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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These stem from the new research on the quality of concrete necessary to resist sulfate attack, including TSA. The overall design process is summarised in Section D3. Compare the sulfate class for total potential sulfate with the sulfate classes determined in Section C5.
It is not used in Aggrressive Assessment of and management of risks to buildings, building materials and services from land contamination. In respect of environmental conditions, bacterial action has been widely reported as aiding the oxidation, particularly so when conditions are acidic. Furnace bottom ash fba and pulverized fuel ash pfa from the current power generation process contain only small amounts of calcium sulfate.
If mobile water is present, there will be some seepage into the trial pit or borehole within 24 hours, but often the water intake will be much more rapid. This immediately reacts with water to form hydrogen sulfide H2Sa gas that rises into the air space above the sewage. However, the likelihood of encountering the large majority of these in the ground is low, and only the more likely ones are described in this section or are referred to in the sections on site investigation Part C.
Concrete in Aggressive Ground:3rd edition
London, Spon Press, rigest However, their presence may well affect the setting of concrete through an inhibition or modification of the hydration of the cement. In addition to these, sulfates may be found in locally significant concentrations in a wide range of other natural strata ranging from Carboniferous mudstones to Recent alluvium and peat.
Factors that are specific to the concrete construction eg type of element, section thickness, curing conditions, application of hydraulic gradient associated with groundwater and the intended working life are taken account of separately in Parts D to F when specifying concrete quality to meet the assessed ground conditions.
Representative samples should be taken for sulfate classification from key depths in the ground in each test pit or borehole, bearing in mind the preliminary structural design concept and the likely distribution of sulfides as indicated in Section C2.
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However, if the water-soluble sulfate results for soil vary widely, it may be appropriate to test further samples to obtain a more representative data set. The reactions have been demonstrated to depend on the type of cement, on the availability of reactive carbonate in, for example, the aggregate and groundwater, and on the temperature.
If a better understanding is required, a comprehensive suite of soil and groundwater analyses can be carried out to include determining calcium, magnesium, sodium and potassium ions.
They also gave incremental rules for modification of these primary classes to account for other factors that affect the severity of chemical attack, including: Introduction 7 Hydraulic gradient Sacrificial cover layer The hydraulic gradient across a concrete element is the difference in hydrostatic head on the two sides of the concrete, in metres, divided by section thickness, in metres.
For the reasons given in D5. Specialist hydrological advice may be required if site evidence is meagre or difficult to interpret. The recommendations for the protection of steel reinforcement in BS should be followed. The category of a site or individual site location should be provisionally established by desk study Section C4.
Box C1 lists the main sulfur species found in the UK, most of which are either sulfates or sulfides. Laboratory testing can give precise values for chemical contents at particular locations but will not necessarily be fully representative.
Cements and combinations prepared from the same ingredients, taken in the same proportion, are equivalent for resistance to sulfate attack. Recommended test methods for the chemical analysis of aggressive groundwater are given in Appendix C1. The result may be a relatively rapid oxidation of all or part of the pyrite .
Concrete in Aggressive Ground:3rd edition – PDF Free Download
The permitted relaxations are applied in Table E1 on page 51 which here replaces Table D1. The carbonic acid reacts with the cement paste matrix or any limestone aggregate.
The consideration of the effects of site drainage in relation to structures and foundations is essential and, in particular, the presence of porous carrier drains which gruond divert water into the area of the foundations Section D6. The brf through this sulfate classification Section C5. This leads to a loss of the binding properties. The reaction produces calcium carbonate CaCO3 and is associated with a loss of alkalinity. The availability of carbonate ions CO32— changes the reaction products when sulfates enter the concrete.
However, specialist advice should be sought with regard to the detection of these hazards and to appropriate concrete specification. Effects of substances on concrete and guide to protective treatments. This measure is not appropriate where the surface of the concrete must remain sound comcrete prevent loss of frictional resistance or settlement eg for skin friction piles.
The usual procedure is to accommodate agbressive water courses in the new site layout, or for them to be efficiently diverted.