What is bitumen mastic?

What is bitumen mastic?

Bitumen mastic is a single component, solvent based bitumen rubber mastic joint sealant. The sealant on curing forms a tough and flexible seal. it has excellent adhesion to concrete, brickwork, asphalt and most construction material substrates. The mastic sealant is modified with non-asbestos fibers to make the sealant thixotropic and slump free when applied on vertical areas.

Application of bitumen mastic:

Flexible joint sealant

Stability at high ambient temperatures

Excellent adhesion, strong durable bond

Single component

Where you can use the bitumen mastic?

Bitumen mastic is ideally suited for sealing and filling gaps and joints on roofs, pointing horizontal chases for waterproofing membranes and felts. Sealing around roof/ wet service pipes.  Pointing between brickwork and roof flashings. Sealing cracks in asphalt and concrete pavements. Filling horizontal joints in concrete and asphalt where movements are not expected.

How to use bitumen mastic?

Surface preparation

Surface must be free from all dirt, dust and loose material. Any oil and grease contamination  must be removed completely. The surface must be made dry prior to the application of the sealant.

Masking

Prior to application of primer and sealant, apply masking tape to the adjacent sides of the joints for getting a neat finish and to avoid the spilling over of the sealant on the edges.

Priming

Under normal circumstances priming is not required. However, for very dry and porous surfaces, it is recommended to apply one coat of a solvent based bitumen primer. Similarly for joints subjected to continuous immersion, priming is recommended.

Application

The bitumen mastic can be applied by means of a spatula or trowel. As the product is solvented, it is recommended to mix the contents of the pail with a paddle mixer for a few minutes prior to the application to ensure a homogenous mix. Sealant application should start form the bottom of the joint/groove and continued to the top. Immediately tool the joint with the spatula or putty knife to smoothen and compress the sealant to effect total contact with joint surfaces. The putty knife shall be moistened with a cleaning solvent to prevent the sealant to adhere to the knife and ensuring a smooth and neat finish. Where masking tape has been employed to keep building surfaces clean, it is advisable to remove them at the moment the sealant filling is completed.

Curing time of bitumen mastic

The sealant cures on solvent release. The initial surface skinning will occur within 24-48 hour, however full cure depends on relative humidity. A10mm depth of seal will typically cure within 14-21 days @23°C  @50% rH.

Specification of bitumen mastic

Properties

Values

Color

Black

Form

paste

Solids content, [%]

>80

Slump

Nil

Density, [g/cc]

1.1 ± 0.05

mAF, [%]

±10

initial set @ standard condition [hrs]

24 -48

Full cure @ standard condition [days]

14-21 days (10mm)

Chemical resistance

Sea water, chlorides and sulphate ions.

Service temperature,  [°C]

0 to 80

Application temperature,[°C]

5 to 45

Cleaning

Tools and equipment should be cleaned immediately after use with a cleaning solvent. Hardened materials can be cleaned mechanically only

Storage & shelf life

The pails and drums must be stored in a covered, dry and shaded area, away from direct sunlight, UV and other sources of heat and protected from extreme temperatures.  The shelf life of the bitumen mastic is up to 12 months if stored as per the recommendations. Excessive exposure to sunlight and UV will result in the deterioration of the quality of the product and reduce its shelf life.

MSDS of bitumen mastic

Bitumen mastic contains petroleum distillate, is flammable.  Keep away from fire, sparks or other source of ignition. Wear protective clothing, rubber gloves, and mask and safety goggles.

1. Fire – Flammable when wet.

2. Skin – Avoid repeated or prolonged contact. Remove bitumen stains with a suitable cleaner that is able to remove oil or grease and then clean with soap and water.

3. Eyes – Contact could cause irritation.  Flush with copious amount of clean water.

4. Inhalation – can cause dizziness. if difficulty in breathing  persists, administer oxygen.

Estimation

Theoretical Coverage: linear meter per kg of sealant

Joint Depth (mm)

 

6

10

12

15

20

25

30

40

6

27.7

16.6

14

11

8.3

6.6

   

8

 

12.5

10.4

8.3

6.2

5

4.1

 

10

 

10

8.3

6.6

5

4

3.3

2.5

12

   

6.9

5.5

4.1

3.3

2.7

2

15

     

4.4

3.3

2.6

2.2

1.6

20

       

2.5

2

1.6

1.3

How to produce bitumen mastic?

