Waste polymers recycling in high performance asphalt mixtures

Building a road pavement requires large amounts of constituent materials, whose extraction can lead to the devastation of natural resources and causes negative impacts on the environment. As aggregates comprise nearly 90% of asphalt mixtures, their partial substitution by waste thermosetting polymers (12 million tons of waste polymers are presently mislaid into landfills, every year, in Europe) can be considered as a sustainable technology, given that an equivalent performance can be assured. Thus, this study aims on evaluating possible advantages of introducing polyethylene based wastes in asphalt mixtures, namely high density polyethylene (HDPE) and cross-linked polyethylene (PEX), incorporating HDPE as a bitumen modifier and PEX as partial substitute of the aggregates. The laboratory tests carried out in this work showed that the use of HDPE significantly improves the behavior of the asphalt binder/mixture. The use of PEX considerably decreases the density of the mixtures, which can be attractive to lighten structures. The mixtures with PEX have similar performance to the conventional one in terms of water sensitivity, improving the permanent deformation resistance and reducing the temperature susceptibility. In brief, the mixtures incorporating waste polymers could be considered a good technical and environmental alternative for paving works.Portuguese Foundation for Science and Technology (FCT) in the scope of the Strategic Project UI 4047 2011‐201

Rheological and functional evaluation of the interactions between bitumen and rubber

It is estimated that about ten kilograms of tires are discarded per inhabitant annually. The negative impact of this residue can be reduced, since rubber can be reused as a constituent of asphalt rubber (AR) binder in road pavements. However, the materials which constitute the AR binders and their interaction are not sufficiently characterized. In this work several base bitumens interacted with crumb rubber, in order to produce AR binders, which were subsequently separated, by using a modified “Basket drainage method” to recover the residual bitumen and rubber. EN 12591 or 14023 standards tests and the Dynamic Shear Rheometer (DSR) were used to evaluate the changes in the properties of the binders during AR production. The swelling and depolymerisation changes in the rubber were evaluated through microscopic tests. It was observed that the characteristics of the base bitumen significantly affect the rubber and the AR binder properties (mainly for interactions with softer bitumens)

Can oil, plastic and RAP wastes have a new life in novel asphalt mixtures?

The pavement recycling allows to reuse reclaimed asphalt pavement (RAP) or other waste materials in new asphalt mixtures for road construction or rehabilitation, thus re-ducing the use of virgin materials (aggregates and bitumen). Thus, the main aim of this study is to minimize the use of natural resources through the reuse of three waste materials: HDPE, mo-tor oil and RAP. Different amounts of waste motor oil and HDPE were added to an asphalt binder with 50% aged bitumen. The best solutions to produce the modified binders (4.5 to 5.0% HDPE and 10 % waste motor oil) performed as well as a conventional bitumen although they only used 35 % of virgin bitumen. Asphalt mixtures with 50 % RAP were produced with the selected modified binders, improving some characteristics in comparison with conventional asphalt mixtures. In conclusion, these wastes can revive in new asphalt mixtures.RDF funds through the Operational Compe titiveness Program – COMPETE and the National funds by FCT – Portuguese Foundation for Science and Technology in the scope of PLASTIROADS Project FCOMP - 01 - 0124 - FEDER - 020335 (PTDC/ECM/119179/20

Substituent and ring effects on enthalpies of formation: 2-methyl- and 2-ethylbenzimidazoles versus benzene-and imidazole-derivatives

The enthalpies of combustion, heat capacities, enthalpies of sublimation and enthalpies of formation of 2-methylbenzimidazole (2MeBIM) and 2-ethylbenzimidazole (2EtBIM) are reported and the results compared with those of benzimidazole itself (BIM). Theoretical estimates of the enthalpies of formation were obtained through the use of atom equivalent schemes. The necessary energies were obtained in single-point calculations at the B3LYP/6-311+G(d,p) on B3LYP/6-31G* optimized geometries. The comparison of experimental and calculated values of benzenes, imidazoles and benzimidazoles bearing H (unsubstituted), methyl and ethyl groups shows remarkable homogeneity. The energetic group contribution transferability is not followed, but either using it or adding an empirical interaction term, it is possible to generate an enormous collection of reasonably accurate data for different substituted heterocycles (pyrazole-derivatives, pyridine-derivatives, etc.) from the large amount of values available for substituted benzenes and those of the parent (pyrazole, pyridine) heterocycles.We acknowledge the financial support of the DGI/MCyT (project nos. BQU-2003-00976, 01251 and 05827). This work has been partially supported by the DGI project no. BQU-2003-00894. A generous allocation of computational time at the CCC of the Universidad Auto´noma de Madrid is also gratefully acknowledged. Thanks are also due to Instituto de Cooperac¸a˜o Cientı´fica e Tecnolo´gica Internacional (ICCTI), Lisbon, Portugal, and Consejo Superior de Investigaciones Cientı´ficas (CSIC), Madrid, Spain, for a joint research project ICCTI/CSIC. MLPFA thanks Fundac¸a˜o para a Cieˆncia e Tecnologia (FCT), Lisbon, Portugal, for the award of a postdoctoral fellowship (PRAXIS XXI/BPD/16319/98) and MT thanks MECD/SEEU (AP 2002-0603), Spain, for financial support

