Laser system for testing early shrinkage of concrete elements in conjunction with the determination of the setting time / Laserowy system do badania skurczu wczesnego elementów betonowych w powiązaniu z oznaczaniem czasu wiązania

The paper presents a method for testing the shrinkage of concrete beams with dimensions of 10×10×50 cm. Measurements followed from setting into the form until 24 hours after setting. It was used modified TLS system, which originally was for the determination of changes in the length of thin-mortar. It was also measured changes of speed propagation of sound waves by Vikasonic, which allows you to specify the setting time of binders. It could be a base for determining the scratch resistance of the concrete in the first 24 hours after casting