Ultrasonic Device Gauges Concrete Set Time, Optimal Mix Placement Rate

Until now the so-called knead bag test has been used to determine concrete hardening or solidification time, tE. It entails filling a plastic bag with a small amount of mix, testing at different time intervals to measure when the concrete can no longer be pressed by thumb. European practitioners find the method subjective and uncertain, which is why the time determined in accordance with the German DIN 18218 standard must be extended by 25 percent.

BEUS determines the exact hardening or solidification time, noted as tE. The device is contained in a sturdy transport box, equal to construction site or precast plant use. Riese Electronic engineers cite among the BEUS advantages: certainty in the evaluation of the pressure exerted by fresh concrete; measurement of supplied concrete under actual conditions; portability, with power supply unit or battery charging; and, tE measurement in real-time, without add-on time typical of knead bag test method.

BEUS is an ultrasonic device that accurately measures the hardening or solidification time, and takes the guesswork out of the process. It operates on the principle of an ultrasonic sensor sending a measurement signal that bounces off a specimen cube, with the reflected signal varying depending on the concrete hydration.

Compared to the knead bag test, the method yields results that are user independent and reproducible; uncertainties that previously made setting moment determination difficult are eliminated.

The time determined with BEUS does not need to be increased by a certainty factor, thereby enabling contractors to remove formwork earlier and transfer to the next project. In addition, taking the permissible
formwork pressure into account, users can pinpoint maximum mix placement speed.

In BEUS development, Germany’s Riese Electronic GmbH attached great importance to ensuring the device suits construction sites and precast plant operations.

Accordingly, it is embedded in a sturdy transport box and weighs only 25 lb. (12kg). BEUS can be connected to an external AC power grid or powered by batteries, and deployed on all types of cementitious, aggregate and admixture combinations. To determine the hardening time, a 15-cm cube is prepared with the candidate mixture. Quality control technicians or plant staff then press two buttons and the measurement is made automatically in real time.

With a 100-member team, Riese Electronic has established itself as a system partner for the development, production and testing of customized modules since 1958. Its devices and equipment are used
in industries from mechanical and apparatus engineering to switchgear construction and automation technology.

Riese Electronic will demonstrate the BEUS device at 2014 World of Concrete, Booth N2007. — Riese Electronic GmbH, 49 (0) 7451 55010; [email protected]; www.beus-controls.de