Tiling on Gypsum

Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO. 2H2O. It is widely mined and is used as a fertilizer, and as the main constituent in many forms of plaster, blackboard chalk and wallboard. Gypsum is used for making Plaster of paris, Hard wall plaster, Flooring plaster, Gypsum boards, GFRG(Glass Fibre Reinforced Gypsum) walls, Plaster blocks, Gypsum based self levelling screed, etc.

6 mm coat of gypsum plaster (termed as POP punning) is usually applied on the top of cement plaster to give a smooth finish to it before painting. This is a two stage process and involves various elements like sand, cement and water which has to be mixed onsite. This process is slowly being replaced by a direct application of single coat of gypsum plaster. In gypsum plaster, readymade POP powder is mixed with water and applied directly on the wall.

Gypsum plaster cannot be used for outside walls since they retain dampness. Also gypsum plastering cannot be done in areas which are continuously damp such as bathroom etc.,

• Gypsum plaster is costlier than traditional cement mortar plaster (cement and sand) for same thickness of plaster. But in areas where natural/river sand is not available for construction, cement mortar plastering would require a 6 mm gypsum layer to finish it making cement plaster more costly.

Gypsum surface is a relatively weak material in terms of surface tensile strength in comparison to wood, block work, concrete and metals.

Gypsum plaster is classified as follows:

a) Plaster of paris,
b) Retarded hemihydrate gypsum plaster
               Type I – Under coat:
a) Browning plaster b) Metal lathing plaster
               Type II-Final coat plaster
a) Finish plaster b) Board finish plaster,
c) Anhydrous gypsum plasters are for finishing only, and
d) Keene’s plaster is for finishing only.

Both Indian and Imported gypsum usually comply with IS 2547-1.
1. Loss on Ignition (should be >4 and <9)
2. Insoluble residue
3. SO3 by mass (Min 35% as per IS 2547)
4. CaO by mass (Min 2/3 of SO3)
5. Soluble Mgo (Min 0.3%)
6. Soluble Sodium Salt (Na2o - Max 0.3%)

Gypsum surface is water sensitive and is therefore not good to use in wet areas such as bathrooms, showers, kitchens or wet rooms and at exposed situations.

Gypsum surface can be very dusty or, it can be very dense and shiny.

When cement based / dispersion / reaction adhesive used on gypsum surface, the bonding will be weak.

Tiling can be done on Gypsum surface by adopting the following procedures:

1. Remove the surface dust, weak layer and other contaminants.

2. Check with the manufacturer of Gypsum material for its surface strength, how much it can bear the load, accordingly chose the tiles.

In general, maximum weight of tiling acceptable on a dry, well-adhered gypsum background is of 20 kg/Sqm.

3. Apply sealer coat / waterproofing coat by taking the advice of tile adhesive manufacturer.

4. Install the tiles using specified adhesive.

5. Maintain minimum tile joints of 2mm in walls and 3mm on floor.

4. Grout the tile joints using cement based adhesive in non-wet area and epoxy based grout in wet areas.
Know more details regarding different type of putty and POP: https://gharpedia.com/pop-white-cement-acrylic-wall-putty/ Courtsy of Gharpedia.com

NATURAL STONE PROTECTION - sealers

Stones are the naturally available materials and are used from the ancient times in the civil construction. None of the stones are like other in this world in terms of look, chemistry and properties – this makes the stone beautiful and demand in increasing the aesthetic of the structures. Molten rocks below the earth called magma and, on the surface, called lava when solidified forms igneous rocks like granite, Quartz, Obsidian, Pumas, etc. Blend of organic materials when eroded, broken down through the action of glaciers, rivers, wind, oceans and plants forms rock beds (carbonates) called Sedimentary Stones like lime stone, Sandstone Gypsum, Conglomerate, Travertine, etc. Transformation of a pre-existing rocks in a process called metamorphism, which means change in form creates the Metamorphic Stones like Slate, Marble, etc. Apart of these natural stones, artificial stones are also available in market which are made from the mixture of natural stones, resin and hardeners.

