Visser J.,TNO |
Couto S.,CeNTI |
Gupta A.,BASF |
Alvarez I.L.,Acciona |
And 9 more authors.
Heron | Year: 2015
Producing concrete with secondary raw materials is an excellent way to contribute to a more sustainable world, provided that this concrete has at least the same performance during its service life as concrete made with the primary raw materials it replaces. Secondary raw materials for Light Weight (LW) aggregates (rigid polyurethane foams, shredded tire rubber and mixed plastic scraps) have been combined with secondary raw materials for the binder (fly ash, slag and perlite tailings) making sustainable concretes that were investigated for their suitability as LW, highly insulating concrete for four different types of applications. Compliance to desired engineering properties (workability, setting time) was not always feasible: it was mostly the low workability of the mixtures that limited their application. Contrary to well established cements, steering the workability by adding water was not an option for these binders that rely on alkali-activation. Eight successful mixtures have been tested further. The results have shown that it is possible to produce a non-structural sustainable concrete with good mechanical and thermal insulation properties. Design of concrete made with novel materials is currently not feasible without extensive experimentation as no design rules exist other than empirically derived rules based on traditional materials. As a radical different approach, a flexible concrete mix design has been developed with which the concrete can be modelled in the fresh and hardened state. The numerical concrete mix design method proves a promising tool in designing concrete for performance demands such as elasticity parameters and thermal conductivity.
Leone M.,University of Salento |
Aiello M.A.,University of Salento |
Rametta R.,CETMA |
Mechanics of Composite Materials | Year: 2014
The paper deals with the structural response of mechanically fastened fiber-reinforced laminated thermoplastic composite joints. An experimental investigation was carried out to analyze the behavior of single-pinned joints made with woven glass-reinforced polypropylene composite laminates. A detailed experimental analysis was performed in order to predict the bearing response, failure strength, and failure mode of composite laminates containing a pin-loaded hole. The results obtained allow one to evaluate the influence of geometric parameters and the stacking sequence of laminates on the behavior of such joints. © 2014 Springer Science+Business Media New York.
De Riccardis M.F.,ENEA |
Martina V.,CETMA |
Journal of Physical Chemistry B | Year: 2013
Recently a great interest has been expressed in electrophoretic deposition (EPD) of polymers, both as particles and as chains. It is generally accepted that also for polymer particles, the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory is valid, therefore, in principle, polymer suspensions suitable for EPD could be easily obtained by dispersing polymer particles in an aqueous or nonaqueous medium. Nevertheless, this work demonstrated that in order to obtain good quality deposits based on poly(ether ether ketone) (PEEK) and poly(tetrafluoroethylene) (PTFE), some additives have to be used. In the case of PEEK, a dispersant providing citrate anions was successfully used, whereas for PTFE a steric suspension stabilization was reached by adding polyvinylpyrrolidone (PVP). In such a way, codeposition of PEEK and PTFE was achieved. The efficiency of the EPD process was demonstrated by means of differential scanning calorimetry (DSC) measurements. A thermal program consisting of heat/cool/heat cycles at a low rate was used in order to evaluate the crystalline amount of each polymer in the deposits. In order to explain the obtained results, it needed to also consider the dimension and structural characteristic of the polymer particles. © 2012 American Chemical Society.
Lignola G.P.,University of Naples Federico II |
Angiuli R.,CETMA |
Prota A.,University of Naples Federico II |
Aiello M.A.,University of Salento
Materials and Structures/Materiaux et Constructions | Year: 2014
International and National Building Codes provide requirements for design and construction of new masonry structures, but design provisions for the repair, retrofitting, and rehabilitation of masonry structures are not always available and included in the same documents. Due to the extremely large variability in masonry performances, equations of general validity cannot often be provided, namely relationships suitable for every masonry type. Despite the great research effort in the experimental field, considerable theoretical work is still needed to fully outline a definitive analytical model to predict the behavior of FRP confined masonry. Most of the available models, empirical in nature, have been calibrated against their own sets of experimental data, or they are simply derived from concrete. Even if large amount of results obtained for concrete led to consolidated design guidelines, they cannot be simply extended to masonry. In this study, a mechanically based confinement model is proposed based on mechanical parameters able to differentiate similar masonry types and to highlight that they present different confinement performance. Crucial aspects of masonry confinement will be also discussed, namely: lateral dilation; confinement effectiveness; lateral pressure also in non-circular shapes; effective strain of FRP. © RILEM 2014.