Modern technology and automation have finally entered the concrete testing laboratory. Several technical committees have updated traditional standards to accommodate this new technology. And many of these same experts have drafted, validated, and approved new standards that have evolved from the use of new laboratory equipment.
The use of microprocessors, computer-controlled systems, robotics, and optics has helped increase testing precision and laboratory efficiency. Automation can provide greater reproducibility and less variability. Other benefits include improved lab workflow, reduced training, and most important to producers, faster turnaround.
For the concrete industry, automated paste and mortar mixers, time-of-setting machines, fineness measuring systems, preprogrammed vibration tables, and tamping machines to fabricate strength specimens are already on the market. Standards agencies have widely accepted some of these machines, while others are still in various stages of considering them.
ASTM subcommittees for fineness (C01.25), workability (C01.22), and chemical admixtures (C09.23) are considering changes to allow automation to enter their areas of testing. A new standard also is being developed for calorimetric testing of cement and cement/ admixture combinations.
Some of the technologies now standardized for the industry include:
- Machines to automatically compact 2-inch cube specimens;
- Automatic determination of initial and final set of cement pastes;
- Microprocessor-controlled laboratory mixers;
- Automated measurement of the fineness of powdered materials;
- Devices that measure and monitor hydration reaction and heat generation of cementitious mixes (calorimetry);
- Wireless technology for determining the initial and final set of concrete mixtures;
- Air-void analyzer for fresh concrete;
- Image analysis to analyze air void systems in hardened concrete; and
- Fully automatic aggregate gradation units.
Others in the industry also are monitoring technology and how it can be applied in laboratories. The Federal Highway Administration's Mobile Concrete Laboratory led the way in presenting new technologies to local and state agencies, as well as to independent labs that serve the construction industry. The fully equipped laboratory can perform physical tests on concrete and also use nondestructive techniques to evaluate in-place concrete.
In December 2005, the American Association of State Highway and Transportation Official developed a steering group for technology deployment. This so-called Technology Implementation Group is charged with evaluating innovative technologies and considering how best to deliver these technologies to both state and local transportation agencies.
The future likely will bring more automation to the physical testing of cement and concrete, which in turn should allow us to improve the quality of laboratory testing. Progressive producers who stay abreast of these innovations will be able to streamline their lab operations, while making better, more consistent concrete and products.
— Michael Morrison is principal materials technologist and laboratory manager for CTLGroup, a consulting, engineering, and materials testing firm in Skokie, Ill. He has been with the company for 24 years and supervised the cement and mortar laboratory for 11 years. Morrison has been active in developing standard test methods as a member of ASTM Committees C01 -Cement, Lime, Gypsum; and C09 -Concrete and Aggregates. For more, visitwww.ctlgroup.com.