Ryoichi ISHIZUKA
         Study on the Application of the Permeable Mat to the Playing Field
                              Osamu TAKAHASHI
  Recently, the amount of the waste of plastic bottles has rapidly increased. At 
the same time, in many playing fields, bad drainage due to the malfunction of 
drainpipe is a serious problem. In order to reuse the plastic bottles as a drainage 
material, the permeable mat that is made with plastic bottles cut into pieces has 
developed. This has high permeability, so it is valuable to lay it under the ground. 
  To evaluate the performance of the field with permeable mats, two kinds of tests 
are held on this study. One is the permeability test; the other is the bearing power 
test. 
  Research results are summarized as follows:
1)The field where the permeable mats laid is well drained. Except a heavy rain, 
  there are no puddles after the rain. 
2)If the permeable mats are laid under a field, it will bring about lack of bearing 
  power. To obtain enough bearing power, it is necessary to thicken the surface 
  course considerably.