1、Section 21 WATERPROOFING 21.1 GENERAL This work shall consist of furnishing and installing ma- terials to waterproof or dampproof concrete or masonry surfaces. The surfaces to be waterproofed or dampproofed and the type of system to be installed shall be as shown on the plans or otherwise specified.
2、 21.1.1 Waterproofing Waterproofing shall consist of either a constructed-in- place asphalt membrane system or a preformed membrane system, both of which include appropriate priming mate- rials and, when required, protective coverings. Unless a specific type of waterproofing system is shown on the p
3、lans or specified, the type of system to be used will be at the option of the Contractor. 21.1.2 Dampproofing Dampproofing shall consist of a coating of primer and two moppings of waterproofing asphalt. 21.2 MATERIALS 21.2.1 Asphalt Membrane Waterproofing System 21.2.1.1 Asphalt Waterproofing asphal
4、t shall conform to the Specifica- tion for Asphalt for Dampproofing and Waterproofing, AASHTO M 115 (ASTM D 312). Type I shall be used below ground and Type II used above ground. 21.2.1.2 Primer Primer for use with waterproofing asphalt shall con- form to the Specification for Primer for Use With As
5、phalt in Dampproofing and Waterproofing, AASHTO M 116 (ASTM D 41). 21.2.1.3 Fabric The fabric shall conform to either the Specification for Woven Cotton Fabrics Saturated with Bituminous Sub- stances for Use in Waterproofing, AASHTO M 117 (ASTM D 173) or the Specifications for Woven Glass Fabric Tre
6、ated with Asphalt, ASTM D 1663. The Fabric shall be stored in a dry, protected place. The rolls shall not be stored on end. 21.2.2 Preformed Membrane Waterproofing Systems 21.2.2.1 Primer Primer for use with the rubberized asphalt membrane shall be a neoprene based material, and the primer for use w
7、ith the modified bitumen membrane shall be a resin or solvent based material. Primers shall be of a type recom- mended by the manufacturer. 21.2.2.2 Preformed Membrane Sheet Preformed membrane sheet shall be of either the rub- berized asphalt type or the modified bitumen type. The rubberized asphalt
8、 type shall consist of a rubberized as- phalt sheet reinforced with a polyethylene film or mesh. The modified bitumen sheet type shall consist of a poly- mer modified bitumen sheet reinforced with a stitch- bonded polyester fabric or a fiberglass mesh. The mem- brane sheet shall conform to the follo
9、wing requirements: For Surfaces Other Than Bridge Decks Value Rubberized Modified Bitu- Property Test Asphalt 5Pe men VPe Tensile Strength ASTh4 D 8822 20 Ibs/in? 20 Ib/in. % Elongation at ASTh4 D 8822 150%3 25%3 BreaK Pliability ASTM D 146 No cracks No cracks Thickness (Min.) 60 mils 60 mils Soften
10、ing Point AASHTO T 53 165F 2 10F (Min.) (continued on next page) 639 640 HIGHWAY BRIDGES 21.2.2.2 For Bridge Deck Surfaces Value Rubberized Modified Property Rst Asphalt 5pe Bitumen Qpe Tensile Strength ASTM D 882 50 lbs/in? 40 lbdin.) Breap Pliability ASTM D 146 No cracks No cracks Thickness (Min.)
11、 65 mils 70 mils Softening Point AASHTO T 53 165F 2 1 0F (Min.) % Elongation at ASTM D 882 159b3 109b3 Breaking Factor in machine direction. Method A, 1“ wide strip with 4“ minimum initial grip separation and 4“ gage length at 2“ per minute. Average 5 samples. at 73.4T 2 3.6“F Machine Direction 180
12、Bend over a 1-inch mandrel at 10F 21.2.2.3 Mastic The mastic for use with preformed rubberized sheets shall be a rubberized asphalt cold applied joint sealant. The mastic for use with modified bitumen sheet shall be a blend of bituminous and synthetic resins. 21.2.3 Protective Covers Materials for p
13、rotective covers shall conform to the following unless another type is shown or specified. For surfaces against which backfill will be placed, the protective cover shall consist of K-inch hardboard or other material that will furnish equivalent protection from damage due to sharp coarse backfill mat
14、erial or from construction equipment. For roadway surfaces of bridge decks, the protective cover shall consist of a layer of special asphalt concrete as specified in the special provisions. For horizontal surfaces above which reinforced con- crete structures are to be constructed, the protective cov
15、er shall consist of a 2-inch course of concrete mortar con- forming to the requirements of Article 8.14 except that the proportions shall consist of 1 part Portland cement to 3 parts of fine aggregate. This mortar course shall be rein- forced midway between its top and bottom surfaces with 6 X 6-W1.
