Background to the revision One of the key drivers for revision of BRE Digests dealing with concrete in aggressive ground since the s has been a growing recognition of the occurrence the thaumasite form of sulfate attack TSA in UK buildings and structures. It has long been known in the UK that concretes made with Portland cements are vulnerable to attack by sulfates in the ground. Guidance on designing concretes to resist conventional sulfate attack was developed in a series of BRE Digests, the most recent of which was Digest Sulfate and acid resistance of concrete in the ground, the first edition of which was published in In the early s, the thaumasite form of sulfate attack TSA became recognised as a separate mechanism affecting concrete in the UK. In all three cases the concrete contained carbonate-bearing limestone aggregates. It was concluded that the concrete had suffered attack despite it satisfying the recommendations of the then-current version of Digest in respect of Sulfates Class 3 ground conditions.
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This new edition SD1: , funded by The Concrete Centre, was published as a single volume in June, following the completion of a four year research programme on combating the thaumasite form of sulphate attack TSA. There are two key changes to the procedure for assessing the ground; 1. This will result in some sites being rated as more aggressive to concrete than hitherto.
High magnesium levels are no longer taken into account for natural ground. There are five key changes to the procedure for the specification of concrete; 1.
A new classification for cements and blended cements has been introduced to harmonise with European standards. The recommended concrete quality now caters for the inherent possibility of exposure to an external source of the carbonate required for TSA.
The number of additional protective measures to be applied at higher sulphate levels has been reduced, in general by two. BRE has told FPS that the take up of its revised SD1 would likely be slow as it has received no funding to mount a promotional campaign. It is relevant to note that currently some of the on-line information services are still offering just the SD version, some 6 months after publication of the latest edition.
Also, even if professionals do know of the existence of SD, they may not feel obliged to use it at the moment as the current edition of BS Concrete refers to SD BS will unlikely to be updated before the latter part of It is often not clear which version of SD1 has been used to classify the ground and the concrete.
Currently it is often not clear in these which version of SD1 has been used to classify the ground and the concrete. It is the exception when clear reference is made to say SD1: FPS requests that in future all site investigation reports and Particular Specifications make clear reference to SD1: Our Clients can then be confident that piling concrete is provided in accordance with the latest requirements by eliminating the potential for misunderstanding to enter into the specification process.
Grout is a different material to concrete and SD is only applicable for concrete. In addition, FPS also requests that where the foundation solution may comprise minipiles, ground anchors, soil nails, grouting, base or shaft grouted piles, permanent sleeves to piles, or cross-hole sonic logging of piles, i.
This is due to the fact that grout is a different material to concrete and SD1: is only applicable for concrete.
BS 1377 Part 3 Chemical Tests
SD 1 Concrete in aggressive ground. 3rd edition
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