Real-Time, In-Situ Measurement of Void Fraction and Specific Surface in Fresh Concrete

Water expansion during freeze-thaw cycles can cause deterioration in concrete, leading to scaling, cracking, and crumbling over a period of years. Resistance to this damage is achieved with a system of voids formed by adding surfactants to the fresh concrete to stabilize air bubbles naturally entrained during mixing. The volume fraction, size, and spacing of these voids are critical. It is important to verify these parameters in fresh concrete as it is delivered to the job-site, particularly for large public works projects where costly reductions in lifespan may otherwise not be apparent until years after the project is complete. Current pressure-based measurement methods are cumbersome, prone to error, and yield information only on total void fraction, giving no information about void size or spacing. The Creare Air Meter will provide an instant, in-situ measurement of both void fraction and size. This simple, robust, hand-held wand can be inserted into any fresh concrete sample and return an accurate result at the touch of a button. This technology will enable real-time monitoring at the job-site as the concrete is delivered, or even in the forms as it is poured.