Pervious Concrete Improvements

ET-494 Senior Design Project

Instructor: Cris Koutsougeras

Advisor: Mohamed Zeidan

By: Alex Rodney

May 5, 2015

Table of Contents:

Page 1 – Title Page

Page 2 – Table of Contents

Page 3 – Abstract / Introduction

Page 4 - Testing

Page 5-7 – End Result

Page 8 – Completed Work

Page 9 – Timeline / Deliverables

Abstract:

This project will consist of mixing and testing different mixtures of concrete to develop a

more cost efficient pervious concrete with equal or possibly higher compressive strength than the

existing mixtures that are typically used today. We will be using different kinds of aggregates

and admixtures to determine cost, time of mixing, and strengths of different mixtures. I have

partnered with Ascension Ready Mix Concrete out of Baton Rouge, Louisiana to help assist me

with supplies and testing for this project. The performance analysis of which will be done using a

slump test, compression test, and a permeability test. The cost of each different mixture will also

be presented on a spreadsheet as price per cubic yard comparing the raw materials cost to that of

different alternatives.

Introduction:

Pervious concrete is a special type of porous concrete that allows water from

precipitation and other water sources to flow directly through the material. This reduces runoff

and allows for the possibility for groundwater recharge. The main objective of this senior design

project is to create a pervious concrete with high compressive strength using recycled concrete.

However, I will also focus on just the compressive strength of pervious concrete and try to

improve the strength by simply using different aggregates, differing amounts of sand, and

changing other variables to find the most suitable materials. An integral part of this project will

be experimenting with some chemicals (admixtures) that Ascension Ready Mix has requested

that I try. Concrete is made up of four different main parts: aggregates, air, water, and binding

materials. By changing the amounts of these four components and adding the admixtures that

will be provided, I will determine what the best mixture is by doing numerous experiments and

testing each sample.

Testing:

The tests that I will be performing on each sample will be a slump test, compression test,

and a permeability test. Some of these test will be performed here at Southeastern, however, as I

mentioned earlier that Ascension Ready Mix will be assisting me with my testing so that I can

have the most accurate results as possible. I have the mix designs that Ascension Ready Mix uses

for their pervious concrete and will be altering those to suit what I will be doing.

Compression Test Machine

End Result:

The end result of this senior design project is to have come up with an alternate way to

mix and pour pervious concrete with the assistance of recycled materials while giving the

concrete a higher compressive strength. This will hopefully lower the cost of pervious concrete

and give it a wider range of uses with a higher compressive strength. The idea of attempting to

improve the compression strength was based on the fact that the admixtures would significantly

help the strength of the bonding between the aggregates. It turns out that the ad mixtures, alone,

were not enough to improve the compressive strength. Therefore, the use of RCA to improve

compressive strength by using just ad mixtures was not successful.

Compression Test

Compression Test      Natural Aggregate Recycled Concrete AggregateTest 1 2,450.8 psi 1,392.5 psiTest 2 2,575.1 psi 1,106.8 psi     Average: 2,512.95 psi 1,249.65 psi

The permeability test had similar results to the compression tests. Although the slab used

to test the RCA was highly permeable, it did not quite stand up to the permeability of the slab

made with natural aggregate. The RCA slab allowed water to flow through it at a rate of 10.6

gallons per minute, while the slab made of natural aggregate flowed at an impressive rate of 16.9

gallons per minute. Therefore, once again, the natural aggregate came out on top. However, there

are no set specifications as to what the rate of flow should be in a pervious slab, therefore, many

people in the concrete industry would say both are acceptable.

Permeability Test:

Permeability Test      Natural Aggregate Recycled Concrete AggregateTrial 1 19.33 seconds 28.5 secondsTrial 2 16.5 seconds 28.6 secondsTrial 3 17.77 seconds 28 seconds     Average: 17.77 seconds 28.36 seconds

Compression Test      Natural Aggregate Recycled Concrete AggregateTest 1 2,450.8 psi 1,392.5 psiTest 2 2,575.1 psi 1,106.8 psi     Average: 2,512.95 psi 1,249.65 psi

Cost Analysis

The cost factor is another promising end result. However, when the price in analyzed on a

truck by truck basis, it does not look like it is saving that much money. When you look into how

much a company would save who is pouring a 3000 cubic foot parking lot for a mall or a movie

theater, the concrete company that is providing the pervious concrete can charge more for the

concrete because it is a specialized concrete while at the same time save money because the cost

of the recycled concrete aggregate is priced much lower.

Cost Analysis

Cost Analysis    Natural Aggregate    Materials Amount CostNatural aggregate (pea gravel) 2800 lbs $26.60Cement 625 lbs $37.50Sand 220 lbs $0.50Water 125 lbs $2.50       Total: $67.10     Recycled Concrete Aggregate    Materials Amount CostRCA (pea gravel) 2800 lbs $18.20Cement 625 lbs $37.50Sand 220 lbs $0.50Water 125 lbs $2.50Darex AEA 1.5 gallons $1.50VMAR VSC 500 3.5 gallons $3.50       Total: $63.70

Conclusion

This semester I have thoroughly researched pervious concrete and have learned how to

create mix designs with the correct air void content. I have successfully mixed and tested each

kind of pervious concrete set out to create. The compression test and permeability test have been

successfully completed. The final result was not as planned, however, there were many

improvements made and strides were taken in making improvements in the pervious concrete

industry as well as the recycled concrete industry. The permeability test was the most interesting,

because this test really shows if the product is doing what it was meant to do. Luckily, both slabs

were permeable and seemed to have passed the tests. The cost analysis went as planned while a

less expensive way to create pervious concrete is now in the infancy stages of production.

Timeline/Deliverables:

September 2014: Research pervious concrete mix designs - Completed

October 2014: Secure testing lab to test cylinders along with materials needed - Completed

October 2014: Gather materials / Adjust mix design accordingly - Completed

November 2014: Design mixture and prepare trial mix - Completed

December 2014: Mix and pour 1st set testing cylinders - Complete

January 2015: Conduct tests at Ascension Ready Mix lab - Completed

February 2015: Readjust mix design accordingly – Completed

March 2015: Pour #2 and #3 to ensure effective mix design - Completed

March – April 2015: Perform cost analysis and prepare final report - Completed