16、4 X W1.4 welded wire fabric, .or its equiva- lent. The top surface shall be finished smooth and true to grade. 21.2.4 Dampproofing The primer and asphalt used for dampproofing shall conform to that specified in Article 21.2.1. 21.2.5 Inspection and Delivery All waterproofing and dampproofing materia
17、ls shall be tested before shipment. Unless otherwise ordered by the Engineer, they shall be tested at the place of manufacture, and, when so tested, a copy of the test results shall be sent to the Engineer by the chemist or inspection bureau which has been designated to make the tests, and each pack
18、age shall have affixed to it a label, seal, or other mark of iden- tification, showing that it has been tested and found ac- ceptable, and identifying the package with the laboratory tests. Factory inspection is preferred, but, in lieu thereof, the Engineer may order that representative samples, pro
19、perly identified, be sent to him or her for test prior to shipment of the materials. After delivery of the materials, represen- tative check samples shall be taken which shall determine the acceptability of the materials. All materials shall be delivered to the work in original containers, plainly m
20、arked with the manufacturers brand or label. 21.3 SURFACE PREPARATION All concrete surfaces which are to be waterproofed or dampproofed shall be reasonably smooth and free of for- eign material that would prevent bond and from pro- jections or holes which might cause puncture of the membrane or damp
21、proofing. The surface shall be dry and, immediately before the application of the primer the surface shall be thoroughly cleaned of dust and loose materials. No waterproofing or dampproofing shall be done in wet weather, nor when the surface temperature is below 35“F, or that recommended by the manu
22、facturer, without special authorization from the Engineer. Should the sur- face of the concrete become temporarily damp, it shall be covered with a 2-inch layer of hot sand, which shall be al- lowed to remain in place from l to 2 hours, or long enough to produce a warm and surface-dried condition, a
23、fter which the sand shall be swept back, uncovering sufficient surface for beginning work, and the operation repeated as the work progresses. 21.4 APPLICATION Waterproofing shall not be applied to any surface until the Contractor is prepared to follow its application with the placing of the protecti
24、ve covering and backfill within a sufficiently short time that the membrane will not be damaged by men or equipment, exposure to weathering, or from any other cause. Damaged membrane or protec- 21.4 DIVISION II-CONSTRUCTION 64 1 tive covering shall be repaired or replaced by the Con- tractor at own
25、expense. Care shall be taken to confine all materials to the areas to be waterproofed or dampproofed and to prevent disfig- urement of any other parts of the structure by dripping or spreading of the primer or asphalt. 21.4.1 Asphalt Membrane Waterproofing 21.4.1.1 General Asphalt membrane waterproo
26、fing shall consist of a coat of primer applied to the prepared surface and a firmly bonded membrane composed of two layers of saturated fabric and three moppings of waterproofing asphalt and, when required, a protective cover. 21.4.1.2 Installation Asphalt shall be heated to a temperature between 30
27、0 and 350F. The heating kettles shall be equipped with thermometers. In all cases, the waterproofing shall begin at the low point of the surface to be waterproofed, so that water will run over and not against or along the laps. The first strip of fabric shall be of half-width; the sec- ond shall be
28、full-width, lapped the full-width of the first sheet; and the third and each succeeding strip shall be full- width and lapped so that there will be two layers of fabric at all points with laps not less than 2 inches wide. All end laps shall be at least 12 inches. Beginning at the low point of the su
29、rface to be water- proofed, a coating of primer shall be applied and allowed to dry before the first coat of asphalt is applied. The wa- terproofing shall then be applied as follows. Beginning at the low point of the surface to be water- proofed, a section about 20 inches wide and the full length of
30、 the surface shall be mopped with the hot asphalt, and there shall be rolled into it, immediately following the mopping, the first strip of fabric, of half-width, which shall be carefully pressed into place so as to eliminate all air bubbles and obtain close conformity with the surface. This strip a
31、nd an adjacent section of the surface of a width equal to slightly more than half of the width of the fabric being used shall then be mopped with hot asphalt, and a full width of the fabric shall be rolled into this, completely covering the first strip, and pressed into place as before. This second
32、strip and an adjacent section of the concrete surface shall then be mopped with hot asphalt and the third strip of fabric “shingled” on so as to lap the first strip not less than 2 inches. This process shall be continued with each strip of fabric lapping at least 2 inches over the second previous st
