Electrometric quality control of concrete compaction in hydraulic construction

Abstract

Electrometric control of the relative density of the concrete mix is based on measuring its electrical parameters, which are related directly to its density. This method, which was first used successfully in the construction of the Dnepr hydroelectric station dam [i], was subsequently used on the Toktogul, Ingurl, and other hydrostatlon projects. However, for the wide industrial use of electrometrlc compaction control a more detailed check of individual problems of the method of its use was required.First of all, the design of electrode-sensors placed in the concrete mix was developed. Single-electrode spear-sensors and double-electrode probe-sensors submerged in the concrete and electrodes left in the concrete mix ~Ig. i) were used in the work. The operating principle of all types of sensors is based on the principle that when an alternating current is supplied to them an electric field is created in the concrete mix whose strength (for constant parameters of the current and composition of the medium) depends on the density of the concrete [2]. Since the electric field potential in the medium decreases with distance from the current source, it was necessary to estimate the zone of action of the sensors and parameters of the electric current, The investigations were carried out under laboratory conditions and directly in the concrete blocks.In the laboratory experiments we used a homogeneous medium (water) and plastic mortar, which were placed in a Plexiglas mold equipped with a probe connected to the measuring instrument, A dielectric plate slmulating nonconducting inclusions, having an area 3-4 times greater than the area of the probe electrodes, was introduced into the mold. The distance between the plate and probe was changed, the resistance of the medium being measured at each position.