Showing papers on "Deck published in 1973"

Safety barricade for a roof

Abstract: A barricade for a roof, which can be used as a safety railing or a parapet. The barricade includes a series of supports which are spaced at intervals along the edge of the roof. Each support comprises a plate provided with a series of inclined parallel slots and nails are driven through the slots to secure the plate to the roof deck. A tubular support is pivotably connected to each plate and can be locked with respect to the plate to enable the support to be adjusted to a vertical position regardless of the roof pitch. A pipe is inserted within each tubular support, and horizontal rails are connected to the pipes to provide a barricade or railing at the edge of the roof. The plates can also be attached to a vertical concrete block wall rather than being secured to the roof deck. To mount each plate on the wall, an Lshaped bracket is positioned between the concrete blocks with the upper flange of the bracket resting on the upper edges of the blocks. Threaded bosses are formed on the vertical leg of the Lshaped bracket and extend within the vertical joint between adjacent blocks. Studs connect the plate to the bosses on the bracket.

Modular prestressed concrete marine vessels and method of making same

Abstract: A preferred method of fabricating a prestressed concrete barge is disclosed in which the hull is constructed from a plurality of longitudinal modules. All modules, including the bulkhead modules, are cast in a horizontal plane as a full-transverse cross-sectional element with appropriate spaced openings. Then the modules, which have ducts extending therethrough and a gasket sealing one end of each duct, are rotated 90* to a normal, or vertical, orientation, post-tensioned in two complementary directions, and transported to an assembly site. Steel tendons are passed longitudinally through the ducts so that the modules can be lightly prestressed until the adjacent modules are in alignment. The joints defined by adjacent modules are then temporarily sealed by applying a putty-like cement or grout thereinto; an adhesive epoxy is subsequently pumped into the temporary joint to form a full-strength, long-lived, water-tight bond. The procedure is repeated until the hull has been completed, and then the entire hull is longitudinally prestressed by applying considerable force to the tendons. Grout is then pumped into the ducts and allowed to harden to maintain the tensioning forces of the tendons, which act in a third complementary direction. Storage tanks are then installed from the open ends of the assembled hull onto saddles located in the interior of the hull. Concrete plugs are then sealed in the openings of the bulk-head modules. The bow and stern, which are cast as separate, doublecurved, non-prestressed concrete sections, are then joined to the modular hull. Lastly, the barge is launched and a plurality of tanks are secured to saddles on the deck. The unique method outlined above, with minor variants, is applicable to the fabrication of concrete barges for transporting liquid petroleum gas (LPG), liquid natural gas (LNG), vinyl chloride and various cryogenic cargoes. Furthermore, such method may be utilized to fabricate diverse modular floating platforms well-suited for use as self-contained electrical power generating stations, waste treatment facilities, fish canneries, heliports, and the like.

Supporting apparatus for an upper bed deck of a mobile home vehicle

Abstract: In a mobile home vehicle means are provided wherein an upper bed deck can be rotated toward a side wall, engaged with rails extending along said side wall and readily moved into storage position against the ceiling wall. A second upper bed deck may be hinged so that it can be readily rotated into storage position against the opposite side wall, or alternatively, can also be moved along rails to storage position along the ceiling wall.

Boat windshield mounting means

Abstract: A gasketed windshield holding frame rests on top of a boat deck or hood and is held down securely by an anchoring bracket or plate having a flange which interlocks with a groove formed in either the outer or inner side of the windshield frame near the bottom thereof. It is unnecessary to pierce through the boat deck and variations in windshield rake and boat deck contour can be accommodated.

Twin-hull ship for drilling in ice-covered waters

Abstract: A drilling ship having twin hulls bridged by a deck operated as a drilling platform. The twin hulls have a deep-draft narrow beam configuration with a small waterplane area. Each hull extends outwardly fore and aft at the waterline and has appendages along the sides to provide icebreaking capability in all directions. Rolling and/or pitching motion is induced by pumping of air in and out of ballast tanks to induce the motion at or near the natural roll and pitch frequency of the vessel.

