REPAIR OF DEEP CRACKS
Cause of cracks --- Cleaning the crack --- Epoxy method of healing --- Filling the crack --- Smoothing the surface --- Protecting the components --- Cleaning up
Cause of surface cracks --- Acrylic emulsion repair --- Use of acrylic slurry --- Curing --- Protecting the acrylic --- Cleaning up
Types of material --- Acrylic bonding --- Performance of polypropylene --- Preparing the court
COLORING THE REPAIR
Strengthening the paint with acrylic --- Surface preparation --- Smoothing the application --- Flash coat
The methods of lining --- Construction of tool --- Type of paint --- Cleaning spills
STRAIN RELIEF SLOTS
Two methods of cutting --- Cleaning up --- Two methods of filling the slot
PORTLAND CEMENT LATEX FILLER
When to use --- Materials and characteristics --- Cleaning up
Tack coating surface --- Filling with macadam --- Stock piling macadam --- Asphalt slurry fortified --- Smoothing the surface --- Testing repairs --- Cleaning up --- Desirable pitch of court --- Effect of pitch on game --- Courts not in a plane
Miscellaneous cracks --- Water freezing damage --- Repair of above
Painting galvanizing --- Priming rusted fence --- Painting primed fence --- Methods of painting --- Safety precautions
Timing repairs --- Irreparable courts --- Overlaying a court
Sources of materials END OF TABLE OF CONTENTS
REPAIR OF DEEP CRACKS
The most common form of failure of all weather macadam (hot mix asphalt) tennis courts is cracks. It is commonly thought that those cracks are caused by frost heaving. However, this is not what causes them. They are formed by cold contraction of the slab in winter. The low temperature makes the court brittle. A sudden cold snap contracts the court; and, if the underlying base is rough with large aggregate at the surface or is an asphalt impregnated clean stone, the slab cannot move, and forms deep cracks instead that go all the way down to the base. A defect in the macadam will also cause a crack.
On some courts, the base is so rough that the cracks are numerous and, therefore, irreparable. However, if there are only a few deep cracks, it is possible to make a permanent repair. A permanent repair is especially likely if the crack is near an edge, or parallel to the net, and if a contraction slot under the net is acceptable.
I will describe a procedure that does an excellent job on reparable cracks. It makes use of a resilient epoxy, made resilient by use of Versamid hardener. This hardener has the advantage of having very low toxicity, of having a wide range of mixing ratios, and a long pot life (time to cure). It soaks into the macadam and has excellent adhesion. Some manufacturers I have obtained it from are shown in the appendix, where I have listed similar information for all the materials mentioned in this article.
Versamid-epoxy is as viscous as honey and, therefore, does not flow out from under the crack unreasonably. If the base is porous, a fairly thin bead, say 1/4 inch in diameter, allowed to harden, will seal off the bottom if applied several times.
If there is debris in the crack, as there usually is, the best way to remove it is with a power washer. Compressed air is sometimes feasible, because a thin film of earth will be penetrated by the epoxy, but power washing is more thorough, safer, and is probably usually necessary on thin cracks. Wide cracks can be wider at the bottom. It is, therefore, sometimes advantageous to widen the top of the crack so the top of the crack won't clog up before the bottom is full. This can be done either with a water cooled saw or by softening the macadam with an electrical heating coil and peeling the top off. A water-cooled saw is necessary for thin cracks rather than a dry saw because, otherwise, the crack will smear shut. Heat and careful use of a razor utility knife will also work well and uses less labor for thin cracks.
Materials poured into the cracks for previous repairs must also be usually removed. Any thermoplastic materials which can cold flow, such as asphalt slurries and compositions, must be removed. It is probably necessary to remove brittle materials; such as, concrete because of differences in expansion and contraction introducing shear stress. Sometimes the pressure washer will do it. More often, removing these materials is onerous. Sometimes they have to be manually chiseled off inch by inch or diamond-sawed out. The job is especially difficult if the court has been overlaid with concrete or macadam has been placed in the crack in the lower slab. Macadam fill has to be removed because it is very unlikely that the macadam has been compacted to an optimum density and it will, therefore, be a zone of weakness. If polypropylene straddles the crack, this must be cut out as well. The fact that the geotextile has not broken does not mean that it won't elongate in the future. Also, it is essential that the underneath layer be healed as well as the thin (usually) top layer.
The side walls of the crack must be dry. A hint of dampness will not prevent the bond, but the safest is to get the walls dead dry. This can be done in cooler weather using a long coil of nichrome resistance wire overlaid by a 16-inch wide insulation bat. An hour or so should be sufficient. The heat also permits the epoxy to flow in more rapidly. A few hot, dry summer days should also dry the crack out reasonably well. It is imperative that it not rain while the crack is being filled. If it does rain, you will have a major job with a silicon carbide or diamond saw to remove the damaged epoxy surface.
After you have sealed the bottom and filled the crack, it will be necessary to grind the surface smooth. It is impossible to avoid a build-up of epoxy on the surface. Small amounts can be removed with a belt sander. Larger amounts can be removed with a disc sander using a very coarse disc, which goes much faster. It is important to remove surface epoxy or you run the risk of the epoxy curling up after a few months. A leaf blower is the tool of choice for removing dust that a broom leaves behind. I will discuss later how to smooth over gouges or low spots and color the results.
The stoichiometric ratio (ratio in which all molecules react) of versamid-epoxy is about one to one by volume. To make the epoxy more resilient, about like a very hard leather, I increased the amount of versamid and used 3/4 epoxy to one versamid. The small decrease in strength is immaterial because the set epoxy is at least ten times as strong as the macadam at its stochiometric ratio. The epoxy must be mixed thoroughly. I have found that an offset flat-nosed trowel, mixing the material in a square milk carton, works well. Continuously scrape the fluid off the sides until you are sure it is well mixed.
