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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The first will provide data on a fround source of external carbonates that can fuel TSA in the absence of wpecial aggregates, while the inclusion of all three will enable an ion balance check to be made to provide an assurance that the principal constituents of the groundwater have been accurately spexial.
Chemical attack on concrete B3. The recommendations for the protection of steel reinforcement in BS should be followed. As in the laboratory, it is likely that the extent of TSA will be increased at the cooler temperatures if the chemical conditions are satisfied.
Want access to British Standards? During the reaction, ammonia is liberated and escapes as a gas. The category of a aggrrssive or individual site location should be provisionally established by desk study Section C4.
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.
This leads to a loss of the binding properties. Chemical and electro-chemical tests BS The local authority and the Environment Agency may need to be consulted to ensure that any change in the drainage does not adversely affect surrounding land and groundwater.
Risks of contaminated land to buildings, building materials and services.
Concrete in Aggressive Ground:3rd edition
These should give good protection if correctly applied. Surface protection is needed to prevent ingress of rainfall and for safety of personnel. Specifying concrete for general cast-in-situ use D3 Design process The overall process of design of concrete for use in aggressive ground conditions is summarised in Figure A1 of Part A.
More rarely, sulfate may also be present in relatively insoluble forms, as in the dugest barite barium sulfate. Having established the appropriate Design Sulfate Class, modifications are applied which relate to the mobility and pH of groundwater. 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.
This is particularly true of concretes eg for piling where mechanical compaction cannot be used. The process may be aggravated by repeated wetting and drying of the exposed concrete surface; this leads to cyclical salt precipitation and dissolution aggressice fatigue stressing of the concrete fabric.
Attack is distinguished by onset of expansion and related cracking of the concrete Section B2.
SD 1 Concrete in aggressive ground. 3rd edition, BRE – Publication Index | NBS
Consequently there has been a basic harmony between these documents in respect of concrete specification for general use in the ground. E3 Design process The design process for surface-carbonated precast concrete for use in the ground is similar to that outlined in Section D3 for the general use of cast-in-situ concrete, excepting that reference to Table D1 should be replaced by reference to Table E1. A list of recommended test methods and source documents for the chemical analysis of soils and groundwater is given in Appendix C1 on page On brownfield sites that have industrial residues, the presence of chloride ions, together with a pH below 5.
Take the highest of Results 1, 2 and 3 as the Design Sulfate Class. The Amber document status indicator indicates that some caution is needed when using this document – it is either: A more cautious design is required. Design guides for common applications.
In respect of the latter, particular consideration should be given to the base of retaining structures that rely partially on base friction and on the design of piles that depend on side friction.
In practice the high magnesium levels will be found in the UK only in ground having industrial residues. The ground description should particularly note the following features relevant to assessment of the aggressiveness of a chemical environment: In brownfield locations, chloride and nitrate should also be quantified as respective indicators cigest hydrochloric and nitric acids. The concrete cover to embedded steel caters for this.
This is because, in natural ground conditions in the UK, magnesium levels are invariably well below values that may significantly affect concrete. Alternatively, a standpipe piezometer can be installed; for example, by embedding it in a sand column brf a borehole and sealing over the top 0.
Appropriate sampling and test procedures for determining aggressive carbon dioxide are given in prEN To avoid contaminating the samples, only a minimum amount of water should be added to the hole during boring, preferably none. The procedure for taking account of the measured chloride content in this particular circumstance is given in Section C5.
The chemical classification of a given site location should be carried out in the following five steps. Finally, this part explains how aggressive carbon dioxide in flowing water can be destructive to concrete. In addition to the corrosive action of ammonium ions, some further deterioration may be caused by the action of the associated anions. The availability of carbonate ions CO32— changes the reaction products when sulfates enter the concrete.
Site investigation and assessment. Part D deals with Stages 3 and 4 of the overall process. The Design Sulfate Class for the location should then be taken as the highest of the sulfate classes derived by the differing procedures. Higher levels of aggressive carbon dioxide will be associated with low pH, but pH cannot be used as the principal indicator since pH will be affected by digesst presence of humic and mineral acids.
Simply cutting through ground without opening up the ground beyond the cut face eg piling operations or excavation without backfill does not generally aggreswive in disturbed ground.
BRE Digests Site investigation for low-rise building: Unusual green patches, reeds, rushes or willow trees often indicate wet ground.
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BRE Client Report The rate and extent of oxidation will depend on the type of pyrite and the local environmental conditions. 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.
It is important to test groundwater spdcial if these are obtainable from the location because groundwater is generally the agent by which aggressive chemicals reach the concrete.