In present market, stone are available in polished finish, Tumbled finish, Sand blasted finish, Flamed rough finish, Bush-Hammered finish, etc. Client / architects now popularizing the use of stone more and more in their project and buildings, and this creates the additional demand for stone care products like cleaners and sealers.

Let see some of the types of sealers available in the present markets and how they are classified:

A. Famous in market by name:

1. Penetrating sealer: They penetrates the surface of the stone up to some depth and seals the surface making stains to repel when spills. These sealers are absorbed by the stone. These sealers are recommended for exterior applications, thick stones, smooth or polished stone types such as granite or marble. These sealers usually take times to dry as they shall have sufficient time to penetrate in the stone. These sealers are of 2 kinds:

a. Enhancing sealers: They sealers enhance or darken the color stones. These sealers are not right for the polished stones.

b. Natural look sealers: They create a thin coating on the surface of stone without effecting OR leaving the stone looking natural. Natural sealers neither darken the stone nor alter the color or provide a sheen of any kind. Natural sealers are perfect for polished stone.

2. Topical Finishing / Coating sealer: These sealers will create a layer and bonds the surface of the stone. They are used for interior use, textured surfaces. These sealers provide wet or glossy finish on to the stone. These sealers are of 2 kinds:

a. Wet look sealers: They seal the surface of the stone and make the stone to look like wet. These sealers are not suitable for polished stones.

b. Glossy look sealer: They are the best suitable sealers to seal the stone with glossy finish and saves the cost, time and effort of grinding and polishing process.

B. As per the safety concern:

1. Solvent based sealers: They are very famous type of sealer from the past time for sealing the surface of stones. They are flammable in nature. Becomes thicker in cold temperature.

2. Water based sealers: As the technology developed, sealers were formulated with water and named as water-based sealer. They are not flammable in nature. Becomes thicker in cold temperature.



In both the cases, the polymer is the chemicals which plays important role of sealing the stone surface. This polymer needs something as carrier to move in the stone or to float on the stone. Say, solvent or water, when polymer reaches the destination, these carriers i.e. water or solvent evaporates leaving polymer in place. Both sealer can be applied using brush / roller / spray. Both good to UV resistance and durability. They can be used in interior as well as exterior applications. Solvent based sealers often have a higher VOC (volatile organic compound) rating than Water-based sealers. Solvent based sealers dry faster than the water-based sealers. Silicone content depends on the manufacturer’s formulation.

C. Silicon based sealers: Silicon based sealers when applied, increases the life and protect them from staining, spalling, cracking which usually caused by absorption of water. Silicones function by imparting durable water repellent film on the surface of capillary pores on stones about 1.5-3mm depending on the surface porosity.

1. Class A: They are of silicone formulations contain silicone-oxygen-silicone and hydrocarbon groups and are used for natural and cast stone masonry of a predominantly siliceous nature.

2. Class B: They are of silicone solution in a voltaic solvent or an aqueous emulsion and are used are for natural and cast stone masonry of a predominantly calcareous nature and calcium silicates nature.

3. Class C: They are of aqueous solution of an alkali metal salt of silicone and non-volatile content and are used for natural and cast stone masonry of a predominantly calcareous nature.


A good stone sealer shall be resilient to everyday cleaners and contaminates and not break down for long time. Stone sealers should not absorb dirt and stains when left on stone for long time. Stones like limestone, travertine and marble are sensitive to acids say cleaners, liquid contaminants, acidic / alkaline food items like vinegar, lemons, pickles, tea, coffee, etc. sealer applied stones can resist the effect up to some extent depending on the type of sealer used. Sealer must work on the stone as well as on the joint grout surface similarly. At exposed conditions, sealer must protect from the rain, wind carrying carbon-dioxide, stains, harmful chemicals and UV rays. Regular house-keeping with non-acidic cleaners or heavy-duty stone cleaners can safeguard the installed stones.


