Colored Pervious Arrives in Washington State

In 2006, the City of Sultan, Wash. completed a 20-home residential demonstration project. Stratford Place included 800 yd³ (600 m³) of pervious concrete to pave
32,000 ft² (3000 m²), replacing traditional concrete for a road, connecting driveways, and associated sidewalks. Integral color was added to the sidewalk mix. Tinting the concrete not only improved the appearance of the walkways, it delineated then. Because curbs and gutters are not necessary for storm water control with pervious pavements, the color difference visually separates the road from the sidewalk, making the road safer for pedestrians.

This was only the second public road in Washington State to be built with pervious pavement. Besides the storm water benefits, using pervious pavement saved two lots for development, which would otherwise have been needed for use as catch basins and vaults. Doing away with the traditional storm water system and related items ultimately saved the developer money and was better for the environment. Rick Cisar, Sultan engineer, was so impressed with the Stratford Place results that he plans to use pervious pavement for a city street. He says pervious pavement resolves drainage problems, protects critical areas and stream corridors, and helps to protect adjacent properties from encroaching storm water. More.

Putting a Pretty Face on Pervious Concrete

In today’s environmentally conscious climate, the benefits of pervious concrete to sustainability have reinvigorated interest in these free-draining pavements. But, although it’s appealing for its technical benefits, pervious concrete hasn’t necessarily been attractive…until now. Renewed attention to pervious pavements has led some people to experiment with improvement of the surface aesthetics—and spawned a new type of concrete sometimes referred to as “architectural pervious concrete” (APC).

Most pervious concrete has a sort of popcorn look about it: Uniformly sized aggregate, falling within a narrow aggregate gradation, leading to a concrete with open void areas that promote fast drainage of large volumes of water. Some like the organic, rough-textured look of plain pervious concrete. But for those who want a different look, there are several options for enhancing the aesthetics. Treatments include color, stamping, jointing, and grinding. More.

PCA and the National Ready Mixed Concrete Association have teamed up with Land Development Today magazine to offer the seminar "Pervious Concrete—A Stormwater Solution." More.

Click here for more about white cement and decorative concrete.

IMCP Manual Helps Prevent Problems

Most problems that occur during or after concrete placement can be prevented or fixed if the construction team is (1) familiar with the materials involved, and (2) prepared to address changes in the environment that affect material performance.

The recently released FHWA publication, Integrated Materials and Construction Practices for Concrete Pavement: A State-of-the-Practice Manual (IMCP)contains an extensive “Troubleshooting and Prevention” section that lists potential problems during and after the concrete has been placed and provides a guide with actions to be considered or avoided. Even though the IMCP manual is a guide for concrete pavement construction, many sections—including “Troubleshooting and Prevention”—apply to other concrete work as well. Example:

Q: What is the effect of high concrete temperature (above 25°C or 77°F) on transporting, placing, and finishing concrete, and on hardened concrete properties?

A: When the temperature of freshly mixed concrete exceeds 77°F (25°C) there may be a number of effects on the fresh and hardened properties of concrete. One of the effects on fresh concrete properties is accelerated setting, which leads to a shorter time period for transporting the concrete to the job site, and a shorter window for placement, consolidation, and finishing of the material.

The effect on hardened concrete properties is a high early strength but low ultimate strength compared to mixtures placed with a lower temperature. In addition, if no precautions are taken, there is an increased potential for plastic shrinkage cracking during the finishing operations, and increased potential for cracking due to volume changes caused by drying shrinkage and thermal effects. More.

Click here for more cement and concrete FAQs.

Effect of Relative Humidity on Expansion and Microstructure of Heat-Cured Mortars (RD139)

This research report describes the effect of moisture exposure on expansion in heat-cured mortars due to delayed ettringite formation (DEF). Mortar bars were cured at 90ºC, and then stored for more than 4 years in moist air at 75%, 80%, 84%, 90%, 92%, 97%, and 100% relative humidity (RH). Periodic weight and length measurements were made along with chemical analyses. The results show that DEF-related expansion is influenced by the level of moisture exposure. The study suggests that a threshold level of moisture exposure for expansion to occur seems to be between 92% and 90% RH. Click here for free download (PDF format, 2321 KB).

ACI and ACBM Publish New Reports

Self-consolidating concrete (SCC) has been successfully used in many projects around the world and has made a major impact on concrete placement and construction practices. Two reports published by the American Concrete Institute (ACI) and the Advanced Cement-Based Materials Center (ACBM) summarize the state of knowledge and recent research on SCC, respectively.

ACI’s report contains information on fresh and hardened properties of SCC as well as a guide to proportioning SCC mixtures. The document also covers production, mixing, placing and finishing of SCC in detail. SCC specification guidelines and an introduction to test methods are provided. Click here for a summary of test methods published by ASTM. Order the ACI report.

The second report summarizes recent work on self-consolidating concrete by ACBM researchers. The research focused on the following three areas crucial to SCC: robustness, innovations in testing, and formwork pressure. Click here for free download of the report (PDF format, 2138 KB)

Both of these documents will be valuable to those new to use of SCC as well as concrete producers, users, specifiers and other technical personnel interested in controlling and optimizing performance of SCC.

PCA Cement and Concrete Technology Research

When questions are raised concerning cement and concrete, chances are that Portland Cement Association engineers can provide the answers. In addition to serving as a clearinghouse for technical information on cement and concrete from sources worldwide, PCA itself continues to sponsor research directed at extending the boundaries of technical knowledge in the field. Click here for some of the latest research reports related to cement and concrete technology.

Concrete Finishing Presentation

This PowerPoint ® presentation demonstrates the standard practices and procedures for planning, building, and finishing interior or exterior concrete flatwork (sidewalks, driveways, patios, floors) and steps. With expanded information pertaining to material selection and construction practices, this presentation supplies the user with a wealth of new information from the recent PCA publication Concrete Finisher’s Guide (EB122). For a limited time, you can save 30% on the printed publication.

Concrete Knowledge Center

The American Concrete Institute has established a new benefit to their members on the ACI website. The Concrete Knowledge Center is a valuable resource for users to quickly find practice-oriented information useful in the design, construction, and repair of concrete and concrete structures. For example, troubleshooting topics are presented in a question and answer format and provide an instantly accessible bibliography. ACI members are allowed to download full-text articles that discuss the topic as well as a regular reference list for papers, articles, or books. More.

ACI Field Testing Technician Certification Open Enrollment—May 11 and Sept. 21
PCA will hold two ACI Concrete Field Testing Technician Grade I Certification examinations in the coming year at its Skokie, Ill., headquarters. Our qualified and experienced instructors will administer the written and performance evaluations for certifying concrete testing technicians. Registration is now open for the May course.

Concrete Technology Forum: Focus on High Performance Concrete—May 22-24
The 2007 Concrete Technology Forum, will bring researchers and practitioners together to discuss the latest advances, technical knowledge, continuing research, tools and solutions for high performance concrete on May 22-24, in Dallas, Texas.

Undergraduate Faculty Enhancement Workshop—June 18-20
The Center for Advanced Cement-Based Materials (ACBM) and the Portland Cement Association jointly sponsor the Undergraduate Faculty Enhancement Workshop being held at the PCA headquarters in Skokie, Ill. The Faculty Workshop will address the issues of adding and expanding coverage of concrete materials properties in undergraduate and graduate courses and laboratories.

18th ACBM/NIST Computer Modeling Workshop, June 25-28, at National Institute of Standards and Technology, Gaithersburg, Md.

For a complete listing of industry conferences, click here.