REVIEW OF U of IL, CHICAGO TESTING

MECHANICAL PROPERTIES AND DURABILITY OF HIGH PERFORMANCE PROTECRETE^® Concrete:

A summary of the 180-day progress report by the University of Illinois
at Chicago

February, 1999

INTRODUCTION

The University of Illinois at Chicago was looking for ways to improve the strength, durability and reliability of concrete. The manufacturer of PROTECRETE was looking for an independent source of impeccable reputation to confirm the field tests, which had shown that PROTECRETE Mix Water ConditionerTM improves the strength, durability and reliability of concrete. Which brings us to this study...

The U of I is now conducting an extensive study to evaluate the mechanical properties and long-term corrosion-resisting characteristics of selectable strength high performance concrete (HPC) using PROTECRETE Mix Water ConditionerTM. Over 40 mix designs were evaluated before the final selection was narrowed to just three high quality mixes (with one of the three being treated with PROTECRETE DensifierTM for a fourth type of concrete), and over 850 specimens have been cast. The preliminary study will run for one year, and subsequent studies will run for another estimated two to three years.

OBJECTIVES

The U of I recognizes that HPC is widely used in the civil infrastructure as a construction and maintenance material, but many aspects of HPC require further studies in order to understand the effects of various environments and loads. Corrosion is a serious problem for reinforced concrete, so finding a way to eliminate corrosion is key. The goal is to create concrete with adequate compressive strength as well as very low porosity and extremely low permeability. This is possible by using low water-cement ratios, superplasticizers, Mix Water ConditionerTM, DensifierTM and appropriate aggregates, cements, and mineral admixtures.

Cost is also a factor, however. HPC made using finely divided admixtures is not always reliable and can be complex to use. The U of I reports that Mix Water ConditionerTM and DensifierTM enhance the durability of concrete at a fraction of the cost of other pozzolanic materials.

Another objective is to evaluate permeability, which is among the most relevant characteristics of concrete affecting its durability. Concretes with equal compressive strength may have different permeabilities, thus providing different levels of resistance to corrosion.

Mix Water ConditionerTM is being studied because it yields higher quality concrete at a fraction of the cost, quicker and easier placement which reduces finishing time, less shrinkage and cracking, stronger bond of concrete to steel and increased compressive strength. DensifierTM requires only a one-time permanent application that makes concrete virtually impermeable, while significantly densifying, improving thermal resistance, increasing strength and lowering creep deformation potential.

RESULTS

The following conclusions have been drawn at the end of 180 days:

1. The addition of Mix Water ConditionerTM increased the slump through increased lubricity, greatly enhancing the concrete's workability. It also yielded a better surface finish and improved aesthetic appearance.

2. There was a significant increase in strengths and modulus of elasticity for specimens prepared with Mix Water ConditionerTM.

3. The splitting tensile strength at 7 and 14 days was 6 percent lower than the control for the Mix Water ConditionerTM specimens, which were treated with DensifierTM; however, this strength increased by 6 percent at 28 and 90 days, and subsequently increased at 180 days.

4. The flexural strengths for the control specimens were the lowest among all four different types of concrete.

5. The flexural strengths for the Mix Water ConditionerTM specimens in both normal and severe environments showed a continuous increase up to 180 days.

6. The percentage of air voids in the Mix Water ConditionerTM specimens is the lowest, by about 50 percent compared to the control. Mix Water ConditionerTM provides greater density and less permeability.

7. The use of DensifierTM protects the surface from abrasion, scaling, and deterioration and prevents the penetration of aggressive materials. DensifierTM also provides a better surface appearance.

THE MIXES

After careful evaluation, the 40 different mix designs initially tested were narrowed to the following three:

U.S. Customary

Metric

ENVIRONMENTAL CONDITIONS

The specimens were placed in three environments prior to testing:

1. NORMAL: Placed in moisture room with 100% saturation and a constant temperature of 73°F (23°C) within 24 hours from casting until testing.

2. SEVERE: Placed in normal environment (above) within 24 hours from casting for 7 days. Then placed in tank with 15% by weight sodium chloride solution until testing. Specimens are fully immersed in the 15% saline solution for 31/2 days. Then the water is removed leaving the specimens to dry for another 31/2 days. This weekly wetting and drying process will be continuously performed for one year.

3. LAB: Placed in room temperature and moisture until testing.

MECHANICAL PROPERTIES

US CUSTOMARY

PERMEABILITY

The Mix Water ConditionerTM mix is five times less permeable than the control mix at the preliminary stage.

CHLORIDE CONTENT

Overall, the specimens with Mix Water ConditionerTM showed the lowest penetration.

A copy of the full 53-page report may be obtained by contacting your authorized PROTECRETE distributor:

Concrete & Tile Technologies, Inc.
6501 Geil Lane
Louisville, Kentucky 40219
800/754-2914 or 502/964-5557
FAX 502/964-9930
E-mail: info@concrete-tile.com
Web: http://www.concrete-tile.com

ACKNOWLEDGEMENTS

The ongoing study at the University of Illinois at Chicago is being performed by Dr. Mohsen A. Issa, Dr. Mahmoud A. Issa, Dr. Mohamad Faraj, and Dr. Krishna Reddy of the Department of Civil and Mateirals Engineering. Applied Concrete Technology, Inc., the manufacturer of PROTECRETE, would like to gratefully acknowledge their thorough and outstanding effort. Thanks are also due to graduate students Alfred A. Yousif, Mohammad S. Islam, Mark Bendok, and Cyro Luiz Ribeiro do Valle.