ASTM C1260 PDF
This standard is issued under the fixed designation C ; the number immediately 1 This test method is under the jurisdiction of ASTM Committee C09 on. All the Controls products ASTM C standard. Enter now!. Originally approved in Last previous edition approved in as C – 05a. 2 For referenced ASTM standards, visit the ASTM website,
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This repository is part of the V1260 Research Commons. Then simply check on them periodically and record your results. Clinker alkali had no or little effect on moderately reactive aggregate; whereas it had considerable effect on highly reactive aggregate.
Knowing this is essential to understand what needs to be done asgm mitigate this destructive process. Metal atoms lose the electron, astj electrons, in their highest energy level and become positively charged ions. Specification of fineness and alkali content of cement, or both, might be beneficial to further improve the reliability and reproducibility of ASTM C In addition to discovering ASR, he was the first to explain that expansion was negligible when the alkali content of the cement was below 0.
Frank Bowen, a Master Precaster graduate, received his M.
ASTM C1260 – 14
Signs of ASR are typically random map-cracking and spalled concrete. Lithium compounds have also been used, but they may be cost-prohibitive and limited in availability. Petrographic examination can conclusively identify ASR. Petrography may be used to classify an aggregate as atsm reactive, but expansion testing is required to determine the extent of wstm reactivity and appropriate levels of prevention.
Non-metal atoms gain an electron, or electrons, from another atom to become negatively charged ions. The alkali content of cement is not a significant factor in affecting the expansion. The same goes for calcium, but since it is in the second column of the periodic table, it must lose two electrons for this to happen. However, we must take the time to review the current ASTM standards and check our mix designs to assure material confidence.
This new ASTM standard and related AASHTO provisional standard provides detailed protocols and guidelines using previous ASR testing data, petrography and historical performance to provide a prescriptive decision-making process for mitigation. ASR can be avoided with a proper concrete mix design. This makes them highly reactive. This method is one of the best ways to see ASR happen if you intentionally use aggregates with a high silica content like glass in concrete.
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Ions are electrically charged particles formed when atoms lose or gain electrons. For precasters in identified ASR areas, the following methods for new concrete may be the most critical: This is all critical to ASR to show where the reactivity is taking place. However, C takes one year to perform when evaluating aggregate reactivity, or two years when evaluating the efficacy of SCMs to mitigate deleterious expansion.
The results show that mortar-bar expansion was promoted with increased cement fineness regardless of clinker alkali, aggregate reactivity, or soak solution normality. Map cracking, also known as three-point cracking, can cause other issues as well, such as shrinkage. Keep in mind that some cements contain a higher proportion of potassium sulfate K 2 SO 4 than sodium sulfate Na 2 SO 4. Photo provided by Frank Bowen. Skip to main content. When dealing with ASR, a process that takes place over decades, accelerated tests should be conducted with bias.
A s I scrolled through the few articles and reports I have collected over the past decade regarding alkali-silica reactions, I began to realize I had developed an ignorance to this elusive subject.
At least, this was the blame at the time.
ASTM C Potential Alkali Reactivity of Aggregates | CTLGroup
Consequently, the two tests are often run together. While the fundamental physical and chemical reactions remain poorly understood, it is well known that ASR destroys the durability of concrete and can cause serious maintenance and reconstruction costs. Cement mill certificates contain information that can prove useful for tracking changes in your concrete and controlling variability in your mix design. Atoms are comfortable with themselves when they are fully loaded on that outer band.
Stanton, began his research on a few of these structures and found an expansive reaction between cement and aggregate taking place. Though Stanton might not have been the first to visually recognize ASR, he is credited with the first serious research into why it occurred. Federal Highway Administration, fhwa.
Development of a more economical and more abundant admixture may be the future for ASR mitigation. Regardless, here is a list of key ASR points for precasters to know: That is, if you have questions about the durability of your concrete, save some samples and leave them exposed to the elements.
In addition to the standard 1 N NaOH solution, a 0. C is used as an initial screening test for aggregates and C determines the effectiveness of the SCM being considered to moderate the aggregate activity. Overall, ASR is characterized primarily by four main features: Cracking usually appears in areas with a frequent supply of moisture.
If ASR has been identified by the specifying authority within the region, it is recommended that precast producers perform long-term testing on concrete samples. Many consider C to be the best test method for evaluating deleterious ASR potential because it provides the strongest correlation to field performance. If you compare this with the composition of your aggregates, you should give yourself a pat on the back.
Ask your aggregate provider first for test results before contacting a laboratory.
Comments Frank, Great article that gives a simplified overview of ASR, expansion testing, and mitigation techniques. Publication Version Published Version. It is important to understand the benefits and deficiencies offered by various testing procedures. What we do know, however, is important for precasters to understand.
Mitigation methods can be split into those methods suitable for new concrete and those that can be used for existing structures. Highly reactive aggregate qstm to be more sensitive to cement fineness and alkalinity.