Good practice manufacturer of sealer shall test their sealer at the formulation and development stage and provides the results for the following test as per the standards while promoting to the market as follows:

1. ASTM D 3960 / IS 101 - PART 01 Sec 7 – PART 02 Sec 2: Volatile mater, specific gravity and VOC.
2. IS 13603: PART 8 – Resistance to staining. Resistance to house hold chemicals and swimming pool water cleansers except to cleaning agents containing hydrofluoric acids and its compounds. Resistance to acids and alkaline (with the exceptions of hydrofluoric acids and its compounds).
3. UNE-EN ISO 12572 - Determination of water vapor transmission properties, Water vapour permeability.
4. BS EN 13755 / UNE-EN 13755 - Determination of water absorption.
5. UNE-EN ISO 10545:14 - Stain resistance test.
6. BS EN 1925 / UNE-EN 1925 - Determination of water absorption coefficient by capillarity.
7. UNE-EN 1504-2 and UNE-EN 14630 - Depth of penetration test.
8. IS 3495:PART3 – Efflorescence test.
9. IS 12027 – For silicone-based sealer – Early water repellence, Water absorption, Evaporation of water and Durability test.

Last one more point to be noted is that, the stones protected from the top, also needs to be protected from bottom. I.e., from the rising dampness / moisture / chemicals from the substrate. If not, efflorescence, water marks, white patches, warping, buckling of stone may happens. So, always apply under stone primer to the bottom surface of the stone and all other sides (except, the top surface) prior to the installation.

Finally, considering “Prevention is better than cure” let us choose and apply correct sealer, in time, as per the stone nature to increase the beauty of the space for providing looooong pleasant time for occupants.

See some the best sealer applications:

https://annayyachandrashekar.blogspot.in/2017/12/fc-ss-natural-look-providing-sealer-for.html

https://annayyachandrashekar.blogspot.in/2017/10/heavy-duty-impregnating-tile-stone.html

https://annayyachandrashekar.blogspot.in/2017/09/tile-stone-sealer-application.html

CURING OF CONCRETE

Today, Mr Neeraj Sumersingh, Seinor Technical Executive of my team from Delhi (my junior) asked me, why should not we use plastic sheets for curing purpose. To make it clear and what are the other method of curing, I prepared this blog. Many thanks to Mr Neeraj for asking this query…

Curing is the process of controlling the rate and extent of moisture loss from concrete during cement hydration. It may be either after it has been placed in position (or during the manufacture of concrete products), thereby providing time for the hydration of the cement to occur. Since the hydration of cement does take time – days, even weeks rather than hours – curing must be undertaken for a reasonable period. Curing plays an important role on durability of concrete, development of strength, volume stability, resistance to freezing and thawing, abrasion & scaling resistance, prevents cracking due to thermal stresses, can minimize plastic shrinkage, protection against moisture loss.

Let see - Strength of concrete and effects of temperature along with time on concrete

 

Curing time is dependent on the following factors:

1. Mixture proportions

2. Specified strength

3. Size and shape of concrete member

4. Ambient weather conditions

5. Future exposure conditions

Let see what does curing process makes the concrete & how?

a. Curing maintains mixed water in concrete during it’s early hardening process

1. Ponding OR immersion – around flat and small jobs water will be made to stand for specific height by constructing temporary bund. Immersion is mainly used in the laboratory for curing concrete test specimens.

2. Water spraying and fogging - are used when the ambient temperatures are well above freezing and the humidity is low.

3. Saturated wet coverings – wet gunny bags should be used after concrete has hardened enough. They should be kept constantly wet.

4. Left in Place Forms – shuttering forms usually left in place, if the construction schedule allows. If the forms are made of wood, they should be kept moist, especially during hot, dry weather. Extra cost for no’s of forms – Obstruction in working areas – metal are good conductor of heat, they transfer heat from out to in. Note: As per IS 456 – minimum time for removing the form / shuttering for RCC works has been established.

