AAC Block Joint Mortar | >7 MPa | 3mm Thin Bed | 40kg

Name: AAC Block Joint Mortar
Brand: SilicaMix
SKU: aac-block-joint-mortar
Availability: InStock

Technical Specifications

AAC Block Joint Mortar at a glance

Full published specification. No gated download, no email request — the numbers your engineer needs are on this page.

Property	Value
Compressive Strength	> 7 MPa
Split Tensile Strength	> 0.4 MPa
Open Time	20 minutes
Pot Life	1.5 – 2 hours
Joint / Bed Thickness	3 mm
Coverage	160 – 180 sq.ft per 40 kg bag @ 3 mm
Water Demand	10 – 10.5 litres per 40 kg bag
Packaging	40 kg HDPE laminated waterproof bag
Shelf Life	6 months from date of sealed packaging

Values are typical and determined under standard laboratory conditions. Site results vary with substrate, ambient temperature and workmanship. Figures are from SilicaMix in-house laboratory testing. Download the technical data sheet for full test methods and referenced standards.

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Bulk and project pricing available. Free sample delivered to your site on request.

Where It Is Used

Applications

Typical use cases where this product is specified on site.

AAC block partition and infill walls in RCC frame structures
High-rise residential and commercial blockwork
Any AAC installation where joint cracking has been a recurring defect
Projects specifying thin-joint masonry per block manufacturer guidance

Application Guidance

How to use AAC Block Joint Mortar

Follow this sequence for consistent results. Deviating on water ratio or open time is the most common cause of on-site failure.

1

Prepare

Ensure the block bed course is level and true. Clean block faces of dust. Lightly dampen — AAC is highly absorbent.

2

Mix

Add 10 to 10.5 litres of clean water per 40 kg bag and mix mechanically for 3–5 minutes to a uniform, lump-free consistency. Allow to stand 5 minutes, then remix briefly. Do not re-temper with extra water once it stiffens.

3

Apply

Apply a 3 mm bed to the horizontal and vertical faces using a notched AAC trowel sized to the block width.

4

Lay the block

Place the block and tap into position with a rubber mallet within the working time. Check level and plumb every course — thin-joint masonry gives little room for later correction.

Common Questions

Frequently asked questions

The questions contractors and site engineers ask us most about this product.

Why can't I use ordinary cement mortar for AAC blocks?

AAC blocks are laid with a 3 mm joint. Sand-cement mortar cannot be placed reliably at that thickness and shrinks as it cures, opening hairline cracks along the joint lines. A polymer-modified thin-bed mortar stays dimensionally stable in a thin section.

How much wall area does one 40 kg bag cover?

160 to 180 sq.ft per 40 kg bag applied at an even 3 mm thickness between blocks. Consumption rises if joints open beyond 3 mm.

What is the compressive strength?

Above 7 MPa, with split tensile strength above 0.4 MPa.

How much water per bag?

10 to 10.5 litres of clean water per 40 kg bag. Pot life after mixing is 1.5 to 2 hours.

What is the open time?

20 minutes. Place and tap the block into position within this window — thin-joint masonry gives little room for later correction.

How does thin-bed mortar reduce cost?

A 3 mm joint consumes far less mortar than a conventional 10–12 mm sand-cement bed. The saving in material and mixing labour typically outweighs the higher per-bag price.

What is the shelf life?

6 months from date of originally sealed packaging, stored cool and dry.