Real Case: Assessing Sulfate Resistance of Coastal Protection Precast Elements

Abstract

As part of a new harbor development, a new offshore breakwater will be constructed, for which the use of coastal protection plain precast concrete elements (AccropodesTM II) is required. The applicable exposure class is S1 (ACI 318). Over 4'000 elements have been produced. The owner required guarantees on the sulfate resistance of the elements before accepting them for usage in the project. For this, a revision of the documentation available was conducted, complemented by a thorough field investigation, measuring the coefficient of air-permeability kT (Swiss Standard SIA 262/1) of preselected elements (damaged during transportation) and elements representing the 28 weeks of production. The site NDTs confirmed a high quality of the majority of elements that were judged fit for the purpose. However, the NDTs confirmed the questionable quality of those cast during the initial period, requiring further evaluation before acceptance.The paper presents the results of: water aggressiveness, cement chemistry, strength quality control and air-permeability kT, and the criterion used to assess sulfate resistance of the elements.

The Quest for Absolute Concrete Durability Performance Criteria

“…As an example, air-permeability measurements can be conducted on-site according to the prescriptions of Swiss Standard SIA 261/1 [10] using the PermeaTORR instrument [11]. More details on this on-site monitoring method can be found in [12], illustrating its application to verify In this way, the concept of durability indicators [13,14] can go along with the concept of absolute durability performance testing in laboratory, based on correlation studies and materials science. The monitoring of the real concrete by some durability indicators can be very helpful both for owner and for contractor, in view of achieving a final structure with a certified durability performance.…”