Corrosion autopsy of a structurally unsound bridge deck

Abstract: An investigation was performed on a 12-year old salt-contaminated, reinforced concrete bridge deck that had to be replaced because of its deteriorated condition In this investigation, the electrical half-cell potential measurements and effect of chlorides present seem to be related to some threshold amount that changes the steel from a passive to an active state Beyond this point, the amount of salt present has little or no effect except as it might infleunce the area of corrosion involved The chaining or soundind of the deck to locate delaminated concrete performed the function very well but did not necessarily locate the corroded steel From the observation of the type of cracking, it appeared that the final mode of distress was concrete fatigue An investigation of actual concrete cover disclosed that there was reinforcing steel corrosion at depths greater than 3 in It was determined that estimating the pit depth of steel by visually estimating the thickness of rust is not a very useful inspection technique In this highly slat-contaminated bridge deck, no relation was found between variations in the chloride content of the concrete and the relative severity of the corrosion of the steel /Author/

Lateral Stability of Wood Beam-and-Deck Systems

Abstract: Modern timber structures frequently employ large wood beams bridged by 2 in. wood decking. Economy of material dictates the use of deep narrow beams whose design is limited by considerations of lateral instability. Such constructions must rely upon the in-plane shear rigidity of the attached deck to prevent collapse, yet when decks of low rigidity such as 2 in. decks are employed, the stability of the resulting structure is seriously in question. This report quantitatively answers the question of how much shear rigidity a deck must possess in order to provide adequate lateral support when attached to the top of a set of deep beams. A variational method of derivation is employed, and buckling curves are presented for five cases of load and support. The use of these results by structural engineers will facilitate the safe design of lightweight economical wood structures.

Motion compensating device for surface supported underwater structures

Abstract: A stable platform for handling small submersibles and other underwater apparatus from the surface employs a self-reeling buoyant winch to isolate the platform from surface motion. A ballasting arrangement is controlled from the surface to recover the platform and its load without platform or vehicle manipulation. The deck recovery boom and winch arrangement permit the platform to be placed on the deck for on-and-off loading.

Camper converta boat

Abstract: A camper converta-boat which is a camper-boat combination utilizing a conventional automotive camper, the body of which is removable from the truck chassis and is coupled with a flat bed trailer on which is supported for transportation purposes a catamaran type boat with a flat deck, including catamaran type pontoons for flotation purposes which are hinged to the deck body and foldable inwardly to reduce width for transportation, and swung down at the sides and locked in position for boating purposes.

Method of making a platform structure

Abstract: A roof platform or deck structure consists of a plurality of elongated prefabricated reinforced-concrete elements of inverted-Y or cross-section interconnected contiguously and independently self-supporting so that the structure is self-supporting when formed without the need to cast concrete in place. The individual elements are formed in a mold having a removable inner member which remains in place after withdrawal of the partially hardened concrete body until the latter becomes at least self-supporting.

Process and apparatus for handling bulk building materials at construction sites

Abstract: Bulk materials, such as wallboard panels, are carried to a desired floor level of a building under construction from a source of supply at the building site by loading the bulk material onto raised support members on the deck of a pallet carrier through an open side thereof by a mechanical lift device, hoisting the loaded pallet carrier to the desired floor level of a building having a side wall opening, and engaging the outer edge of the building floor with friction padded support extensions projecting forwardly from the front end of the pallet carrier deck. A hinged ramp at the front end of the pallet carrier is then lowered against the building floor to permit a hand operated lift dolly to be rolled onto the carrier deck under the raised load to pick up the load of bulk material and deposit it on the building floor. Four lift cables extending from the corners of the pallet carrier are attached to the corners of a rectangular bar assembly, which, when held in an elevated position over the pallet carrier deck, holds the four lift cables in vertically extended positions wherein they do not interfere with the loading or unloading of the carrier.

Deck panel for roof and floor structures

Abstract: A deck panel useable in roof and floor structures characterized by a continuous peripheral skeleton formed of a plurality of connected together metallic members that have adequate structural strength to bear a predetermined design load without requiring additional support, such as columns, beams and the like; and a lightweight concrete center portion carried by the peripheral skeleton and including a depending beam of lightweight concrete extending longitudinally of the panel. A plurality of first and second longitudinally and transversely extending panel reinforcing bars are embedded in the concrete center portion and connected with the peripheral skeleton. A plurality of beam reinforcing bars are embedded in and extend longitudinally of the depending beam of lightweight concrete. The beam reinforcing bars are unprestressed at the time of pouring the concrete center portion such that the panel has a flat upper surface and does not bow upwardly in the longitudinal center as do prestressed beams or the like of the prior art. Also disclosed are specific details of construction and emplacement.

