Pumpability of Blast-Furnace Slag Aggregate Concrete


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Title: Pumpability of Blast-Furnace Slag Aggregate Concrete

Author(s): Hideo Kasami, Tadashi Ikeda, Shinichi Numata, and Hisamitsu Harada

Publication: Special Publication

Volume: 79


Appears on pages(s): 1143-1164

Keywords: absorption; aggregates; blast furnace slag; coarse aggregates; compressive strength; field tests; fine aggregates; porosity; pumped concrete; ready-mixed concrete; slump tests; workability.

Date: 5/1/1983

Laboratory and field studies were conducted on blast-furnace slag aggregates to establish nationwide material standards and recommended practices. Absorption of air-cooled blast-furnace slag kept in water was 2 to 9 times that of natural gravel, while that under pressure of 2.0 MPa was 1.2 to 4 times that kept in water. Absorption characteristics of air-cooled blast-furnace slag under pressure varied depending on its porosity and pore size distribution. Field studies were conducted on the pumpability of blast-furnace slag aggregate concretes. Air-entrained concretes containing air-cooled and granulated blast-furnace slags, and those containing crushed stone and natural sand were pumped and tested for pumping pressure and properties before and after pump-ing. Concrete with air-cooled blast-furnace slag indicated higher pumping pressure than that with crushed stone due to pressure absorption, while no significant change was found for granulated blast-furnace slag concrete. It is concluded that blast-furnace slag aggregate concrete is pumpable without significant slump-loss when such aggregate does not have excessive absorption, and is properly presoaked in water before the mixing of concrete.