Quality Control, Testing, and Code Compliance

Quality Control, Testing, and Code Compliance

Chapter Introduction

Bricklaying is not just a trade of construction; it is also a trade of verification. As a journeyperson bricklayer, you must understand that every joint, every alignment, and every mortar mix is subject to precise regulatory requirements. This chapter covers all the knowledge required for the Red Seal exam concerning quality control, standardized testing, and compliance with Canadian codes. You will learn key definitions, sampling procedures, strength calculations, dimensional tolerances, and the classic pitfalls that cause candidates to fail.

1. Canadian Regulatory Framework

1.1 Applicable National Standards

In Canada, bricklaying is governed by national standards published by the Canadian Standards Association (CSA) and the National Research Council of Canada (NRC). The main references are:

The National Building Code of Canada (NBC) is the primary reference document. It references CSA standards for technical details. On the exam, you will often be asked to cite an NBC requirement, then relate it to a CSA standard. For example, the NBC requires that mortar compressive strength comply with CSA A179, but it is Standard A371 that specifies the sampling methods.

1.2 Hierarchy of Documents

It is essential to understand the following hierarchy:

Golden Rule: In case of conflict, the strictest specification prevails. If the specification requires a strength of 20 MPa and the NBC requires 15 MPa, you must achieve 20 MPa.

2. Quality Control of Materials

2.1 Burned Clay Bricks (CSA A82)

Standard CSA A82 classifies bricks into three grades according to their frost resistance:

Main physical requirements (CSA A82):

Saturation coefficient formula:

Saturation coefficient = Cold absorption (24 h) ÷ Boiling absorption (5 h)

A coefficient greater than 0.78 indicates a brick at risk of freeze-thaw deterioration. This is a classic exam trap: you are given absorption values and asked to calculate the coefficient.

Calculation example:

2.2 Concrete Blocks (CSA A165)

Concrete blocks are classified according to their density:

Key points for the exam:

2.3 Mortar (CSA A179)

Mortar is defined by its proportions and strength. Standard CSA A179 establishes the following mortar types:

Proportion calculation rule: Proportions are always by volume (measured by bucket or bag), never by mass. A 30 kg bag of cement is equivalent to approximately 25 L of volume.

Bag-to-volume conversion formula:

Volume (L) = Mass (kg) ÷ Apparent density (kg/L)

For Portland cement, the apparent density is approximately 1.2 kg/L. Therefore, a 30 kg bag gives 30 ÷ 1.2 = 25 L.

Frequent trap: You are given a mix by mass and asked whether the proportions are compliant. You must convert to volume before comparing to the table.

2.4 Mixing Water

Water used for mortar must be potable or of equivalent quality. Non-potable water is acceptable only if it meets the following criteria:

For the exam, remember that seawater is prohibited for mixing mortar due to its chloride content, which causes efflorescence and corrosion of reinforcement.

3. Standardized Testing

3.1 Mortar Compressive Strength Test

The test is performed according to CSA A179, Annex A. The specimens are 50 mm cubes, taken from the job site.

Sampling procedure:

Number of specimens: One set of 3 cubes per 40 m² of wall or per working day, whichever is more frequent.

Strength calculation:

Strength (MPa) = Maximum force (N) ÷ Area of loaded surface (mm²)

Example: A 50 × 50 mm cube supports a force of 18,750 N.

3.2 Masonry Prism Test

The prism test is used to determine the actual strength of the brick-mortar assembly. It is performed according to CSA S304 (Design of Masonry Structures).

Principle: A prism of 3 to 5 stacked bricks is built with the job-site mortar, then loaded in compression after a 28-day cure.

Correction factor: The measured strength must be corrected according to the height-to-thickness ratio (h/t) of the prism.

Formula:

Corrected strength = Measured strength × Correction factor

Example: A prism 400 mm high and 200 mm thick (h/t = 2.0) gives a measured strength of 12 MPa.

3.3 Brick Water Absorption Test

The absorption test is performed according to CSA A82. The procedure is as follows:

Calculations:

Cold absorption (%) = [(M₂ − M₁) ÷ M₁] × 100

Boiling absorption (%) = [(M₃ − M₁) ÷ M₁] × 100

Saturation coefficient = (M₂ − M₁) ÷ (M₃ − M₁)

3.4 Brick Flexural Strength Test

Flexural strength is measured according to CSA A82. The test consists of applying a load at the center of a brick supported at both ends (3-point flexural test).

Formula:

Modulus of rupture (MPa) = (3 × F × L) ÷ (2 × b × h²)

Where:

Minimum value: 1.0 MPa for Grade SW (average of 5 bricks).

4. Dimensional and Alignment Tolerances

4.1 Installation Tolerances (CSA A371)

Standard CSA A371 defines the following execution tolerances:

Practical rule: The verticality tolerance is 1/500 of the wall height, with a maximum of 12 mm. For a 3 m wall (3,000 mm), the tolerance is 3,000 ÷ 500 = 6 mm.