What is the difference between Formwork, Shuttering, Staging, Centering and Scaffolding

Formwork: It is a temporary structure which is used as a mould to pour the concrete. It is a vertical or horizontal arrangement made to keep concrete in position until it gains strength & shape.

Shuttering: It is a is a vertical temporary arrangement which is arranged to bring concrete in a desired shape. In a technical point of view, Formwork for columns, footings, retaining walls is called as a Shuttering.

Centering: It is a temporary arrangement & part of formwork which is arranged to support horizontal members. In a technical point of view, the formwork for floor beams & Slabs is called as a Centering.

Staging: It is a temporary member which is used to support formwork (either it may be for centering or shuttering). It is done by props, jacks, H frames, cup lock system, wooden ballies, etc. (Refer below image for clear understanding)

Scaffolding: Formwork is arranged to support the structural members, whereas scaffolding is provided as a workers platform around the building to work at heights, Scaffolding is a movable/fixed platform.

b. Reduces the loss of mixed water from the surface of the concrete

1. Covering concrete with impervious paper or plastic sheets – In case of non-normal temperature or it is high, impervious paper and plastic sheets can be shall be installed thoroughly wetted concrete till it hardened enough to prevent surface damage from the other working activities. As soon as concrete hardened enough, curing shall be started. Sheets shall be covered thoroughly, color of sheet must be light, holes shall not be there in sheet. Sheet shall be maintained in place by placing the load on it. Air tightness maintenance may be the challenge here. Suitable for floor area. All vertical structures may not be covered perfectly.

2. Applying membrane-forming curing compounds - Membrane-forming curing compounds are used to retard or reduce evaporation of moisture from concrete. Curing compound shall comply with ASTM C3094 or ASTM C13155 or BS 7542.

I came across one of the best curing compound which can be applied using brush / roller / spray is C 20 tested as per BS 7542. Below are the details:

Hint: As per BS 7542, The mortar (you can prepare the concrete) cubes as per the said dimensions, after setting time, weight the cubes, apply curing compound as per manufacturer's specification to some cubes and some do not apply. Allow them to be in specified condition for 72 Hrs and again weight them, Find out the loss of water in both applied with curing compound (test sample) and non applied (control sample). then express the curing efficiency.

c. Accelerating strength gain using heat and additional moisture

1. Live steam - Live steam at atmospheric pressure or high-pressure steam will be sent on the concrete in autoclaves over the concrete. Best used for pre cast products.

2. Heating coils - Heating coils are usually used as embedded elements near the surface of concrete elements. Their purpose is to protect concrete from freezing during cold weather concreting.

3. Electrical heated forms or pads: Are primarily used by precast concrete producers. Let us understand this with video:

Video curtesy of : https://www.youtube.com/watch?v=1RCqAd1ah3M

4. Concrete blankets - Concrete insulation blankets are used to cover and insulate concrete surfaces subjected to freezing temperatures during the curing period.

Other forms of curing include internal moist curing with lightweight aggregates or absorbent polymer particles. For mass concrete elements (usually thicker than 3 feet), a thermal control plan is usually developed to help control thermal stresses. Additional information can be found in ACI Committee 308 report Guide to Curing Concrete. For specialty concretes, it is recommended to refer to other ACI reports as follows:

1.    Refractory concrete ACI 547.1R

2.    Refractory concrete ACI 547.1R

3.    Insulating concrete ACI 523.1R

4.    Expansive cement concrete ACI 223

5.    Roller-compacted concrete ACI 207.5R

6.    Architectural concrete ACI 303R

7.    Shotcrete ACI 506.2

8.    Fiber-reinforced concrete ACI 544.3R

9.    Vertical slip form construction ACI 313

General comparison of different types of curing methods:

