WATERPROOFING WITH BITUMEN

It’s the ages since Bitumen is being used for waterproofing jobs in residential construction… probably since its existence. Now also its one of thee most preferred options for the purpose for the fact that it has so many strong advantages against equal number of drawbacks. The most important factor is of thee cost feasibility. There are more efficient systems available over Bitumen, but the cost difference for some extra benefits is very high. Some of the common drawbacks of using bitumen as a waterproofing material are enlisted:

1.      Low tensile and flexural strength.

2.      Very low Abrasion resistance.

3.      Temperature Sensitive.

(Low melting Point. This the most objected character of bitumen in countries like India where the temperature fluctuations are quite high. In summer season the tar melts to flow in the direction of slope and dumps itself at one end in bulk leaving a thin fragile layer on the higher end of thee area.)

4.      Hydrophobic nature.

This is a great benefit and a great disadvantage. In the presence of the slightest amount of moisture bitumen wont bind with the substrate for the simple reason that it cannot stand water.

5.      Bonding in liquid condition.

Bitumen bonds in a semi-liquous condition only and for that it is normally required to heat the matter before application, to enable a good quality bond with the substrate.

To overcome the above and other drawbacks of the basic bitumen the bitumen based waterproofing products are modified to contain bitumen and other matter to aid in tensile strength abrasion resistance etc.

In process of modifying the properties of waterproofing products Tar felt sheet came in the market some twenty years back and since then there has been some changes being made in the material of the sheet to accompany Bitumen.

EPOXY RESINS are considered to be the best material for any use in construction industry, but neglected due to its high costs. Considering the qualities of Epoxy Resins and the cost benefits of the bitumen the combination has recently been worked out. The combination has proved to do the wonders, long awaited for the drawbacks of bitumen. A brief comparative of the quality aspects of BITUMEN TAR SHEETS v/s the BITUMEN TAR EXTENDED EPOXY- COATING is given based on the experimental studies.

Aspect

PERFORMANCE OF BITUMEN SHEETING

PERFORMANCE OF

BITUMEN-EPOXY COATING WATERGUARD CE

Continuity And

Joints

Sheets are laid in discontinuous layers, joined to each other at ends, since manufacturing and transportation requires standardization of product size.

Coatings are applied continuous through the area of the substrate and there are no joints since the application is as a coating.

Bonding Of

Bitumen

This is achieved by heating the sheet to bond with each other and to thee substrate.

Heating may burn the sheets and permanently disable the bonding capacity of bitumen in that area.

No heating is required and there is an excellent bond to the substrate since the carrier keeps bitumen in liquid form till the application leaving a tough layer of Epoxy-Bitumen while it evaporates.

Application

Difficulties

The application involves D-moisturising of the whole site, bringing bundles of sheets to the site cutting them into required shapes and sizes, laying, spreading, heating the sheets to bond to the substrate and to each other at joints

The application is relatively simple. The area to be applied needs to be cleaned thoroughly as in all other cases, material to be mixed in small quantities and applied using brush or an airless spray.

Reaches &

Application In

Restricted Areas

In restricted areas and places of difficult reaches, the sheet laying and heating is most difficult and not possible at times leaving behind critical spots of moisture entry.

Since the application involves coating it is not difficult to reach even the smallest opening where a brush or a spray nozzle can reach or the matter can be poured.

Heterogeneity &

Bond With The

Topping And The

Substrate

Sheet laying produces a distinct shear layer between the substrate and the top layer though the practices of aggregate sprinkling (sand) increases shear strength to some extent but is not enough to compare with that of the concrete or floor strengths which are the normal substrates.

Coating with lower viscosity reaches to the smallest of the surface grooves and bonds very well as such also the Epoxy is known to be the best bonding and tensile strength matter as of date in construction industry.

Flexural &

Tensile Strength

& Elongation

These characteristics will greatly depend on the base material of the sheet. Normally the elongation is high with low tensile strength.

Bitumen paint without Epoxy support has a very low tensile strength and high flexibility and elongation. This is overcome by the addition of EPOXY to the Bitumen, which gives very tough, hard and strong layer in tension and abrasion resistance, as the basic nature of epoxy.

FAIRMATE CHEMICALS offer such a combination of bitumen-epoxy coating for effective waterproofing with long life and economy.

  

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