Experimental thermochemical study of two 2-alkylbenzimidazole isomers (alkyl = propyl and isopropyl)

This paper reports the values of the standard (p∘=0.1 MPa) molar enthalpy of formation in the condensed, at T=298.15 K, for 2-R-benzimidazoles (R=propyl, isopropyl), derived from, the respective enthalpies of combustion in oxygen, measured by static bomb combustion calorimetry and the standard molar enthalpies of sublimation, at T=298.15 K, obtained using Calvet microcalorimetry in the case of 2-isopropylbenzimidazole and, by the variation of vapour pressures, determined by the Knudsen effusion technique, with temperatures between (344 and 365) K for 2-propylbenzimidazole. Heat capacities, in the temperature ranges from T=268 K to near their respective melting temperatures, T=421 K for 2-propylbenzimidazole and T=464 K for 2-isopropylbenzimidazole, were measured with a differential scanning calorimeter. These values were used to derive the standard molar enthalpies of formation, of the two 2-benzimidazole derivatives, in gaseous phase.Thanks are due to Instituto de Cooperação Cientı́fica e Tecnológica Industrial (ICCTI), Lisbon, Portugal, and Consejo Superior de Investigaciones Cientı́ficas (CSIC), Madrid, Spain for a joint research project CSIC/ICCTI; M.L.P.F.A. thanks Fundação para a Ciência e Tecnologia (FCT), Lisbon, Portugal, for the award of a postdoctoral fellowship (SRFH/BPD/5595/2001). The Spanish DGI/MCyT is acknowledged under projects BQU2000-0252, 0906 and 1497; M.T. thanks MECD/SEEU, AP2002-0603, Spain for financial support

Substituent effects on enthalpies of formation of nitrogen heterocycles: 2-substituted benzimidazoles and related compounds

The enthalpies of combustion, heat capacities, enthalpies of sublimation and enthalpies of formation of 2-tert-butylbenzimidazole (2tBuBIM) and 2-phenylimidazole (2PhIM) are reported and the results compared with those of benzene derivatives and a series of azoles (imidazoles, pyrazoles, benzimidazoles and indazoles). Theoretical estimates of the enthalpies of formation were obtained through the use of atom equivalent schemes. The necessary energies were obtained in single-point calculations at the B3LYP/6-311++G(d,p) on B3LYP/6-31G* optimized geometries. The comparison of experimental and calculated values of all studied compounds bearing H (unsubstituted), methyl (Me) ethyl (Et), propyl (Pr), isopropyl (iPr), tert-butyl (tBu), benzyl (Bn) and phenyl (Ph) groups show remarkable homogeneity. The remarkable consistency of both the calculated and experimental results allows us to predict with reasonable certainty the missing experimental values. The crystal and molecular structure of the 2-benzylbenzimidazole (2BnBIM) has been determined by X-ray analysis. The observed molecular conformation permits the crystal being built up through N−H···N hydrogen bonds and van der Waals contacts between the molecules. An attempt has been made to relate the crystal structure to the enthalpies of sublimation.Thanks are due to Instituto de Cooperac¸a˜o Cientı´fica e Tecnolo´gica International (ICCTI), Lisbon, Portugal, and Consejo Superior de Investigaciones Cientı´ficas (CSIC), Madrid, Spain. L.M.P.F.A. thanks Fundac¸a˜o para a Cieˆncia e Tecnologia (FCT), Lisbon, Portugal, for the award of a postdoctoral fellowship (PRAXIS XXI/BPD/16319/98). This work has also been financed by DGICYT (BQU-2003- 00894, -00976 and -01251)

