Search results for "rumb"
showing 10 items of 34 documents
Regarding the influence of the particle size of crumb rubber from waste rubber on the physical and mechanical characteristics of reclaimed rubber
2017
Thus, at present, a large amount of rubber waste cannot be higher harnessed due to recovery technologies used. Also, the requirements for new products of rubber worldwide are greater than the production capacity and the availability of raw materials. To offset this balance is necessary to improve technologies for recycling waste rubber so to can get regenerated rubber with the best mechanical physical characteristics. The main technology for obtaining the regenerated rubber is based on the rubber waste shredding and making the powder, so that it can be carried out de-vulcanization in autoclave. All the time it was monitored as the de-vulcanization process to be as economical and less pollut…
An investigation of the mechanical properties of rubber modified asphalt mixtures using a modified dry process
2017
Incorporating recycling tyres into asphalt mixtures contributes to solving a serious environmental problem as well as the potential of improving the mechanical performance of asphalt mixtures. The recycled tyre rubber is added by two technologies known as the dry process (when rubber particles are treated as an aggregate modifier) and the wet process (when rubber particles are treated as a binder modifier). Although, the dry process is easier and requires minimal or no modification in the asphalt plant, the inconsistency in field performance makes the dry process not widely used. The main reason for this is believed to be the lack of interaction between the rubber particles and binder. In o…
Austrumbaltijas eksperts Karls Reinholds Kupfers
2022
Raksts par vācbaltu botāniķa Karla Reinholda Kupfera (1872-1935) dzīvi, Austrumbaltijas pētījumiem un citiem zinātniskajiem sasniegumiem.
Ieinteresēto sociālo grupu ietekme uz eiropeizācijas procesu Austrumbaltijā (1199-1229)
2020
Balstoties uz to, ka katra sociālā grupa ir kādas latīņu kristīgās Eiropas garīgās vai laicīgās sfēras reprezentante, bakalaura darbā “Ieinteresēto sociālo grupu ietekme uz eiropeizācijas procesu Austrumbaltijā (1199-1229)” identificēti četri Austrumbaltijas eiropeizācijā ieinteresētie aktori – garīdzniecība, Dānijas Karaliste, bruņniecība un tāltirgotāji – un analizēta viņu nozīme eiropeizācijas procesā laika periodā no 1199. gada līdz 1229.gadam. Izmantojot viduslaiku Livonijas 13. gs. hroniku materiālu, pētījuma rezultātā ir izdevies padziļināt skatījumu uz Austrumbaltijas integrāciju latīņu kristīgās Eiropas kultūrtelpā un tajā iesaistīto aktoru mijiedarbību.
Eksperimentālā pieeja neolīta dzintara apstrādes procesu izzināšanā
2022
Dzintars Austrumbaltijas piekrastē izskalots, vākts un apstrādāts kopš vēlā akmens laikmeta. Tradicionāli dzintara izstrādājumiem galvenokārt veikta tikai to tipoloģiskā analīze, mazāk pētījumi pievērsušies izstrādājumu tehnoloģiskajai izpētei. Maģistra darba ietvaros izstrādātā eksperimentālā pētījuma gaitā izvirzīti un pārbaudīti vairāki svarīgi un neskaidri procesi saistībā ar dzintara izejmateriāla apstrādi akmens laikmeta beigās Austrumbaltijā. Eksperimentālie pētījumi devuši nozīmīgu praktisku ieskatu par procesiem, kas saistīti ar dzintara apstrādi, par dzintara kā apstrādājamā materiāla īpašībām, kā arī materiāliem un tehnikām, kas ir efektīvas dzintara apstrādē. Izmantojot trasoloģ…
Skandināvijas un Austrumbaltijas kultūras sakari vikingu laikmetā (7.-11.gs.)
2017
Zinātnisko pētījumu par 7.-11.gs. skandināvu kultūras sakariem ar Austrumbaltijas iedzīvotājiem ir nedaudz. Lielāka interese ir par kontaktiem ar Rietumeiropu un Krievzemi. Maģistra darba mērķis ir izpētīt skandināvu un Austrumbaltijas teritorijas iedzīvotāju kultūras sakarus 7.-11.gs. balstoties uz arheoloģiskajām liecībām un ziņām rakstītajos avotos. Darbā ir četras nodaļas 1. Vikingu laikmets Skandināvijā un Austrumbaltijā 7.-11.gs. 2. Arheoloģiskās liecības par militārajiem konfliktiem starp skandināviem un Austrumbaltijas iedzīvotājiem. 3. Arheoloģiskās liecības par tirdzniecības un kultūras kontaktiem starp skandināviem un Austrumbaltijas iedzīvotājiem. 4. Skandināvijas un Austrumbalt…
A comparative life-cycle assessment of asphalt mixtures for railway sub-ballast containing alternative materials
2018
Abstract Bituminous sub-ballast in railway track-bed can mitigate the variation of the moisture content in the subgrade and reduce vertical stiffness variations of the track leading to a more durable infrastructure. Nevertheless, durability is only one of the aspects that affects the sustainability of an infrastructure. Other relevant aspects are related to the environmental and economic issues. This research work joins the worldwide effort towards a paradigm shift in civil engineering devoted to assess the sustainability of infrastructures at the design stage. With this in mind, in this study different alternative bituminous sub-ballast mixtures containing recycled materials, namely crumb …
Comparison between bitumen modified with crumb tyre rubber and styrene butadiene styrene
2009
The improvements in terms of mechanical properties due to the use of polymers to modify bitumens in road paving applications have already been widely demonstrated. The aim of this paper is to show how the rheology and the performance of a bituminous binder mixed with crumb rubber recycled from used tyres (CR-MB), could be comparable with a styrene butadiene styrene (SBS-MB) created with the same base binder and currently used for road applications. Physical, chemical and performance characterization followed by rheological and storage stability analyses have been undertaken as the basis for the comparison. The results of the investigation indicate that the blended CR-MB shows large improvem…
Analytical approach for the mix design optimisation of bituminous mixtures with crumb rubber
2018
The present paper provides a basis for defining a mix design method specifically tailored to rubberised asphalt that takes into account the behaviour of crumb rubber. An analytical approach to quantifying the recovered deformation of crumb rubber in the post-compaction phase has been developed in order to adjust the number of gyrations proposed by the Superpave method for compacting specimens of hot mix asphalt using a Superpave gyratory compactor. The maximum allowable amount of rubber has been calculated. Finally, a step-by-step protocol has been proposed in order to fabricate and compact crumb rubber modified mixtures with the gyratory compactor.
Increased Stability of Rubber-Modified Asphalt Mixtures to Swelling, Expansion and Rebound Effect during Post-Compaction
2017
The application of bituminous mixtures modified with rubber from scrap-tires require attention and care during mixing and compaction. Rubber modifies the properties because it reacts in the internal structure of bitumen at high temperatures changing the performance of the mixture (interaction process of solvents with binder-rubber aggregate). The main change is the increasing of the viscosity and elasticity of the binder due to the larger sizes of the rubber particles by dry process but, this positive effect is counteracted by short mixing times, compared to wet technology, and due to the transport processes, curing time and post-compaction of the mixtures. Therefore, negative effects as sw…