In order to make the epoxy match the macadam in its coefficient of expansion in cracks larger than 1/8 inch, I have been using sand and/or 1/8 inch grit mixed into the epoxy. The grit can be placed in the crack in a thin layer or poured in after the epoxy. I don't know whether this addition is necessary or not. A small amount of sand can be placed at the bottom of wide cracks if the base is too porous to help soak up the epoxy. Sand can also be used to permit players to use the court before the epoxy is completely hard. Make sure that any loose sand is removed to avoid liability.
I have not filled any cracks over about ¾ inch wide with the above procedure. For them, I have coated the side walls with the versamid-epoxy, and then immediately pounded hot macadam into the crack with a hot caulking tool driven by an eight-pound sledgehammer or small air hammer. This procedure has worked. However getting the macadam in before the edges cool is difficult. Also the epoxy triggers off rapidly on a hot day. A moderate temperature is best and more than one worker. I have no reason to believe that filling the wide cracks wit versamid-epoxy as previously described would give problems, and is worth trying, because the hot macadam method is time consuming. The material cost is much less though. It is important that the crack be completely filled the same day if rain threatens, because it is not possible to dry hardened epoxy with heat or hasten its setting because it is degraded by high temperatures. The water can be blown out with compressed air, but safest and least laborious is for water not to get in in the first place. It is also desirable to protect the top of the hardened epoxy within a few weeks with asphalt or acrylic paint if for some reason the job can not be completed immediately for the epoxy is degraded slowly by ultraviolet light.
It is important that no water get into the liquid versamid, since the water dissolves in the versamid, and is very difficult to remove. It is probable that a vacuum would dry it, but most likely salvaging it would not be practical. The water can not be removed by evaporation in air because carbon dioxide ruins Versamid. Because of the carbon dioxide, it is necessary to keep a lid on the container when not in use.
Water into the epoxy part is not so serious, since water floats on top, and can be largely removed by decanting. The remaining drops can be soaked up with a paper towel. It also can be safely dried by exposure to air.
The mixed resin can be easily removed from hands and tools with water. After it B stages (gummy), acetone is fairly effective. After it hardens, only a flame will remove it from tools. If putty knives get too hot, they will warp. From hands only sandpaper or time will work.
Some cracks are present only in the surface layer. They are able to materialize if the builder did not get a good bond. The most likely reason for a poor bond is slurrying or painting over a court stained with mud or algae.
There is an excellent way to correct nearly all surface defects. The way is to use an acrylic emulsion equivalent to Rohm and Haas' Rhoplex AC 261. This material is extremely strong compared to asphalt. It has a low viscosity, almost as low as water, and can penetrate every nook and crevice. Once it sets by water evaporation, it is very strong and adherent. It is sufficiently though that its sand slurry can be used instead of asphalt where people are going to use the court wearing street shoes and would probably even work for street hockey.
Sixty to eighty mesh sand (fine sand) can be used with it to make a slurry; and, in fact, some kind of filler is necessary to give it body and porosity where larger voids are involved. It is tolerant of a fairly wide ratio of sand to emulsion. There is an application problem, since the sand settles out very rapidly. However, if fine wood flour is added also, the sand remains suspended for a long time. Almost as great a volume of wood flour is desirable as sand.
The biggest disadvantage is that it does not develop its tough qualities unless it dries warm, at least 60 degrees, and preferably 70. There are no coalescents in it. If coalescents are added, there is a significant decrease in strength. It can be warmed with a propane torch in a pinch. However, there is no equivalent to a summer sun, especially since some of the cure goes on for a considerable time after it is apparently dry.
It is possible to add color coat to it to make a fairly presentable color, say one part color to five parts acrylic. However, this concoction darkens considerably after a few months. Therefore, spring green should be used. That way one can smooth court and color it fairly satisfactorily in one operation with a very tough coat. In the absence of green pigment it dries to an adobe tan color which darkens considerably in a few months.
Any tools which can handle a liquid, slurry, or paste can be used with it. If it is not washed off the tools while wet, a flame may be used to soften it on steel tools. If acrylic were allowed to build up on a rubber syringe, it probably wouldn't be practical to save it. A flame is practical on a rubber squeegee though. Removing it from tools after hardening is especially easy if they are coated with a thin coating of asphalt first. The least laborious way is to have a bucket or tray of water handy to place the tools when not in use or for periodic moistening. Acetone softens acrylic to a considerable extent.
Acrylic emulsions are biodegradable. That is, some species of bacteria can live in them and give them a rancid odor. When the odor first appears, the emulsions have lost little of their desirable properties. The growth of the bacteria can be prevented completely by pouring a shot glass full of formaldehyde in each 5 gallons of emulsion, including paint. Please keep in mind that if you use this procedure to over-winter emulsions, (there should be no problems with in a single season) formaldehyde is poisonous to virtually all life. In particular, it must be kept out of reach of children, and it may be inadvisable to place one's hands in the emulsion thereafter. Some emulsions come with traces of formaldehyde in them already. It may e required by law to notify workers of the procedure, depending on circumstances.
I cannot emphasize too strongly that any tennis court repairman should not be without acrylic emulsion in his stockpile of materials. It can salvage a host of seemingly impossible situations.
Epoxy alone should be enough to make permanent repairs of most deep cracks. Epoxy alone is a little risky, though. It is especially risky if the crack is a long distance from a strain relief slot or edge, the court has been overlaid with macadam, or has been repaired using the hot macadam bonded with epoxy method. If it is desired to make the job really certain under these circumstances, it is necessary to use glass cloth.
