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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Can also be downloaded from www. The new limits bring sulfate classifications based on 2: Two categories are defined: Chemical attack on concrete B1 B2 B2.
A more cautious design fround required. We provide research, consultancy, information and testing services to customers worldwide. 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.
When the concrete is provided with surface protection APM3 appliedno further APM is needed for a section thickness which is less than mm or a hydraulic gradient due to groundwater which is greater than 5. The thaumasite form of sulfate attack in the UK. Diversion pipes or culverts around dams retaining moorland waters containing high concentrations of aggressive carbon dioxide can be subject sepcial erosion, as can poorly compacted concrete or permeable concrete products eg some aggregate concrete blocks used in foundations.
Code of practice BS EN Examples of such serious consequences could include: State requirements and options for concrete specification, including: Step 2a 33 For ground suspected of containing mineral acids of industrial origin, an additional procedure, Step 10, is recommended prior to taking account of the mobility of the groundwater.
Concrete in Aggressive Ground:3rd edition
These products have dedicated guidance for using in aggressive ground owing to their distinctive characteristics. The characteristic red shale generated from the self-combustion of colliery spoil often contains variable amounts of common sulfates which originated from pyrite present in some Coal Measures strata Figure C3.
Code of practice for design and construction BS Sulfate specification for structural backfills. This reaction product also has a greater solid volume than the original constituents and in some cases can contribute to degradation of the concrete. Here it comes into contact with aerobic concfete that live in microbial films on the moist surface of the pipe crown.
Moreover, preventing the surface of the concrete from drying out during the first day of curing will ensure continued hydration and help to maintain the protective surface zone. Part F includes design guides for specification of specific precast concrete products, including pipeline systems, box culverts, and segmental linings for tunnels and shafts. Rotterdam, Balkema, pp 77— ACEC Class can be found from column 7 of Table C1 Consider all water-soluble sulfate and pH results for soil and find characteristic values for site or individual locations C5.
A typical example would be clayey soils with tight fissures and no included sand or silt jn Section C3. Ground chemistry implications for construction Edr: No adjustment for chloride is necessary where the presence of chloride ions is from brackish water or seawater. During the reaction, ammonia is liberated and escapes as a gas. 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 nre DS-2 would now be considered as being DS Sources of information for site investigations in Britain.
Figure B1 Formerly high quality concrete from a highway bridge foundation that has been severely affected by TSA.
Further detail is given diagrammatically in Figure D1. 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. The procedure for the latter is specifically included owing to severe TSA found in highway sub-structures embedded in pyrite-bearing Lower Lias Clay fill; generation of sulfate due to oxidation of the pyrite following ground disturbance proved avgressive be a major factor.
Some geotechnical problems associated with pyrite bearing mudrocks.
Concrete in Aggressive Ground:3rd edition – PDF Free Download
In addition to the corrosive action of ammonium ions, some further deterioration may be caused by the action of the associated anions. Specification, performance, production and conformity prEN Other factors will include strength class of concrete, the consistence, the availability and cost of materials, and any other contract requirements Figure D1 Specification of concrete for general cast-in-situ use 40 D4 Selection of the DC Class and APMs D4.
There were minor revisions to the guidance in a new edition published in Step 1 a Grkund samples If only a small number of soil samples have been tested for water-soluble sulfate using the 2: In the absence of dissolved oxygen in the sewage, anaerobic bacteria split oxygen from the sulfate ion SO42— generating sulfide S2—. The most severe occurrence had resulted in severe concrete deterioration to a concrfte of up to 50 mm, exposing steel reinforcement to corrosion.
For many years it was considered that the affected components of the concrete matrix were the calcium aluminate phases and calcium hydroxide, and that the minerals formed by this attack were ettringite and gypsum. Effects of substances on concrete and guide to protective treatments.
The new limits bring sulfate classification dugest on 2: This acid is not highly ionised and will not produce a pH below about 3. Such an ion balance check will require: Having established the appropriate Design Sulfate Class, modifications are applied which relate to the mobility and pH of groundwater.
Appendix C2 on page 36 gives guidance on a more comprehensive site investigation that may be needed for a case of sulfate attack on concrete.