Concrete in the Canal

The main component of the physical construction of the Fourth Welland Canal that differentiates it from its predecessors was the concrete used in its construction.

While concrete has been used in construction since ancient Rome, it fell out of use as a major material in construction until the late 19th century with the creation of modern cement, colloquially known as Portland Cement. Portland Cement was created in the late 1800s, and once standardized as a construction material it was used in tandem with steel pipes and rods as reinforcement for industrial projects in monuments and public works globally.

While cement was used prior to Portland Cement, it was not reinforced with steel inside the cement, and the cement itself was weaker. The new Portland Cement used silica, a type of sand, and limestone and clay to strengthen the cement as it dried. For Projects such as canals, Portland Cement was a game changer, as it would not erode the same as rock bricks. 

To build large projects such as the Welland Canal, large amounts of concrete were necessary. This meant that in order to keep up the supply and use it, concrete plants were constructed alongside the construction of the canal itself. Each Lock would have a concrete plant for their construction, to prevent transportation delays in the building process. Materials were gathered from the region, with limestone from local quarries making up the majority of the rocks delivered to the concrete plants, and quality sand for concrete making being brought from the mouth of the Niagara River. Once the raw materials were sorted, processed, refined and mixed, water would be added and the cement would form. 

To use the cement in construction, giant moulds were created for the cement to dry in. Steel pipes reinforced outside with wood were filled with cement and steel reinforcements were placed in the cement. Once that cement was dry and removed from the casing, the cement pillars were placed upright at the bottom of the canal to form the foundation. When pillars were all in place, cement was poured overtop and left to dry, creating a strong foundation for the canal and locks. Many different types of concrete moulds were used in the construction process. The walls were made using large wooden moulds, the concrete being laid and dried layer by layer, reinforced with steel, and further covered in concrete to ensure they were water-tight. 

The careful construction of the canal and the quality materials used have meant that while maintenance has been done on the canal, with the occasional repair job to eroding concrete, there have been few major issues with the Locks. The concrete laid nearly 100 years ago remains strong.