Unsinkable Concrete and Rot-Proof Wood Combine in Remarkable Floating Docks

Nearly I,000 slips for as many ships are being built in Huntington Beach, Calif. with concrete blocks that won't sink and wood that won't rot.

In a system of marina construction embodying a number of innovations that add stability and durability to the floating docks, Huntington Engineering Corporation is casting huge reinforced concrete o'boxes" which are made stable and un. sinkable by sealing within them as much as 55 cubic feet of extremely buoyant foamed plastic. Atop these, framing and decking is of woodn pressure-treated with chemical Wolman salts which provide longlife protection against attack by fungus and decay.

These two products-unsinkable floats and non-rotting woodhave become major factors in Huntington Engineering's improved system of marina construction. The foamed plastic inserts for the concrete t'boxes" are Dylite expanded polystyrene, made by the Plastics Division of Koppers Company, Inc. A cubic foot of this foamed plastic weighs only one pound, tt0AIlNG Otl C0I{CREIE, starrcr hitches a ride aboard unique floating marina of concrete that won't sink and wood that won't rot, as it is towed to Redondo Beach, Calif. The floats are one-inch thicknesses of corcrete cast around a 55 cubic foot cake of highly buoyant foamed plastic. The wood framing has been pressure-treated with Wolman salts to make it rot-resistant. The foam'ed plastic and the pressuretreated wood are both products of Koppers Company, Inc. but will support nearly 60 pounds in water. Largest floats built here, with a cast concrete shell one inch thick, have dimensions of 6 x 8 x 4 feet and weigh 2,000 pounds. The foamed plastic accounts for only 55 pounds of this weight, yet it supports more than 3,000 pounds in water.

While concrete shell floats with dead-air space have been used in the past, tie combining of buoyant foamed plastic with concrete produces floats that will never sink, even if they should be severely damaged. Precision of the concrete casting also adds to stability of the floats.

Wood, pressure-treated with pres€rvative chemicals repels decay, fungus and termites in many types of ccnstruction. For marina construction, Huntington Engineering Corporation is using lumber pressure-treated in large retorts, with Wolman salts at the Wilmington, Calif. plant of Koppers Forest Products Division. This pressure treatment produces wood that is immune to attack by rot, mold or decay even under extreme conditions of dampness.

Revolutionory Lqser Sow

qAWS, SYNONYMOUS WITH TREES and the timber industry, \J may be replaced in the future with revolutionary new cutting devices.

Progress made in experimental use of new instruments, according to James C. McClellan, chief forester for American Forest Products Industries, Washington, D.C., suggests that the saw may follow the axe into limbo as tlle traditional cutting tool for felling trees and turning them into useful products. AFPI sponsors tle American Tree Farm System and other forestry programs.

One of the more dramatic applications (besides military and medica,l) under study is the use of the laser (light amplification by stimulated emission of radiation). This is an optical electronic device providing impulses of extremely high energy light. Initial results in wood cutting indicate that 'okerfless" (without space cut) sawing may result as laser technology improves.

The laser holds intriguing futuristic possibilities for tirrbermen. In addition to simplifying the sawing of timber, it is likely that foresters will be able to easily prune high branches from tlte ground with the hot, needle-pointed beam. This will eliminate the present practice of shooting them off with a rifle to make grafts of superior quality trees for seed orchards.

Another application will help foresters in the starting of back fires in fighting forest fires. It has been reported that it is within the capability of present lasers to do this from aircraft.

Dweloped in 1960, the laser produces an intense, coherent beam in excess of one million watts per square centimeter-a sufficient concentration to vaporize all materials. A ruby laser, it has been found, can be millions of times hotter than the sun's surface.

Work with the laser for controlled cutting of wood represents one phase of a cooperative project by the University of Michigan, Ann Arbor, and the U. S. Forest Products Laboratory, Madison, Wis. Despite the extraordinary progress of the laser in less than four years, and its useful projected application to the timber industry, the economic feasibility of this remarkable development will not be ascertained for several years.

Another approach (see CLM, January, page 12), to the saw substitute is the use of powerful jets of water travelling at three times the speed of sound which would sever rather than cut down trees. To obtain this velocity, the jets of water (as small as .0I0 inch in diameter) is compressed under pressure to 50,000 pounds per square inch.