Modular boat system

Abstract: This invention is a system of modular floating deck sections to provide additional deck space for a primary powered boat such as a houseboat or a cabin cruiser. The deck sections are removably hinged to the primary boat such that they can be towed by the boat during cruising, or detached for independent operation in the water when the primary boat is stopped at a selected location. In the transportation mode, the floating deck sections are winched aboard and carried by the primary boat. The modular floating deck sections are easily disassembled and stored in a small package when not in use.

Anchor handling vessel

Abstract: This invention relates to improvements in auxiliary vessels of the type used to handle the anchors, buoys, etc., used in mooring large ships such as offshore drilling vessels. The improvement comprises a bridge structure elevated above, and movable longitudinally of, the deck of the anchor handling vessel. The bridge structure includes an anti-friction support for a winch line and, when positioned near the stern of the vessel, greatly reduces the forces necessary for breaking an anchor or similar object over the stern and onto the deck of the vessel. In the preferred form, the bridge structure also mounts a powered winch or bridge crane movable transversely of the bridge which may be used for moving anchors to other cargo about the deck. This abstract is not to be construed in any way to describe or limit the invention set forth below.

The use of grillage analogy for the analysis of slab and pseudo-slab bridge decks

Abstract: THE REPORT GIVES DETAILS OF COMPARISONS MADE BETWEEN EXPERIMENTAL RESULTS AND RESULTS OBTAINED FROM ANALYSES USING GRILLAGE IDALIZATION. COMPARISONS WITH 53 BRIDGE DECKS OF A VARIETY OF DIFFERENT TYPES ARE GIVEN AND THE EFFECTS OF ALTERING THE IDEALIZATIONS ARE DISCUSSED. THE COMPARISONS ARE MADE BETWEEN DEFLECTIONS, LONGITUDINAL AND TRANSVERSE BENDING MOMENTS AND REACTIONS. REFERENCE IS MADE TO A DESIGN BOOKLET WHICH GIVES RECOMMENDATIONS ON THE USE OF GRILLAGE ANALYSIS FOR PRACTICAL BRIDGE DECKS, METHODS OF CALCULATING THE TORSIONAL PARAMETERS FOR THE ANALYSIS AND A SET OF EXAMPLES FOR DIFFERENT TYPES OF DECK. /AUTHOR/

High speed skid resistance and the effects of surface texture on the accident rate

Abstract: THE CALIFORNIA STATE DIVISION OF BAY TOLL CROSSINGS HAS USED DENSE GRANDED EPOXY ASPHALT PAVEMENT FOR SURFACING TWO ORTHOTROPIC STEEL DECK BRIDGES AND OPEN GRANDED EPOXY ASPHALT PAVEMENT FOR RESTORING THE SKID RESISTANCE OF A DETERIORATED EPOXY COAL TAR CHIP SEAL PLACED ON A CONCRETE BRIDGE. IT HAS PROVED TO BE DURABLE, WITHSTANDING REPETITIVE FLEXURE, AND PROVIDING GOOD SKID RESISTANCE WHEN PLACED ON STEEL DECKS. IT ALSO HAS PROVED TO BE A DURABLE AND SKID RESISTANT PAVEMENT WHEN PLACED ON A CONCRETE DECK AS THIN AS 1/2 IN. TO LIMIT INDUCED DEAD LOAD STRESSES. THE THERMOSETTING EPOXY ASPHALT BINDER WILL NOT FLUSH TO THE SURFACE AND HOLDS THE AGGREGATE WITH A STRONG BOND THAT ALLOWS FULL EXPOSURE OF THE PARTICLE FACES. AGGREGATE THAT PROVIDES HIGH FATIGUE LIFE FOR ORTHOTROPIC STEEL DECKS WILL PROBABLY PRODUCE HIGH SKID RESISTANCE. SIXTEEN TEST SECTIONS OF PAVEMENT WERE PLACED IN LATE 1971 FOR SKID RESISTANCE EVALUATIONS. SIX OF THESE ARE DENSE GRANDED EPOXY ASPHALT PAVEMENTS. THE RESULTS TO DATE INDICATE GOOD DURABILITY AND GOOD SKID RESISTANCE. GRAPHS OF VARIATION OF SKID NUMBER WITH TIME ARE PRESENTED FOR TWELVE EPOXY ASPHALT PAVEMENTS. /ASTM/

Dividing apparatus and method

Abstract: A dividing apparatus and method of dividing a continuously flowing stream of particulate material into two separate streams. The apparatus, in a specific embodiment, is used with a plural deck screen, the apparatus being secured over the loading end of a screen deck, a first screen deck being positioned beneath the second screen with its loading end disposed beneath but displaced from the loading end of the second screen deck such that the loading ends of both screens are exposed from above. The divider has an impingement surface upon which a continuously flowing stream of particulate material is directed, a portion of the stream passes the impingement surface and is deposited upon the loading end of the second screen deck, the remainder impinges on the divider and is deposited upon the loading end of the first screen deck.

