Fatigue Life of Asphalt Pavements on Bridge Decks

AbstractPavement is one of the basic elements of a bridge structure. In Europe and Poland pavements for engineering objects are made in the asphalt technology. Requirements for ensuring the sustainability of the entire object also refer to pavement. Fatigue life is one of the parameter that must be satisfy but there is no requirements connected with it. It is directly related to the stresses and strains which occur in the pavement. Based on a state of art and using calculation results of software with finite element method (FEM) the strains in characteristic points of the bridge pavement were presented. Strains in pavements on the soil, concrete and steel deck were compared. One of the classic and one of the modern criteria for fatigue life were described. Calculation models for fatigue life of asphalt pavement does not classify separately bridge pavements. A typical technology and materials used in the bridge deck pavements were presented. Fatigue life of asphalt bridge pavements were estimated. The analysis of the results and evaluation of the adequacy of fatigue life models were made

Przyjazne dla środowiska naturalnego rozwiązania materiałowo-technologiczne nawierzchni drogowych

In recent years road construction is a subject of dynamic changes. The main challenge for designers and technologists is to develop durable and environmental friendly road technologies that can be successfully applied on natural valuable areas. The paper presents selected modern material and technological solutions used for road pavements on areas under special protection (eg Natura 2000). An example of modern environmentally friendly solutions in road construction are: asphalt pavements with the addition of rubber from used car tires, asphalt mixtures with reduced emissions of volatile substances, “quiet” pavements, pavements from recycled materials and from local materials, “biologically active” pavements (permeable mineral layers). Modern and ecological pavements are the important part of science activity of Warsaw University of Technology. New ongoing project is designed to identify the main directions of technological development of road construction in the next 30 years, with a particular emphasis on the sustainable development and environmental protection. As a part of the two ongoing projects, test sections of pavement have been completed. One of test sections with the addition of crumb rubber and the second one as a “quiet” pavement. For the next years, the sections will be monitored.The proper selection of materials and technologies on natural valuable areas does not deteriorate the durability of road pavement, comfort and safety on the roads and at the same time it can improve environmental safety without interfering with the functioning of valuable ecosystems.Budownictwo drogowe podlega w ostatnich latach dynamicznym zmianom. