United States Patent (19) 11) Patent Number: 4,564,310 Thelen Et Al
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United States Patent (19) 11) Patent Number: 4,564,310 Thelen et al. 45 Date of Patent: Jan. 14, 1986 54) RESLENT PAVNG COMPOST ON FOR Primary Examiner-Allan M. Lieberman PLAYFIELDS SPORTS FELDS AND Attorney, Agent, or Firm-Paul & Paul RECREATION AREAS 57 ABSTRACT 76) Inventors: Edmund Thelen, 658 Davis La., A porous resilient paving system for use on well Strafford; Daniel N. Black, III, 330 drained soil as a playing surface is described as having Gulph Hills Rd., Radnor, both of Pa. (1) a soil-covering layer consisting essentially of mineral 19087; Thomas L. Kiley, 3908 aggregate having a thickness in the range of from Newport Gap Pike, Wilmington, about 2 to about 4 inches; Del. 19808 (2) a layer of fibrous vulcanized rubber particles cover (21) Appl. No.: 618,495 ing layer (1), said layer (2) having a thickness in the range of from about one-half to about two inches; 22) Filed: Jun. 8, 1984 (3) a core composition layer covering layer (2) consist 51) Int. Cl.' .......................... E01C 5/02; E01C 5/18; ing essentially of a matrix formed from about 70 to 87 EO1C 5/22 weight percent vulcanized rubber fibers bonded with (52) U.S. C. ........................................ 404/31; 404/32; from about 13 to 30 weight percent of a rubber latex 428/331 selected from the group consisting of natural rubber (58) Field of Search ..................... 404/31, 32; 428/331 latex and synthetic rubber latex; and (4) a topping layer covering layer (3) consisting essen 56) References Cited tially of from about 68-74 weight percent vulcanized U.S. PATENT DOCUMENTS rubber particles of from about 12-30 mesh, zinc oxide 4,044,179 8/1977 Haas, Jr. ............................. 428/331 in an amount from about 1-7 weight percent and 4,099,943 7/1978 Fischman et al. .................. 428/331 bonded with about 25 weight percent of a rubber 4,263,184 4/1981 Lee et al. ............................ 52.5/935 latex. 4,389,435 6/1983 Haas, Jr. ............................. 428/331 4,396,653 8/1983 Tomaria .............................. 428/331 4 Claims, No Drawings 4,564,310 1. 2 quired frequently, as the materials wash or are kicked RESLENT PAVING COMPOSTION FOR away. Furthermore, the materials tend to get dirty and PLAYFIELDS SPORTS FELDS AND to cling to the clothes of the players. RECREATION AREAS SUMMARY OF THE INVENTION This invention relates to soft, resilient, self-draining, In accordance with this invention, there is provided a economical pavement compositions for use in play, resilient paving composition which possesses a degree sports and recreation areas such as: of softness and energy-of-impact absorption, the degree a. underlayment for playground and athletic equip being selected to assure maximum safety or comfort of ment, where it prevents or minimizes injuries due to 10 persons engaging in sport or at play. A primary goal is falls, to reduce the injuries of children and sports people b. complete playgrounds where it minimizes or pre incident upon their recreational and athletic endeavors, vents accidental injuries due to tripping, shoving or and to reduce fatique and joint deterioration in joggers, other violent collision with the surface, and injuries to walkers, and standing workers. joints and muscles in feet, legs, hips, back and neck due 15 It is an object of this invention to provide such a to repeated impact during running or jumping, and composition with a surface which is non-skid wet and c. football, soccer, baseball and other sports fields to dry, and which will normally not burn or abrade the minimize or prevent accidental or fatigue-type injuries skin. due to tackling, falling, running, jumping, or other It is an additional object to provide such a composi contacts with the surface incidental to the sports, and 20 tion as a porous pavement through which precipitation d. in recreation areas and around pools, where the will pass into the underlying agregate or soil, so the play pavement composition provides comfort and safety for area will be free of standing water and may be built sitting, laying, rolling, walking and lounging around. dead level. Synthetic pavements for tennis courts and football It is a further object of the invention to provide a low fields are well known to those versed in the art. They 25 cost paving material whose major component by are intended to be more durable and more-or-less simi weight consists of scrap rubber, such as from tires. lar in playing characteristics to clay tennis courts and It is still a further object to provide paving which is grass football fields. Resilient synthetic surfaces for durable in outdoor exposure, and under hard use, but running and jogging tracks also are known and at least which nevertheless is