Hand-driven water craft

Abstract: A hand-driven water craft having a narrow main hull portion cooperating with a submerged ballast member for the support of a generally flat deck partially overlying the hull and partially extending rearwardly therefrom as a cantilever, the hull supporting a hand crank propeller assembly for imparting forward propulsion to the craft, and the rear portion of the deck supporting a rudder adapted to be engaged by the feet of an operator lying in a prone position atop the deck.

Pile mounted drilling rig and method

Abstract: A rig for drilling in a pile projecting from a submerged surface to a location above the surface of a water body includes an elongate derrick operable to support drilling equipment and a deck fixed to the derrick at one end thereof. An elongate open ended sleeve for telescopingly receiving a pile is suspended from the deck. An apertured rig support, fixed to and generally aligned with the sleeve, is engageable with a pile received by the sleeve and provides freestanding support of the rig on the pile. A conduit communicates with the interior of the pile and projects through a sleeve aperture. The conduit provides an outlet for drilling fluid and impedes turning of the rig on the pile. A method for drilling in piles of an offshore structure entails supporting the rig in a freestanding manner on one pile, drilling a borehole at the pile base, and lifting the rig from the pile with lifting cables arranged in a sling arrangement. Thereafter the rig is supported on another pile and a borehole is drilled at the base thereof.

Shakeout and crushing apparatus

Abstract: A shakeout and crushing apparatus for reducing foundry sand to a condition for classification and reuse. The device comprises a shakeout chamber which is caused to orbitally vibrate. The chamber has an upper shakeout deck, a second disintegration deck supporting a plurality of metal balls, and a third wire screen deck. The sand is successively passed and progressively classified through the three decks. Material remaining on the wire screen deck is recycled to a disintegration chamber on the second deck which assures crushing of friable material and the removal of any tramp metal which may be present in the sand.

Experimental study of prestressed concrete under combined torsion, bending, and shear

Abstract: THE DESIGN AND CONSTRUCTION OF A 159-FT DUAL TRACK RAILWAY BRIDGE THAT WAS BUILT NEAR SYDNEY, AUSTRALIA, USING PRECAST PRESTRESSED CONCRETE SEGMENTAL CONSTRUCTION IS DESCRIBED. THE BRIDGE CONSISTS OF SEVEN SIMPLY SUPPORTED 159-FT SPANS GIVING A TOTAL SPAN LENGTH OF 1113 FT 2 IN. THE SUPERSTRUCTURE IS MADE UP OF TWIN PRECAST POST-TENSIONED BOX GIRDERS. EACH OF THE FOURTEEN 159-FT SPANS IS COMPOSED OF SIX SEGMENTS ABOUT 7 FT WIDE BY 12-1/2 FT DEEP. THE DECK IS FORMED BY CAST-IN-PLACE POST-TENSIONED CANTILEVER SLABS. BECAUSE OF POOR SOIL CONDITIONS, 92 INCLINED COMPOSITE PILES (UP TO 166 FT IN LENGTH) WERE USED TO SUPPORT THE SOUTH ABUTMENT AND PIERS. THE PILES CONSIST OF 12 X 12-IN. STEEL H SECTIONS CONNECTED TO 21-IN. SQUARE PRESTRESSED CONCRETE PILES. THE BID PRICE FOR THE BRIDGE WAS $2.6 MILLION. /AUTHOR/

Helicopter haul-down and securing system

Abstract: A system for hauling down and securing a helicopter or the like with a haul down cable loop which attaches at one point to the helicopter and at another point to a deck winch. The cable loop passes through the deck at two separated locations via swivel sheaves so that while the helicopter is being hauled down, the cable acts like a single cable, exerting a downward force and, after the helicopter is on the deck, exerts both vertical and lateral forces to secure the helicopter on the deck. The cable loops over a draw sheave below deck, which is connected to the winch by a draw line so that the haul down cable is free to run over the draw sheave to equalize tension during haul down. After landing, the sheaves and cables would be locked by suitable braking means so that the two cables from the helicopter to the deck-mounted sheaves can restrain the helicopter.

