CONSTRUCTABILITY BENEFITS OF THE USE OF LIGHTWEIGHT FOAMED CONCRETE FILL (LFCF) IN PAVEMENT APPLICATIONS

摘要

Lightweight Foamed Concrete Fill (LFCF), also known as cellular concrete, has been growing in use in transportation infrastructure projects over recent years. LFCF is a versatile construction material that has now been in use for over 30 years. A number of recent road rehabilitation projects have demonstrated some of the benefits of use. With a greater emphasis on sustainability on all provincial and municipal road projects, new solutions are being sought to minimize the generation of waste and deliver better performing pavements that require less maintenance interventions. Roads over peat and organic deposits pose challenges for road agencies. They are subject to continual and long term settlements that necessitate frequent patch repairs. The downside of such repairs is that the additional weight of the new asphalt, triggers further settlement. Traditionally, permanent solutions have necessitated the total reconstruction of the road section and removal of the underlying organic layers. This is expensive, creates huge traffic disruptions, generates waste and consumes large volumes of aggregate for the reinstatement. The use of lightweight fill offers an alternative as it allows the pavement to be 'floated' above the organic layer. However, the traditional lightweight materials, such as polystyrene, have been prohibitively expensive for such applications. In recent years, LFCF has been successfully used as a cost effective solution in road works. LFCF is a foamed, pumpable, cementitious fill with a density of only 475 kg/m~3, about a quarter of that of conventional granular fill. With a compressive strength of at least 0.5 MPa, it has sufficient strength to support pavement loads. However, the real advantages relate to constructability, since the material can be installed very quickly, minimizes excavation time, can be placed in winter and does not require conventional compaction or associated testing. This paper will provide an overview of the use of LFCF for road works, including typical specifications, quality control/assurance requirements, and performance based on a number of case study applications.