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It is a long-term confirmation test (1 or 2 years) at 38 °C in a water-saturated moist atmosphere (inside a thermostated oven) with concrete prisms containing the aggregates to be characterised mixed with a high-alkali cement specially selected to induce ASR.
Alkali–aggregate reaction is a term mainly referring to a reaction which occurs over time in concrete between the highly alkaline cement paste and non-crystalline silicon dioxide, which is found in many common aggregates. This reaction can cause the expansion of the altered aggregate, leading to spalling and loss of strength of concrete.
On the surface of concrete pavements, the ASR can also cause pop-outs, i.e. the expulsion of small cones (up to 3 cm (1 in) in diameter), corresponding to aggregate particle size. A quite similar reaction (alkali-silicate reaction) can occur when clay minerals are present in some impure aggregates, and it may also lead to destructive expansion.
The U.S. Food and Drug Administration (FDA) defines analyte specific reagents (ASRs) in 21 CFR 864.4020 as “antibodies, both polyclonal and monoclonal, specific receptor proteins, ligands, nucleic acid sequences, and similar reagents which, through specific binding or chemical reaction with substances in a specimen, are intended to be used in a diagnostic application for identification and ...
The alkali–carbonate reaction is an alteration process first suspected in the 1950s in Canada for the degradation of concrete containing dolomite aggregates. [1] [2]Alkali from the cement might react with the dolomite crystals present in the aggregate inducing the production of brucite, (MgOH) 2, and calcite (CaCO 3).
The test reports loss of mass to abrasion and impact, expressed as a percentage of initial sample mass. [7] Maximum acceptable loss for the base course of the road is 45%; the more demanding surface course must be 35% or less. [1] The test was developed by the city engineers of Los Angeles in the 1920s. [8]
Alkali–aggregate reaction – Expansive chemical reaction damaging concrete Energetically modified cement – Class of cements, mechanically processed to transform reactivity Pozzolanic reaction – Capacity of silica-rich materials to react with calcium hydroxyde to form calcium silicate hydrates Pages displaying short descriptions of ...
It also reduces the deterioration of concrete by Alkali Silica Reaction (ASR), particularly useful when using recycled crushed glass or glass fines as aggregate. [6] The amount of slaked lime that can be bound by metakaolin is measured by the modified Chapelle test. [7] [8]