Determination of master curves for asphalt mixtures by means of IT-CY tests
The concept of ecologically conscious and energy saving roads must be expanded to the performance of the asphalt mixtures as well as to the test related to it. This paper investigates the tests focusing on a better description of the behaviour of asphalts as well as on a deeper revelation of the impact of different compositions. Based on the international experiences the recording of the asphalt´s complex module over the entire temperature range by the determination and evaluation of the mater-curves appeared as a possible solution for more precise description of the asphalt behaviour.
Evaluation of the rejuvenating effect of different additives on bituminous mixtures including hot-recycled RA as a function of the production temperature
The increasing bitumen cost, the growth of the traffic loads and the need to find more sustainable paving practices are forcing agencies to identify new ways to maximise the re-use of Reclaimed Asphalt (RA). If RA could theoretically be 100% recycled, its content in bituminous layers is still restricted in most countries mainly due to legislation limitations and technical issues. In particular, the stiffer and more brittle mixes, usually resulting from RA addition, have raised concerns about the long-term properties of the pavement. In order to further increase the amount of usable RA, rejuvenating additives can be included in the mixtures. The paper deals with the analysis of seven additives, with particular focus on their ability in mitigating the effects of the presence of RA in the mix as a function of production temperature. In particular, FTIR analysis was carried out on the additives to evaluate the differences in their chemical composition. Moreover, the mechanical properties of the mixtures including 50% RA and produced at 140°C or 170°C were investigated. The results showed the reduction of the mixing temperature from 170°C to 140°C determined a slight increase of the air voids content but also allowed a significant decrease of mix stiffness and strength with a contemporary increase of ductility. The mixtures containing 50% RA and the additive had an intermediate behaviour between the mix without RA and the mix with 50% RA and no additive. The additives investigated in this research showed, in most cases, different chemical structures, which reflected in their rejuvenating performance. The comparative analysis of the results from mechanical and chemical tests provided remarkable information about the characteristic properties of a good rejuvenator, particularly the presence of esters and the high flashpoint.
Antimicrobial activity in pulp extract of Neem(Azadirachta indica Linn.)
Antimicrobialactivityin leaf extract of neem ( Azadirachta indica ) against human pathogenic bacteria. E.coli, Staphylococcus aureus, Pseudomonas aeruginosa , Salmonella typhimurium, Bacillus pumilus. Antimicrobia l activities of alcoholic extracts of neem leaves were used. Varying concent ration of each extracts 200mg/ml, 150 mg/ ml,100mg/ml, 50mg/ml, 25mg/ml prepared by using disc diffusion method. When compared with gentamycin 200mg and gentamycin 10mg, the methanol and ethanol extract shows maximum inhibition on Bacillus pumillus, Pseudomonas aeruginosa and Staphylococcus aureusin an asending order.