33、rip so that the entire surface is covered with at least two layers of fabric. The entire surface shall then be given a final mopping of hot asphalt. The completed waterproofing shall be a firmly bonded membrane composed of two layers of fabric and three moppings of asphalt, together with a coating o
34、f primer. Under no circumstances shall one layer of fabric touch an- other layer at any point or touch the surface, as there must be at least three complete moppings of asphalt. In all cases the mopping on concrete shall cover the surface so that no gray spots appear, and on cloth it shall be suffic
35、iently heavy to completely conceal the weave. On horizontal surfaces not less than 12 gallons of asphalt shall be used for each 100 square feet of finished work, and on vertical surfaces not less than 15 gallons shall be used. The work shall be so regulated that, at the close of a days work, all clo
36、th that is laid shall have received the final mopping of asphalt. Special care shall be taken at all laps to see that they are thoroughly sealed down. 21.4.1.3 Special Details At the edges of the membrane and at any points where it is punctured by such appurtenances as drains or pipes, suitable prov
37、isions shall be made to prevent water from getting between the waterproofing and the waterproofed surface. All flashing at curbs and against girders, spandrel walls, etc., shall be done with separate sheets lapping the main membrane not less than 12 inches. Flashing shall be closely sealed either wi
38、th a metal counter-flashing or by embedding the upper edges of the flashing in a groove poured full of joint filler. Joints which are essentially open joints but which are not designed to provide for expansion shall first be caulked with oakum and lead wool or other material ap- proved by the Engine
39、er, and then filled with hot joint filler. Expansion joints, both horizontal and vertical, shall be provided with sheet copper or lead in “U or “V” form in accordance with the details. After the membrane has been placed, the joint shall be filled with hot joint filler. The membrane shall be carried
40、continuously across all expan- sion joints. At the ends of the structure the membrane shall be car- ried well down on the abutments and suitable provision made for all movement. 21.4.1.4 Damage Patching Care shall be taken to prevent injury to the finished membrane by the passage over it of workpers
41、ons or equip- ment, or by throwing any material on it. Any damage which may occur shall be repaired by patching. Patches 642 HIGHWAY BRIDGES 21.4.1.4 shall extend at least 12 inches beyond the outermost dam- aged portion and the second ply shall extend at least 3 inches beyond the first. 21.4.2 Pref
42、ormed Membrane Waterproofing Systems 21.4.2.1 General Preformed membrane waterproofing systems shall consist of a primer applied to the prepared surface, a sin- gle layer of adhering preformed membrane sheet and, when required, a protective cover. 21.4.2.2 Installation on Bridge Decks Prior to apply
43、ing the primer, an oil resistant construc- tion paper mask shall be taped or held with an adhesive to any deck areas which will later be covered by expansion dams or headers. The membrane seal and asphalt concrete shall be placed continuously across such paper masks; however, the mask and the prefor
44、med sheet shall be cut at or near the expansion joint when ordered by the Engineer. The neoprene based primer shall be applied in one coat at a rate of approximately 300 square feet per gallon. The resin or solvent based primer shall be applied, in one coat, at a rate of approximately 120 square fee
45、t per gallon. Primer shall be applied to the entire area to be sealed by spray or squeegee methods. All primers shall be thoroughly mixed and continu- ously agitated during application. Primers shall be allowed to dry to a tack free condition before placing membrane sheets. Should membrane sheets no
46、t be placed over sol- vent based primed surfaces within 24 hours, or neoprene based primed surfaces within 36 hours, or resin based primed surfaces within 8 hours, the surfaces shall be reprimed. The preformed membrane sheets shall be applied to the primed surfaces either by hand methods or by me- c
47、hanical applicators. The membrane sheet shall be placed in such a manner that a shingling effect is achieved in the direction that water will drain. First, a 12-inch minimum width membrane stripe shall be placed along the juncture of deck and base of barrier railing or curb face at the low side of t
48、he deck with the sheet extending up the face 3 inches. Next, starting at the gutter line, sheets shall be laid longitudinally and side lapped with adjacent sheets by not less than 2% inches and end lapped by not less than 6 inches. A 12-inch minimum width strip shall then be placed at the juncture o
49、f deck and base of curb or railing at the high side of the deck extending up the face 3 inches. After being laid, the membrane sheets shall be rolled with hand rollers or other apparatus as necessary to develop a firm and uniform bond with the primed con- crete surfaces. Procedures shall be used which minimize wrinkles and air bubbles. Any tears, cuts, or narrow over- laps shall be patched, using a satisfactory adhesive and by placing sections of membrane sheet over the defective area in such a manner that the patch extends at least 6 inches beyond the defect. On mo