readily patched if any area needs one type, made of wood, is claimed to be faster than 30 replacement or repair. cinders. The materials and designs of the track and field The compositions of our invention are especially sports products are diverse but are typified by (1) a useful in paving systems which include, as a minimum, fabric glued on a pad which is laid on a solid asphalt the pavement composition itself, or core; the base it is concrete or cement concrete base, or (2) polymer laid over; and the topping which is spread over the bonded rubber particles formed in panels and mounted 35 core. These and additional and alternate elements are on a solid base. set forth herewith. In the former (1), the fabric contains nylon or poly The base for the pavement compositions of our inven propylene tufts anchored into a web by polyurethane tion typically is a layer of mineral aggregate 2 to 4 adhesive. This is glued to a closed cell polyethylene or inches thick, spread over a draining soil which may or other pad which has been fitted to and glued to asphalt 40 may not be covered with filter cloth. The soil may be concrete paving. The cost of the materials and the elab permeable enough to drain itself, or it may contain orate construction make this pavement too expensive pipes, french wells or other features. for widespread economical use. Furthermore, due to While a cement, concrete or asphalt concrete base loss of tufts and collapse of the pad under concentrated may be used if it is properly drained and if the soil under use, as well as the lack of a suitable method for replac 45 it is well drained and stable, this kind of base is expen ing the worn areas, this pavement requires replacement sive and unnecessary. The fact that in the use of the in as little as five years. compositions of our invention such bases are neither These earlier pavements compared to natural grass required nor desired distinguishes our system from all surfaces are hard, providing a more damaging impact other resilient pavement systems known to us. when fallen on, and a livelier bounce to a baseball. They 50 The preferred aggregate base consists of crushed permit a player to slide for some distance when tackled stone in the size range of to inch. This may be used in football, which reduces the force of his fall; whereas, throughout the aggregate base, or better, as a choke in games like soccer a non-skid surface would be more layer on top of coarser stone such as 1 inch to 2 inch appropriate and safer. Their lack of adequate cushion material. ing, resulting in unnecessary or unduly severe injuries, 55 The aggregates are open-graded, i.e., the stones in is a serious deficiency in amateur or school sports and any one layer are all about the same size. Hence, about an expensive one in professional sports where large 40% of the aggregate volume consists of voids; these sums of money are involved. The latter (2) materials serve as reservoirs to store the water percolating consist of semi-rigid tough blocks of polymer such as through the pavement until it can percolate into the soil polyurethane filled with rubber particles of various 60 underneath. shapes and sizes. These products are expensive and In accordance with one embodiment of our inven although they vary in resiliency in general they are tion, a layer of coarse vulcanized rubber fibers is laid deficient in this property and hence inadequate in safety over the aggregate base or soil and covered with the and comfort. core composition. We have found that for this purpose Moreover, sand, tanbark, sawdust and wood chips 65 rubber particles shredded from tires, particularly the are sometimes used in play and athletic areas, under fibrous buffings retained on a 4 to 8 mesh screen, in a acting bars and swings and in jump pits, for example. layer to 2 inches thick, contribute significant resilience Maintenance or replacement of these materials is re to the system and thereby permit the use of thinner core 4,564,310 3 4. compositions. A one-inch layer of fibers under a one with a inch to inch layer of a topping containing inch core gives the same deceleration on impact, "Gs,' small rubber particles, a greater percent of latex, and as a two-inch core composition alone, at a much lower zinc oxide in the following proportions: COSt. The use of wood chips, tanbark, sand and other par ticulates under playground equipment provides a mud Percent by weight free surface that is easily sheared, but does not provide Rubber fibers - 12 + 30 mesh 68-74% much of a cushion for impacts normal to the surface. On ZnO 1-7 the other hand, rubber fibers covered with the core Latex (anionic) 25 compositions of the invention are not easily displaced in O shear, and are quite compressible, hence shock-absorb Pigments which do not react with the latex, generally in ing under normal impacts.