Durable anchor systems

Within foundation engineering, anchors are frequently used to stabilize retaining wall structures, basement/tunnel floors or as micro-piles. The systems are normally installed using a vibration-free drilling technique so that application in the vicinity of existing infrastructure is possible. When used as active anchoring (prestressed) there are significant benefits to be gained due to a reduction in size and weight of structural components which reduces the use of primary raw materials. For permanent anchors with a service life of at least 100 years, durability in the form of corrosion protection is crucial. The application of appropriate corrosion protection is, in current practice, also still often a misunderstood principle.

Protection class according to standards approach 

Within the European implementation standards, a clear distinction is made between active systems (prestressed elements) and passive systems. For all systems, it is basically recommended, in a permanent application, to work with a double corrosion protection. A double corrosion protection involves a combination of a (conditionally applied) cement grout filling and one or more plastic casings.

Applying corrosion protection, by means of charging a theoretical "rusting off" is not acceptable according to EN-1537 (ground anchors) for active systems. This is because no reliable method exists to determine the risk regarding corrosion with sufficient accuracy and to predict the corrosion rate in the subsurface.

In the Netherlands, the standard NEN 6766:2023 has recently become available, which provides direction for calculating theoretical rusting off of steel elements in the subsurface). Taking theoretical rusting into account is applicable in passive anchoring systems according to EN-14199 (micropiles) and EN14490 (soil nails). This application often involves a lower risk situation and often involves redundancy elements.

The application of galvanized coatings, whether in combination with epoxy coatings or not, is not considered full-fledged corrosion protection. This is because they are in fact sacrificial systems, often with a different creep behavior than the anchor elements and there is a high risk of damage during in-situ installation. The service life is variable and highly dependent on the aggressiveness of the soil conditions. Thereby, local mounting damages give an increased
risk of corrosion.

Model and finish of the anchor head

From practical experience, long-term damage, in most cases, is due to the application of an incorrect permanent anchor head/anchor post head or its finish. Anchor heads are frequently assembled to local specifications where crucial components and connection details are often overlooked. ANP-Systems has complete models available for permanent situations. These are unambiguous and integrated into the construction approval documents available to ANP-Systems.

Experienced with reliable availability

ANP-Systems has extensive experience in applying corrosion protection to anchoring systems. As the owner of numerous construction approvals, in several European countries, this ensures the highest level of safety and reliability for the anchor systems produced by ANP-Systems.

ANP-Systems' involvement in major infrastructure projects, such as the rehabilitation of the Prinses Margriettunnel, Sluis Terneuzen, Europaterminal Antwerp and the A9 Badhoevedorp-Holendrecht is evident. ANP-Systems can supply anchoring systems in the Benelux directly from its production facilities in Austria and Germany, which have ample stock positions. Reliable availability is thus guaranteed.