The Indian building industry is rapidly substituting bricks with light weight blocks in its construction process.
As more and more AAC blocks are used, the demand for ready-made mortars, used to fix the blocks, is increasing. The traditional mix with its properties makes it quite unsuitable to be used as a block adhesive in most cases.
These ready-made mortars are known as masonry mortars, and Weber blokset, is the only product conforming to ASTM C-1660-09 in India. This ASTM standard is the only international standard which provides specifications about the masonry mortar to be used for fixing AAC blocks.
Masonry mortars bond together the different masonry units (AAC Blocks) into a stable and durable structural assembly or masonry structure.
An ideal masonry structure should be treated as a composite material, where in a flexible matrix (mortar), the rigid elements (AAC blocks) are immersed and all wall components remain in optimal relationship with each other in terms of appropriately selected strengths, modulus of elasticity and permeability.
Masonry mortar represents approximately 7 per cent of total wall area.
An ideal masonry mortar
An ideal masonry mortar should have a compressive strength around 3-4 MPa, which is almost equal to the compressive strength of an AAC block. Such a comparable compressive strength makes the total block wall a very stable structure.
A jobsite sand-cement mix has been traditionally the fixing mortar used in most of the construction processes. However, as sand mining has become illegal and water expensive, there has been a shift towards premix products like Weber blokset. Like all Weber adhesives, Weber blokset is a self-curing system, which does not require additional external water for curing. The water entrapping agents in this product ensure self-curing. There is no addition of sand at site, reducing wastage, pilferage and labor associated with the process of sieving the sand. Weber blokset is available in a self-explanatory 30 kg packing and requires only the addition of water at specified quantity before being used as a paste. Weber blokset is a thin bed adhesive and requires only a minimum thickness of 3 mm for excellent bonding. A notch trowel with 6 mm notch ensures this bed thickness, thereby making the product very easy to apply.
On the technical front, Weber blokset has properties superior to conventional jobsite mixes and other masonry mortars available in the market. The product ensures a complete, strong and durable mechanical bond, despite the blocks being very porous. The polymers do not allow the block to absorb water from the paste mix. They also reduce the tendency to shrink and crack, the two most common phenomenon with a conventional mix and most other masonry mortar alternatives. The polymers also provide flexural properties making it for high-rises.
The only disadvantage this product encounters is the apathy of the uneducated and unskilled Indian labourers. Taking this into account, Saint-Gobain Weber has started providing training at construction sites. This has had an immediate impact on the mindset of the workers and their productivity making Weber blokset a unique adhesive for AAC blocks.
(Communication by the management of the company)