Special Digest Third editionConcrete in aggressive groundBRE Construction Division BRE is committed to pro. Download Citation on ResearchGate | BRE report – Concrete in aggressive grounds: An introduction to BRE Special Digest 1 | The codes and standards for. The introduction of the edition of BRE Special DIgest 1 (SP1) provides the guidance on concrete in sulfate-bearing ground. The range of exposure.
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Design guides for common applications incorporating March amendment No longer current but cited in Building Regulations guidance. The acidity or alkalinity of water can be tested on site using pH test strips or a portable meter.
Field investigation of severe TSA on motorway bridge sub-structures, built with Portland cement concrete containing carbonate aggregate and buried in reworked pyritic clay, showed attack to a depth of up to 50 mm in about 30 years. Specification, performance, production and conformity 16 Part C Assessing the aggressive chemical environment C1 General This part describes the occurrence of chemicals in the ground that are potentially harmful to concrete and gives procedures that lead to assessment of the Aggressive Chemical Environment for Concrete ACEC Class of the ground.
If no desk study has been carried out, it should be assumed that pyrite may be present in the ground and the site testing procedures given in Sections C5. Aggressive carbon dioxide is usually only present to an appreciable extent in rather pure natural waters since in most cases, where the water contains dissolved salts, sufficient calcium carbonate is available to combine with the carbon dioxide as calcium bicarbonate.
Contact BRE for information about its services, or for technical advice: Free to use BIM project management tool provides digset 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.
Using phenolphthalein indicator is not appropriate as a proving test for surface carbonation of dense structural precast concrete: Concrete Society Technical Report No The distinguishing features of TSA are that it: It is therefore necessary to consider the distribution of sulfides as well as sulfates in ground which may affect buried concrete. Part D Some contracts may alternatively opt for full prescription of the concrete requirements and APM.
SD 1 Concrete in aggressive ground. 3rd edition, BRE – Publication Index | NBS
At times of year when groundwater levels are high, mobile groundwater conditions can be confirmed by either digging a trial pit or drilling a borehole to the relevant depth and leaving it temporarily open. This immediately reacts with water to form hydrogen sulfide H2Sa gas that cobcrete into the air space above the sewage. The Amber document status indicator indicates that some caution is needed when using this document – it is either: Ground chemistry implications for construction Edr: Code of practice grounc design and construction BS Compare the sulfate class for total potential sulfate with the sulfate classes determined in Section C5.
Generally these agents are found in troublesome concentrations only in land concrrete by contamination. This cracking, together with white crystalline accumulations, are the characteristic signs of the conventional form of sulfate attack.
It also gave recommendations for further research on the occurrence of TSA and mitigating measures. Bristol, Environment Agency, Treatment of fill and capping materials using either lime or cement or both. Definitions, requirements, quality control and evaluation of conformity.
Concrete in Aggressive Ground:3rd edition
The starting point for an investigation of chemical agents in the ground that may be aggressive to concrete is a good visual description of the ground profile to the full depth of concrete construction.
A common example is the occurrence of low-to-moderate concentrations of sulfate which may be harmful to concrete, but not to organisms. The change stems from several research investigations on ground by BRE and others. The ACEC Class of the ground can then be found from the row of Table C2 that correlates first with digeat Design Sulfate Class, second with the water conditions, and third with the characteristic value of pH.
Table F1 lists the categories of product covered and the six design guides that apply to particular exposure conditions. Photograph available from ballh bre.
BRE – Special Digest 1
Moreover, preventing the surface of the concrete from drying out during the first day of curing will ensure continued hydration and aggressife to maintain the protective surface zone. We provide research, consultancy, information and testing services to customers worldwide. Drains should be inspected and maintained to avoid leakage close to buried concrete. The overall design process is summarised in Section D3. The larger test laboratories currently follow in-house procedures using this latter approach rather than BS and BR Transport Research Laboratory Report Following the walk-over survey, an assessment should be made of the presence and distribution of conditions likely to be aggressive to concrete.
The initial stages for assessment of chemical aggressiveness Figure C6 are broadly similar to the procedure given in Steps 1 and 2 of Section C5. The site investigation should be carried out by suitably experienced persons.
For some uses of concrete, the definition of flowing groundwater is extended to cover water that is flowing in surface conduits or streams. Migration of sulfate ions from unsaturated ground into the concrete can take place by diffusion provided there is sufficient water to coat the particles of soil, but the rate will be slow and dependent on the sulfate concentration.
Coal mining areas 19 Box C2 How sulfides are converted to sulfates in disturbed ground Construction activities eg excavation and backfilling that substantially disturb the ground may allow pyrite in initially unweathered geological strata to have access to air, water and bacteria.
However, the basic ranking with respect to performance in sulfatebearing ground is mostly unchanged. Care should be taken to avoid water that has entered the pit directly from rainfall or surface run-off.
Care is needed during construction to avoid temporary or permanent situations that increase risks. If a better understanding is required, a comprehensive suite of soil and groundwater analyses can be vigest out to include determining calcium, magnesium, sodium and potassium ions. The concrete encountered in each case satisfied the recommendations of the then-current version of Digest But sulfides can be converted relatively rgound to sulfuric acid and sulfates if psecial to air and water by construction activities sometimes aided by bacterial action or high pH Box C2.
For reinforced concrete, the cover should be sufficiently thick to allow for estimated surface degradation during the intended working life. Cements and combinations Cements are pre-blended from appropriate cementitious materials and are supplied by cement manufacturers.
BRE Digests Site investigation for low-rise building: