EVOLUTION OF WATERPROOFING TECHNOLOGIES
In the 1960s and 70s, reactive acrylics, acrylic emulsions, styrene butadienes and unsaturated polyesters were developed and huge steps in improvements to the quality and durability of the liquid coating industry were seen.
Not until 1983 when two component polyurethane roof coatings with higher UV resistance were developed, did the waterproofing technologies could meet the requirement characteristics.
The development of polyurethane based liquid applied membrane waterproofing system by ALCHIMICA in 1983 which was then and now branded as HYPERDESMO System became the global game changer in liquid waterproofing technologies and techniques.
There have been technological advances in waterproofing materials over the past two decades, including advanced waterproofing systems. The Traditional waterproofing techniques that were adopted for more more than 5 decades are; Brick bat coba system or lime terracing, Bituminous treatment and Box-type waterproofing system.
These traditional waterproofing systems had many disadvantages like short service life period, low durability, frequent failures due to structural movements and non-suitability to modern architectural structures.
Pre-formed waterproofing Membrane, also known as sheet-based waterproofing is applied on the surface through the use of a primer and adhesive or torch. The membrane consists of several thin layers of waterproof materials and composed together to create a pre-formed waterproofing membrane. The membranes overlap each other by at least 100mm and sealed using polymer-based adhesives or torch welded. These pre-formed membranes are available in various types like Bitumen, EPDM, chemically treated fabric and Thermoplastic Polyolefin (TPO) based.
The biggest disadvantage of pre-formed membranes are that if water does happen to enter beneath the membrane from a point, it spreads across a surface debonding the membrane, and the water stays trapped between the structure and the membrane.
Their joints are weak areas which either can be badly welded with excess temperature or weakly welded which detaches in course of time.
Also, if a membrane has to be installed over a complicated shape, such as the junction of a column and beam, or a drain then sheet membrane would form folds and creases and leave gaps between the underlay and membrane.
Cementitious Polymer Coating
Cementitious waterproofing systems are basically cement slurries modified with polymer additives to enhance the bonding and waterproofing properties of a cementitious coating. Cementitious waterproof coating requires proper curing of the coating, usually a wet cure of 24–48 hours. Some systems may have a chemical additive to promote proper curing. But the chances of cracking on the surface are more if not cured properly.
The failure of Cementitious Waterproofing coatings are also due to its poor elongation and tensile strength properties. Elongation is a must in buildings that will move, such as high-rise buildings, or buildings made with steel, which is flexible.
Acrylic coatings are generally lower-end DIY market of waterproofing. Most of these products are one-component and can be applied by anyone with some basic technical knowledge. It is easy-to use, and less sensitive to humid substrates. The quality of an acrylic polymer is based on the chemical composition of a polymer coupled with the actual synthesis process reacted to produce the final emulsion polymer.
The main disadvantages of Acrylic coatings are significantly lower lifetime, sensitivity to UV, limited elongation properties and low service temperatures.
PU Liquid Applied Membranes
Polyurethane technology based waterproofing coatings are the most established family of like; long-term protection, exceptional flexibility, resistance to UV and freezing temperatures.
There are new developments using polyurethane technologies (polyurethane and Silylated polyurethanes), as well as products that combine polyurethane with materials of different technologies, such as bitumen, water and cementitious mortars. With a only disadvantage of relatively low shelf some of the polyurethane products have certified life expectancy for more than 25 years.