The glass cloth must be a heavy grade; at least 20 ounces per square yard. The light cloth usually used just is not strong enough, and will usually rip apart. I have used both woven and chopped glass fiber successfully. Probably, woven is a little stronger; but it is difficult to work with. I suspect that on balance the best strategy is a 24 ounce chopped fiber cloth.
Acrylic emulsion is the only way to adhere the glass cloth to the court. Asphalt is subject to cold flow and is hopeless. Epoxy is liable to curl up, and no macadam is strong enough to stop it. Acrylic emulsion is also the only reason why chopped glass mat works. The acrylic can be applied after the glass cloth is laid down. However, for woven cloth, it is safer to wet the court with acrylic first. If a void is left under the cloth, the ball will bounce dead. If you do end up with a void, cutting the cloth perpendicular to the crack and flowing acrylic under the cloth or injecting acrylic into the void will usually work.
The glass patch can then be smoothed either with asphalt sand slurry or acrylic sand slurry. If acrylic slurry is used, it will usually have to be ground smooth after it dries with a disc or belt sander, because it is too tough to e smoothed with an ice chopper or a heavy roller. A slurry can also be made of one part of acrylic to five or less parts of asphalt emulsion. Thus, one can gain some of the economics of asphalt emulsion. However, one cannot gain the labor economics implied in rolling because such a concoction is too tough for a roller to flatten.
I have seen cracks locked together with acrylic bonded polypropylene successfully. However, I am apprehensive of the use of polypropylene even when so bonded.
Polypropylene geotextiles bonded with asphalt and overlaid with macadam will not work because, while they are strong, they will elongate or neck and, thus, put the onus back on the macadam overlay.
If an overlay is put on, isolating both the asphalt bonded geotextile and the new macadam from the underlying slab would probably work, although I have never seen it tried. However, a reasonably sized macadam overlay without the geotextile would probably also work, say three inches thick. Such a procedure is extremely expensive, and if it is opted for, it is my belief that the underlying slab should be repaired with the epoxy method at least, even if it is isolated.
If glass cloth is bonded to the surface, it is essential that any surface sheet or paint be removed which is the least bit loose, as the resulting repair will only be as strong as the surface sheet, otherwise. If the surface sheet is bonded well in spots, it is a difficult procedure, implying one kind of grinder or another. If the surface sheet is loosening its bond below the asphalt slurry layer, a propane torch would usually work if the sides are masked to prevent damage to the adjacent area. In the absence of such a step, the court will pull out from under the glass cloth.
COLORING THE REPAIR
When the repair is smoothed, it is ready for a color coat. The color coat itself cannot be practically used for smoothing because it is subject to mud cracking and, because it has a low porosity, takes too long to dry.
If ten or fifteen percent by volume of acrylic emulsion is added to the surfacing paint, the coating will be noticeably toughened. Such an addition also increases somewhat the amount of fine sand which can be safely used with the paint and, thus, achieve a slower bounce and more fail-safe mixing ratios. Even with the extra acrylic, it is probably not wise to add more than 3/4 of a volume of fine sand to one volume of paint as constituted before the acrylic is added. Such paint is slow enough and skid proof enough when wet, while it still won't chalk. More acrylic can be used than the above, but additional acrylic darkens unacceptably with a few months of aging. The sand is desirable because it prevents blistering. I believe the blistering is caused by tiny amounts of water getting into the macadam through pin holes in the paint or diffusing up from the soil and then suddenly expanding into steam by a hot summer sun. The sand makes the paint slightly porous.
Whenever the coating overlaps onto the existing court, the court must be free of mud or algae. If it isn't, the coating has a good change of peeling off. A power washer or sander will work. The power washer is faster and does a better job, in that it misses no spots, and does less damage to weak court surfaces.
The coating can be applied with almost any tool, such as a brush, for instance, or even be poured on. However, to avoid brush marks, deep sections, trowel marks or the like, it must be usually smoothed the last time with a steel wide putty knife, held at an angle as if one were chiseling off material, rather than smearing it on. By pushing the paint ahead of the trowel in chisel mode, chatter marks and edge ridges are avoided, and a dead smooth surface is possible. One has to go over the slurry this way several times in some areas. If an edge ridge is left, it can usually be rubbed out with your fingers or a smooth bottom tennis sneaker.
Some apply a flash coat of sand-free paint over the coating. The main reason is to eliminate any textural visual differences in the coating. It also has the advantage of decreasing wear on balls and sneakers somewhat. A disadvantage is that the slow bounce is defeated somewhat. In my opinion, it is not worth the extra cost.
If the crack or repair has crossed a white line, the line must be reestablished. There are three ways of doing this. Masking with masking tape, applying with a sprayer designed for the job, and brushing on within a steel jig made of two parallel angle irons. If masking tape is used with a brush, there is no guarantee that the paint won't run under the tape. It is an extremely laborious method whether used with a brush or sprayer. A sprayer designed for the job requires expensive difficult to use equipment, and leaves a slightly fuzzy edge, very difficult to match during future repairs.
The best way is to weld a strap across the tops of each end of two parallel two-inch angle irons which are two inches apart inside. If the angle iron edge which touches the court is ground to a knife-edge and the paint is applied with a good brush held vertically, an excellent job can be done. I suspect that the chamfer of the knife-edge should be inside. The jig edge must be wiped clear of wet paint after half a dozen or so applications. Build up of dry paint should be removed with a razor knife or torch after several hundred feet of line. A four or five foot long tool is practical. If it is too long, slight rises in the court will lift it too clear of the court in spots and it will be awkward to move. If it is too short, it must be moved too often.
