Foundation Requirements
1.Foundation Requirements
No facility lasts for ever, but it is entirely reasonable to expect the foundation of an athletics track to continue to function effectively over a time period that may encompass several replacements of the synthetic surface. To do this,it is necessary to ensure that a very good standard of road construction is emploved. It should be noted that even on the most ideal site, a minimum of 150mm of free-draining aggregate below a minimum of 60mm bitumen/asphaltic concrete will prove to be necessary. On less than ideal sites, a build-up of 400mm or 500mm is quite likely to be needed. The bitumen/asphaltic concrete would typically comprise a base layer 40mm to 60mm thick and a finishing course 25mm to 30mm thick.
1.1 ESSENTIAL CRITERIA
The foundation to any synthetic surfaced athletics track should be designed to meet the following criteria:
- It should be capable of supporting and transmitting to the existing ground the loads of all vehicles, construction machines and materials to be used in the construction, without causing deformation of the site,or exceeding the ground- bearing capacity
-It should be capable of supporting and transmitting all the loads on the surface from athletes and maintenance equipment without permanent deformation o the surface.
-It should provide protection to the surface from the effects of ground water. subsoj ground movementand rost heave.
-it should ensure that water whether rainwater or natural aroundwater will drain away freely, either into the subsoil,or into a drainage system.
- It must quarantee porosity to rainfall in excess of the heaviest likely rainstorm and ensure that no standing water remains on the track surface which could impair the use of the facility. Porous surfaces must permit such rainwater to seep away freely.
-It should contribute towards providina suitable performance characteristics o the surface. in respect of athlete /surface interaction.
-It should ensure that the above criteria are retained throughout the life of the installation.
- It should provide al the above at the most economical costs in terms of initia capital outlay and subsequent maintenance costs.
1.2FOUNDATION CONSTRUCTION TECHNIQUES
The procedure adopted for the foundation construction will normally consist of the following operations:
- Excavation to remove vegetable matter soil.
- Rolling or other treatment, to identify any weak or soft spots which should be dug out and replaced with suitable compacted hard,non-degradable filling
-On some sub-soils,compaction only may be necessary
-Drainage installation for subsoil or sub-section
-Laying and compacting of first stone base.It should be graded to falls, and checked for accuracy of finished level within the tolerances specified
- Laying and compacting second and subsequentif necessarystone layers as above, to provide total construction height of the unbound base lavers
-Blinding with small, angular crushed stone(sand or ash may be acceptable, depending on the finishing(topcourse)
- Laying and compacting bitumen-bound base and finishingtopcourses.There are a number of alternative forms of finishing course on offer.The choice is determined in consultation with the surfacing installer in the light of the particular synthetic surfacing system to be used.The bitumen binder in bituminous bases should be "straight run", unfluxed, unless the finishing course is intended to be left exposed for sufficient time to allow all solvents to evaporate.
