AAC Block Jointing Mortar: Better Than Traditional Cement?

For your modern construction needs, using the right material is very important. As a builder, architect, engineer, or contractor you always seek materials that enable you to work more quickly, save you money, and decrease issues on site. AAC Block Jointing Mortar is a material that has numerous advantages over common cement mortar.  

AAC block jointing mortar and conventional cement reflect two very distinct approach towards contemporary masonry buildings. Traditional cement-sand mortar has dominated the marketplace for generations, but dedicated AAC block jointing mortar has emerged as a functionally designed option with enhanced performance. The distinction goes beyond simple formulation; these products have noteworthy differences in usage, thickness, thermal characteristics, and structural response. For example, AAC mortar permits 2-5mm-thin joints compared to 10-15mm joints by conventional cement. Moreover, the thermal performance of AAC jointing mortars (~ 0.3 W/mK) surpasses that of ordinary cement mixes (0.6-1.0 W/mK), potentially increasing the energy efficiency of a building.

Contractors and homeowners must choose bonding agents based on considerations such as workability, durability, expense, and environmental influence. In this guide, we're going to discuss both in-depth to assist you in deciding which material actually binds better for your construction requirements.

In construction, mortar is a mixture that is used to join building blocks such as bricks or stones together. Traditional mortar is prepared by mixing cement, sand, and water.  

Material Composition and Formula 

Although Cement and mortar both may seem similar, there are certain deliberate distinctions in the formulation of AAC Block Jointing mortar and cement due to which the two materials cannot be used one for another. The basic distinctions between AAC block jointing mortar and ordinary cement start from their actual composition, each of which is specifically formulated for different construction applications. 

Cement mortar has been in use for decades and is great to work with old clay bricks. However, if we apply it to use with new, lightweight products such as AAC blocks, it can cause some issues such as cracks, wastage, and irregular finishes. 

AAC Block Jointing Mortar is a pre-mixed, ready-to-use mortar for AAC blocks specifically. It is different from the common cement mortar we apply to bricks.

This mortar is ready to use, just add water and mix. It contains:

• Cement that gives strength
• Fine sand for smooth texture
• Polymers for strong bonding help in better sticking (adhesion)
• Additives are easy to work with; they are water control additives, reduce shrinking that help it set quickly and remain crack-free.

AAC Block Jointing Mortar is formulated to be applied in extremely thin coats only 3 to 5 mm, ideal for AAC blocks. It also avoids problems such as cracks, gaps, and uneven joints which normally arise from the use of normal cement mortar.

Cement-Sand Mix vs Polymer-Modified Mortar

Normal cement-sand mortars are usually made of cement, sand, and water in specified proportions. These classical mortars are available in different strength grades based on their cement-to-sand ratio:

• Strong mortar (SCM1):using a 1:3 cement-to-sand weight proportion with 62% water-cement ratio
• Medium-strength mortar (SCM2): using a 1:6 cement-to-sand weight proportion with 76% water-cement ratio
• Brittle mortar (SCM3):using a 1:8 cement-to-sand weight proportion with 96% water-cement ratio

Conversely, AAC block jointing mortar has a polymer-modified composition designed specifically for autoclaved aerated concrete blocks. Such specialized mortar includes cement, graded aggregates, and polymers in specific ratios

The polymer element profoundly changes the way that the mortar acts. As indicated in a scientific research paper, "The incorporation of polymers greatly improves strength, resilience, adhesion, impermeability, chemical resistance and durability properties of mortars."

In addition, the application thickness varies drastically; conventional cement-sand mortars need 10-15mm joints, while polymer-modified AAC mortars require only 2-5mm. This thin-bed application is a radical change in masonry construction methods.

Additives and Chemical Enhancements in AAC Mortar

In addition to the mere polymer modification, AAC block jointing mortars have a number of specialized additives which improve performance in particular ways.

Lime is a critical additive that enhances workability and pliability. As a result, it makes the mortar hold water for a longer period, helping with the curing process. Interestingly, lime also minimizes shrinkage within the mortar, thus reducing the probability of cracking after some time.

Fine aggregates in the form of sand or silica are selected with great care to enhance bonding within the mixture. The aggregates should be accurately graded so that they perform optimally.

