Abstract
Slab track is replacing obsolete ballasted track. This work proposes crushing out-of-service ballast and sleepers for use as aggregates for constructing the slab track. Three kinds of recycled self-compacting concretes were designed; the first one with aggregates from crushed ballast, the second one with aggregates from crushed sleepers and the third one with both kinds of aggregates in the proportion they appear in the track. The mechanical and durability properties of these concretes were analysed. The durability test was focused on freeze-thaw and drying-wetting cycles. The results obtained lead to the conclusion that out-of-service track could be used to build the new one, closing the loop.
Highlights
For approximately 130 years, rail traffic has been carried out, mostly on ballasted track
recycled concretes (RC)-B and RA from crushed sleepers (RC-S) were designed using 100% of incorporation of recycled aggregates (RA) and the RC-M using a proportion of 1/7 RA from sleeper and 6/7 RA form ballast)
It can be observed that the mix which uses RA from crushed sleepers is lower than the one which uses crushed ballast, which might be expected [9], but due to the geometry of the RA-B, it is necessary to increase the quantity of water required for obtaining a self-compacting concrete
Summary
For approximately 130 years, rail traffic has been carried out, mostly on ballasted track. The slab track involves an important economic saving in maintenance and a better mechanical behaviour, it requires a higher initial investment with lower constructive performances [1]. It is proposed that, when the superstructure is obsolete, a second life should be given to any element of the superstructure that can be recycled This solution is a better solution from the mechanical point of view and involves lower maintenance costs. The use of fine particles has been studied and shows that the concretes with RA have a worse behaviour to durability and worse mechanical properties [10,11] For these reasons, the standards impose some limitations on the use of coarse aggregates and ban the use of fine recycled aggregates, for example, the EHE-08 or EN 13242 [12,13] or provide catalogues such as the Construction and demolition waste catalogue [14], which classifies each waste, specifying its possible uses, these regulations are rather conservative. In a second test round, the recycled aggregate concretes were tested with different durability tests such as the frozen-thaw and drying-wetting cycles test
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