The water jets, it is predicted, could be used to remove tree limbs quickly as logs are prepared for mills and smaller jets could machine furniture pa.rts.

A more conventional development, but no less important because of its efficiency and immediate availablity, is a new saw blade that is said to increase the amount of salable lumber, reduce sawdust by more than 70 percent, produce a smoother cut and increase the speed of sawing.

Called a Griffsawo this new refinement in saws has been termed a long-sought breakthrough in the sawmill industry. Among other thinp, it will make a kerf only two-thirds as wide as a normal saw. And instead of the usual sawdust, it produces long, fibrous chips usable for making high quality paper.

Recently a oosalety sawo' prototype was developed by two Florida college professors. This is a circular power saw with a cutting edge 9n both sides of the blade which does not rotate but osrcillates back and fqrth in a tiny arc. The safety factor lies in the change from rntation to oscillation.

The saw cuts by rapid vibration against rigid surfaces only, like rrood orplaster (as in the case of e surgicalsaw)* Thugsofr substanc€s such as flesh or clothing are not rigid enough to produce vibratiorrc necessary for cuttingo eliminating the danger of serious injury.

Aiaska Quake

(Continued lron Page 10) be learned from the earthquake and that a full analysis will take months. "But," he added, "We're convinced that wood frame construction in general and plywood construction in particular 'performed superbly in Anchorage. Our basic laboratory data was proven in what may be the most powerful earthquake ever recorded by man. The new construction experience in Alaska has significance for all areas of the United States that are exposed to seismic loadings or high wind forces from hurricanes or tornados. The building industry can learn much from this disaster. And so can those involved in the development and application of building codes."

Bob Clay, president of the Anchorage Chapter of the National Association of Home Builders, said that most of the homes built in the city in the last 15 years have employed the kind of construction Turnbull described: Plywood roof and wall sheathing and plywood floor systems. This large panel construction with high nail-bearing strength develops diaphragm action wherever plywood is nailed properly to framing.

Clay said most of his own homes have either 3f-inch or yz-inch plywood wall sheathing (both exceed FHA requirements) , t/r-inch plywood roo{ decking; r/r-inch plywood subfloor and 3/s-inch ply- wood underlayment. Clay said the basic system is typical for the area First, the building code in Anchorage requires construction to resist seismic loadings. And second, the construction season in Anchorage is short, and builders there tend to use those materials and methods which reduce time and labor requirements.

In terms of single family dwellings, the hardest hit section of Anchorage was Turnagain By The Sea, an exclusive residential section west and south of the city. Homes in this section ranged up to $200,000.

A report quoted local authorities as saying about I25 homes were lost in the Turnagain area when a massive landslide separated a huge clay bluff from the mainland, dumping it into the tide-swept waters of Cook Inlet.

Totat Loss

Engineer Joseph L. Leitzinger, head of the plywood association's Technical Writing Department and ranking member of the Alaska survey team, said that the damage in the heart of the Turnagain slide area was total. "No material or standard building method survived unscathed in that massive land movement,'n he said. "However, the wood frame buildings performed superbly, retaining their structural integrity in almost every case, We saw homes upended; we saw homes that sank into fissures more than 30 feet deep; we saw homes that were cantilevered over deep crevasses when the earth sloughed away beneath them. Yet, only a very few of those homes broke apart or lost their shapes. The occupants in most cases were able to ride out the earthquake in the buildings safely-and salvage teams were able to recover heavy applianees, cooking ware, clothing, personal belongings and even drapes and carpets from the homes."

Tives Saved

He continued, ooThe fact that the loss of life was low relative to the high property loss is a testimony to the solid house construction. The residential units withstood shocks strong enough to start hundreds of tons of earth sliding; forceful enough to open huge crevasses in the earth surface, and vibrant enough to topple huge public buildings."

The report touched only briefly on the prospects for rebuilding the stricken city. Leitzinger said the general feeling of the architects, engineers and building officials he talked with was that there's not likely to be much rebuilding for some time, at least as far as single family homes are concerned.

One of the big reasons is economic. ooThe city seems to be waiting to hear what will be forthcoming from Washington, (Conti,nued, on Page 82)

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