CJ8 – Sealent

CJ8 – Sealent

Concrete Joint Bituminized Thermoplastic Sealant


This sealing compound (CJ8) was developed to provide strongest adhesion and flexibility when used in flexible surface as well as in concrete, bricks, stone and glass. There are many such materials in use like Rubberized Bitumen, Siliconised Rubbers, Acrylics, Urethane and Sulphate etc.; However if applied properly CJ8 gives far better results.

The Rubber based Bitumen is good only if not heated because once Rubber is treated with heat in presence of Bitumen it become very hard and flexibility is reduced to half; thus reducing its life. Similarly other products mentioned above including epoxy resins are very expensive to use. Thus this product which is made with selected Bitumen and Thermoplastics is best due to the reason that if heated many times it will come back to same flexibility and adhesion on cooling. Moreover, price is only up to 25% to 30% and its ability to heat more than once has advantage over other materials used in the world.


ASTM-D3405, D3406, D3407/78 or ASTM – C920/98


Only dark black.


Because of its ability to extend and recover many times without losing bond and their resistance to heat and water they are extensively used to provide fully water-tight seals in horizontal joints subjected to high degree of movements.

CJ8 is recommended for horizontal joints like in road cracks, flexible surface joint, concrete, bricks, steel, pavement, factories, roofs, ship decks, between pre-cast concrete panels, dams, reservoirs, culverts, water treatment plants, high rise buildings, bridges, curtain walls, around service pipes and sewerage.

Preparation of Surface

The joint faces where adhesion is critical must be dry, free from dirt, dust, cement laitance and any loose materials for the correct performance of the sealant. The joints should be thoroughly cleaned with wire brushing and then blown clean with compressed air. Apply Concrete Joint Primer with ordinary brush on the joint faces at least 2 to 4 hours before pouring in hot sealant.


Under normal conditions if dust and dirt is not there it can be poured directly into the joints. If it is an old joint or some material was previously used or if good adhesion is required then apply with brush Concreted Joint Primer at least 2 to 4 hours before pouring in hot joint sealer.

Method of Application

Heat the container to 140° c to 160° c until the entire compound becomes liquid. Pour the sealant between the prepared joints slightly above the joint. Apply prime coat of Concrete Joint Primer before pouring in hot material.

Movement Accommodation

It will provide satisfactory seals in joints subject to regular movements or permanent deformation within 33% to 50% of the original joint width. For horizontal joints, movement accommodation be designed to minimum of 12 and to maximum of 25 mm. The width and depth ratio should be as in the table below:

All Size in mm Width Depth
12 12
20 20
25 20
30 20
40 25

Maintaining Correct Joint Width

Compressed fiber filler boards impregnated in bitumen or cork sheet boards or poly propylene rods or thermopore sheets be inserted inside the expansion joint up to the required depth and bond breaking polyethylene tape should be inserted on top of boards to prevent the sealant to adhere with the filler board. This will ensure flexibility of the sealant. See Fig.1

Some times polypropylene support strip are used. Then correct the depth as in Fig. 2 before pouring in joint sealant.

Estimated Guide

Chemical Resistance

CJ8 Sealant has excellent resistance to oils, most of the chemical, water, emulsions etc. Petroleum based oils if stand for longer periods will effect its qualities. However, drippings for short periods are ineffective. For fuel resistant sealant ask for our fuel resistant sealant CJF10.

Storage and Shelf Life

CJ8 Sealant can be stored anywhere and it has very long storage life. The only need is to heat it at specified temperature before use.


  • 4 kgs, 20 kgs and 215 kgs packing are available.
  • For 4 kgs packs just heat the tin directly until the sealant liquefies.
  • For 20 Kgs packing it is required to remove the material from the container and heat it in some open pan slowly and steadily.
  • For 215 kgs packing DO NOT heat the drum in standing position rather position it horizontally and cut the drum from center in such a way that it works like an open pan or remove the sealant from the container and heat it in some open pan until it liquefies.