on SCC form pressure. Chapters 4 and 5 identify the main material and casting parameters that influence form pressure characteristics, respectively. Chapter 6 presents the primary models available to estimate SCC form pressure. Chapter 7 discusses the results of two major round-robin field validation studies conducted in 2012 and 2014 to evaluate the suitability of various models to estimate SCC form pressure. Chapter 8 summarizes the key findings from this report.