| This dissertation presents the results of a broad study of damping in cement paste, mortar, and concrete, focusing upon the latter. The objective was to identify means by which damping in concrete might be significantly increased as part of the design process, and to document damping, modulus and engineering properties associated with those modifications.; The extensive literature survey found that the bulk of the extant literature demonstrated few options that would introduce significant damping changes, except for the introduction of polymers in one form or another. Many polymers exhibit desirable damping properties that are functions of temperature and frequency. Some of these polymers have been found in previous studies to be compatible with hydraulic cement. The experimental phase of this study examined what appeared to be the most efficacious approach: introduction of polymers---in the form of latex admixtures---that could be uniformly dispersed in the resulting concrete matrix. The effects of several polymers were studied. These included ethyl-vinyl acetate (EVA) and several variants of styrene-butadiene rubber (SBR).; It was found that the resulting polymer-modified concrete (PMC) had dynamic properties that depended upon temperature and frequency, more like polymers alone than concrete alone. The dynamic properties of PMC were found to conform substantially to the known traits of polymers, as modified to account for the presence of the concrete matrix.; The temperature and frequency dependence of damping and modulus was related to the glass transition temperature of the polymer being used. Thus, the damping of PMC will be better under some conditions of temperature and frequency than under others. A designer employing these materials must give consideration to operational temperature and frequency during material selection.; Applicability of this technology is limited to settings in which the vibration amplitudes are quite small, tending to exclude (or significantly limit) its use for seismic or wind engineering applications. In those applications, the structural deformations tend to be large enough that the predominant damping mechanism is material failure, yielding, or connection slippage, and that contribution significantly overshadows whatever might be contributed by the polymers in the concrete. The most useful applications for these modifications tend to be associated with advanced technology buildings and related applications, or to applications involving structure-borne sound. |
