SPRAYED CONCRETE - ADVANCED TECHNOLOGIES

Abstract

Developments in sprayed concrete technology based on the use of the wet-mix process involving modern robotic spraying techniques, advances in sprayed concrete mix proportions and the availability of liquid accelerators are described. The durability of tunnel linings made with sprayed concrete is discussed. Specifications for sprayed concrete, ways of achieving low permeability in the sprayed concrete mix, alkali-free accelerating admixtures, and application requirements are outlined. Ways of minimising the proportion of steel reinforcement to prevent water ingress are discussed. The production of watertight sprayed concrete linings and fire-resistant tunnel linings are considered with reference to MBT's Masterseal 340 and 345 sprayable membranes and the MEYCO Fix Fireshield 1350 thermal barrier system.