Statistical modelling of the shrinkage behaviour of South African concretes
Date
2012-02-03
Authors
Gaylard, Petra Cornelia
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Abstract
A hierarchical non-linear model was developed for the time-dependent shrinkage
behaviour of South African concretes, from historical laboratory data.
The fit of fifteen growth curve models to the shrinkage-time profiles was evaluated
and MCDA was used to identify the best model. The three parameters of the chosen
growth curve model were modelled in terms of covariates (relating to concrete raw
materials, concrete composition and shrinkage testing conditions) by multivariate
multiple regression to produce the WITS model. The model largely conformed to
existing knowledge about the factors affecting concrete shrinkage.
Published models for concrete shrinkage were compared to the WITS model
regarding their predictive ability with respect to the South African data set. The WITS
model performed the best across a variety of graphical and numerical goodness-of-fit
measures.
The importance of the study is two-fold:
The concept of hierarchical non-linear modelling has been applied for the first
time to the modelling of the time-dependent properties of concrete.
This is the first comprehensive model to bring together laboratory data on the
shrinkage of concrete generated in South Africa over a span of thirty years.
Description
MSc., Faculty of Science, University of the Witwatersrand, 2011
Keywords
Concrete construction, Concrete mixers, Concrete (expansion and contraction), Concrete (curing), Building materials, Construction equipment