Advanced polymer additives play various key roles:

• They improve adhesion, with tensile adhesion strength greater than 1.0 MPa after 28 days
• They increase flexibility so that the mortar can absorb small structural movements
• They enhance water retention to ensure effective curing even in adverse conditions
• They retain their effectiveness even in severe climatic conditions

In short, the creation of AAC block jointing mortar is an advanced innovation above conventional cement-sand mixtures, with every material individually chosen to cater to the unique needs of AAC block construction.

Here is a comparison between conventional cement mortar and thin set mortar like AAC Block Jointing Mortar:

Please note: AAC Block Jointing Mortar falls under the category of thin set mortars.

Application Thickness and Workability

Practical usage of bonding materials provides numerous contrasts between conventional cement and AAC block jointing mortar, with implications for construction efficiency and quality.

Joint Thickness: 10-15mm vs 2-5mm

The most visible difference between these bonding agents is their thickness of application. Conventional cement-sand mortar demands enormous joint thickness usually 10-15mm. This creates notable thermal bridges across wall systems and consumes significantly more material. AAC block jointing mortar, on the other hand, requires only 2-5mm thickness for successful bonding.

This extreme reduction in joint thickness has the following benefits:

• Material consumption goes down by about 70-75%
• Thermal bridging is reduced, improving wall insulation overall
• Reduced overall material usage lowers construction expenses

Ease of Use: Hand Mixing versus Ready-to-Use

Preparing old cement-sand mortar through the conventional method is a multi-step process. Masons have to:

• Measure the accurate ratio of cement and sand (the commonest being 1:4 and 1:6)
• Mix well with water to get the right consistency
• Apply within a comparatively narrow working time of 30-60 minutes

Conversely, AAC block jointing mortar simplifies this process considerably. The ready-mix formulation requires only adding water. This streamlined approach offers several advantages:

• Mixing time reduced substantially
• Consistent quality due to factory-controlled formulation
• Extended working time of 2-3 hours versus traditional mortar's 30-60 minutes
• Zero wastage compared to site-mixed cement-sand mortar

Alignment and Finish Quality

The thin-joint use of AAC block jointing mortar provides more accurate alignment. When used with a notched trowel at 3-5mm thickness, it facilitates:

• More accurate block alignment
• Straight, more professional-quality walls
• Less requirement for heavy plastering later

The polymer-modified product also offers flexibility that regular cement mortar does not have. This feature accommodates minor structural movement without cracking, an asset in avoiding hairline cracks that typically require callback repairs.

The total construction timeline is also greatly reduced. The 7 days' curing time of traditional mortar joints is needed before the wall can support heavy loads. AAC jointing mortar, on the other hand, is functional within 24-48 hours, so construction can be carried out more quickly.

The smooth texture of AAC jointing mortar produces joints with little finish work required. With that, plus its excellent bonding qualities, it aids in both structural stability and aesthetic appeal of the completed wall.

Thermal and Moisture Performance

In addition to structural, thermal and moisture properties of bonding compounds significantly influence a building's long term performance and energy usage. The distinction between AAC block jointing mortar and conventional cement makes major differences in wall performance under temperature changes and moisture exposure.

Thermal Conductivity: 0.6-1.0 W/m·K vs ~0.3 W/m·K

The thermal conductivity difference between these materials is considerable. Regular cement mortar has fairly high thermal conductivity values of 0.6-1.0 W/m·K. Contrarily, AAC block jointing mortar shows significantly higher insulation capability with a thermal conductivity of around 0.3 W/m·K.

Water Resistance: Absorption vs Repellency

Moisture management is a further key performance differentiator. Conventional cement mortar is easily water-absorbing, with potential for dampness problems throughout the life of a building. AAC materials, though not completely waterproof, provide much better moisture resistance.

AAC block jointing mortar incorporates water-resistance properties that protect the overall wall system. The proprietary polymers in its composition form a semi-permeable membrane that does all of the following at once:

• Repels liquid water penetration
• Permits water vapor to evaporate (preventing internal condensation)
• Maintains adequate moisture for good curing

This balanced approach to moisture control is particularly worth it in damp climates or regions with continuous rain, where conventional mortar joints tend to act as water entry points with time.

