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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Water seeping from the base or sides of a trial pit can be collected in a container such as a clean, sealable sample jar.
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It seems reasonable, therefore, that an additional surface protective layer of sacrificial concrete 50 mm thick would be adequate for a reinforced concrete structure with an intended working life of at least years.
There is extensive research literature on the topic, including some recent collaborative books and conferences[1—4]. 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 The contract may include also: Table F1 lists the categories of product covered and the six design guides that apply concret particular exposure conditions.
Brownfield sites A brownfield location is defined as a site or part of a site that has been subject to industrial development, storage of chemicals including for agricultural use or deposition of waste, and which may contain aggressive chemicals in residual surface materials or in ground penetrated by leachates Gfound C5.
Other types of membrane may be applied to the surface of the concrete after curing. The mass of samples required for chemical testing should be as given in BRE Report BRSection 4, or BSSection 7; that is, g for fine grained soils, g for medium grained soils and 3 kg for coarse grained soils. Skokie IllinoisPCA, However, the levels of chloride found in the ground are generally chemically innocuous; indeed, they may be beneficial since there is considerable evidence, from seawater studies, that the presence of chloride generally reduces sulfate attack.
Disturbed ground This is, initially, natural ground that is substantially disturbed; for example, by cutting and filling to terrace a site, or by excavation and backfilling, so that air can enter and oxidise any pyrite contained therein.
It caters primarily for the general use of cast-in-situ concrete, but additionally will cover any precast concrete that does not meet the qualifying carbonation conditions that apply to precast concrete in Parts E and F.
Garston, BRE Bookshop, In the UK, sulfates and acids, naturally occurring in soil and groundwater, are the agents most likely to attack concrete. Also, the mobility of any groundwater must be known for some categories of concrete construction since site drainage may need to be designed to protect concrete foundations.
Specialist advice should be sought if the presence of ammonium ions is suspected. This would be particularly aggressive to concrete if the backfill contains sulfate or sulfide bearing material eg pyritic clay.
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Step 8 Step 6 Determine the sulfate class equivalent to the characteristic value of the total potential sulfate content using columns 1 and 6 of Table C2 on the next page. London, The Stationery Office, Adjusted characteristic values of sulfate may be derived and, from these, adjusted sulfate classes for soil and groundwater be obtained.
Flowing groundwater may be expected on a site that contains very permeable soil and is sloping or could be subject to a hydraulic head from a nearby speciao or embankment.
In all of the geological strata shown on the opposite page, except Ahgressive Mudstone, unweathered material at some metres depth may contain sulfides, particularly pyrite.
However, it is important to note that: However, sulfides usually provide no hazard to concrete in the absence of oxygen and mobile water. Design Sulfate Class DS Class This is a five-level classification for sites based principally on the sulfate content, including total potential sulfate, of ground or groundwater, or both.
BRE – Special Digest 1
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. Most of the subsequent research recommended by the Thaumasite Expert Group has been completed. Controlled procedures need to be used for aggressjve, handling and storing groundwater samples. Laboratory tests show that the first effect of the conventional form of sulfate attack is to increase the strength and density of the concrete as the reaction products aggressivve the pore space.
Swindon, Environment Agency, This portion of the dissolved carbon dioxide is termed aggressive carbon dioxide.
This acid is not highly ionised and will not produce a pH below about 3. The Design Sulfate Class for the location should then be taken as aggressive highest of the sulfate classes derived by the differing procedures. Report of the Thaumasite Expert Group. 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. The extra test requirements, compared with the procedure given in Section C5.
Only in two cases is flowing water intrinsically catered for in the precautions recommended for concrete.
Sections D4 to D8 give the detailed guidance. Ammonium sulfate NH4 2SO4 is used in agriculture as a fertiliser.
If breaching the naturally impermeable ground around concrete is unavoidable, the APM can often be achieved aggrsssive resealing the possible routes eg by trenches for service pipes by which groundwater can reach the concrete. See Section C5 Determine the intended working life of proposed building or structure, and the form and use of specific concrete elements.