As per standards, American Concrete Institute (ACI) Committee 301 recommends a minimum curing period corresponding to concrete attaining 70% of designed compressive strength. The 70% percent strength level can be reached sooner when concrete cures at higher temperatures or when certain cement/admixture combinations are used. Similarly, longer time may be needed for different material combinations and/or lower curing temperatures. For this reason, ACI Committee 308 recommends the following minimum curing periods:

A. ASTM C 150 Type I cement seven days

B. ASTM C 150 Type II cement ten days

C. ASTM C 150 Type III cement three days

D. ASTM C 150 Type IV or V cement 14 days

E. ASTM C 595, C 845, C 1157 cements variable

According to the National Ready Mix Concrete Association (NRMCA), strength for concrete air cured for one day followed by 27 days moist cured will be approximately 8 percent lower than for concrete moist cured for the entire period. The strength reduction is 11 percent and 18 percent for concrete specimens initially cured in air for three days and seven days, respectively. For the same air/moist curing combinations, but 100 degrees Fahrenheit air curing temperature, the 28-day strength will be approximately 11 percent, 22 percent, and 26 percent lower, respectively.

So, it is always to better to use the curing admixture or polymer modified products which does not requires the curing at all.

Details curtesy of : CEMENT CONCRETE & AGGREGATES AUSTRALIA – CIP 11 - concurring of concrete.

AAC blocks and adhesive for installation

This blog explains about the AAC blocks and the adhesive to be used for the installation of AAC block as wall:

AAC is also known as AUTOCLAVED CELLULAR CONCRETE (ACC), AUTOCLAVED LIGHTWEIGHT CONCRETE (ALC), AUTOCLAVED CONCRETE, CELLULAR CONCRETE, POROUS CONCRETE, AIRCRETE, HEBEL BLOCK, AND YTONG. It is a lightweight, precast, foam concrete building material invented in the mid-1920s that simultaneously provides structure, insulation, and fire- and mold-resistance. AAC products include blocks, wall panels, floor and roof panels, cladding (façade) panels and lintels.

AAC is produced from the common materials lime, sand, cement, water, gypsum and a small amount of rising agent. After mixing and molding, it is then autoclaved under heat and pressure to create its unique properties.

At the point when AAC is blended and cast in structures, a few compound responses occur that give AAC its light weight (20% of the heaviness of cement) and warm properties. Aluminum powder responds with calcium hydroxide and water to frame hydrogen. The hydrogen gas froths and copies the volume of the crude blend making gas rises to 3mm in distance across. Toward the end of the frothing procedure, the hydrogen escapes into the air and is supplanted via air.

The chemical reaction due to the aluminum paste provides AAC its distinct porous structure, lightness, and insulation properties, completely different compared to other lightweight concrete materials.

When the forms are removed from the material, it is solid but still soft. It is then cut into either blocks or panels, and placed in an autoclave chamber for 12 hours. During this steam pressure hardening process, when the temperature reaches 190 Deg C and the pressure reaches 8 to 12 bars, quartz sand reacts with calcium hydroxide to form calcium silicate hydrate, which gives AAC its high strength and other unique properties. Because of the relatively low temperature used AAC blocks are not considered fired brick but a lightweight concrete masonry unit. After the autoclaving process, the material is ready for immediate use on the construction site. Depending on its density, up to 80% of the volume of an AAC block is air. AAC's low density also accounts for its low structural compression strength. It can carry loads of up to 8 MPa, approximately 50% of the compressive strength of regular concrete.

AAC is produced out of a mix of quartz sand and/or pulverized fly ash (PFA), lime, cement, gypsum, water and aluminum and is hardened by steam-curing in autoclaves. As a result of its excellent properties, AAC is used in many building constructions, for example in residential homes, commercial and industrial buildings, schools, hospitals, hotels and many other applications.

