026

Title:

The Impact of Conversion on the Durability of Calcium Aluminate Cements

Discipline: Civil Engineering (Structures)

Presenter:

Marwa Korayem

Abstract:

The deterioration of infrastructure in North America has resulted in a significant need for concrete repair materials that can be used to maintain service life of these structures. Hydraulic cement based rapid repair materials can be used to repair pavement and bridge deterioration with minimal impact on economic activities such as freight handling or public transportation. While there are many options for use in repair situations, calcium aluminate cements have become more popular recently, particularly in situations where repairs must be completed rapidly. Calcium aluminate cement (CAC) is a cement characterized by its rapid strength gain, even at low temperatures approaching 0℃. This key feature has made CACs extremely useful in certain concrete repair applications, particularly in cold regions. CAC systems undergo a unique process known as conversion, in which metastable hydrates convert to stable hydrates, resulting in an increase in porosity and strength loss. Understanding the time at which this conversion occurs, and the magnitude of strength loss is important for long-term design decisions involving repaired concrete systems. There has been significant previous research work on the kinetics of the conversion process in the CAC systems. However, there is very little information available on the impact of conversion on long-term concrete durability. This research discussed the capability of using electric resistivity testing and indication of higher porosity to detect conversion in CAC systems. The research will also focus on understanding the relationship between converted and unconverted CAC concretes in terms of drying shrinkage coupled with studying their microstructures.

Author(s):

Marwa M.Korayem, Matthew P.Adams

Funding Acknowledgements:

NJIT