The behaviour of recycled rubber shockpads for synthetic sports pitches

Shock-absorbing layers perform vital roles in the user comfort, safety and ball interaction characteristics of synthetic sports pitches. This layer typically comprises a porous composite of granulated recycled rubber bound in a polyurethane resin, mixed on site and compacted and cured to form a flat continuous pad upon which the synthetic carpet is laid. A lack of published scientific information regarding shockpad behaviour or design prompted research at Loughborough University. This research investigated fundamental behavioural aspects of in-situ shockpad layers, including: their design; construction; mechanical behaviour; and sought appropriate and novel test methods for their assessment in the laboratory and field. This paper provides a summary of these unique findings in relation to the effect of mix design variables, including binder content, bulk density, layer thickness and rubber size distribution. Data are presented for shockpad energy restitution, impact behaviour, and shockpad tensile strength. In addition, the effect of short pile and long pile carpet systems placed above to replicate whole pitch systems is presented. Conclusions are presented and include recommended requirements for the industry to incorporate changes in design and construction quality assurance.