Advantages or benefits of AAC Blocks:

1.    AAC Block is relatively uniform when compared to other wall unit and does not contain coarse aggregate phase.

2.    It is made from the mixture of fly ash, cement, lime, gypsum and an aeration agent.

3.    The Problem of fly ash utilisation is solved by the use of fly-ash in AAC Block. This was a major problem till day.

4.    AAC Block can be used to build internal and external walls.

5.    It can also be used as load bearing and non-load bearing walls.

6.    AAC blocks are very easy to handle and ordinary tools are used for cutting.

7.    AAC blocks are available in large sizes and hence less no of joints. This ultimately results in faster construction on site and less consumption of cement.

8.    Earthquake forces are proportional to the weight of the building and it ultimately reduces the load on buildings and hence less steel in case of RCC structure.

9.    AAC blocks are made from an inorganic material which helps to avoid termites, damages or losses.

10.Saves steel and concrete due to the reduction in dead weight.

11.Increase in floor area due to a reduction in the size of columns and thickness of the wall.

12.Easy to transport on upper floors.

13.Time-saving in construction

14.AAC blocks have a very low thermal conductivity which keeps interior remain cool in summer and warm in winter.

15.AAC blocks reduce interior temperature variation maintaining pleasant and healthy temperature for habitant.

16.AAC blocks reduce the energy cost of air-conditioning to a great extent due to its thermal property.

17.AAC blocks are appropriate for fire rated application for desired safety.

18.One AAC block of size (600 x 200 x 100 mm) is equivalent to 6 bricks hence it reduces 50% of joints resulting in saving of mortar up to 48%. In the case of 150 mm or thicker block masonry, the mortar saving is even more due to avoidance of vertical joint in conventional brick masonry.

19.Minimal wastage of AAC blocks.

20.It is environment-friendly and also saves water. Hence it is popularly used as a green product.

21.The production cost of AAC Blocks is expensive but on the whole project cost decrease.

22.Colour of AAC Block is Grey.

23.Available sizes of blocks, 400-600 x 100-200 x 100-300 mm However, it defers from manufacturer to manufacturer.

24.The AAC Blocks are accurate in size because it is produced by wire cut technology and is a factory product. Variation in Size 1.5mm(+/-).

25.AAC Blocks is a unique and excellent type of building material due to its super heat, fire and sound resistance.

26.Water Absorption of this block should not be 10 % its weight.

27.The thermal conductivity of block is lower and less heat transfer from the block.

28.Moisture resistance of AAC block is better than the Red Brick.

29.AAC block consists of unconnected micropores which prevent the capillary transport of moisture over a long distance.

30.The AAC block has good sound transmission property due to the presence of air voids. 40-45 db sound is reduced for 200 mm thick.

31.AAC blocks are insect resistant, inorganic and solid wall construction material.

32.AC block does not allow spread of  termites and pests and hence increase the life of wall.

33.The Speed of work will be double than that of clay brick work.

34.More carpet area available due to less thickness of the block.

35.AAC Blocks are recommended for high-rise buildings because it substantially reduces the total dead load of the building.

36.Requires less mortar due to flat and even surface & less number of joints.

37.Speedy construction of wall due to the bigger block size, light in weight and less number of joint.

38.Block is cured by steam and block masonry also requires less curing hence less water is used and there is saving in electricity bill.

39.Negligible breakage almost 100 % utilisation is possible.

40.Readily available at any time & in any season at a short notice, so no storage required.

41.Efflorescence occurs through mortar and water, but not through blocks.

42.K value for AAC Blocks is around 0.21 to 0.42W/Mk and this results in strong thermal insulation of walls with energy saving upto 20%.

 See what IS 2185 Part 3 - says about the AAC blocks

See what ASTM C 1386 - says about the AAC blocks

See what IS 2250 - says about the mortar to be used for the installation of AAC blocks

Also see what IS 6041 - says about the mortar to be used for the installation of AAC blocks

See what ASTM C 1660 - says about the compressive strength of AAC block adhesive

Cure the specimens in air at a temperature of 75 ±6 15°F (24 6 8°C) and a relative humidity of less than 80 % for at least 28 days, or for a time prescribed by the mortar manufacturer, in a stacked position.

