| Title |
Field Application and Economic Analysis of Using Bubble Sheets for the Mass Concrete Construction during Cold Weather |
| Authors |
경영혁(Kyoung, Young-Houck) ; 한민철(Han, Min-Cheol) |
| DOI |
https://doi.org/10.5659/JAIK.2020.36.7.173 |
| Keywords |
Cold Weather Concrete; Mass Concrete; Heat of Hydration; Double-Layered Bubble Sheet; Maturity Method |
| Abstract |
The aim of the research is to verify the efficiency of the double-layered bubble sheets method by evaluating the basic properties and
temperature history, and analyzing the economics through the field application under the conditions of mass concrete construction during cold
weather. In the case of the fresh concrete, all tested properties of slump, air content, and chloride content were satisfied the target values.
Furthermore, the compressive strength at 28 days achieved designed compressive strength. From the temperature history of the mass concrete
constructed during cold weather, gradual increase of the temperature up to 50.3℃ was observed about 60 hours after the placing. At this
time, the top-surface temperature was 32.6℃ which was 17.7℃ difference to the core part and it could restrain the cracking due to the heat
of hydration with 0.85 of thermal crack index. It can be analyzed that the combined effect of decreasing the maximum temperature of the
concrete at core part by controlling the mix design to decrease the heat of hydration, and further reducing the temperature difference between
top and core parts of the mass concrete by keeping the surface temperature by insulating cure using bubble sheets was successful. The
measured values of average curing temperature at all measuring points were confirmed higher than 10℃. Additionally, since all measuring
points were calculated 66°DD of maturity, 5 MPa of minimum compressive strength of preventing early-age frozen damage was secured. In
aspect of economics, comparing with currently used heat-curing method, the suggested double-layered bubble sheet method showed cost
reducing effect in all parts of materials, labor, and other costs. Furthermore, the cost could be reduced more as the number of re-using was
increased, so it could reduce 85 % of cost to the currently used heat-curing method. |