Shrinkage and Cracking: Rigid vs Flexible Bond

Shrinkage properties are a key distinguishing feature between such materials. Old cement-sand mortars form hard bonds that are prone to cracking under pressure. Tests confirm such traditional mortars tend to form micro-cracks as a result of drying processes and further shrinkage. Such sensitivity is mainly due to traditional cement developing rigid bonds between blocks.

Alternatively, the jointing mortar of AAC blocks uses polymer modifications to significantly improve crack resistance. Such specialized mortars have "lower shrinkage, which prevents cracks from forming in the joints over time". The polymer components form a semi-flexible bond that can accept small structural movements without loss of integrity.

Laboratory tests confirm that well-formulated AAC jointing mortars prevents cracks and shrinkage, improving the durability and stability of walls and structures. Such flexibility is crucial for maintaining structural continuity despite environmental stress or minute foundation shifts.

Longevity in Different Climates

Environmental resilience varies widely among these binding agents. AAC block jointing mortar exhibits "weather-resistant and moisture-resistant properties" that make "the structure intact even in extreme environmental conditions".

Unlike mortars that degrade in extreme weather conditions, AAC jointing mortars stay stable in varying climates. This is due to their chemical make-up and water-resistant nature, which makes them appropriate for areas with extreme temperature fluctuations or moisture issues.

Material Usage and Wastage

AAC block jointing mortar significantly lowers material usage with its thin-joint technology. Whereas normal cement demands 10-15mm joints, AAC mortar only requires 2-5mm, reducing material use by around 70%. This drastic cut translates into savings directly on massive projects.

Wastage statistics reveal an equally significant difference. Traditional cement-sand mortar typically results in 20-30% waste during application, primarily from excess mixing and spillage. In contrast, AAC block jointing mortar produces virtually zero waste.

Labor and Construction Time

Construction speed represents a decisive advantage for AAC jointing mortar. Projects using AAC blocks with specialized mortar progress up to 20% faster than those using traditional materials. This acceleration stems from several factors.

To begin with, AAC mortar preparation is as easy as adding water to the ready-mix mix, avoiding the tedious task of measuring and mixing cement, sand, and water in the required proportions. Further, the longer working time permits more structured application without haste.

Most significantly, curing is vastly different. Old-fashioned cement mortar requires 7 days of curing, while AAC block jointing mortar gains usable strength in only 24 hours. This alone can save days from the construction timeline for multi-story structures.

Carbon Footprint and Sustainability

Environmentally, AAC block jointing mortar is a big step up. First and foremost, formulation of it includes fly ash as an ingredient, which is an industrial waste product otherwise contributing to landfill volumes.

Energy consumption analysis shows conventional brick production takes five times more fuel than AAC production. In addition, transportation energy use for AAC materials is much less because they are lighter in weight—7.7 tons for 100m² of AAC wall and 27.6 tons for conventional brick walls.

AAC block jointing mortar is designed in such a way that it gives improved results with AAC blocks. AAC Block Jointing Mortar includes cement, polymers, and additives that strengthen the bond and minimize cracks. It doesn't involve pre-soaking of the blocks before application and requires minimal curing. One major benefit is that you don't have to soak AAC blocks in water before using this mortar. That conserves water and accelerates work. You also do not have to cure the wall extensively after the application of the mortar. Light curing alone will do. Due to its thin-layer application (just 3-5 mm), the coverage is higher than with conventional mortar. You use less material, which means more walls with less cost.    

Quality and Compliance: 

Now, for professionals looking at block jointing mortar coverage, here's something important: Magicrete’s AAC block jointing mortar gives up to 5 times more coverage than traditional cement mortar. This makes it ideal for large projects and fast-paced construction. 

Magicrete AAC block jointing mortar is tested and certified, which adds reliability to your work. 

• It meets ASTM C1660-09, the international standard for thin bed mortar used in AAC masonry. 
• It also meets IS 15477, which is the Indian Standard for adhesives used in block work. 

Note to professionals: ASTM = American Society for Testing and Materials—global standard for building materials. 

With a tested product such as Magicrete, you are assured of quality, safety, and long-term performance in your projects. 

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Do you need to upgrade your construction with better mortar solutions? Contact our expert team today and discover the ideal product for your construction. For innovative, environmentally friendly construction, particularly with AAC blocks, employing advanced mortars such as Magicrete's AAC Block Jointing Mortar is the smarter choice .