A process of producing bitumin mastics and sealants is as follows:

1. 4% to 11% treated Bentonite clay was to be added into clean water in the mixer. When clay is dispersed, or high sheared in colloid mill, after mixing it turns into clay slurry. The viscosity of clay slurry is between 20,000 to 180,000 centipoise (CPS) at 77 deg. F.

2. Asphalt bitumen cutback consists of 60 to 80 percent asphalt and 20 to 40 percent mineral spirit Stoddard solvent.

3. The clay slurry and asphalt bitumen cutback are mixed together to form a soluble system.

4. An additive is added to enhance the stability of the soluble system.

5. Non-asbestos fiber is added to reinforce the soluble system mastics and sealer film strength. It also provides additional viscosity and texture.

Included are cellulosic paper, fiberglass, mineral fiber, polymer fiber including polypropylene and polyethylene.

6. Non-reactive fillers commonly called pigment extenders are e.g. natural or calcined clay, mica and silica powder, slate powder, coal ash, fly ash, etc. are added to the system to improve film strength and product's consistency.

7. The elastomers impart buffering as well as tensile strength and elongation to the formulations and include SBR, SBS, SIBS, acrylic, styrene, neoprene, polyvinyl, etc.

EXAMPLE 1 The Preparation of Bituminous Mastic

   
 

% By weight

 
   
     
 

Treated Bentonite clay slurry

 3-60

 

Asphalt Bitumen Cutback

20-90

 

Fibers

 2-10

 

Fillers

 3-15

 

Additives

0.2-1.0

   

100.0

   

This formulation is used for patching repair, roof flashing repairs and installation.

EXAMPLE 2 The Preparation of Bituminous Sealants

   
 

% By weight

 
   
     
 

Treated Bentonite clay slurry

 3-60

 

Asphalt Bitumen Cutback

20-90

 

Fibers

2-6

 

Fillers

 3-10

 

Additives

0.2-1.0

   

100.0

   

This formulation is used for recoating by brush application on foundation walls, roof, metal, wood, concrete and other building materials.

EXAMPLE 3 The Preparation of Bituminous Non-fiber Sealants

   
 

% By weight

 
   
     
 

Treated Bentonite clay slurry

 3-60

 

Asphalt Bitumen Cutback

20-90

 

Fillers

 3-10

 

Additives

 .2-1.0

   

100.0

   

This formulation has similar uses as Example 2, except for spray application.

EXAMPLE 4 The Preparation of Elastomeric Bituminous Non-fiber Mastics

   
 

% By weight

 
   
     
 

Treated Bentonite clay slurry

 3-60

 

Asphalt Bitumen Cutback

20-90

 

Fibers

 2-10

 

Fillers

 3-15

 

Additives

0.2-1.0

 

Elastomers (Elastomeric polymers)

0.5-5  

   

100.0

   

This lends itself to both roofing and foundation application.

EXAMPLE 5 The Preparation of Elastomeric Bituminous Sealants

   
 

% By weight

 
   
     
 

Treated Bentonite clay slurry

 3-60

 

Asphalt Bitumen Cutback

20-90

 

Fibers

2-6

 

Fillers

 3-10

 

Additives

0.2-1.0

 

Elastomers

0.5-3  

   

100.0

   

EXAMPLE 6 The Preparation of Elastomeric Non-fiber Sealant

   
 

% By weight

 
   
     
 

Treated bentonite clay slurry

 3-60

 

Asphalt Bitumen Cutback

20-90

 

Fillers

 3-10

 

Additives

0.2-1.0

 

Elastomers (Elastomeric polymers)

0.5-6  

   

100.0

   

Subject to the foregoing, the ranges and descriptions of components are about:

   
 

% By weight

 
   
     
 

Drilling mud bentonite

 .5-11 

 

Water

 3-55

 

Asphalt bitumen

20-90

 

Cutback containing 60 to 80 wt. % asphalt and

 
 

20-40 wt. % mineral spirit Stoddard Solvent

 
 

Additives

.2-1 

 

Non Asbestos fiber

 0-10

 

Fillers

 3-15

 

Elastomer

0-8

   

Of course, the individual amounts are selected to provide a 100% total.

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