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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In the four years sincemuch of the research recommended by the TEG Report has bfe completed. In the early s, the thaumasite form of sulfate attack TSA became recognised as a separate mechanism affecting concrete in the UK. Key outcomes in respect of the mechanism of TSA and concrete specification have been:. 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.
It also gave recommendations for further research on occurrence of TSA and mitigating measures. The distinguishing features of this are that it. In all three cases the concrete contained carbonate-bearing limestone aggregates.
In particular, it can come from bicarbonate dissolved in groundwater.
The new limits bring sulfate classification based on 2: SD 1 Concrete in aggressive ground. Again there may be more recent versions of the document.
A review of the historical background to sulfate assessment has thrown light on how the current discrepancy came about. These ball-park limits were converted in in BRE Digest to 2: No field data would appear to have been available sdd1 correlation with sulfate classes based on sulfate levels in groundwater.
It has long been known in the Sv1 that concretes made with Portland cements are vulnerable to attack by sulfates in the ground.
BRE – Special Digest 1
The current and intended new limits for sulfate classes ber on 2: Background to the revision One of the key drivers for revision of BRE Digests dealing hre 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.
Specifying concrete and additional protective measures incorporating March amendment No longer current but cited in Building Regulations guidance. This was published in as Special Digest 1: Design guides for specific precast products incorporating March amendment No longer current but cited in Building Regulations guidance. They were further changed in BRE Digest Want access to British Standards? Design guides for common applications.
Design guides for specific precast products. The change stems from findings of numerous research ground investigations carried out by BRE and others on BRE concrete trial sites and locations where TSA has occurred.
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. BRE helps its government and private sector clients meet the significant environmental, social and economic challenges they face in delivering homes, buildings and communities.
SD 1 Concrete in aggressive ground. 3rd edition, BRE – Publication Index | NBS
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 Key outcomes in respect of the mechanism of TSA and concrete specification have been: As in the previous cases, the concrete contained carbonate-bearing aggregates. Accordingly, in a new version of 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.
Provides guidance on the specification for concrete for installation in natural ground and in brownfield locations. Home Background to revision Key changes in SD1: The Amber document status indicator indicates that some caution is needed when using this document – it is either: Assessing the aggressive chemical environment incorporating March amendment No longer current but cited in Building Regulations guidance.
The Trust ed1 the profits made by the BRE companies to fund research and education that advances knowledge of the built environment. 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 procedures given for the ground vre 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.
This is used to create products, tools and s1 that drive positive change across the built environment.
BS 1377 Part 3 Chemical Tests
It was apparent ssd1 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. 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 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. Changes to sulfate classification The current and intended new limits for sulfate classes based on 2: Development of guidance on classification of sulfate-bearing ground for concrete. The Red document status indicator indicates that the document is an old version The document has likely s1d 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.
Document Status Indicators The Green document status indicator indicates that the document is: BRE is a building science centre that generates new knowledge through research. Design guides for common applications incorporating March amendment Ad1 longer current but cited in Building Regulations guidance.
This document Newer versions Older versions. Together with other findings, such as deficiencies in guidance for ground assessment, the new knowledge has prompted the current major revision of SD1. Subsequently, inseveral cases of TSA were identified in the foundations to motorway bridges in Gloucestershire.
Home Background to revision Key changes in SD1: Gives procedures for specification of concrete and applies to both buildings and civil engineering construction.