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Evaluating soundness of concrete containing shrinkage-compensating MgO admixtures
https://orcid.org/0000-0002-2222-6188
Highlights Periclase particle size and its internal crack volume fraction affect the r-MgO reactivity. The autoclave expansion test failed to realistically estimate the long-term expansion of cement. The MgO powder admixture having lower reactivity resulted in unsoundness at higher curing temperatures. Drying shrinkage was more effectively mitigated in concrete than paste specimens. Extending the water curing period from 1 to 4 weeks in paste samples resulted in partial compensation of drying shrinkage.
Abstract Reactive MgO admixtures are available to counteract drying shrinkage of concrete. However, since excess amounts of MgO in the form of periclase in cements can cause unsoundness, there is a concern whether these admixtures can result in unsoundness. Hence, the volume stability of paste and concrete specimens partially substituted with up to 10 and 15% wt of r-MgO, respectively were subjected to 23, 38, 60, and 80 °C moist curing conditions and expansion monitored for six months. In addition, the ASTM C151 autoclave expansion test (AET) used to assess the soundness of cements was conducted but was found to underestimate the 6-month expansion of cement pastes containing r-MgO admixtures. And, the impact of the MgO admixtures on compressive strength of the concrete cylinders was evaluated at different curing temperatures. It was found that with sufficient moist curing, r-MgO admixtures can effectively limit the drying shrinkage of concrete.
Evaluating soundness of concrete containing shrinkage-compensating MgO admixtures
https://orcid.org/0000-0002-2222-6188
Highlights Periclase particle size and its internal crack volume fraction affect the r-MgO reactivity. The autoclave expansion test failed to realistically estimate the long-term expansion of cement. The MgO powder admixture having lower reactivity resulted in unsoundness at higher curing temperatures. Drying shrinkage was more effectively mitigated in concrete than paste specimens. Extending the water curing period from 1 to 4 weeks in paste samples resulted in partial compensation of drying shrinkage.
Abstract Reactive MgO admixtures are available to counteract drying shrinkage of concrete. However, since excess amounts of MgO in the form of periclase in cements can cause unsoundness, there is a concern whether these admixtures can result in unsoundness. Hence, the volume stability of paste and concrete specimens partially substituted with up to 10 and 15% wt of r-MgO, respectively were subjected to 23, 38, 60, and 80 °C moist curing conditions and expansion monitored for six months. In addition, the ASTM C151 autoclave expansion test (AET) used to assess the soundness of cements was conducted but was found to underestimate the 6-month expansion of cement pastes containing r-MgO admixtures. And, the impact of the MgO admixtures on compressive strength of the concrete cylinders was evaluated at different curing temperatures. It was found that with sufficient moist curing, r-MgO admixtures can effectively limit the drying shrinkage of concrete.
Evaluating soundness of concrete containing shrinkage-compensating MgO admixtures
https://orcid.org/0000-0002-2222-6188
Highlights Periclase particle size and its internal crack volume fraction affect the r-MgO reactivity. The autoclave expansion test failed to realistically estimate the long-term expansion of cement. The MgO powder admixture having lower reactivity resulted in unsoundness at higher curing temperatures. Drying shrinkage was more effectively mitigated in concrete than paste specimens. Extending the water curing period from 1 to 4 weeks in paste samples resulted in partial compensation of drying shrinkage.
Abstract Reactive MgO admixtures are available to counteract drying shrinkage of concrete. However, since excess amounts of MgO in the form of periclase in cements can cause unsoundness, there is a concern whether these admixtures can result in unsoundness. Hence, the volume stability of paste and concrete specimens partially substituted with up to 10 and 15% wt of r-MgO, respectively were subjected to 23, 38, 60, and 80 °C moist curing conditions and expansion monitored for six months. In addition, the ASTM C151 autoclave expansion test (AET) used to assess the soundness of cements was conducted but was found to underestimate the 6-month expansion of cement pastes containing r-MgO admixtures. And, the impact of the MgO admixtures on compressive strength of the concrete cylinders was evaluated at different curing temperatures. It was found that with sufficient moist curing, r-MgO admixtures can effectively limit the drying shrinkage of concrete.
Evaluating soundness of concrete containing shrinkage-compensating MgO admixtures
Kabir, H. (author) / Hooton, R.D. (author)
2020-04-08
Article (Journal)
Electronic Resource
English
Reactive MgO (r-MgO) , Acid neutralization test , Soundness , Autoclave expansion test (AET) , A , ASTM type I cement , AET , autoclave expansion test , B , ASTM type II cement , BET , Brunauer–Emmett–Teller , BSE , back-scattered electrons , HPC , high-performance concrete , ITZ , interfacial transition zone , PC , Portland cement , r-MgO , reactive MgO admixture , SEM , scanning electron microscopy , SRA , shrinkage reducing admixture , SSA , specific surface area , UHPC , ultra high-performance Concrete , W/C , water to cementitious materials Ratio