This study evaluated the impacts of construction on the air content and air-void system structure of Portland cement concrete pavements. The primary intent was to quantify the air content of fresh concrete before and after it has gone through the slipform paver. The air-void system parameters of hardened concrete were then assessed using cast and extracted core specimens. The results of the air content testing on fresh concrete and the concrete cylinder specimens cast in the field suggested that there is some loss of air as the concrete passes through the paver. Laboratory testing performed on cores extracted from the pavement did not provide any conclusive evidence that entrained air is lost during the slipform paving process. In fact, many of the extracted cores had measured air content values that were much higher than the specification requirement. If excessive, this could result in increased permeability and low-strength related issues. Although a rigorous statistical analysis was not performed, the results suggest that the air content testing on fresh concrete is not capturing the true air content of the concrete placed with a slipform paver. The fresh concrete air content is generally lower than the air content measured in the cores.

This book contains selected papers resulting from the 2020 International Conference on Road and Traffic Engineering (CRTE 2020) covering Road Engineering and Traffic Engineering, aiming to provide an academic and technical communication platform for scholars and engineers engaged in scientific research and engineering practice in the field of Road Engineering and Materials, Traffic Engineering and Management and Transportation Engineering. By sharing the research status of scientific research achievements and cutting-edge technologies, it helps scholars and engineers all over the world to comprehend the academic development trends and broaden research ideas. So as to strengthen international academic research, academic topics exchange and discussion, and promote the industrialization cooperation of academic achievements.

Includes the ACT news letter (title varies slightly).

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.