title: Investigation of Reactive Powder Concrete and it's Damping Characteristics when Utilised in Beam Elements
Creators: name: Menefy, Luke
Publisher: name: Griffith University
Year: 2008
Subjects: subject: Reactive powder concrete
subject: Concrete damping
subject: Concrete beams

description: Reactive Powder Concrete (RPC) is a relatively new ultra high strength concrete with a wide range of capabilities. Currently it is used in high performance applications where either impact resistance, high durability and/or member size are governing factors in design. The relatively high cost, required production control, and lack of industry knowledge have generally precluded its widespread use in more common engineering applications. Accordingly, the major component of this Thesis aims to contribute new knowledge with respect to the understanding of the material behaviour and damping characteristics of RPC. To achieve this goal a staged experimental study was undertaken encompassing the following (1) the production and material behaviour including a parallel study on the durability of RPC in an aggressive environment (2) the static performance and damping characteristics of RPC when utilised in beam elements. The initial component of the investigation involved several trial mix programmes to ascertain the viability of RPC production using local Queensland materials. A further large scale production programme of RPC was carried out utilising two mixer types: (1) vertical pan mixer representing a precast mix and (2) a mobile inclined drum mixer representing an onsite mix. The results indicated that the onsite application of RPC was viable and resulted in only a minor reduction in characteristic strengths when compared to precast operations. A parallel experimental study investigating the relative performance of RPC immersed in acidic solutions indicated that the range of RPC’s investigated were more susceptible to sulphuric acid attack when compared to a standard high strength concrete (HSC) used in the investigation. Following verification of RPC characteristic strengths, twenty three test beams were produced as part of a large scale RPC production programme. These test beams were incrementally loaded to failure under simply supported conditions during which static measurements were observed both under load and upon the removal of load. The results indicated that the fibre reinforced (FR) RPC test beams exhibited a higher load capacity, an increase in first cracking loads, significantly reduced crack widths and an overall reduction in shear behaviour when compared to the non-fibre reinforced (NF) RPC and HSC test beams. Concurrent free vibration tests through the use of an impulse force hammer were carried out during the static loading of each of the twenty three test beams in an effort to ascertain the damping characteristics throughout the various levels of test beam damage. A new program using analytical and theoretical techniques was developed to analyse the excitation response histories (ERH) obtained at each load increment, the program was found to be more efficient when compared to previous analysis methods. A method of assessing the current and previous analysis methods was also incorporated within the program enabling the user to compare the damping ratio determined through the various analysis methods.