National Center for Wood Transportation Structures

About the research

This Phase II project contained two parts. Part A focused on the investigation of the characteristics and thermal properties of commonly used slags in Iowa cementitious materials and their effects on adiabatic temperature rise (ATR) in Iowa mass concrete structures. A new hydration model for slag-containing cementitious materials and a three-parameter ATR prediction model were developed and validated. These models were incorporated into the ConcreteWorks software, significantly improving its thermal predictions for mass concrete with slag. Part B focused on the development of a new seal slab component in the ConcreteWorks software. This new component is simple, user friendly, and well-integrated into the existing ConcreteWorks software and enables the prediction of the temperature profile of a bridge footing placed on a seal slab.

In Part A, the research included the following: (1) characterizing physical and chemical properties of slags and concrete materials, (2) studying slag’s effect on cement hydration using isothermal calorimetry, (3) evaluating temperature rise in mass concrete with various slag types and dosages using semi-adiabatic calorimetry, (4) testing large concrete blocks with various slag replacements, (5) developing and validating the ATR prediction model for slag concrete, and (6) integrating the models into the ConcreteWorks software. In Part B, the research included the following: (1) developing a new seal slab component in the ConcreteWorks software and (2) conducting trial analyses to investigate the effects of the time of footing placement, the sizes of the footing and seal slab, and environmental conditions on the temperature profile of a bridge footing placed on a seal slab.

The updated ConcreteWorks software now features enhanced input parameters and equations for better heat prediction, confirmed through thermal and sensitivity analyses. The improved slag hydration model, which accurately incorporates slag’s chemical properties, enhances temperature prediction accuracy for concrete containing slag. The maximum core temperature of a footing placed on a seal slab was generally found to be higher than that of a footing with no seal slab. In addition, it was found that a seal slab generally enhances the capacity for heat retention in the footing, keeping the core temperature of the footing high for a longer period.