The Building Research Establishment (BRE) has recently revised Special Digest 1 “Concrete in aggressive ground”. This new edition (SD1. Find the most up-to-date version of BRE – SD1 at Engineering Provides guidance on the specification for concrete for installation in natural ground and in brownfield locations. The procedures given for the ground.
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It has long been known in the UK that concretes made with Portland cements are vulnerable to attack by sulfates in the ground. Key outcomes in respect of the mechanism of TSA and concrete specification have been:. Free to use BIM project management tool provides step-by-step help to define, manage and validate responsibility for information development and delivery at each stage of the asset life cycle in level 2 BIM projects.
Accordingly, in a new version bbre Digest was issued which drew attention to the risk of TSA in concretes containing internal calcium carbonate and promised further guidance based on on-going research.
SD 1 Concrete in aggressive ground. 3rd edition, BRE – Publication Index | NBS
Again there may be more recent versions of the document. No field data would appear to have been available for correlation with sulfate classes based on sulfate levels in groundwater. As in the previous cases, the concrete contained carbonate-bearing aggregates. 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 is unfortunate that, through these changes, they gained an apparent precision that has imparted greater confidence in the derived classification than is warranted.
In the majority of cases, the sulfate class limits based on soil extract tests were both lower than sulfate class based on sulfate in groundwater and were also low when compared to the actual occurrence of TSA. The consequence of this adjustment will be to make the ground classification based on soil tests more conservative, eg some soils that were previously classified as DS-2 would now be considered as being DS Gives procedures for specification of concrete and applies to both buildings and civil engineering construction.
In the four years sincemuch of the research recommended by the TEG Report has been completed. The Trust uses the profits made by the BRE companies to fund research and education that advances knowledge of the built environment. A review of the historical background to sulfate assessment has thrown light on how the current discrepancy came about.
Changes to sulfate classification The current and intended new limits for sulfate classes based on 2: Assessing the aggressive chemical environment. Design guides for common applications incorporating March amendment No longer current but cited in Building Regulations guidance. 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.
The Red document status indicator indicates that the document is an old version The document has likely been withdrawn by the publisher, also the meta data presented here may be out of date as it is no longer being maintained by the editorial teams at NBS.
This was published in as Special Digest 1: Home Background to revision Key changes in SD1: Design guides for common applications. It also gave recommendations for further research on occurrence of TSA and mitigating measures.
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. Subsequently, inseveral cases of TSA were identified in the foundations to motorway bridges in Gloucestershire.
It was apparent that the Digest needed to be revised to counter the risk of TSA occurrence and, in particular, to take into account the contribution made by carbonates. BRE is a building science centre that generates bte knowledge through research. Key outcomes in respect of the mechanism of TSA and concrete specification have been: Sc1 all three cases the concrete contained carbonate-bearing limestone aggregates.
Development of guidance on classification of sulfate-bearing ground for concrete. Design guides for specific precast products. The Amber document status indicator indicates that some caution is needed when using this document – it is either: SD 1 Concrete in aggressive ground. These ball-park limits were converted in in BRE Digest to 2: BRE helps its government and private sector clients meet the significant environmental, social and economic challenges they face in delivering ds1, buildings and communities.
The high profile of these cases ensured a co-ordinated national review, culminating in with a report from a Thaumasite Expert Group TEG set up by Government.
BRE – Special Digest 1
In the early s, the thaumasite form of sulfate attack TSA became recognised as a separate mechanism affecting concrete in the UK. This document Newer versions Older versions. Assessing the aggressive chemical environment incorporating March amendment No longer current but cited in Building Regulations guidance. The distinguishing features of this are that it. The current and intended new limits for sulfate classes based on 2: Home Background to revision Key changes in SD1: The procedures given for the ground assessment and concrete specification cover the fairly common occurrences of sulfates, sulfides and acids, and the more rarely occurring aggressive carbon dioxide found in some ground and surface waters, which affects concrete foundations and sub-structures.
BS 1377 Part 3 Chemical Tests
Design guides for specific precast products incorporating March amendment No longer current but cited in Building Regulations guidance. This is used to create products, tools and standards that drive positive change across the built environment.
The new limits bring sulfate classification based on 2: Want access to British Standards? Document Status Indicators The Green document status indicator indicates that the document is: They were further changed in BRE Digest 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 Specifying concrete and additional protective measures incorporating March amendment No longer current but cited in Building Regulations guidance.