Civil engineers have a very particular set of skills. Skills they have acquired over a very long time in engineering school. Skills that make them a nightmare to city planners and architects. Here are 15 things only civil engineers know.

## 1. How many different types of cement there are

Portland cement, high alumina cement, white cement, sulfate-resisting cement. The list goes on. As civil engineers, we have a pretty good idea of what goes into different types of cement, how they work, and what we could add to make them perform better.

## 2. Technical names of the curves on roads

We civil engineers know that there are four types of road curves: simple, compound, reverse, and deviation. We know how to use the right equations to design a road with each one of these curves. Not only that, but we know how to calculate what slope the road needs to be in the curve to keep cars from sliding off the road.

## 3. Concrete is never dry

As a civil engineer, I probably love concrete a little too much. It is gray and mushy, then it soon turns into strong rock. If that's not what love looks like, then I don't know what is. In all seriousness though, we know how dry concrete is at certain points in its curing cycle. We also understand that concrete technically continues to dry and strengthen over its entire lifespan.

## 4. Particle sizes for different types of soil

We know the minute size differences between silt (.05 to .002 mm), sand (2mm to .05mm), and clay (<.002 mm). Some of us may not even have to calculate the particle size, we can just look at the soil and know. Along with these tidbits of knowledge, we can determine which combinations of soil make for better foundations and what needs to be done to make the ground more suitable for construction.

## 5. Why there are gaps in the road on bridges and in the track on railways

Civil engineers know that there need to be expansion joints in roadways and railways to allow the metal to expand and contract with temperature. If these aren't built into the infrastructure, then the roads and railways can fail or bow.

## 6. There is a very big difference between concrete, cement, and mortar

I don't know how many times I've heard someone refer to cement as concrete – the inside of me just cringes. We know that concrete is cement with a fine and coarse aggregate and that mortar has a higher amount of cement with added fine aggregate like sand. Cement alone is simply the binding material. Civil engineers probably also know that those trucks that carry concrete aren't called cement mixers, which is wrong anyway, they are called transit mixers.

## 7. How fast is too fast for sewage in a pipe

One of the less glamorous parts of civil engineering is knowing how to handle wastewater. We know that sewage has to flow over 3 feet per second in horizontal pipes. We also know that if sewage flows too fast, like over 12-18 feet per second, then dangerous gasses can be produced and everyone has a bad day. There's a lot more science around handling your waste than you may think.

## 8. The differences between a total station and a theodolite

Civil engineers know their way around surveying equipment. We know that a total station uses GPS, lasers, and leveling sensors to measure precise elevations and distances to develop point clouds. Theodolites or auto levels simply can detect the change in elevation between two points, without distance measurements.

## 9. Every kind of truss and what makes them different

There are hundreds of different kinds of trusses, each with its own specific structural loading capabilities. Civil engineers know when to use a certain truss and how to calculate their strength.

## 10. Most structure loading calculations are just estimations

Every civil engineer remembers their first structures class. We also remember that calculating loading values is so complicated that you can get different answers with different methods. We also probably realize that no loading calculation is 100 percent right, so we slap on some factor of safety to cover ourselves.

## 11. Why the leaning Tower of Pisa hasn't fallen over yet

Civil engineers probably understand that the Leaning Tower of Pisa was kept from collapsing thanks to some ingenuitive geotechnical engineering. Engineers kept the tower from collapsing by placing weights on the north end of the foundation to right the structure. Now it is believed that the structure will survive for hundreds of more years.

## 12. Where pipes lead to and where our water comes from

As a civil engineer, you probably have caught yourself once or twice figuring out where exactly the water from your house flows to. Civil engineers are trained to design infrastructure that never gets seen, so we have a keen sense of where all of our utilities are routed.

## 13. Not all rebar is made alike

Rebar isn't just a steel rod that gets put into concrete – anything but. Civil engineers understand what the different external patterns on rebar are for and how each kind is used. There's European rebar, carbon steel rebar, epoxy-coated rebar, and the list goes on.

## 14. A cone of depression isn't something you wear

The cone of depression has always been one of my favorite things about civil engineering. A cone of depression is a depression in an aquifer's water table when water is drawn out of it through a well. It's also a great way to explain to your friends how you feel when you are doing your fluids homework.

## 15. How to test dirt for tons of weird values

Civil engineers understand that dirt is a crazy complex thing and all sorts of *weird *tests are needed to understand it. Tests like the standard penetration test, determining the Atterberg limits, or the oedometer test. If you see an odd little device in a civil engineer's office, it might be to test some small property in the dirt.

If you want to know more about any of these things, you should get a civil engineering degree... or you can just Google them. You should probably just Google them and avoid the debt. If you are too lazy to Google and you are interested in the degree, here's a post that might help you.