EVALUATION OF A VIBRATING SPADE TO ELIMINATE SURFACE VOIDS ON FORMED CONCRETE SURFACES.
Abstract
Surface voids on formed concrete surfaces are normally caused either by air bubbles trapped between the form and concrete and/or by angular coarse aggregate interlocking and preventing mortar from filling the cavity. Structurally, such voids are not objectionable except as they might cause cavitation forces in fast-moving water; but in many cases they are objectionable on aesthetic grounds. In this investigation, two flat, flexible, vibrating spades, designed to be inserted between the freshly placed concrete and the forms to release entrapped air bubbles, were evaluated. During operation both spades were attached to a standard internal vibrator. One of the spades was designed so that a low-magnitude vacuum could be applied through its flat surfaces to aid in withdrawing entrapped air. To investigate the effectiveness of the spades, similar batches of concrete were made and each was placed in a form designed to produce a sloping and a vertical concrete test surface. All the concrete specimens were initially consolidated in the molds in a similar manner with an internal vibrator. Control specimens received only this initial consolidation, while the vertical and sloping test surfaces of the others were spaded to varying degrees. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1968
- Accession Number
- AD0667967
Entities
People
- B. J. Houston