In-situ Measurement Of Formwork Pressures Generated By Self-Compacting Concrete
Free (open access)
M. M. Giammatteo, A. Gregori & G. Totani
Self-Compacting Concretes (SCC) are a special category of concretes and directions for designing formwork relative to ordinary concretes do not apply to them. In this paper an experimental study on formwork pressure exerted by SCC is reported. The behaviour of the SCC was investigated in instrumented formworks provided for two different types of pressure sensors: common diaphragm pressure transducers and dilatometer cells. In situ measurements of formwork pressure were carried out on walls and concrete columns 6m and 9m high, 0.30m thick and 2.50 or 0.50m wide respectively. Successfully, both types of sensor were in agreement describing the continuous time variation of the pressures. Keywords: in-situ measurements, self-compacting concrete, formwork pressures, dilatometer cells. 1 Introduction The horizontal pressure exerted by ordinary plastic concretes is generally calculated as a function of many parameters: final height and casting rate, vibration method, temperature of the environment and of the concrete, nominal dimension and shape of the aggregate, consistency of fresh concrete, setting time, typology of the additives used, formwork’s shape. Currently, design purposes for ordinary concrete are various, but the resulting pressure diagrams along the casting height are relatively unvarying (CIRIA , ACI ). Unfortunately, recommendations for designing formworks relative to ordinary concretes do not apply to Self-Compacting Concrete (SCC) which represents a relatively new technology developed in Japan since the 1980s (Ozawa et al. ). Driven by their own weight, SCCs quickly flow in the formwork and reach an optimum compaction degree without the need for vibration, also in case of
in-situ measurements, self-compacting concrete, formwork pressures, dilatometer cells.