WHAT IS BEST FOR JOINING AAC BLOCKS? MORTAR OR ADHESIVE.

Nowadays we are looking for the best material to construct our house therefor we are tends to use AAC block for masonry walls due to its many benefits and cost effectiveness. Our most residential structures are uses AAC blocks for wall units. They are lightweight blocks which are easy to handle and are sustainable. AAC blocks have good thermal insulation and use fly ash in the production. Use of flyash makes it an eco friendly or green building material.




In a brick masonry construction cement sand mortar is used since many decades. But the use of conventional mortar with recently invented AAC blocks has lead to low construction quality, due to their unsuitable properties with AAC blocks. The cement mortar is heavier to bond with AAC blocks and also does not have thermal insulation properties, which leads to less thermal insulation when the whole masonry is considered.

Hence, special adhesives have been formulated to match the properties of AAC blocks. This AAC block adhesive has more advantages over conventional cement mortar when used with AAC block. Now we are confused in what is the best to use with AAC block. so here we are showing a comparison between both.

AAC Block Adhesive

AAC block adhesive is specially formulated adhesive made from cement, lime, sand and specialized polymers. These adhesives replace the 12 mm thickness of mortar to just 3-4 mm. There are many advantages when compared with conventional cement sand mortar.

Advantages of AAC Block Adhesive

1. Thin Joints :
Only 3-4 mm of adhesive is sufficient to join AAC blocks as compared to cement sand mortar, which takes 8-12 mm thick mortar joints. Hence the jointing material is reduced by 75%.

2. Less Material Required:
There is less volume of adhesive consumed for the same wall, when compared with cement mortar. Hence, less material is required for joining AAC blocks. Also the joints are thin in case of AAC block adhesive. This leads to reduction in storage space of the material, fewer labours to handle and also reduced cost of transportation.

3. Speed in Construction:
AAC block adhesive is a ready-mix material and only water is to be added in it for application. While in case of cement sand mortar, the raw materials are to be correctly proportioned and then mixed carefully to obtain the paste, which is time consuming.

4. No Water demand:
The adhesives are formulated such that they are self curing. No water is needed for curing the adhesive, and hence they help in saving water as well as money.

5. Easy to clean:
In case of conventional mortar, due to mixing on site and curing, the cleanliness of site is not maintained. While AAC block adhesive comes in premix form, and is to be mixed with water only. Due to this and its self-curing nature, the cleanliness of site is maintained.


6. Quick further application:
As no curing is to be done, the masonry wall is ready in just 24 hours. While in case of cement sand mortar, curing is done for 7 days.

7. No storage issue:
AAC block adhesive is available in dry form and available anytime. It does not required more space as cement as sand storage for mortar.

8. Less Wastage:
Cement mortar accounts for 20-30% of wastage during its use. While there is negligible or no waste of AAC block adhesive.

9. Thermal Insulation:
The AAC block adhesive is specially formulated to match the thermal insulation property of AAC blocks. Hence, the whole masonry acts as a thermal barrier which is not the case of cement mortar.

10. Quality Control:
As the adhesives are manufactured in factories under controlled conditions, the quality control measures can be effectively observed and the ultimate product is of superior quality. Cement mortar is prepared on site, and sometimes it is difficult to maintain the quality of mortar as it is being prepared on-site. When mortar is prepared on site, the raw materials cannot be checked for quality. The manufacturers will test the raw materials and then use them in the manufacturing of the adhesives.

Cost Comparison of AAC Block Adhesive and Mortar
Cost of Cement Mortar proportion 1:6: 
Consider size of AAC block as 600 x 200 x 200 mm. Hence the volume of AAC block is:
= 0.600 x 0.200 x 0.200 = 0.0240 cu.mt.

For joining this AAC block, mortar is to be applied on two surfaces of the blocks. Considering the mortar thickness of 10 mm. Hence the volume of block with mortar is:
= 0.600 x 0.210 x 0.210 = 0.0265 cu.mt.

Number of AAC blocks with mortar in 1 cu.mt. are:
= 1/0.0265 = 37.7 = 38 blocks

Total volume of block without mortar:
= 38 x 0.0240 = 0.912 cu.mt.

Volume of mortar = 1 – 0.912 = 0.088 cu.mt.
Considering 25% bulking of sand in mortar, final volume of mortar:
= 0.088 + 0.088 x 0.25 = 0.110 cu.mt.

Total volume of cement required to make the mortar:
= 1 x 0.11 /(1+6) = 0.016 cu. mt.

Total weight of cement required = 1440 x 0.016 = 23.04 kg.
Generally, in the market 50 kg bags are available. Thus, cement bags required to make the mortar:
= 23.04/50 = 0.46 Bag.

Total Volume of sand required to make the mortar
= 6 x 0.016 = 0.096 cu. mt.

Hence, weight of sand required
= 1600 x 0.096 = 154 kg.

Generally, in the market 50 kg bags of sand are available. Thus, bags of sand required to make the mortar = 154/50 = 3.08 Bags.
The average cost of a cement bag is Rupees 310. Hence, cost of cement required:
= 0.46 x 310 = Rupees 143.

The average cost of sand per bag is Rupees 170. Hence, the cost of sand required:
 = 3.08 x 170 = Rupees 524.

Hence Total Cost of the Cement Mortar to be used in 1 Cu. mt. = 524 + 143 = Rupees 667.


Cost of AAC Block Adhesive:

Consider size of AAC block as 600 x 200 x 200 mm. There are many manufacturers which manufacture AAC block adhesive. Here we are taking MYK laticrete AAC block adhesive which have coverage ranges from 250 – 300 sq.ft./ 50 kg bag.
Taking the average coverage for 200 mm thick AAC wall is 110 sq.ft./ 50 kg, i.e. 10 sq. mt./ 50 kg bag.
Volume of mortar:
= 10 x 0.2 = 2 Cu.mt./ 50 Kg bag.

Hence number of bag of adhesive required for 1 Cu. mt. of wall = 0.5 Bag

The cost of adhesive for AAC block is Rupees 700. 

Hence, the total cost of adhesive for 1 cum wall is = 700 x 0.5 = Rupees 350.

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