A chalk line must be put down to guide the jig. Before laying the job out, check the dimensions. Macadam courts shrink with time. This is probably because the court can contract in winter, but when spring comes, each slab can not expand all the way back again. This is also related to the reason why cracks widen with time. It is something similar to pulling a piece of spaghetti apart and then trying to push it back together again. You also, sometimes, have to contend with lines that were measured incorrectly in the first place. The dimensions go up to the outside of the lines. Make two chalk lines for the serving box divider to avoid painting the wrong side.
Very short white line repairs can be made using a wide putty knife or a sheetrock knife as a masking agent on one side of the line at a time. The above angle iron line jig is rather awkward for that kind of reestablishment.
It is absolutely essential that a 100% acrylic emulsion be used for the paint. If road paint made of fish oil or other materials is used, failure in the form of crazing is virtually certain. Since acrylics are more expensive than other paints and tend to clog up spray nozzles more than oil paints, there is a tendency to select road paints. Don't ever use them or tolerate their use by others.
If any white paint accidentally spills on the color, the situation can be saved by immediately pouring a little water on it, then mopping it up with absorbent paper.
A single coat of a good white paint does a nice job. To get absolutely perfect hide, two coats are necessary, but I feel that this is usually an unnecessary expense. On a repair of old lines, it is definitely unnecessary, of course.
STRAIN RELIEF SLOTS
If strain relief slots are not cut under the nets and between the courts for multiple courts, the above repairs will probably be an exercise in futility. An especially severe winter, at least, will crack the court again. The new crack will not necessarily be in the original crack. If it is in the original crack, it will usually show up as failures on alternate sides of the repaired crack at zone where the epoxy stopped soaking in.
The best way of cutting the slots is with a water-cooled diamond saw. A wax crayon line must be applied first if a straight cut is to be achieved. The slot must go all the way down to the bottom of the macadam slab. To determine this, rub a putty knife along the bottom. If it feels hard and smooth, you are not all the way through. You should test every five or ten feet because the slab can vary somewhat. The slot will open up all the way the following winter if it isn't all the way down. However, it could put an unacceptable strain on the court first.
This operation will generate large amounts of silt and fine asphalt particles. The silt is not quite as much of a problem as the asphalt particles. If these fines dry on the court, it is extremely difficult to remove them. They must be washed off immediately. This presents a severe problem on a sunny summer day when cutting across the dip of the court if you are alone. It must be solved, however, if the court is not going to be resurfaced.
A dry silicon carbide blade also works, but is very slow. It is feasible when a small distance must be finished up, or the diamond saw can't get into the spot. A leaf blower is the tool of choice for cleaning any dust off the court which a broom has too much difficulty with.
The slot does its job. Each year the slot increases in width. An eighth inch blade will make a 3/16-inch slot. It will widen in a few years to at least 1/2 inch. The slot becomes sufficiently wide that there is an uneasy fear of a liability problem for slots between the courts because some one falling can catch fingers in the slot.
I have filled such a slot with Portland cement and sand, one part Portland to two parts sand by volume made up to a loose paste with butadiene-styrene latex cement additive. This worked fairly well for awhile. However, a good release agent or plastic sheet must be applied to one side of the slot. Grease would probably do, but soap is unacceptable, because when it gets cold soap holds on tenaciously enough to defeat the contraction relief. It also holds well enough for a short time to insure that the slot itself will reopen on alternate sides.
I suspect that the best filler would be neoprene sponge rubber, glued on one side, and applied in the winter when the slot is at its maximum width. If the rubber is a little wider than the slot, it should be a long time before there is an unacceptable gap. However, I have virtually no experience with such a procedure.
PORTLAND CEMENT FILLER
If the court is so badly cracked that it cannot be permanently repaired, and there are no funds for replacing the court or overlaying it, the butadiene-styrene cured Portland cement just mentioned for slots can provide an inexpensive way to improve ball bounce and remove liability. If there are more than two parallel cracks per court, the court is probably incapable of being repaired permanently.
Such a paste can usually be applied quickly in one or two pours. After it dries and is ground, it makes a smooth, hard surface with a resiliency and strength approaching some wood. It is even free of cracks the first season. In the winter, narrow cracks will reappear. The repair will be adequate for a considerable time, however. Tennis can be played on it as is, or it can be colored. It accepts an acrylic latex paint very well. The cost can be as little as 1/20 the cost of a permanent repair. It can be played on by at least the next day, and on a hot summer day, within a few hours.
The material is impervious to ultraviolet, ozone, and water. The ball will bounce normally on it. If the crack opens up unacceptably wide in time, more paste can be poured in. A fairly wide consistency of the paste gives good results.
If asphalt or spongy rubberized materials are used to fill cracks on the playing area, unacceptable problems can arise. The material can sag down in the cracks (asphalt slurries) or the ball can bounce dead. For low cost repairs to remove liability or to improve the play, the latex-Portland cement is probably best. It has the added advantage that fairly unskilled workers can handle it.
Water easily removes it from tools and skin while still wet. It takes several hours to cure if it doesn't dry, somewhat longer than Portland cement and water. If it hardens, gasoline or muriatic (hydrochloric) acid will remove it. A flame will disrupt it off of steel tools, much easier if the tools have a thin film of asphalt on them. A container of water nearby is helpful.
