What is 20% Time? What is pervious concrete? Why do you want to create it?

Twenty Time is a project idea that has been used by huge companies like Google as well as schools like Saratoga High. The basic idea is that students (or employees) are given 20% of their time in school (or at work) to do something they are passionate about. In our Biology class, everyone is doing a 20% Time project related to the sciences because the project needs to be relevant to what we are learning in some way.

In California, we have a huge drought problem. Even when it rains extremely hard, the water just floods and flows into the ocean rather than entering underground water deposits, known as "aquifers". The main reason for this runoff is that concrete covers virtually every square inch of ground in Saratoga. Pervious concrete, which was originally used due to it's lower cost, allows water to pass through it. Water is able to pass from the surface of the concrete to the soil beneath due to the absence of fine aggregates (small particles) in the concrete. The only problem is that most surfaces are paved with regular concrete rather than porous. And removing this regular concrete to put down porous concrete is a big hassle.

To get past this problem of having to remove and repave, my 20% Time Project asks the question "Can you convert regular concrete into pervious concrete by using chemicals? Can it be done while retaining the concrete's compressive strength? Can it be done using environmentally friendly chemicals?".

To answer this question, I will purchase regular concrete slabs and test their porosity. I will first place each concrete slab in a tub to spray it with a chemical and let it sit for 24 hours. I will then place the slab above a bucket and spray water onto the concrete slab. The amount of water that passes through and enters the bucket in 30 minutes after pouring will be measured. I will rate the concrete's porosity on a scale from 0 to 100 based on what percentage of water that I poured passed through the slab. My control will be conducting the porosity test on an untreated slab of concrete. I will execute the test on multiple concrete slabs that are each treated with a single chemical. I doubt I will find a "perfect" chemical by the end of this project that causes complete permeability, does not remove structural strength, and is environmentally safe.

By Saturday, March 19th, I aim to have completed my research on what 14 chemicals I will test. By the Saturday after that (3/26), I aim to have 15 18" x 18" concrete slabs as well as the chemicals that I will either find at home, order online, or get from a local science store. Each Friday evening starting April 1st, I will spray 3 chemicals onto 3 concrete slabs and let it sit for 24 hours. Then on Saturday evening, I will pour water on all three at the same time and watch them for 30 minutes while taking notes. At the end, I will measure any water that has entered the bucket. The following Monday I will write a blog post in class summarizing my observations. Because I will be out of town for 1 week in April, I should be done testing all 15 concrete slabs on May 6th.

If any of these tests give considerable results (porosity of more than 30 on my scale), I will check whether the chemical is environmentally friendly. If it isn't, I will find similar chemicals that are. This will all be done while another batch of 15 slabs is on the way. After determining 6 eco-friendly chemicals to test, I will spray all 6 slabs on Friday (maybe 5/27) and test them the next day. If any of these have the same effect as the prior ones that worked, I will name it the winner and consider my 20 Time project very, very, very successful.

However, I doubt I will ever get to this point and find an environmentally friendly chemical that converts regular concrete into porous concrete. But if I do, I may continue into summer break and find a chemical that not only increases porosity and is eco-friendly, but also preserves the structural integrity of the concrete.