Title:
Formwork Pressures in Tall Walls With Extended Set Concrete Admixtures; Blast Furnace Slag; Fly Ash; Formwork (construction); Loads; Placing; Tests; Walls; Construction
Author(s):
Phillip S. Dunston, David W. Johnston, and Paul P. McCain
Publication:
Concrete International
Volume:
16
Issue:
11
Appears on pages(s):
26-34
Keywords:
admixtures; blast furnace slag; fly ash; formwork (construction);
loads; placing; tests; walls; Construction
DOI:
Date:
11/1/1994
Abstract:
Findings are presented from an investigation of concrete formwork pressures conducted on test walls up to 28 ft in height with concrete containing high levels of fly ash and slag and extended set admixtures. Measurements were made of form tie forces during the placements. The test wall was 2 ft (0.61 m) thick, and the finished heights of the three wall segments were 28, 27, and 27.8 ft (8.53, 8.23, and 8.47 m). Rates of placing were approximately 11.0 ft/hr (3.35 m/h), 5.5 ft/hr (1.68 m/h), and 5.7 ft/hr (1.74 m/h) for the three segments, respectively. Analysis consisted of estimation of lateral pressures based upon the tributary area for each instrumented tie. Both an approximate area approach and a more rigorous area approach based upon finite element analysis of the form were used. The results were compared to pressures predicted using ACI and CIRIA equations.