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Construction Sealants
This document provides information about sealants used in construction. It defines sealants as materials used to prevent the passage of moisture, air, dust, and heat through joints and seams in structures. Sealants serve functions like waterproofing, thermal and acoustic insulation, and acting as fire barriers. They are used in applications like expansion joints, curtain walls, and perimeter joints. The document discusses different types of sealants including silicone, epoxy, polyurethane, and butyl sealants. It outlines advantages like improved durability and design flexibility, as well as potential problems like deterioration, loss of adhesion, and improper sealant selection. The document compares sealants to adhesives, noting sealants typically have lower
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Construction Sealants
- 1. SEALANTS ADVANCE CIVIL ENGINEERINGMATERIALS(2721401) M.E. Construction Engineering Management (Semester II) Prepared By: Badatiya Pintu (140490714001) Patel Vimal (140490714010) Guided By: Asst. Prof. Rusabh Shah
- 2. CONTENTS • Introduction •What is SEALANT? • Functions • Applications • Types of Construction Sealants • Advantages • Common Problems OR Disadvantages • Comparison with Adhesives
- 3. INTRODUCTION • TheEarly 1950s saw the application of the new concept of curtain-wall construction in high-rise structures through out the world. • This concept was based on the use of a skeleton of steel or concrete that was then wrapped in a separate envelope or non bearing curtain wall. • This reduced the use of the low-rise bearing wall type construction and introduced greater flexibility in design through the use of precast concrete panels, glass or metal panels, unit masonry, and combinations of these materials. • Construction was also become much faster, also these structure are inherently more flexible than bearing-wall construction, but present new problems in weather proofing.
- 4. • The introductionof the curtain wall was accompanied by the introduction of elastomeric sealants that would adhere to the various surfaces and take greater movement than had existed in the older expansion joints. • The old oil-based caulking compounds no longer qualified, and the new materials became “SEALANTS” rather than caulks. • However, the term “SEALANT” has been too broadly used and now includes a wide assortment of weather proofing joint materials. • Sealants or caulking compounds include viscous liquids, pastes, tapes, gaskets, and even water proofing membranes. • The materials can either cure to a rubber or remain in a mastic stage.
- 5. What isSEALANT? • The Layman’s definition of ‘SEALANT’ is “any material placed in a joint opening generally for the purpose of weather proofing a building, so designed to prevent the passage of moisture, air, dust, and heat through all joints and seams in the structure.” OR • The ASTM Committee C-24 definition for ‘SEALANT’ is “in building construction, a material that has the necessary adhesive and cohesive properties to form a seal.”
- 6. Functions • Sealants,despite not having great strength, convey a number of properties. They seal top structures to the substrate, and are particularly effective in waterproofing processes by keeping moisture out (or in) the components in which they are used. • They can provide thermal and acoustical insulation, and may serve as fire barriers. • They may have electrical properties, as well. Sealants can also be used for simple smoothing or filling. • They are often called upon to perform several of these functions at once. • A corking sealant has three basic functions: It fills a gap between two or more substrates; it forms a barrier through the physical properties of the sealant itself and by adhesion to the substrate; and, it maintains sealing properties for the expected lifetime, service conditions, and environments. • The sealant performs these functions by way of correct formulation to achieve specific application and performance properties.
- 8. Applications • Horizontaland vertical metal-to-metal and masonry-to-masonry expansion and control joints • Dissimilar material joints, such as metal-to-masonry or concrete-to-wood • Joints between precast concrete façade panels • Spandrels • Perimeter of doors and fixed window frames • Exposed exterior masonry control joints • Expansion or control joints in curtain wall • Joints in exterior walls • Concealed masonry-to-floor structure joints • Repair of larger cracks
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- 10. Types ofConstruction Sealants • Silicone Sealants • Epoxy • Hybrid Polyurethanes Sealants • Polyurethanes Sealants • Elastic Sealants • Varnish • Acrylic Latex Sealants • Bituminous Sealants • Synthetic Rubber Sealants • Thermoplastics Sealants • Butyl Sealants • Hot Wax • Proof Sealants • Polysulfide Sealants
- 11. Silicon Sealants ButylSealants Epoxy Sealants Bituminous Sealants Elastic Sealants
- 12. Advantages • ImprovesProduct Durability and Reliability. • Increases Product Performance. • Increases Design Flexibility. • Increases Product Quality. • Enhances Product Aesthetics. • Improves Process Productivity and Reduced Manufacturing Costs. • Increases weathering characteristics.
- 13. Common ProblemsOR Disadvantages • Deterioration of sealants causes due to prolonged exposure to water, ultraviolet light, and freeze-thaw cycles. • Loss of Adhesion caused by the presence of coatings or contaminants that prevent proper adhesion. • Cohesive failure due to deterioration of the internal integrity of the sealant; cracking parallel to the interface of the joint is an indication of this type of failure. • Inappropriate Choice of Sealant and Improper Joint Design may fail the joint and losses the adhesion. • Uncured Sealant that is uncured is often due to incomplete or improper mixing of the sealant components, or from using materials that have outlived their shelf life losses the adhesion and fails the joints. • Bubbling and Blistering of the Surface losses the adhesion and fails the joints.
- 14. Comparison withAdhesives • The main difference between adhesives and sealants is that sealants typically have lower strength and higher elongation than adhesives do. • When sealants are used between substrates having different thermal coefficients of expansion or differing elongation under stress, they need to have adequate flexibility and elongation. • Sealants generally contain inert filler material and are usually formulated with an elastomer to give the required flexibility and elongation. • They usually have a paste consistency to allow filling of gaps between substrates. Low shrinkage after application is often required. • Many adhesive technologies can be formulated into sealants.
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