4.2 Joint Dimensions

Trap: Head joints must not be vertically aligned for more than two consecutive courses. The maximum alignment of vertical joints is 25% of the brick length (approximately 75 mm for a standard 300 mm brick).

4.3 Calculating the Number of Bricks

Formula for a simple wall:

Number of bricks = (Wall area in m²) ÷ (Area of one brick including joints in m²)

Example: 10 m² wall with 200 × 100 mm bricks and 10 mm joints.

Add 5 to 10% for waste depending on project complexity.

5. National Building Code Compliance

5.1 Structural Requirements (NBC, Division B, Part 4)

The NBC requires that load-bearing masonry be designed according to CSA S304 (Design of Masonry Structures). Key requirements are:

5.2 Moisture Protection Requirements (NBC, Division B, Part 9)

The NBC imposes the following rules for masonry foundation walls:

Rule 9.20.4.1: Concrete block foundation walls must have a minimum thickness of 140 mm for backfill height ≤ 1.2 m, and 190 mm for backfill height > 1.2 m.

5.3 Fire Safety Requirements (NBC, Division B, Part 3)

Masonry is a non-combustible material. The NBC requires that fire separation walls have a minimum fire resistance rating of 45 minutes for buildings of 3 storeys or less.

Minimum thicknesses for fire resistance:

5.4 Quality Control Requirements (NBC, Division B, Article 9.20.1.1)

The NBC requires that masonry work be inspected at the following stages:

Mandatory documentation: Results of mortar strength and prism tests must be recorded and available upon request.

6. On-Site Quality Control

6.1 Material Inspection at Delivery

Upon receipt of materials, the bricklayer must verify:

Quick sand test: Place a handful of sand in a jar of water, shake, and let settle for 24 h. An organic layer greater than 3 mm indicates unsuitable sand.

6.2 Installation Conditions

Temperature: Masonry installation is prohibited when the temperature is below 5 °C and falling. In cold weather, materials must be warmed and mortar must be protected from freezing for 48 h.

Humidity: Bricks must be dry at the time of installation. Water-saturated bricks reduce mortar adhesion and increase the risk of efflorescence.

Protection: Freshly built walls must be protected from rain and frost for at least 48 h.

6.3 Efflorescence Control

Efflorescence is a whitish deposit of soluble salts on the masonry surface. It is caused by:

Prevention:

Treatment: Efflorescence can be cleaned with a diluted muriatic acid solution (1 part acid to 10 parts water), followed by thorough rinsing. Caution: acid must never be used on clay facing bricks or concrete blocks.

7. Mix Proportion and Yield Calculations

7.1 Calculating Mortar Volume

Formula:

Mortar volume (m³) = Total masonry volume (m³) − Brick volume (m³)

Example: 10 m² wall with 200 × 100 × 65 mm bricks and 10 mm joints.

Practical rule: Mortar represents approximately 30 to 35% of the total masonry volume.

7.2 Calculating Material Quantities for Mortar

Formula for a Type N mix (1 : 1 : 6):

Cement volume = Mortar volume ÷ (1 + 1 + 6) = Volume ÷ 8

Lime volume = Mortar volume ÷ 8

Sand volume = 6 × Mortar volume ÷ 8

Example: For 0.437 m³ of Type N mortar.

7.3 Grout Calculation

Grout is used for reinforced walls. Its minimum strength is 20 MPa at 28 days.

Typical grout proportions:

Slump: Grout must have a slump of 200 to 250 mm on the Abrams cone to ensure complete filling of voids.

8. Non-Destructive Testing

8.1 Rebound Hammer (Schmidt Hammer)

The rebound hammer measures the surface hardness of concrete or mortar. It is used to estimate in-place strength.

Limitations:

8.2 Ultrasonic Testing

The ultrasonic method measures the propagation velocity of waves through masonry. It can detect:

Formula:

Velocity (m/s) = Distance traveled (m) ÷ Transit time (s)

A velocity below 3,000 m/s in concrete indicates questionable quality.

8.3 Pull-Out Test

The pull-out test measures the force required to extract a rod inserted into a drilled hole. It is used to evaluate mortar adhesion to bricks.

Minimum value: 0.5 MPa for an exterior wall exposed to weather.

9. Documentation and Traceability

9.1 Quality Control Records

The bricklayer must maintain the following records:

9.2 Material Compliance Certificates

Each delivery of bricks, blocks, or cement must be accompanied by a compliance certificate indicating:

Trap: A compliance certificate does not replace on-site testing. The NBC requires that tests be performed on the materials actually used.

10. Summary

Quality control in bricklaying is based on five essential pillars:

Formulas to memorize:

11. Pitfalls to Avoid

Final exam advice: Read each question twice. Identify the reference standard, the data provided, and the unit required (MPa, mm, %, etc.). Perform your calculations with consistent units. Verify whether the result is plausible: a Type N mortar cannot have a strength of 20 MPa, and a Grade SW brick cannot have an absorption of 25%. If the result seems abnormal, recheck your calculation.