Its properties are said to be better if it dry cures. Since it is a latex, a warm curing temperature is desirable. As with ordinary concrete, adding water decreases all properties. The strongest is a stiff putty. However, additional latex (not water) will improve its resilience somewhat while decreasing compression strength a small amount. Since it is much more than adequate in compression, extra latex is probably the way to go on a first pour to get penetration if there is no intent to make a more permanent repair later. Shrinkage starts to be a problem with additional latex. You can also increase resilience somewhat by using less or no sand. All these variables tend to make its use arty. However, it is a user-friendly material, and is difficult to install wrong. Any surface to which adhesion is important should be damp, because if the surface sucks water out too rapidly, adhesion is markedly impaired. If adhesion is very important, wetting the surface with latex is to be recommended. All its properties are better than wet-cured Portland cement. As for punky, dry-cured water based Portland cement; the two are not in the same league.
It can salvage some difficult repairs elsewhere than on a tennis court. It is the surface repair of choice for damaged concrete not subject to gasoline. Keep in mind that it assumes a color darker than ordinary Portland cement and an exact color match is not usually possible. It is very good for giving fire resistance to asphalt roofing and protects the roofing from ultraviolet and wind damage at the same time. A brushed-on coating will erode off in about ten or fifteen years because the composition is slightly soluble in water (NJ, USA rainfall). For this reason, a coat of acrylic paint over it can usually be justified, but such paint is not necessary on a tennis court except for appearance. Acrylics adhere to it well. I have even used it with some success on a bare plywood roof made water tight with epoxy joints. The wet-dry expansion and contraction of wood makes me reluctant to recommend such a procedure at present, though, and it will fail locally in a few years. I suspect that putting down a layer of roofing asphalt first would work, but I have limited experience with large areas. Used to set plaster of Paris (gypsum or calcium sulfate) it makes an extremely tough material, tough enough to make repairs and joints possible without the use of paper reinforcing, and probably possible to use outside for some protected circumstances.
There is also an acrylic emulsion formulated for use with cement that is said to be as good or better than butadiene-styrene in all properties by the supplier. More than likely it is resistant to gasoline and ultraviolet radiation. Both suppliers recommend an antifoam agent, and I can't deny this for sure. I'm inclined to doubt that it confers a significant advantage except, perhaps, where extreme compression strength is imperative, such as under heavy steel structures. The acrylic is more expensive but available from mason supply houses. The butadiene-styrene is only available in four 55-gallon drums in an order.
When the cracks are filled, water which previously drained out of a low spot through which the crack passed, will now remain and create a birdbath. It will, therefore, often be desirable to correct the low spot. If the birdbath is less than 1/4 inch deep, asphalt slurries will work fairly well and are standard in the trade. Deeper birdbaths should receive the lower cold flow properties of solidified hot macadam skin patch. The hot macadam is also less expensive of materials and less susceptible to problems of being washed out by rain during repair.
When hot macadam is used, the surface must be tack-coated first. Asphalt anionic emulsion is the preferred material. The same emulsion paste, which is custom formulated for tennis court smoothing slurries, does a good job; but, is rather laborious to dilute and has a tendency, therefore, to clog sprayers and watering cans. It is necessary to dilute the emulsion one part of tack coat to two or three part of water since the resulting tack coat must be thin. Thick layers can cold flow or bleed, and they can interfere with water vapor transmission when near a paint surface. The latter creates the danger of blistering in the paint. When the surface is black, it is tack coated correctly. If large areas are involved, an excellent applicator can be made out of an old hot water tank. The tack-coat is forced out of a garden hose fitting at the bottom by air pressure at the top. Be sure to use good hoses.
If some tack-coated coarse sand or grit is placed on the surface while wet it will make screeding the macadam much easier by giving the surface some grab. For the same reason, the surface should be dry before the macadam is applied. Another way of giving the surface a little grab is to sprinkle a little hot macadam on the tack coated surface and allowing it to cool.
Acrylic emulsion can also be used as a tack-coat if the macadam is applied while the acrylic is still wet. This preparation is much more difficult to screed. Also, cleanliness of the surface is much more critical.
The skin patch macadam can be stockpiled for small jobs or saved when it is hardening on the job by spreading it out in a layer about one inch thick. It can then be reheated in a wheelbarrow by pouring in about a quart of gasoline and turning the flaming macadam over again with a shovel until the flame goes out. Be sure to use only containers with a wide opening or the opening of which is protected with a metal screen. Gasoline is otherwise a very dangerous explosion hazard. It is a good idea to have a couple of buckets of water handy as well. Fire extinguishers are almost useless for cooling down fire-affected skin or equipment. If the macadam still did not get hot enough, for some reason, it can still be brought to temperature by playing a large propane torch over a thin layer without lingering long in any one spot.
After the bulk of the macadam is placed on a cool day, it must be tamped or rolled immediately. Depths less than 1/2 inch can be compacted any time on a hot summer day; but, it is always desirable to tamp soon. If a roller is used, roll over the macadam slowly to give the macadam time to sag down. Also, if the bath is about the size of the roller wheel, or less, be sure that the macadam is higher than the shoulder and then scrape off the excess while still hot. Another way of solving the last problem is to roll it with a rubber tired vehicle or a vehicle with narrow steel wheels. A pickup truck can be made into a roller by welding two steel cylinders to two rims about one foot wide and mounting on the rear.
To avoid the extra labor implied in hot macadam, asphalt slurry in which the asphalt has been stiffened with about 20% acrylic emulsion does a good job and may be more practical on small jobs. Such a fill is superior to macadam in toughness. One hundred percent acrylic is also possible, although fairly expensive. An additional advantage is that such a repair would allow that part of the court to tolerate street shoe traffic and could be used for basketball and probably even street hockey.
Any roughness on an acrylic fortified bath must be ground off with a disc or belt sander. A roller won't smooth it. An ice chopper has difficulty also. For large areas, a terrazo floor-grinding machine might be more practical; but using knurled steel wheels instead of stones.
