Title: Vacuum-Dewatered Concrete

Author(s): Scott S. Pickard

Publication: Concrete International

Volume: 3

Issue: 11

Appears on pages(s): 49-55

Keywords: concrete construction; concrete finishing (fresh concrete); concrete slabs; mix proportioning troweling; vacuum-treated concrete; water-cement ratio; water content.

DOI:

Date: 11/1/1981

Abstract:
Vacuum dewatering in effect produces a zero-slump concrete from fresh concrete with a high water-cement ratio. The process involves three basic steps: (1) filter pads are placed over the fresh concrete; (2) a suction mat is placed over the filter pad, with a hose connecting the suction mat to a vacuum pump; (3) the vacuum pump is operated for several minutes, depending upon the thickness of the concrete slab. Vacuum dewatering lowers the water con-tent of a freshly placed concrete slab by 15-25 percent, increases the density, strength, and frost resistance of the slab, and decreases the slab’s absorption, abrasion, and shrinkage. This article discusses the mechanics of the process, the steps in the procedure, and conclusions as to vacuum dewatering’s cost effectiveness as a construction technique for certain applications.