Concrete strength and durability of prototype tetrapods and dolosse: results of field and laboratory tests

A number of destructive and nondestructive tests have been carried out on 1 5 t slender-type concrete armour blocks from three Italian breakwaters, in order to investigate the material properties after a long-term exposure at sea. Measured surface hardness from rebound hammer tests in situ appears to be correlated to the results of laboratory breakage tests on core samples. The core position on the unit shows to have an influence on the concrete s trength, with weaker points generally occurring at legs' intersections. Fur ther laboratory results from porosity, carbonatation and ultrasonic pulse v elocity tests and finally from destructive split-out tests on core samples generally show the good quality of aged pozolanic marine concretes, as typi cally used in Italian coastal structures, Despite the data scatter, also du e to the necessarily limited number of cores, the average value of the tens ile strength achieves 4 MPa (with a variation coefficient around 20%) and i ncreases with concrete density (mean value of 24.5 kN with variation coeffi cient of 2%). These test results from prototype armour blocks can be useful for the application of advanced probabilistic methods for the design of ru bble mound breakwaters. (C) 2000 Elsevier Science B.V. All rights reserved.