Smoothing and coloring the bath is the same as discussed for the cracks.
It is If no water remains after a half an hour or an hour that would cover a nickel, they are reasonably good. If the court has no pitch where they are, chasing them out completely will be very difficult.
The main problem is that the one-inch in ten feet pitch specified by the Lawn Tennis Association is too low. A two inches in ten feet specification makes a dramatic difference in avoiding present and future bird baths, while it has no effect on the game. The geometry is exactly the same if the court is in a single plane, except that the top of the net is about one third of an inch closer to the up-hill player. Shifting the lines one sixth of an inch on each side could compensate that. There is a slight change in the maximum speed with which the ball can be hit and still bounce inside the opposite lines. From a point slightly higher than six feet, the speed with which the ball can be hit is infinite on both sides. A beam of light will touch down inside the playing area, for instance. Where the difference is a maximum is for balls hit close to the ground. Assume that it is possible to hit the ball at the surface, that no spin is put on it, and that it is desired to hit it the full length of the court. The maximum speed that one can hit the ball and still arrive in on the other side is 91 feet per second, assuming no air resistance and a level court. If the court is tilted one inch in ten feet, the speed becomes a little less than 90.99998 feet per second on the up hill side and correspondingly higher on the down hill side. The next one-inch in ten feet is almost the same extra difference. If I were skilled enough to factor in air resistance, the speed would increase, as any badminton player could tell you. However, the differential in numbers would still be about the same. The difference is greater for balls retrieved near the net, but still tiny. However, the height at which one can hit the ball with infinite velocity is lower as one approaches the net, so that someone retrieving balls while in the air at the net is not affected by the pitch of the court at all. Since the low pitch currently specified adds a couple of thousand dollars to the cost of the court (in excavating, but primarily in removing bird baths) it is not even remotely in order in the light of these low numbers. Of course, if the pitch goes across the court, there is no difference at all in either the geometry or the maximum speed from one side to the other. A one-inch in ten feet pitch across the court has no justification at all, in that case.
If the court has been constructed so that the pitch is away from or toward the net on both sides, it is a different story. Such a court creates the same effect as raising or lowering the net respectively, and makes it a significantly different game (but different by the same amount for both players). If the court slopes away from the net on both sides (the usual case of error), the matter can be corrected for the serve by lowering the net 2.1 inches. It cannot be corrected for both the serve and the succeeding play, but the serve is the most important for adult men. Therefore, in general, the serve is probably what to correct for adults. When the serve is corrected, the play is about half way corrected at the same time. You could make a case for lowering the net 3.9 inches to accommodate the succeeding play for short players such as children, since children are primarily why we build the courts in the first place. Adults can get their exercise earning the money to pay for the game. Three and nine tenths inches would probably make the game less frustrating for children and short women; and, thus, make it somewhat more fun. Just don't schedule any championship matches on such a court.
If the bird bath is huge in area and the underlying material is clean stone, cinders, rubbish, sand or some such porous material, it is possible to solve the problem without great expense or to buy time against future repairs by drilling a 1/4 inch hole in the macadam or inserting a 1/4 inch ID pipe into the macadam at the lowest spot. If sand, cinders, or other easily clogged materials are underneath, it will probably be necessary to remove enough macadam first to place some clean stone underneath.
If the bird bath is near an edge, especially a bottom edge, sometimes it is practical to remove it by grinding the edge off or heating it with a large propane torch and scraping sufficient macadam off for the bath to drain.
There is one kind of crack which is caused by frost heaving. If a series of short cracks three to eight inches long arranged in the form of an asterisk are present, it is probably because of a stone imbedded in a thin layer of road stone and with its bottom on or near the earth. The only effective way to solve it is to remove enough macadam to remove the stone and then replace the macadam.
Cracks which radiate out from the corners of net post footing are probably initiated by differential heaving. Isolating the footing from the macadam with a saw slot would probably work. A more expensive way would be to remove the concrete to the depth of the macadam, and then overlaying with macadam, the way it should have been done in the first place. If slots are cut in the concrete about three inches apart and a little deeper than the macadam, a chisel will take the concrete off. The resulting surface will be rough. It can be smoothed and isolated from the macadam with sand. Sand, quarry grit, or some other isolating means should be used in any case, even on new construction. The new macadam must be bonded to the existing slab's edges with epoxy-versamide.
Another procedure, if the radiating cracks have been solved, is to bond glass cloth to the macadam with acrylic, but isolating the acrylic soaked cloth from the concrete with a polyethylene sheet. It works very well and is the least expensive method. It is a method which would probably work with a footing built too small which is tilting up on the side away from the net as a result. It certainly would be much less costly than replacing the footing. I have not used this procedure for the last purpose. I have used it successfully on a court where bedrock came too high into the edge of a court.
Cracks along an edge caused by a brick or concrete edging are impractical to solve short of removing the edging, but they are not objectionable, even aesthetically.
If the fence posts are heaving, it is because the concrete flares out at the top and frost can get under the lip. The only way to correct it is to chisel off the bulk of the flair, which should have been done in the first place. If the concrete comes up through the macadam, it would be best to isolate it from the court using one of the techniques discussed elsewhere, because the concrete will tend to defeat movement of the macadam, otherwise. When building a new court, be sure to keep the post footings below the macadam. Also, it is a good idea to isolate the posts from the macadam, especially on the outside, using sponge rubber.
