Testing Materials for Sportsturf Construction
By ANN MURRAY European Turf Laboratories
The Benefits of
YEAR round play has led to increasing demands on golf courses and sports grounds. In the 1960’s the United States Golf Association (USGA) began research, that is still ongoing today, into the best construction for golf greens to facilitate maximum play and satisfactory grass growth. The principles behind this research apply also to the construction of other sports grounds such as football, rugby etc. Sports pitches and golf greens are
expected to resist compaction, be free draining, but retain sufficient water and nutrients to support grass growth. In order to achieve these properties, the materials used to construct sports pitches must be selected carefully. Testing is the means of determining that the construction materials will perform as required.
Construction materials usually comprise of gravel for the drain lines and drainage carpet layer and a ‘rootzone’ layer placed above the gravel in which the grass is grown. The rootzone layer is predominantly made up of specially selected sand with an organic amendment added.
Physical Property Tests
There is a range of tests that can be carried out to assess physical properties.
A) SAND & GRAVEL - PARTICLE SIZE DISTRIBUTION
The most basic test for gravel and sand is the particle size distribution test (PSD). This test will determine the range of different sizes of grains present in sand and rock fragments present in gravel. The PSD of the sand for rootzone or the gravel for drains is critical to the performance of these construction materials in sports pitches.
In both gravel and sand, uniformity of particle size is very important in order that they are able to resist compaction due to foot traffic and remain free draining. Sand that is predominantly comprised of ‘medium sand sized grains’ will produce the correct balance of large pore spaces through which water can drain while having enough capillary (small) pore spaces to retain
water. However, sand that is too single sized can lead to problems with stability at the surface particularly if the sand grain shape is rounded. With this in mind, the ideal PSD for rootzone sand is usually one that has around 20-30% of the particles in the coarse sand fraction, 40-65% of the particles in the medium sand fraction and 12-16% in the fine sand fraction with preferably low levels of very coarse particles >1mm or very fine particles
B) SAND - pH
Sand with a moderate pH level is preferred. Extreme pH levels, either very alkaline or very acidic, are best avoided as problems may be encountered with nutrient uptake and, therefore, grass growth as a result.
TESTING before CONSTRUCTION!
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