The Extensibility and Micro-Cracking of the In-situ Concrete in Composite Prestressed Concrete Beams

The paper describes detailed microscopic investigations of the extensibility and microcracking of the in-situ concrete in composite beams with precast prestressed concrete members and in-situ reinforced concrete members. The experimental work included the use of mirror extensometer gauges (sensitivity = 0.5 x 10 to the minus 6
strain approximately) to indicate the onset of cracking, and the location and examination of the cracks with a microscope of 100 magnification.

R.H. Evans and F.K. Kong