Why do hard-court pavements fail?

Aug 19|Acrylic CourtsBy SPORTENG

One of the major challenges faced by the sports industry today is reducing maintenance and extending the lifespan of sports fields by avoiding premature failure. If not designed, constructed and maintained correctly, pavement failures such as cracking, pavement deformation, and out-of-tolerance surfaces will start to spread on your sports field pavements.

What are the typical hard-court pavements for Fields of Play?

These pavements are rigid (concrete) or flexible (asphalt) with either acrylic or synthetic turf surfacing used for netball, basketball, tennis, cricket practice nets and multi-sports, among others.

Their life spans depend on identical conditions than any other sport field surfaces: if not designed and maintained properly, it will develop failures that will accelerate its obsolescence.

A good understanding of the reasons of pavement failures can greatly help pavement designers to develop higher quality designs with longer life spans and can reduce the level of maintenance required.

This blog post will examine the common reasons why hard-court Field of Play pavements fail, and how the pavements lifespans can be expended while reducing their maintenance costs.

Superficial and structural failures: two types of hard-court pavement failures

There are generally two types of failures: structural and superficial failures.

Superficial failures in asphalt pavements are generally the results of poor-quality asphalt supplied and/or poor workmanship. They often lead to issues such as premature degradation of the aggregate ie unsound stone in the asphalt mix, leaving a ‘pockmarked surface’ or ‘cold joints’ between asphalt runs, resulting in reduced compaction and cracking.  

With concrete pavements, additives in the mix can cause shrinkage cracks during the early stages of curing, or poor workmanship when finishing the surface, can leave a variable textured surface.

These minor defects can be remediated before the sports surface is installed, without long term detriment of life span.

Indeed, structural failures require a greater effort to fix and often require the whole pavement to be redesigned.


cracks in the middle of a netball Field of Play in the cityExample of damaged Field of Play hard court pavement.

 

What are the common reasons for a hard-court Field of Play pavement to fail?

The reasons for hard-court Field of Play pavements failure vary from bad construction practices to poor subgrade characteristics. Most failures of hard-court sports pavements arise due to a combination of highly reactive or moisture changes in the subgrade, poor compaction of subgrade/pavement layers, and inadequate drainage.

However, since hard-court pavements are non- trafficable, traffic loading is typically not the reason for failure.

As most of the failures arise from problems with sub-grade, it is important that careful consideration is given to the sub-grade while preparing pavement designs.

Movement in the subgrade = bad news for the hard-court pavement!

One of the major reasons for a hard-court pavement failure is due to the movement in the subgrade: both rigid and flexible Field of Play pavements are prone to failure when constructed on a poor subgrade without adequate mitigation measures.

It is critical to identify the subgrade characteristics during the initial stages of the project by undertaking a Geotechnical investigation. Combining the strength and knowledge of both civil and geotechnical engineers is key to adequately understanding the site conditions.

But how can movements in the subgrade disrupt a pavement so much? It’s because these movements, which can be caused by many factors, reflects through the sub-base and base layers, and become visible at the surface as cracking or upheaval/deformation.

This phenomenon can become quite problematic with subgrades consisting of highly reactive material. Those subgrades will shrink and swell with changes in moisture content, therefore being easily affected by seasonal variation, inadequate drainage, unsealed pavements, and the presence of trees, among other things.

Another reason for pavement failure can be underlying floaters or rock, that will create differential settlement.

To control the amount of moisture change / reactivity of the subgrade, several measures can be incorporated, including an impervious capping layer, geomembrane, in-situ stabilisation, and sub-surface drainage at the interfaces.

As for the potential presence of underlying floaters or rock, measures must be taken to ensure all rock have been removed to a minimum of subgrade level to ensure consistent subgrade conditions throughout the field of play.

Don’t underestimate construction quality control

Improper quality control measures during construction are another reason for pavement failure. This includes poor compaction of subgrade or other pavement layers, use of unsuitable materials, incorrect placement of drainage and other issues. It doesn’t matter how-well designed the solution is, or how well it will respond to the specific site conditions. If it isn’t constructed properly, it will not bring the desired effectiveness.

The design engineer should provide a clear set of design documents and a technical specification to set out both the end-product requirements, as well as an adequate testing and verification regime. In addition, the design engineer should inspect the works at key intervals to ensure works are proceeding in accordance with the design.

 

A good site-specific pavement design along with good construction practice is key to avoiding pavement failures. SPORTENG provides a full suite of design services to ensure success of your Field of Play pavement, including:

  • An investigation brief to our trusted Geotechnical engineering partners and work with them to adequately characterise the existing site conditions.
  • Produce a design that responds to and mitigates pavement failure risks as far as reasonably practical.
  • Document the design and specification thoroughly.
  • Provide Construction Phase Services to assist in verifying that the works are constructed in accordance with the design.

SE_MK_ReservoirHS_BPNetball court Field of Play designed by SPORTENG for Reservoir High School, Victoria.

Reach out to our team today for consultation on your hard-court sports field project!