What is concrete made with? And how do we know that a concrete recipe will be strong enough to build safe bridges, freeways, buildings, and structures?
Concrete expert and civil engineer Mimi Nwosu shares the answers to those questions in this video visit to her lab at Portsmouth University. Watch as Dr. Shini Somara helps Nwosu make a normal strength concrete, a material “that you would find in your roads, your pavements, and maybe your buildings.” Nwosu explains:
“Normal concrete has cement, water, fine, and coarse aggregates. So a fine aggregate will be like sand, and your coarse aggregates will be like gravels and rocks…”
“High-strength concrete actually has some of the same ingredients as normal strength concrete, so you’ll find your cement and you’ll find your water. However, there won’t be any coarse aggregates; there’ll be fine aggregates: we’ve got some silica fume; it increases the rate of reaction in our concrete. We have something called superplasticizer; because we don’t use a lot of water, this makes sure that the concrete will have a good consistency.”
Higher performance concretes can also include different amounts of reinforcing steel fibers, which can increase the material’s tensile strength, as well as help bridge cracks.
Mimi Nwosu also demonstrates how normal concrete holds up (or doesn’t) in a compression testing machine.
And what’s the award winning civil engineer’s advice for women and girls who are considering careers in engineering? Via Womanthology.co.uk:
1. Somebody wise once said to me “if you don’t ask you don’t get” and now it is my mantra! To know more we should start asking questions and actively seeking the information that you require.
2. Be bold and be brave! Sometimes for great things to happen you have to step out of your comfort zone!
3. Do your research (e.g. around the differences between a degree, apprenticeship or degree apprenticeship).
4. Grasp all opportunities and also create your own opportunities.
5. Set goals, however, don’t be too hard on yourself.
6. It is ok to fail – failure could be the start of a new adventure.
The video is one in a video series by Dr Shini Somara about Engineers Making a Difference, her book of the same name.
Follow Mimi Nwosu on Instagram, and Somara on YouTube, Instagram, and TikTok.
Related reading at MIT: Cement vs. concrete — their differences, and opportunities for sustainability.
Watch these engineering and concrete videos next:
• Concrete Does Not Dry Out – Minute Physics
• The Problem with Concrete
• Seashell inspiration: Growing cement bricks with bacteria
• Recycling plastic waste to make bricks that are stronger than concrete
• How to build with different mud recipes
Bonus: Spaghetti bridges, a DIY engineering activity for kids (and adults).
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