SO YOU WANT TO USE LIGHTWEIGHT CONCRETE - NOW WHAT?

摘要

Lightweight concrete has applications for the railroad industry, especially for reducing the weight of precast concrete elements to reduce costs for transportation and erection. But many designers and specifiers are not familiar with using and specifying lightweight concrete. Lightweight concrete only differs from normal weight concrete by the type of aggregate used - lightweight aggregate. Otherwise, the processes and materials for making lightweight concrete are the same as those used for making normal weight concrete. Lightweight aggregate is simply a lighter type of rock that has been manufactured for nearly 100 years by expanding natural raw materials at high temperatures to produce a lighter type of structural aggregate. This paper will follow the introduction to lightweight concrete that was presented at the 2016 AREMA Annual Conference with practical guidance on how to design, specify and build railway structures using lightweight concrete. This paper will discuss material properties to use in design; how to design using lightweight concrete (using the AREMA Manual of Railway Engineering); how to specify lightweight concrete; and some issues to be considered during construction when using lightweight concrete. Regarding design, several adjustments for lightweight concrete that have been incorporated in design specifications will be highlighted. Several issues will also be highlighted related to specifying lightweight concrete. Issues that the construction team needs to be aware of for successful projects using lightweight concrete will also be explored. The length of the paper is limited, so a complete discussion of all aspects of each topic is not possible.