Cracks caused by deterioration from water welling up under the court are probably caused by water freezing in the interstices of the asphalt slurry. They must have their repair followed, or preferably preceded, by solving the water problem. A symptom of this kind of trouble is flaking off of paint, slurry, or both. One cause of such a water problem is an impervious base layer touching the macadam down slope of a porous base. If the entire base is porous or everything is impervious, there is no problem.
Water flows down hill, so that it should be almost always possible to solve the matter with suitably deep swales (depressions) or French drains upslope of the court. The water under the court must be tied into the system with clean stone and/or conduit drains. A single drain can relieve the pressure, but better would be one every ten feet or so.
Pockmarks on the surface of the court are usually caused by bits of wood or macadam aggregates from glacial till. The wood alternately swells and shrinks with successive wettings and eventually disrupts the coating. Unsuitable stone in an aggregate deteriorates in time and swells upon doing so, with the same effect. This is not difficult to repair using any of the slurries mentioned provided you have been able to pick out the causal material.
If aesthetics are important, it is desirable to coat any galvanized parts with an acrylic enamel, the same enamel that is used on automobiles. A very wide range of colors makes matching easy. It is the only coating, which can be relied upon on top of galvanizing. Don't use the nitrocellulose lacquers. The acrylic "enamels" are, themselves, really a lacquer and have an indefinite pot life if they don't evaporate. If the posts are not coated, acid rain will cause rust spots in about ten or twenty years. Small rust spots can be coated this way also, but with less reliance (but see below). The paint itself is four times as expensive as ordinary paints, but is well worth it. A special thinner is required, which is poisonous. It must not be breathed or put on skin. Non poisonous acetone can be used for cleanup. A clear automobile enamel diluted with its solvent can act as a primer for less expensive acrylic latexes, but that way, probably almost as good as acrylic enamels for durability but not as shiny. See below for a source of enamels.
Posts should be coated this way on new construction. It adds considerably to the court's appearance. Factory vinyl coated posts are more rugged a coating, but they are much more expensive. In my opinion, the acrylic enamel is good enough.
I believe that acrylic enamels are the most logical choice for wolmanized plywood handball wall, also. I can testify that they work very well, indeed. The paint soaks in and, as a result, there is no chance of peeling.
If there is extensive rust on the posts, probably the best strategy is to allow the rest of the galvanizing to erode off. Then, prime the rusty steel with rust inhibited solvated asphalt. Such a primer is very effective on steel but does not adhere well to zinc. It is also extremely inexpensive because the rusty steel does not have to be sand blasted. If black color is acceptable, it can be a final coating as well as a primer, since it resists ultraviolet degradation almost as well as acrylics. If color is necessary, the asphalt is compatible with acrylic latexes. One can also use acrylic enamels if a paint sprayer is used carefully. Such enamels are glossy.
Another inexpensive way that should be practical for rust spots, is phosphoric acid primer. It will work on the iron but probably not on zinc galvanizing. It should be washed off after setting for an hour or so.
Inhibited asphalts are practical for all other rusty steel as well as fences. It is probably less expensive than other methods (except it is not suitable for marine use) by a factor close to ten. Because it has low viscosity (when properly diluted), it soaks into the rust and the combined coating is very tough, very long lasting, and very easy to repair. It penetrates every crack and crevice and gives thorough protection. Auto and truck under bodies, stairways, bridges, scrap steel in outside storage, cable, and machinery are all logical applications. Cosmoline is messy, is slowly washed off by rain, and can not be painted. It is probably better to use grease on the inside of steel net post sleeves, however, or grease over a painted surface for easy removal.
All coats on posts that have the fence fabric already on are only practical to paint with a paint sprayer. The diluted asphalt solutions can be applied with a garden insecticide sprayer. The fabric can be coated with a roller, but a sprayer while someone holds a plyboard shield, with a trough at the bottom of the plyboard, on the other side of the fence does a better job.
Solvated asphalt should always be stored in containers with wide openings. They are an extremely dangerous explosive hazard otherwise. Care must also be taken not to allow them on anything valuable. Theoretically, gasoline removes them, but practically on some items they are almost impossible to remove completely. Gasoline can not be used at all on macadam courts as it badly and instantly degrades them. On existing courts it is necessary to put down plywood or a good tarp impervious to gasoline. The same is true of any concrete that is not going to be colored. If concrete is to be painted, dilute solvated asphalt makes an excellent primer. It is a primer not necessary if the new acrylic solvated concrete paints are used. Asphalt primers must be sufficiently diluted that no free asphalt remains on the surface. For this purpose, it does not have to be rust inhibited. It also can be a way out of a bind where something muddy has to be tack-coated and there isn't time to clean it. Under such a circumstance, it is probably best to heat the tack-coated surface with a propane torch to drive off all the solvent.
The old adage, "a stitch in time saves nine", very rarely applies to a tennis court. One can not even justify resurfacing for preventative maintenance, but only for aesthetic reasons. Additional deterioration will usually be no more than the interest on the cost of a coat of repairs. So, you usually have plenty of time to come up with a strategy of repair or the funds to do it with. About the only time this is not the case with certainty is when liability to an injury suit is possible. However, a circumstance that is ominous so far as preventative maintenance is concerned, is when a short, deep crack opens up after a mild winter. A succeeding severe winter could conceivably send the crack clear across the court. What constitutes a hard winter for tennis courts is not average temperature, snow storms, ice storms, or how much ice water you splash in your boots, but what the minimum temperature was with no snow cover, especially immediately after a mild spell. Everything over 10 degrees Fahrenheit is mild. Ten degrees below is severe. I suspect that you could make a case for covering the court with hay if very low temperatures are forecast, especially on courts with a rough base. I suspect it would be less expensive than repairing cracks. Another possibility on new courts would be heater cables buried in the macadam. Courts are very expensive and so it would be easy to justify.
