SEALING MATERIALS FOR JOINTS IN CONCRETE

There are three types of joints in concrete construction, viz. construction joint, expansion joint and contraction joints. Learn more about Joints in Concrete Structures.

Materials for joints in water retaining structures and water tight structures

(1) Materials for joints in water retaining structures and water tight structures for sewage and effluent treatment shall be resistant to aerobic and anaerobic microbiological attack and resistant to attack by petrol, diesel oil, dilute acids and alkalis.

(2) Materials for joints in water retaining structures for potable and fresh water shall comply with the requirements of BS 6920.

Joint filler
Joint filler shall be firm, compressible, single-thickness, non-rotting filler. Joint filler for joints in water retaining structures and watertight structures shall be non-absorbent.

Bitumen emulsion
Bitumen emulsion for joints in water retaining structures and watertight structures shall comply with BS 3416. Bitumen emulsion for surfaces against which potable or fresh water will be stored or conveyed shall comply with BS 3416, type II.


Fig: Joints in concrete structures

Joint sealant
(1) Joint sealant shall be a grade suited to the climatic conditions of Hong Kong and shall perform effectively over a temperature range of 0°C to 60°C. Joint sealant for exposed joints shall be grey.

(2) Joint sealant other than cold-applied bitumen rubber sealant shall be:

(a) A gun grade for horizontal joints 15 mm wide or less and for vertical and inclined joints,

(b) A pouring grade for horizontal joints wider than 15 mm.

(3) Polysulphide-based sealant shall be a cold-applied two-part sealant complying with BS 4254. Polysulphide-based sealant for expansion joints in water retaining structures and watertight structures shall have a transverse butt-joint movement range of at least 20%.

(4) Polyurethane-based sealant shall be a cold-applied two-part sealant complying with the performance requirements of BS 4254.

(5) Hot-applied bitumen rubber sealant shall comply with BS 2499, type N1.

(6) Cold-applied bitumen rubber sealant shall be of a proprietary type.

(7) Joint sealant for joints in water retaining structures and water tight structures shall be
(8) Primers and caulking material for use with joint sealant shall be of a proprietary type recommended by the joint sealant manufacturer.

(9) Different types of joint sealant and primers that will be in contact shall be compatible.

Bond breaker tape
Bond breaker tape shall be of a proprietary type recommended by the joint sealant manufacturer and approved by the Engineer. The tape shall be a polyethylene film with adhesive applied on one side and shall be the full width of the groove.

Bearing strip for sliding joints
Bearing strip for sliding joints shall consist of two plastic strips of a proprietary type approved by the Engineer. The strips shall be resistant to all weather conditions and to chemicals to which the structure will be subjected without impairing the reaction, durability or function of the strips.

The strips shall be of a type that will not require maintenance after installation. The strips shall be capable of withstanding a vertical load of at least 300 kN/m2 and shall have a maximum coefficient of friction of 0.3 under a constant shearing force.

Waterstops or water stoppers
Waterstops, including intersections, reducers and junctions, shall be of a proprietary type approved by the Engineer. Waterstops shall be natural or synthetic rubber or extruded polyvinyl chloride and shall have the properties

Comments

Post a Comment

Popular posts from this blog

How To Calculate or Estimate Long-span Aluminium Roofing Sheets.

Image
Aluminium roofing sheets, they come in rolls of average of 600mm to 1300mm depends on the manufacture and specifications. As stated in previous articles, the aluminium sheets comes in rolls at the factory just like toilet rolls but with different widths and thickness based on specifications. Calculating the roof required could be done by calculating the surface area in square meters of the area covered by the aluminium and for some companies it could be calculated in meter lengths ,knowing the width which is 600mm above as constant. For a simple gable roof as shown in pic 1 with length of 25.2m. First you must know the height of roof from the section. For this sample we are taken the eight to be 3meters (10 feet)to know the length of leaf “x” or “y” Remember the pythagoras theorem x2=32 +6.12 x=6.8m Hence the area of roof is (6.8 i.e x)+6.8 i.e y) multiply by length 25.2m=342.72m2 If the width of the roof comes in 600mm or 0.6m, the length of the roof
Read more

Post Tension Slab – Advantages and Disadvantages of Post Tension Slab

Image
Post Tension Slab Although concrete is a strong material for construction, it is not resistant to breakdown especially where longer concrete slabs are required like in a bridge or a length of a beam. For this, the concrete slab is tensioned with a process called pre-stressing and the slab of concrete which comes out after this process is known as post tension slab. This slab is much stronger as well as more durable than the normal concrete slabs. In today’s world, where the modern engineering is finding new ways to build longer, more efficient and stronger structures, post tension slab becomes one of their chief requirements. There are many advantages and disadvantages of post tensioned slabs which we will discuss in this post. Advantages of Post Tension Slab Post tension slabs are advantageous in many ways. Some of the major benefits of post tension slabs are as follows. 1. Reduced cost: Post tension slabs are excellent ways to construct stronger structures at an affordable
Read more

How to install POP (plaster of paris) ceilling

Image
Plaster of Paris is regarded as any type of plaster containing calcined gypsum (calcium sulfate dihydrate), sand and water. When these ingredients are combined, they result in the formation of a tough, dry product; however, plaster of Paris can be sanded to achieve a variety of looks. By following some basic guidelines, you can use plaster of Paris to mend cracks, fix dents,for ceiling, in walls and even to create artworks. However in this case our focus is on ceiling. POP popularly called plaster of Paris is used for a lot of purposes because it can easily be formed to any shape and it hardens quickly and is easy to operate. To do a pop ceiling in your home, getting it done is in two ways, you can buy the materials yourself which include pop cement , yarn(sponge-like material) etc then pay the installer based on per square meter of area of coverage, or you can give it out totally as a contract. But these are the basic steps in getting pop ceiling cast-on-site done. Get cemen
Read more