Advanced Bonding and Jointing Techniques for Engineering Bricks

7th Jun 2024 -

Advanced bonding and jointing techniques have emerged as crucial factors in enhancing the performance and longevity of masonry structures. This article delves into these progressive bonding and jointing approaches for engineering bricks. We explore a range of techniques designed to meet the demands of modern projects.

What is traditional jointing and bonding?

A common traditional technique involves the use of conventional cement-based mortar as the binding agent between bricks. This mortar is typically composed of a mortar mix ratio of 6:1 or 5:1 sand to Portland cement. 

To lay engineering bricks, you spread a bed of mortar onto the layer below and position the bricks in a pattern. Brick bond patterns are the following.

• Stretcher bond: Laid lengthwise with their long sides exposed on the wall surface.
• Header bond: Bricks are laid with their short ends exposed on the wall surface.
• English bond: Alternating courses of headers (short ends) and stretchers (long sides) are used.
• Flemish bond: Alternating headers and stretchers in the same course with headers centred over stretchers in the course below.
• Dutch bond: Like the English bond but with fewer header courses, typically every 4th or 5th course.
• Monk bond: 2 stretcher courses alternating with one header course.
• Sussex bond: 3 stretcher courses alternating with one header course.
• Garden wall bond: Alternating stretcher and header courses on both sides of the wall.

A mortar filler is then used between the brick joints to create strong brick bonds. Proper tooling and compaction of the mortar joints are important for ensuring adequate strength and waterproof capabilities. While traditional mortar serves its purpose, it has limitations in strength, flexibility and durability. 

The rigid nature of cement-based mortar may lead to cracking and failure under high stresses or movements. Also, traditional joint techniques often rely on simple butt joints. They may be susceptible to failure under shear or tensile loads.

Jointing and bonding differences between engineering bricks

The principles of jointing and bonding are similar across different types of bricks. However, certain variations accommodate the unique properties of each brick type. Here, we detail the differences to consider for your project.

• Standard: These bricks are designed for general engineering applications and can be bonded using conventional cement-based mortar. Joints are typically filled with mortar and tooled for a smooth finish.
• Perforated: The perforations in these bricks reduce weight and improve thermal insulation. Bonding techniques are the same as standard bricks. However, mortar must be carefully compacted to fill the perforations. 
• Bullnose: With their rounded edges, bullnose engineering bricks require specialised jointing techniques. Mortar joints are often concave or struck to create a smooth transition between bricks and prevent sharp edges.
• Imperial: These larger, heavier bricks may require stronger mortar mixes or reinforcement within the joints. This supports their increased weight and maintains structural integrity.
• Buff: The porous nature of buff engineering bricks allows the use of mortar mixes that can penetrate the brick surface for a secure bond. Pre-wetting the bricks before laying may be necessary.
• Textured: The rough surface texture of these bricks demands mortar mixes with improved adhesion properties. Proper tooling of the joints is important to ensure a complete bond between the mortar and the textured surface.
• Glazed: With their non-porous surfaces, glazed bricks require specialised bonding agents or mechanical anchors for a secure bond with the mortar.
• Angle: These bricks, designed for corners and angles, often involve intricate jointing techniques. Mortar joints may need to be reinforced or shaped to accommodate the dimensions of engineering brick.

How to boost jointing and bonding techniques

Advanced techniques have been developed to unlock the full potential of engineering bricks. These approaches utilise innovative materials, reinforcement and installation methods to boost the strength of brick structures. 

1. Polymer-modified mortars

These mortars use polymer additives including latex or epoxy resins. This helps to improve adhesion, flexibility and water resistance. They are particularly beneficial for engineering bricks exposed to harsh environments or high stresses.

2. Reinforced mortars

Adding reinforcing fibres into the mortar mix offers improved tensile and shear strength, as well as crack resistance. This technique is helpful for applications involving heavy loads. 

3. Thin-bed mortars

These specialised mortars applied in thin layers (1-3mm) allow for tighter joints and improved load distribution. Thin-bed mortars are often used with engineering bricks such as glazed or textured bricks. Overall, it ensures uniform joint thickness. 

4. Chemical anchoring systems

For engineering bricks with non-porous surfaces, chemical anchoring systems using epoxy or polyester resins provide a secure mechanical bond. It compensates for the lack of natural adhesion.

5. Post-tensioning techniques

Post-tensioning techniques involve installing tensioned steel rods within the brick assembly. This method improves structural integrity and resistance to lateral loads, making it suitable for applications like a retaining wall. 

