Concrete vs. Clay Bricks

Clay Brick vs. Concrete Block

When compared to other forms of construction, the durability and resistance of masonry structures is seldom questioned. Masonry systems have stood the test of time, and rightfully earned a reputation for resilience against the elements. Considering even man-made perils, such as fire, masonry still consistently outperforms all other constructions; resisting against outright destruction which is characteristic of wood frame buildings, and outlasting the warping and ultimate collapse of steel-skeleton structures. Notwithstanding these irrefutable benefits, a masonry structure’s environmental and mechanical resistance will naturally vary and depend on the construction method and the materials employed.

Clay Brick

Undoubtedly one of the most fundamental and durable building materials ever invented, clay bricks have been used in construction for thousands of years. The method of construction and materials have been perfected over centuries, and the durability of clay brick is dependent on the following five factors:

1. The quality of the raw/fabrication material;
2. The manufacturing process and firing condition;
3. The resultant properties of the hardened brick;
4. The conditions to which the bricks were exposed since construction; and
5. The rate of maintenance and repair.

The naturally-occurring raw material known as raw clay consists of a complex mixture of minerals in varying proportions. Production begins with selection of the clay materials and ends with the firing of the clay units; with mixing, molding and drying occurring in between. Optimal proportions of sand, clay and water along with the drying and firing temperature are integral to the quality of the hardened brick.

The clay’s composition and the manufacturing process significantly affect the dimension and distribution of the brick’s pores which has a significant impact on its durability. Consequently, treatments to enhance durability after construction is reduced to acting on external conditions – as changing the brick’s composition post-production is not possible. Preventing the invasion of water in to the brick’s mass, controlling moisture and managing the brick’s salt content are the main methods of managing the brick’s exposure to harmful conditions and increasing its durability.

Concrete

Unlike clay brickwork, concrete block masonry is a relatively recent development which started being used as a building material in the mid-19th century. Concrete block walls provide sound structural resistance along with thermal and acoustic insulation all while accommodating for fast and easy installations – facilitated by the block’s precise unit measurements and modular characteristics.

Concrete blocks are composed of Portland cement, aggregates and water with production being highly automated in large industrial plants. The mix of materials is placed in a metallic mold, vibrated in to shape, and cured at an average temperature of 70°C for up to 18 hours. The durability of concrete block masonry is less dependant on externalities, and more on design and construction errors. While concrete can fall susceptible to things like efflorescence (the migration of salts from the interior to the surface material of the masonry) the effects are mainly aesthetic, and without compromise to structural integrity. Furthermore, pathologies can be prevented by deploying low-absorption blocks with high compressive strength and rebar protection.

While both concrete blocks and clay bricks can serve similar functions, skilled masons understand the inherent strengths and weaknesses which influence the conditions in which they are deployed.

Source: Ghiassi, Bahman, and Lourenc̦o Paulo B. Long-Term Performance and Durability of Masonry Structures: Degradation Mechanisms, Health Monitoring and Service Life Design. Woodhead Publishing, 2019.

Masonry in Hamilton

Along with Quebec, New Brunswick and Nova Scotia, Ontario is one of the original provinces, and in 1867 it formed part of the federated colony which was to become a sovereign nation. Although not known for its architectural qualities and still quite young compared to it’s global, sovereign confederates, Ontario is home to some of Canada’s oldest and most unique structures.
Among these historic and celebrated structures is Dundurn Castle, the 18,000 square-foot neoclassical mansion located on York Boulevard in Hamilton Ontario. The castle was raised over a period of 3 years -ending in 1835 – and its construction costs totaled $175,000; equivalent today to over $6,000,000. Established at the former site of a British military encampment, the castle’s heritage and stunning masonry façade overlooks the city of Hamilton, while the back graciously faces Burlington Bay. Hamilton’s masonry marvel is situated on grounds which feature many historically and architecturally significant structures; their heritage value lying in their Italianate, Gothic revival and Classical style design and in the prominent politician and businessman, Sir Alan Napier MacNab for whom they were built. The prominent and picturesque qualities of the buildings and landscape include the 19th century front entrance gates which were originally imported from England and the stone pillars which were cut from the Dundas Mountain. Purchased by the city of Hamilton in 1900 and receiving a significant investment for the renovation of its brick construction, the castle’s halls and rooms along with their characteristic panoramic views are now open to the public.

Hamilton’s ancient architectural implications extend to the English Gothic style St. Paul’s Presbyterian Church: designed by one of the founders of the Canadian architectural profession, William Thomas.  Receiving his architectural training in England, the Anglo-Canadian architect was renowned for designing some of the finest decorated Gothic Revival architecture in Canada. St. Paul’s Presbyterian Church – erected over the years from 1854 to 1857 – boasts a spire that now towers over neighboring structures at 180 feet, and the church holds the title for the highest steeple sculpted entirely out of stone in Canada. Features like the cut-stone masonry and meticulously-proportioned buttresses which reinforce the corners of the tower contribute to preserving its provincial and municipal heritage.  With most of the church’s grey limestone being sourced from Hamilton’s quarries, it is regarded as one of Hamilton’s finest masonry buildings, and was federally designated as a National Historic Site in Canada.

Hamilton’s lands bear some of Ontario’s richest stone-cut masonry formations, dating back to the early days of Canadian settlement, and confederation. With many locations being designated as National Historic Sites, the city has dedicated considerable resources to maintain, repair and restore its historically significant masonry structures.