Enthalpies of formation of N-substituted pyrazoles and imidazoles

Accurate experimental enthalpies of formation measured using static bomb combustion calorimetry, the “vacuum sublimation” drop calorimetry method, and the Knudsen-effusion method are reported for the first time for four azoles:  1-methylimidazole (1MeIMI), 1-methylpyrazole (1MePYR), 1-benzylimidazole (1BnIMI), and 1-benzylpyrazole (1BnPYR). These values and those corresponding to imidazole (1HIMI), pyrazole (1HPYR), 1-ethylimidazole (1EtIMI), 1-ethylpyrazole (1EtPYR), 1-phenylimidazole (1PhIMI), and 1-phenylpyrazole (1PhPYR) are compared with theoretical values using the G2(MP2) and the B3LYP/6-311*G(3df,2p)//6-31G(d) approaches. In general, there is a very good agreement between calculated and experimental values for the series of N-substituted imidazoles, while the agreement is less good for the series of the N-substituted pyrazoles. Experimentally, the gap between the enthalpies of formation of imidazoles and pyrazoles decreases significantly upon N-substitution, while the theoretical estimates indicate that this decrease is smaller.This work has been partially supported by the DGES Projects PB 96-0001-C03-03, PB96-0067, and PB96-0927-C02-01. A generous allocation of computational time at the Centro de Computacio´n Cientı´fica de la Facultad de Ciencias (CCCFC) de la UAM is also gratefully acknowledged. Thanks are due to Junta National de Investigac¸a˜o Cientı´fica e Tecnolo´gica (JNICT), Lisbon, Portugal and Consejo Superior de Investigaciones Cientı´ficas (CSIC), Madrid, Spain, for a joint research project CSIC/JNICT. Financial support from the Praxis XXI, Project 2/2.1/qui/54/94, is acknowledged. L.M.P.F.A. thanks Fundac¸aˆo para a Cieˆncia e Tecnologia, Lisbon, Portugal for the award of a postdoctoral fellowship (Praxis XXI/BDP/16319/98). J.F.L. acknowledges funding from “Dow Chemical Company” for partial support of his thermochemical studies

Avaliação de estruturas de pavimentos rodoviários através de pista e simulador de ensaios acelerados à escala real

Os ensaios acelerados de pavimentos rodoviários consistem na aplicação controlada de um carregamento vertical, através de uma roda normalizada que circula a uma velocidade controlada, simulando as cargas reais introduzidas pelo tráfego pesado. Em condições de temperatura e humidade controladas, os ensaios acelerados permitem simular num período de tempo reduzido as ações a que um pavimento está sujeito ao longo da sua vida útil. No âmbito do Projeto Tropical-PAV foi construída no LNEC uma pista de ensaios à escala real e instalado um Simulador de Ensaios Acelerados sobre Pavimentos Rodoviários possibilitando o estudo e a validação de técnicas de construção e/ou reabilitação de pavimentos rodoviários. No presente trabalho é feita uma apresentação geral dos ensaios acelerados sobre pavimentos rodoviários e em particular do Projeto de I&D Tropical-PAV.Quadro de Referência Estratégica Nacional e à entidade financiadora Agência Nacional da Inovação pelo financiamento ao projeto número 38915 Projeto de I&D Tropical-PA

Soluções de pavimentos rodoviários para países com climas tropicais – projeto de I&D tropical-PAV

Algumas empresas do setor da construção que integram a Plataforma Tecnológica Portuguesa da Construção (PTPC) decidiram promover a cooperação tecnológica entre si e com as entidades do Sistema Científico e Tecnológico Nacional (SCTN) para o desenvolvimento de novas soluções de pavimentação rodoviária para aplicação em países de clima tropical, nomeadamente ao nível das misturas betuminosas e das camadas de solocimento. O objetivo do projeto foi permitir a eventual criação de uma solução de pavimentação inovadora através do desenvolvimento de uma mistura betuminosa e de uma mistura de solo-cimento formuladas com base em ensaios empíricos e de desempenho, à escala laboratorial e, posteriormente, validando esse desempenho num ensaio à escala real recorrendo a uma Pista de Ensaios Acelerados de Pavimentos, onde foram aplicados carregamentos idênticos às solicitações que serão alvo ao longo do seu período de vida útil. Esta Pista de Ensaios Acelerados de Pavimentos construída no âmbito deste projeto integra um protótipo de um simulador de tráfego, que reproduz a simulação do tipo de solicitação a que um pavimento habitualmente está sujeito