6. Advanced reinforcement methods

Advanced methods like fibre-reinforced polymer (FRP) grids or fabrics are added to the mortar joints or embedded within the structure. These lightweight yet high-strength reinforcements enhance the load-bearing capacity and durability of brick assemblies.

7. Specialised jointing profiles

For specific engineer brick types, including bullnose or angle bricks, specialised jointing profiles may be used. These involve shaping the mortar joints to accommodate the unique brick sizes and shapes, ensuring a seamless transition between units.

What are the compliance standards for advanced techniques?

Advanced techniques for engineering bricks must comply with various UK building regulations and codes to ensure structural safety and performance. Bricklayers must adhere to the following key regulations and standards. 

Building Regulations 2010

• Part A (Structural safety): Outlines requirements for load-bearing masonry construction. This includes material specifications, design standards and workmanship.
• Part C (Site preparation and resistance to moisture): Covers provisions for resistance to moisture transfer and weather protection, relevant for advanced jointing techniques.
• Part L (Conservation of fuel and power): Addresses thermal performance requirements. This may influence the selection of certain brick types or bonding techniques.

British Standards (BS)

• BS EN 771-1: Outlines the performance characteristics and requirements for masonry units, including engineering bricks.
• BS EN 998-2: Defines the specifications for masonry mortar, including polymer-modified and fibre-reinforced mortars. 
• BS EN 1996: Provides design guidelines for masonry structures, covering aspects like reinforcement, anchorage and post-tensioning systems.
• BS 8000 Series: Details workmanship standards for construction projects, including specific provisions for brickwork and advanced techniques.
• BS EN 1052: Specifies test methods for determining masonry properties. This is important for quality assurance. 

Engineering bricks vs clay bricks: Jointing and bonding

Both clay bricks and engineering bricks rely on mortar for jointing and bonding. However, there are notable differences in the techniques and considerations for each brick type.

Aspect	Clay bricks	Engineering bricks
Mortar specifications	Portland cement-lime mortar mixes with lower compressive strengths for non-load-bearing applications.	Higher-strength mortar mixes like polymer-modified or fibre-reinforced for greater structural loads.
Joint profiles	Flush or concave joints, tooling focused on aesthetics.	Specialised profiles for mechanical keying, brick movement joints and moisture management.
Bonding patterns	Common patterns (stretcher, header, stack) used for decorative non-loadbearing purposes.	Patterns optimised for structural performance, load distribution, shear and tensile resistance.
Reinforcement	Generally not required because of its primary use in non-load-bearing applications.	Advanced techniques like post-tensioning, FRP grids and reinforcing bars for structural integrity.
Surface preparation	Minimal preparation because of the porous nature allowing mortar adhesion.	Specialised techniques (abrasion, etching) may be required for low-absorption bricks.
Quality control	Focus on aesthetic aspects and basic structural integrity.	Stringent protocols including material testing, tolerances and potential non-destructive testing for performance requirements.

Are engineering bricks easy to maintain?

Proper maintenance of jointing and bonding ensures the long-term durability of engineering brick structures. Regular inspections and timely repairs prevent minor issues from escalating into more significant and costly problems. Here, we detail maintenance considerations for engineering brick structures.

Inspection frequency

• Annual visual inspections are recommended. You should pay close attention to areas subjected to high stress, moisture exposure or environmental conditions.
• Frequent inspections (quarterly or after extreme weather events) may be necessary for structures subjected to harsh environments and heavy loads.

Key inspection areas

• Mortar joints: Look for signs of cracking, deterioration or missing sections that could compromise the bond and allow moisture penetration.
• Expansion joints: Ensure that brick expansion joint areas are free of debris and that sealants or backing materials are in good condition.
• Anchors and reinforcements: Check for any visible signs of corrosion or displacement of anchors, ties or reinforcement elements. 
• Efflorescence and staining: These can indicate moisture issues or material incompatibilities that may impact bonding over time.

Maintenance techniques

• Repointing: Deteriorated or missing mortar joints should be removed and replaced with fresh mortar compatible with the existing materials.
• Joint sealant replacement: Expansion joint sealants may need periodic replacement as they age and lose flexibility. 
• Cleaning: Gentle cleaning such as low-pressure water washing or approved chemical cleaners removes grime or efflorescence, leading to bonding issues.
• Anchor/reinforcement repair: Any corroded or displaced anchors, ties or reinforcement elements should be repaired or replaced to maintain structural integrity.

Key considerations

• Use materials and techniques compatible with the existing brickwork and follow manufacturer guidelines.
• Ensure proper curing conditions for any new mortar or sealant applications.
• Address underlying causes of deterioration, such as moisture ingress or structural movements, before conducting repair work.