AAC are available in block shapes and in larger pre-casted panels suitable for both wall and floor applications. As a lightweight construction material, it has excellent heat and sound insulation properties, is easy to shift, cut, handling, placing, do not add much load to structure. This lightweight concrete has some different properties compared to a conventional concrete. They will have relatively low compressive strength and shear strength, very porous but have excellent insulation property compared to normal concrete or concrete blocks.

Consideration are necessary when it comes for the subsequent application on these AAC blocks or panels are as follows:

1. Control joints movement joints shall be provided in wall and floor systems to relieve stresses due to movement of the structural system and to control the locations where movement can occur without detrimental effects on the finishes. These joints shall be applied with waterproofing membrane system along with the coving bandage.

2. Cementitious putty material shall be applied over AAC which will seal all holes and make the surface and joints in line, level, etc followed by priming coat is required prior to the application of any coatings such as waterproofing or any decorative finish.

3.These walls must be sealed on one side only to allow the Hebel material to ‘breathe’ and expand/contract with changes in the temperature and moisture content in the atmosphere, specially wall at exterior walls.

4. At wet area, waterproofing coating is must for wall and floor with protection like tiling or sloping screed.

5. Internal wall shall be covered by sheet linings say plasterboard / fiber cement boards and then install tiling.

6. Heavy tile finishes may adhere to AAC blocks, but failure may occur due to the low cohesive strength of surface of AAC. Tiles can be installed on the AAC with cementitious putty material which will seal all holes and make the surface and joints in line, level, etc.

7. Tiling is not recommended on to the external surfaces of AAC walls or panels.

8. At floor area, due to low compressive strength, point load will damage the panel. Hard floor finishes such as tiles can spread the load over a wider area, but tile shall be installed with 100% adhesive spread.

9. Vinyl or carpet can be installed over the AAC floor panel by priming and then by installed self leveling compound. All panel joints, gaps, holes shall be sealed using cementitious rapid drying and hardening internal repair mortar prior to the installation of SLC. This is recommended only at internal dry areas.
10. ARCHITECTURE CIVILENGINEERING ENVIRONMENT - (ACE) from The Silesian University of Technology: MORTAR SELECTION IN DESIGN PRACTICE – DESCRIPTION OF THE PROBLEMS, SOLUTIONS AND REQUIREMENTS says: about how should be the mortar / adhesive used for AAC / clay brick:

In market there are many manufacturer who produces adheisve for the installation of AAC block, one best product among them is M15. The below is the snap of the certificate of test report of M15 which passes IS 2250 with two very important parameters with the compressive strength of Approx 19 N/Sqmm:

https://themasonrychandrastore.com/blogs/cold-hard-tuckin-faqs/choosing-the-proper-mortar-for-any-masonry-chandraapplication-and-then-where-tochandra-buy-it

WALL HEIGHT & LINTEL in the construction of AAC block:

1. There should be a coping beam to be placed after every 1.2 meter of height of wall with minimum reinforcement of 2 nos of 8 mm bar. 

2. It is advisable to perform masonry work of maximum six layers of blocks in a one day. 

3. Door and Window Lintel should be rest on full block on the both sides of opening for proper load distribution. 

4. Use proper wire mesh and mortar at Beam & Column Junctions to avoid weak joints.

https://themasonrychandrastore.com/blogs/cold-hard-tuckin-faqs/choosing-the-proper-mortar-for-any-masonry-chandraapplication-and-then-where-tochandra-buy-it

For answer to : Mortar to be used to bond the AAC shall have less or more compression strength? refer to:https://annayyachandrashekar.blogspot.com/2018/12/mortar-to-be-used-to-bond-aac-shall.html


Many thanks to Google.com and doc88.com from where the images and details were took.