Molded chassis for record card handling machine

Abstract: Improvements are provided in an apparatus for transporting a vertically oriented record card carrying a magnetic stripe across a transducer head for recording and playback functions. The improvement is in the form of a chassis system for mounting mechanical and electrical components of the card transport apparatus which can be readily molded in a single operation. The chassis is a unitary structure which includes a deck joined to a battery compartment. An integral upstanding flange on the deck faces a wall of the battery compartment to define a card receiving groove therebetween with the floor of the groove formed by the upper surface of the deck. Openings are provided in the battery compartment side wall at the groove for receiving a capstan to drive the record cards through the groove and for receiving a switch member which controls the capstan motor responsive to the presence of a card in proper position in the groove. The upper surface of the deck has an aligned pair of bearing blocks for receiving a shaft at axially spaced positions. Each bearing block is provided with an associated pair of opposing ears defining a snap receiver for receiving and retaining the shaft within the bearing block. The lower surface of the deck has a plurality of ribs which are adapted to radially engage the base of a post to secure the post in an upright position relative to the lower surface. Arm members also extend from the lower surface of the deck and have opposing projecting fingers for engaging and holding a circuit board. Further, a pair of spaced slide brackets are provided for receiving a slide member for longitudinally sliding movement parallel to the deck.

Deterioration of 249 bridge decks, with discussion

Abstract: A STUDY OF 249 BRIDGE DECKS BUILT IN 1966 IN PENNSYLVANIA WAS INITIATED IN AN ATTEMPT TO LEARN THE EXTENT OF DETERIORATION AND TO ESTABLISH THE RELATIVE IMPORTANCE OF FACTORS COMMONLY ASSOCIATED WITH DETERIORATION. THREE MAJOR FORMS OF DETERIORATION WERE CONSIDERED: SPALLS AND FRACTURE PLANES; SURFACE MORTAR DETERIORATION, INCLUDING WEAR BY TRAFFIC AND THE GENERAL DISINTEGRATION OF WEAK MORTAR; AND CRACKING, INCLUDING TRANSVERSE, LONGITUDINAL, AND DIAGONAL. INFORMATION FROM BLUEPRINTS, CONSTRUCTION AND MAINTENANCE RECORDS, AND INDIVIDUAL CONTRACTORS WAS GATHERED CONCERNING 32 FACTORS RELATED TO DETERIORATION. FRACTURE PLANES AND SPALLS, THE MOST SERIOUS FORM OF DETERIORATION FROM A REPAIR COST STANDPOINT, WERE FOUND ON 22 PERCENT OF THE DECKS AND IN MANY DIFFERENT POSITIONS ON THE DECKS. FROM THE STANDPOINT OF SKID RESISTANCE, WEAR IS THE MOST SERIOUS FORM OF DETERIORATION. NINETY-FIVE PERCENT OF THE DECKS EXHIBITED SURFACE MORTAR DETERIORATION, WITH 97 PERCENT OF THE AFFECTED AREA ATTRIBUTED TO WEAR AND ONLY 3 PERCENT ATTRIBUTED TO DISINTEGRATION OF WEAK MORTAR. ABOUT 6.7 MILES OF CRACKS WERE ENCOUNTERED ON THE 21.5 LANE-MILES OF DECK SURFACE OBSERVED. BY NUMBER AND LENGTH, TRANSVERSE CRACKS OCCURRED MORE FREQUNETLY AND, IN ESSENTIALLY EVERY CASE, OCCURRED DIRECTLY OVER THE TRANSVERSE REINFORCING BARS. IT IS RECOMMENDED THAT PROVISION OF SUFFICIENT CONCRETE COVER BE MADE ON A BASIS SIMILAR TO THAT FOR SLAB THICKNESS OF HIGHWAY PAVEMENTS. ALSO, IT IS RECOMMENDED THAT FLEXURAL STRENGTH REQUIREMENTS FOR BRIDGE DECK CONCRETE BE INCREASED TO 700 PSI.

Loop device for mounting on boat

Abstract: An eye or loop assembly for forming a connection between the boat deck and boat bow or stern through the boat hull in which the eye or loop is in the form of a pair of bow-eyes with legs extending completely through the deck and bow or stern and with an inextensible adjustable tension member connected to each boweye inside the hull and stationarily anchored inside the hull of the boat. The arrangement provides for division of the load imposed on the eye or loop thereby greatly reducing the possibility of damaging the boat deck.

