CONCRETE — THE MAGIC MATERIAL
I watched closely as he weighed quantities of sand and stones using a wheelbarrow, added a bag of cement, mixed them for a while, and then poured water on the materials on the ground. He proceeded to mix them together again with a shovel, and when he felt they looked properly mixed, he poured them into a machine, which I later found out was called a vibration machine. This was to allow compaction to take place and produce a well-mixed and high-quality concrete block. The vibration machine had a rectangular mold, which explained the rectangular shape of the concrete.
I stood there staring for about 30 minutes until I gathered some courage and walked closer, asking, “What is this?” while pointing to the paste on the ground that magically hardened or became a semi-solid substance after some time. He responded, “That’s concrete. We use it to make houses.” I later found out that they were producing concrete blocks for sale.
Importance of Material Proportions
I noticed that you weighed the materials you used. Why? Wouldn’t you still get concrete if you didn’t use that particular weight? They smiled and responded, “You will definitely get concrete, but the properties will be different. There are certain standards that dictate the required quantity based on the desired properties. These standards vary from country to country. For any construction project, specific properties are needed to ensure the structure’s safety. The quantity of material used significantly influences these properties.” They further explained that concrete that fails to meet these properties is usually rejected on the job site. Quality control is an important process in concrete production.
Curing Process and Strength Development
Innocently, I asked, “Are they ready to be used now?” The response was, “No, they will be left for a day for air curing, and tomorrow we will sprinkle water continuously to cure them for seven days. Curing allows the concrete blocks to gain the necessary strength.” I later learned that strength development occurs over time. It’s only after the concrete has reached its full strength that it can be supplied to the construction site. During the curing stage, the blocks should not be stacked on top of each other. They further stressed the importance of quality curing. The weight of the blocks is also crucial, especially for concrete blocks used as load-bearing units.
The basic materials of concrete and their origin
Where do you get the materials you use?’ I asked. The response was, ‘The sand is usually from the river, and the stones are from a stone quarry. Sand can also be obtained from a quarry. Cement is made by heating a mixture of limestone, clay, and other materials in a high-temperature kiln. The resulting clinker is then ground into a fine powder, which is what we call cement.
I asked if I could come around another time and maybe help with the production. They replied, “With permission from your parents, we would gladly have you.” I smiled, said thank you, waved them goodbye, ran home to tell my parents about the new magical material I had just seen and learned about, and begged them to give me permission to join them for a while. “We will think about it,” my parents responded in unison. That’s how I received my first lesson in producing concrete — a material I fondly describe as one of the wonders of the world.
I am now a concrete researcher. Who would have thought? I didn’t
Author Profile
Barbara Aboagye is an Academic, YouTuber, and Co-founder of the Concrete, Adulthood, and Grad School blog. She is also an English as a Second Language teacher. Her research interests revolve around low-cement concrete, concrete sustainability, aggregate packing optimisation, and fillers. Through her blog, she and her co-founders share their journey as researchers shaping the future of low-carbon concrete. Her YouTube channel focuses on providing guidance to international students on graduate school admissions and scholarships. With a new-found interest in cycling, you can find her on the road on the weekends.