Sealants, concrete expansion

Roadways, parking decks, and bridges - Neoprene, two part polymethane and two part polysulfide sealants are excellent sealants for concrete expansion and paving joints. They offer excellent weatherability and 20 year life e ectancy. Neoprene is especially resistant to oil and chemical attack and is... 

Figure 6.2 Joint types (a) butt joint (b) expansion joint (c) (i) glass-to-glass lap joint, (ii) concrete-to-concrete lap joint (d) triangular joint (e.g. sanitary seals and glazing seals). H = sealant S = backing material [part (c)]...

Butt joint Expansion joint Lap joint glass-to-glass concrete-to-concrete Triangular joint High-modulus or mid-modulus, acetic-cured or neutral cured sealant Low-modulus neutral cure sealant, to accommodate the movement in the joint Mid-modulus or high-modulus, neutral cure sealant Low-modulus, neutral cure sealant High-modulus or mid-modulus, acetic-cured or neutral cure sealant... 

Polysulphide sealants fulfil the requirements of expansion joints in concrete structures such as bridges, subways and high-rise buildings where a high level of joint movements occur. They are suitable for compression movement, extension movement and shear movement in butt joints as well as overlap joints. The only joint in which a sealant can accommodate more than +50% movement is in lateral shear in an overlap joint. In all other joint designs the sealant cannot take more than 25% move-... 

If "acid brick" is to be used, the glass-reinforced asphalt membrane is now applied in the usual manner, and the brick laid over it, expansion joints carefully laid out and placed on the usual centers. If a monolithic, whether a %" topping or a polymer concrete, is to be applied, polyethylene separator bars should be set above the cracks around the periphery of every sheet, the monolithic placed, the bars removed, and the cavities thus formed filled with expansion joint sealant. If this is not done, you can be certain that, sooner or later, the monolithic will develop cracks at these points, telegraphing through the surface the pattern of the plywood sheets below it. 

If there is no membrane under the joint, as in an expansion joint in a tile floor laid directly over a crack in the concrete slab, the deformable sealant will adhere to the bottom as well as the sides of the joint. If this happens, the deformable material will not function properly. The joint cannot open without pulling the filler off the sides of the joint at the bottom, or close without tearing it loose at the bottom and top of the joint. 

For many applications these sealants are too high in modulus. For places sealed with silicone sealants that see tremendous movement (>25% expansion and contraction), like expansion joints in highways or buildings, the toughness of the above sealant results in undue stress on the bond line at high elongation. In these applications, either the sealant will fail adhesively or the sealant will pull the concrete surface (or similar surface) apart. 

Chem. Desetip. One-component fluoroelastomer based on Viton Uses Sealant/caulk for industrial applies, such as Joint sealant for steel and concrete, door gasket adhesive on industrial ovens, adhesives for flue duct expansion Joints, acid-resist. Joint sealant for industrial flooring, hazardous abatement material, coatings for fuel inj. hoses in automobiles, coatings for equip, subject to corrosive liq., and adhesives for bonding rubber gaskets to metal... 

At the contraction joint, there is a complete discontinuity of concrete slab. The gap width introduced depends on the slab thickness, the coefficient of thermal expansion of concrete, the developed friction with the sub-base and the spacing between two expansion joints. The gap width is usually 20 to 25 mm. The top part of this gap is always filled with appropriate sealant. The spacing between expansion joints is determined by the pavement design methodology followed. 

The saw-cut and seal technique consists of saw-cutting the asphalt overlay by introducing joints into the asphalt overlay directly above the joints in the concrete slab. The joints created are then filled with an approved sealant. Thus, contraction and expansion of the underlying jointed concrete slab will be accommodated in the joints created and will not cause cracking of the overlay. 

Sonolastic 150 One-part polyurethane based For use on substrates such as aluminium, concrete, masonry, wood, and stone. It can be used in applications such as wet glazing, curtain wall construction, expansion wall joints, EIFS, panel walls, precast units, aluminium and wood window frames, fascia, and parapets Premium-grade, high performance, silyl-terminated, polyurethane-based, non-sag elastomeric sealant. It is a low-modulus formula, possessing extreme joint movement capability. -1- 100/—50%... 

Polymer emulsion sealants can be used on all sorptive substrates, such as concrete, aerated concrete, cement panels, plaster and wood. They are used for sealing aU types of internal joints, connecting joints (internal and external) and expansion joints (internal and external) with a movement capability of 10-15 %. In Europe, the joint design is stipulated in the relevant standards, for example DIN 18540. 

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