The Strength of Bonds in Brick Masonry: Understanding Mortar, English, and Flemish Bonds

In brick masonry, the overall strength of a structure is heavily influenced by the bond created between bricks. Typically, the mortar bond is the strongest, serving as the adhesive that holds the bricks together. This article delves into the various types of bonds, including English bond and Flemish bond, each with its unique characteristics and applications.

Mortar Bond in Brick Masonry

Mortar, a mixture of cement, sand, and water, acts as the adhesive that ensures the bricks are securely bonded. The strength of the mortar bond depends on several factors, including the type of mortar used, the quality of the materials, and the application technique. High-strength mortars, such as those made with Portland cement, can provide a very strong bond. Proper curing and the use of additives that improve adhesion and durability further enhance the bond.

English Bond

The English bond is one of the strongest and most commonly used types of brick masonry bonds. In this bond, only one course of stretcher and one course of header are present, with alternating courses of headers and stretchers. Headers are laid in the middle on the stretchers of the course under, and each alternate row is perpendicularly aligned. To break the link of vertical joints and avoid them forming inline, quoin closer is used at the starting and end of the wall. Additionally, queen closer is placed after the quoin header for each heading course.

Features of English Bond

No continuous vertical joints are formed. In the elevation, alternate courses either show headers or stretchers. Each header in an alternative course comes centrally over the joint formed by two stretchers below it. The stretchers have a minimum lap of one-fourth their length over the headers. Walls with even multiples of half bricks show the same appearance on both faces. Walls with odd multiples of half bricks show stretchers on one face and headers on the other. The middle portion of thicker walls consists of headers. Queen closer is not required for a stretcher course but is used for the header course. Drug closer is made thinner compared to the stretcher course to avoid continuous vertical joints.

Flemish Bond

Flemish bond, also known as Dutch bond, is another type of bond used in brick masonry. It is created by laying alternating stretchers and headers in a single course, with the next course arranged in such a way that the header lies in the center of the stretcher below. In this bond, every alternative course starts with a header at the corner. Flemish bond is typically used for its better aesthetic appearance but is weaker than English bond for load-bearing in walls. It requires higher expertise to construct and has a complex pattern that necessitates the use of more mortar.

Types of Flemish Bonds

Single Flemish Bond: This is a mixture of Flemish and English bonds. The face of the wall can be finished in Flemish bond, while the backside is finished in English bond. This type is used for its aesthetic appeal and required strength. Double Flemish Bond: This bond appears the same from both the front and back elevations. It is somewhat weaker than English bond due to its complex pattern and requires skilled labor to construct.

Conclusion

Understanding the different types of bonds in brick masonry is crucial for ensuring the structural integrity and aesthetic appeal of a building. While the mortar bond is essential for structural strength, the choice between English and Flemish bonds depends on the specific construction requirements and desired appearance. High-strength mortars, proper curing, and the use of additives can further enhance the overall bond strength, ensuring the longevity and durability of the structure.