Swedish contractors are successfully building porous tennis courts that are dry and suitable for play within 30 minutes of a heavy rainfall. The aggregate for the bearing slab should range in size from five-sixteenths to one and one-fourth inches. The cement: macadam proportion is 1:10 by weight, and the most suitable water: cement ratio is usually .35. Any water added during mixing must be kept under careful control at all times. The purpose for this rigid mix control is to achieve a continuous skin of cement paste around all of the aggregate particles. It is important to avoid excess water that can lead to a free-flowing mortar, since this will fill the gaps between particles and prevent surface drainage. The topping for the court consists of a one and one-fourth to two inch thick layer of cement bound aggregate. Optimum particle size recommended is between one-thirty-seconds and one-eighths of an inch. Larger particles should not be used because they will create too open a surfacestructure and this can affect play. Smaller particles must be avoided because they will seal thesurface and reduce drainage. The cement: aggregate proportion and for the topping is 1:4 and the water: cement ratio is normally .35. The topping must be placed in bays that follow the central and outer lines of the court. This avoids any disturbing visual effect that could result from differences in surface color. The bearing slab should be damp, but not excessively wet, when the topping is placed. The topping is compacted by ramming. Because the surface has a high porosity, it must be covered with a continuous sheet of plastic film immediately after troweling. The surface should be wet cured by continuous heavy sprinkling for at least five days.