I am the concrete canoe captain here at Wentworth, so I deal a lot with lightweight concrete mix designs, fibers, and all sorts of other things related to concrete. It is very difficult… There are so many different admixtures, aggregates and supplemental cementitous materials that you can use to make your concrete stronger, lighter, have a less slump, etc. Because we have been asking a lot of questions and the president has been helping me a lot with the mix designs the lab technician, Professor Lee, took some of the canoe members and other civil engineering students to tour W. R. Grace and see what a research facility is like!
So a little background on concrete: Concrete is produced by mixing cement, water, admixtures, and aggregates. The cement reacts with water to form C-S-H (Calcium Silicate Hydrate) which produces the strength of the concrete. Concrete is only really strong in compression and does not have as great of strength in tension. That is why you see concrete used for bridge decks and footings but never in beams or things that will stretch. However, you can add reinforcement to create a larger tensile strength, such as rebar or in our case fiber reinforcement mesh. There is a whole lot more that goes into concrete as well, but the major thing is that concrete is when it is hydrated, so what you see all over, while cement is what you mix with water, so it is a powder! I still say the wrong thing sometimes and get yelled at for it!
Grace is one of the largest research facilities of its kind, so it was really neat to be able to go into the labs and see how they do experiments. They are responsible for developing Super plasticizer, which retards the setting of the concrete so you can prolong the placement. That was a huge discovery at the time!! Now they are working on finding new ways to make concrete greener and lighter and so many other things. This research is beneficial to the buyers of the concrete, the producers, and the general population because they are trying to reduce the cost all while reducing the amount of Carbon Dioxide that is released during the process of making klinker, a material in cement, and using recycled materials, such as fly ash. Fly ash actually is a byproduct of coal burning and adds a great deal of strength to the mix! So we had the opportunity to see where they do mixing and testing and analysis of why concrete has failed. Professor Lee actually worked at Grace for many years before coming to Wentworth and has based our lab off of theirs. It was a really neat experience and I had the opportunity to meet some really great people that will be able to help me with creating a really great concrete canoe!