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Title:

Modelling the Interaction Between the Atmosphere and Curing Concrete Bridge Decks with the SLABS Model

Abstract:

The interaction between atmospheric and construction conditions and the exothermic, temperature-dependent hydration reactions of the concrete's binding components may produce adverse conditions in curing concrete, thereby reducing the quality of that concrete. Accurate model forecasts of concrete temperatures and moisture would help engineers determine an optimal time to pour, an optimal mix design, and/or optimal curing practices. Existing models of curing concrete bridge decks and road surface prediction models lack realistic boundary conditions. The concrete models contain unnecessarily detailed hydration heat generation mechanisms for a simplified field forecast model. In this paper, a new energy balance model (SLABS), which can be easily adapted to predict road surface conditions, is described and applied to predict the temperatures and moisture of curing concrete bridge decks made with New York State Department of Transportation's Class HP concrete. Highest concrete temperatures occurred at high air temperatures, humidities and initial concrete temperatures and at low cloud cover fractions and wind speeds. Peak concrete temperatures can exceed 60°C. To minimise concrete temperatures and temperature gradient magnitudes, concrete should be placed during the late afternoon or early evening. As a field forecast model for which the meteorological inputs are taken from NGM MOS forecasts, the outputs of SLABS include the peak concrete temperature (to within 2°C of the observed in one application), peak temperature gradient, evaporation rate at the time of placement and several warning messages indicating adverse field conditions.

Source(s):

Meteorological Applications, Volume 10, Issue 2 , pp 165-186; State University of New York, Atmospheric Sciences Research Center; and Rensselaer Polytechnic Institute, Department of Chemical Engineering. For a copy of this resource, please direct your request to WeatherFeedback@dot.gov.

Date: 2003

Author:

Wojcik, Fitzjarrald, Plawsky

Keywords:


Pavement temperature

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