Formwork pressure of self consolidating concrete
ACI says: “full hydrostatic pressures are seldom observed during SCC pours, meaning that it is possible to safely relax formwork design specifications.” According to the document, “researchers have developed models that incorporate lab-tested material values to predict formwork pressure, but are affected by changing concrete mixture design, air temperature, humidity, and other factors that cannot be accounted for quickly.” This study presented a simple field test method and model that predicts the formwork pressure using a calibrated behaviour, which is called pressure decay signature.
Lange, addresses industry guidelines which recommends formwork is designed to withstand full hydrostatic pressures when using self-consolidating concrete (SCC) and highly flowable concrete.
: The V-Funnel flow time is the period a defined volume of SCC needs to pass a narrow opening and gives an indication of the filling ability of SCC provided that blocking and/or segregation does not take place: the flow time of the V-funnel test is to some degree related to the plastic viscosity.
: The test aims at investigating the resistance of SCC to segregation by penetrating a cylinder with a given weight into the fresh SCC sample.
The constituent materials for SCC are the same as those used in traditional vibrated concrete conforming to EN 206-1.
To achieve these requirements the control of the constituent materials needs to be increased and the tolerable variations restricted, so that daily production of SCC is within the conformity criteria without the need to test and/or adjust every batch.
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“The simple formwork pressure model is shown to agree well with experimentally measured values during the construction of two tall-walls, suggesting that this method and model can contribute to increased cost efficiency of SCC construction while maintaining safe practices,” ACI adds.
With this reached height, the passing or blocking behavior of SCC can be estimated.The growing interest in the use of self-consolidating concrete (SCC) for a wide variety of structural applications has initiated a reexamination of its properties and current construction practices and how they compare with those of conventional concrete.One property of interest is the formwork pressure of SCC and how it relates to that of conventional concrete.This work presents the results for three tall walls (28,21.7, and 13 ft tall) cast slowly with SCC and a 10.6-ft-high column poured quickly by using the same concrete used in one of the walls.The research demonstrates that the pressure of SCC against the formwork drops quickly just after the concrete material is placed.
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Self-consolidating concrete (SCC) is a recently developed innovative construction material.