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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Sulfate class limits based on 2: Document Status Indicators The Green document status indicator indicates that the document is: These stem from a further study of occurrences of sulfate attack in concrete structures, and recent field and laboratory research Section A3.
Guidance in BRE Digests has necessarily evolved to cater for successive adverse field findings; to take advantage of the emergence of new concrete constituents and construction methods; and to maintain bee with newly published standards, latterly European ones. Specialist advice should be sought if the presence of ammonium ions is suspected. In addition to these, sulfates may be found specia locally significant concentrations in a wide range of other natural strata ranging from Carboniferous mudstones to Recent alluvium and peat.
The concentrations present are rarely sufficient to attack hardened concrete. Metric units BS But sulfides can be converted relatively rapidly to sulfuric acid and sulfates if exposed to air and water by construction activities sometimes aided by bacterial action or high pH Box C2.
Assessing the aggressive chemical environment. However, we can take no responsibility for the subsequent use of this information, nor for any errors or omissions it may contain.
BRE – Special Digest 1
Concrete surfaces that are carbonated are less prone to this form of attack. Thaumasite form of sulfate attack TSA This is a type of sulfate attack that consumes the binding calcium silicate hydrates in Portland cement, weakening the concrete and causing some expansion. If APM4 is to be adopted and blinding concrete is to be used as the APM, the blinding concrete should be at least 50 mm thick and of the same quality as the foundation construction.
Cement and Concrete Composites. An appropriately qualified professional such as a geotechnical engineer, engineering geologist or hydrologist can be asked to prove a case for static groundwater conditions from an evaluation of the site geology and hydrology. However, high chloride concentrations in the ground will increase the risk of corrosion since chloride ions may migrate into the concrete and lead to a reduction in passivity at the metal surface.
However, the condition can often be inferred from an overall consideration of the quantity and rate of flow, the type of soil and the surrounding topography. BRE Client Report White haloes of pure thaumasite can be seen around dolomite aggregate particles Chemical attack on concrete The effect of the temperature regime on the occurrence and severity of TSA has been studied in the laboratory and field.
Part A Conventional form of sulfate attack This is a form bde sulfate attack in which sulfate ions that have penetrated concrete react with calcium aluminate hydrate to form calcium sulfo-aluminate hydrate ettringiteor with calcium hydroxide to form gypsum.
Care should be taken to avoid water that has entered the pit directly from rainfall or surface run-off.
On brownfield sites that have industrial residues, the presence of chloride ions, together with a pH below 5. The Trust uses the profits made by the BRE companies to fund research and education that advances knowledge of the built environment.
These were principally to bring nomenclature used for cements and combinations into line with newly published European Standards.
Only in two cases is flowing water intrinsically catered for in the precautions recommended for concrete. These data should be used to plan the ground investigation. In contrast to this unwanted consequence that can arise from deep penetration of a carbonation front, carbonation of the surface of concrete is beneficial in respect of sulfate attack.
Because this Standard did not cover some tests needed for ground investigation in respect of concrete, it was supplemented in by procedures detailed in BRE Report BR This definition has been adapted here to take some account of structural performance factors such as the consequence of serious concrete degradation and ease of repair.
A list of sponsors and members of the steering group who advised on its preparation is shown on page vi.
Concrete in Aggressive Ground:3rd edition
These are transported to the concrete in various concentrations in water together with cations, the most common of which are calcium, magnesium and sodium. Formation of brucite Mg OH 2 and magnesium silicate hydrates is an indication of attack. This acid is not highly ionised and will not produce a pH below about 3. Specification, performance, production and conformity prEN Guide to the construction of reinforced concrete in the Arabian Peninsula.
This reaction product also has a greater solid volume than the original constituents and in some cases can contribute to degradation of the concrete.