Utilization of Low-Heat Cement with High Content of Finely Ground Blast Furnace Slag for High-Strength Concrete
M. Iwai, A. Takagi, T. Mizobuchi, and Y. Nobuta
Appears on pages(s):
adiabatic conditions; admixtures; blast furnace slag; fly ash; high-strength concretes; low heat cements; mass concrete; thermal stresses; water-reducing agents; Materials Research
When using high-strength concrete in large structures, it is important to minimize generation of thermal stresses during hydration of cement and to minimize variation of concrete properties. The proper workability is also very important. A research program is underway with the above aspects in mind to optimize the requirements of high strength, low heat generation, and pumpability, using both the newly developed low heat cement (LSC) with high content of finely ground blast furnace slag and the high-range, water-reducing admixture. This paper describes the test results on fundamental properties, pumpability, and thermal stress reduction effects on high-strength concrete of 60 MPa, using this type of low heat cement. The following results were obtained. 1. The heat generation of LSC is remarkably lower than conventional low heat cement (blended cement: FMKC). When using LSC, the thermal stress was reduced by 60 percent compared to concrete using normal portland cement. 2. The quality of concrete manufactured in the concrete plant was comparatively uniform. 3.Pressure loss during pumping was three to four times larger than ordinary concrete. However, it was verified that after pumping, the quality of concrete using LSC showed satisfactory workability and had less variation compared to the quality of concrete using FMKC. 4. From results mentioned above, by selecting proper high-range, water-reducing admixture, the use of LSC is considered to be a solution for reducing cracks due to hydration in high-strength concrete while maintaining suitable workability and sufficient strength development.