Multiple cracks on courts built on asphalt impregnated clean stone are probably irreparable. I have successfully healed up the playing areas of such a pair of courts through a single winter using epoxy. However, I have no long-term experience because the courts were overlaid with macadam the following season. I am inclined to doubt that all the repairs would have held up indefinitely.
If you do decide to overlay a court, be certain that the two layers are isolated suitably, say with a thin layer of sand or quarry screenings. I have no experience with such a technique, but I am reasonably certain that it is necessary. Time and time again, I have seen overlays fail, even when reinforced with polypropylene matting, as cracks propagated up through the overlay.
If you do go through the expense of overlaying a court, it is my belief that healing the cracks on the old court with epoxy is in order. However, isolate the new slab from the old even when that is done. You have nothing to lose, but probably a lot to gain.
You may buy the above information in the form of a book by sending $5 to Charles Weber at 1908 Country Club Road, Hendersonville, North Carolina, 28739, email = isoptera1 at yahoo.com
A VERY GOOD HEALTH BOOK
---- There is information here about how to obtain a very comprehensive book about potassium nutrition called “POTASSIUM NUTRITION” and thus cure or prevent rheumatoid arthritis, heart disease, gout, and high blood pressure and ameliorate diabetes. This site shows the introduction, the table of contents.
---- For a list of several articles about health and nutrition access this site.
SOME INFORMATION ABOUT EARTHQUAKE DAMAGE CONTROL
Most of the damage to buildings in an earthquake is from side to side motion, because buildings are very strong against vertical forces. This is . I suspect that creating a concrete slab and then pouring a thick reinforced slab over it but isolating the two slabs with a layer of grease would be an inexpensive and fail safe alternative. A building built onto the second slab and made an integral part of its structure should, I suspect, have very little earthquake damage. That procedure probably would prove to be a practical way to retrofit existing buildings as well since the building could probably be isolated a hundred square feet at a time. You may see the design of existing devices being used or proposed in this site. A similar procedure involving single column sliding bearings has been developed. Probably the most practical way would be by double slab foundations separated by a lubricant. APPENDIX
It is not intended for the products listed here to be inclusive or even necessarily to be the best or least expensive. They are products that the author has used successfully, and have no endorsement beyond that. Safety provisions are available from the supplier, as well as additional information, in many cases. The information is very old (like the author), so you will have to check it yourself.
Akryloid AC-261 ---- Rohm & Haas, Independancd Mall West, Philadelphia, PA 19195
Auto stores that cater to body repairmen carry a very wide assortment of colors. These enamels are really lacquers and may be obtained from this company, among others. They require a specially formulated thinner, which is poisonous and must not be breathed or placed on skin. Acetone can be used to clean tools, etc. and it is not poisonous.. Acetone can not be used to dilute this type of paint.
Acryloid B-48s fromRohm & Haas (above address) may be diluted down and used as an inexpensive clear zinc primer for paints less expensive than the enamels. It is less expensive partly because very thin coats will work for that purpose. It uses the same solvent as the enamels.
*Acrylic Latex Paint
Summer red, other colors ------ Wikel Mfg., PO Box 2277, Sandusky, Ohio, 44870
I suspect that the acrylic content of all the acrylic latexes are about equivalent. I doubt if the so-called resilient coatings are worth the extra cost. Try putting a test patch down and then running across it blindfolded, and see if you can tell where it begins. For resiliency, try sponge rubber on sneakers or, better yet, get enough copper in your diet to make your ligaments tough. Potassium in your diet will be necessary also
All of mine out of business.
*Asphalt rust inhibitor additive.
Pine oil would probably work. Others???
*Butadiene-Styrene Latex Modifier A/NA ---- (only in 4 drum lots, but can sometimes be obtained from contractors)
Dow Chemical USA, 2040 W.H. w
Dow Center, Midland, MI 48674
(609) 234-0400 (NJ No)
Rhoplex E330, mo-7i6, MC 1834 ---- (see acrylic emulsion)
Note: This is said to be at least the equivalent of butadiene-styrene. Vinyl acetate additives are not the equivalent for outside use. The latter has a vinegary smell.
If you wish to experiment with coalescents, Texanol may be obtained from;
---- Mellen, 211 Randolf Rd., Avenel, NJ 07001
DIAMAND SAW BLADES
Sources may be found in Thomas' Register. Also, often available from rental centers.
The epoxy is equivalent to Shell's 828 (their EEW/190) and may be obtained retail (one gallon, five gallons) along with their lowest viscosity Versamid 140 from ---- Smoothon,
Wholesale (55 gallon drum) Epotuf 37140 for epoxy and hardener 37640.
--- Customer Service, Reichold Chemical Co. PO Box 13582 Research Triangle Park NC 27709 (800) 874-5403
Both woven and chopped may be obtained from
Seeman Fiber Glass, PO Box 13704, 3520 Pine Street, New Orleans, LA 70185 (504) 482-1179
I have not bought from ---- Uniman, Deviding Creek, NJ
Triple ought grade in your truck
Ricci Bros., Dragston Rd., Port Norris NJ 08349 (609) 785-0166
*US Tennis Association, 707 Alexander Road, Princeton NJ 08540 (609) 452-2580
*US Tennis Court and Track Builders Association, 113 West Franklin St., Baltimore, MD 21201 (301) 752 3500
They recommend 24, 30, or 50 mesh, 50 finest. I believe I used 50.
P.J. Murphy Forest Products, PO Box 67-t, Montville, NJ, 87845 (800) 631-1936
Minimum order 50 bags.
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Updated October 2011.