Stretched-out aasho-pci beams types iii and iv for longer span highway bridges

Abstract: A METHOD OF INCREASING THE SPAN CAPABILITY OF AASHO-PCI STANDARD I-BEAMS FOR HIGHWAY BRIDGES HAS BEEN INVESTIGATED AND DEMONSTRATED TO BE TECHNICALLY FEASIBLE. WITH A MODERATE AMOUNT OF MODIFICATION TO EXISTING FORMWORK, BEAM SECTIONS COMBINED WITH STRIPS OF DECKS CAN BE PRECAST IN SEGMENTS OF CONVENIENT LENGTH FOR TRUCK TRANSPORTATION FROM A PLANT TO THE CONSTRUCTION SITE. TWO-WAY SEGMENTAL CONSTRUCTION, WITH MAIN TENDONS FOR LONGITUDINAL POST-TENSIONING AND SMALLER TENDONS TENSIONED IN THE DECK SLAB, CAN PRODUCE A STRUCTURE EQUIVALENT TO MONOLITHIC CONCRETE CONSTRUCTION. /DOT/

Bridge deck deterioration study

Abstract: PRELIMINARY SURVEYS MADE IN 1959 AND 1960 INDICATED VARIOUS TYPES OF BRIDGE DECK DAMAGE. THE DAMAGE WAS SUFFICIENT TO WARRANT AN EXTENSIVE BRIDGE DECK DETERIORATION STUDY. THE OBJECTIVES WERE TO DETERMINE THE EXTENT AND CAUSES OF DETERIORATION AND THE DEVELOPMENT OF PREVENTIVE AND MAINTENANCE TREATMENTS. NINE REPORTS HAVE BEEN PUBLISHED FROM THIS STUDY. THIS IS A FINAL REPORT WHICH SUMMARIZES SOME PROJECT FINDINGS. ALL OF THE 2700 BRIDGES WERE SURVEYED IN 1961. FIELD WORK ON SPECIFIC ASPECTS WAS CONTINUED FOR MORE THAN TEN YEARS. NONDESTRUCTIVE DETECTION OF CORROSION HAS BEEN BEGUN QUITE RECENTLY. DETAILED ANNUAL SURVEYS FOR THREE CONSECUTIVE YEARS EFFECTIVENESS OF ASPHALT TYPE BITUMINOUS SEALS IN PREVENTING DETERIORATION ON NEW CONCRETE DECK SURFACES. EIGHT DIFFERENT COVER MATERIALS WERE PLACED ON SIXTEEN DECKS FOR ANOTHER EVALUATION OF SEALING MATERIALS. SPECIAL STUDIES WITH EPOXIES WERE ALSO MADE. EPOXY INJECTION, SEALS, AND PATCHING WERE EVALUATED. CAUSES AND PREVENTION OF SCALING, CORROSION, AND SPALLING WERE INVESTIGATED. SPALLING, SCALING, CRACKING AND DELAMINATIONS OF HOLLOW PLANES WERE OFTEN FOUND SEPARATELY OR TOGETHER. THESE PROBLEMS APPEAR TO BE CAUSED BY A COMBINATION OF CIRCUMSTANCES RATHER THAN BY A SINGLE FACTOR. FACTORS WHICH APPEAR TO BE SIGNIFICANT IN MINIMIZING DAMAGE TO BRIDGE DECKS INCLUDE THE FOLLOWING: TWO INCHES OR MORE OF COVER OVER TOP STEEL; LOW WATER-CEMENT RATIO; AIR-ENTRAINED CONCRETE; QUALITY CONSTRUCTION, INSPECTION AND MAINTENANCE; CORRECTION OF ANY DEFECT AS SOON AS FOUND; AND PROTECTION OF THE DECK SURFACE. /NTIS/

Designing bridge decks that won't deteriorate

Abstract: Thousands of bridge decks across the country now suffer from surface spalls with repair cost running into many $million each year. In the early 1960's most states adopted a bare-pavement policy, resulting in a marked upswing in the salt poured on highways and bridge decks to accelerate melting of ice and snow. The salt penetrated many reinforced concrete bridge decks, rusting the reinforcing steel. As the steel rusts, it expands greatly, fracturing the concrete deck. One promising approach is to use epoxy coated rebars; chemically inert, the coating resists corrosion and no spalling occurs. Another approach is to overlay the reinforced concrete slab with an impermeable membrane and asphaltic concrete overlay; other approaches are also being explored. The biggest problem is what to do about existing decks. It is crucial to protect decks with salt content below 0.5 lb per cu. yd before deck deterioration becomes irreversible.