Experimental study on bond performance of advanced material based on composite Portland cements developed for anchoring systems with post-installed reinforcement bars in concrete

Abstract

Abstract This paper presents an assessment study on the bond performance of new advanced mortars based on composite Portland cements. These developed mortars are used as anchoring material for post-installed reinforcement steel bars in concrete. The anchoring mortars were developed by laboratory studies in the recent years and they met several performance criteria regarding the properties in plastic state as consistency, cohesiveness, stability and in hardened state as strength, rigidity, deformation volume and bond to support. Anchoring systems with post-installed reinforcement steel bars are obtained through installation of reinforcement bars into drill holes in hardened concrete and filled with flowable mortars which may be polymer or cement-based mortars. Generally, post-installed reinforcement bars are used to connect layers of new concrete to old concrete and also new members to old concrete members. So far, the most employed anchoring material is the polymer-based chemical resin which have some undisputed advantages, but the durability and long-term performance along the expected service life is questionable. Recently, inorganic-injection-type anchors have been developed in Japan. These anchors are composed of cement, aggregate and additive agents. In this study, the employed anchoring-mortars are exclusively based on hydraulic binder, namely composite Portland cements which are included in the European class of cement CEM II. These composite cements contain supplementary cementing materials (SCM) as fly-ash or limestone which are combined with Portland clinker at the manufacture. The bond strength of the reinforcement steel bars was assessed based on the prescriptions provided in the European assessment document EAD 330087 and EN 1881. These two technical norms are limited only to deformed reinforcement bars with characteristics in conformity with EN 10080 and designed based on EN 1992-1-1. Within this study, the shear load on the reinforcement bars post-installed into hardened concrete is not considered.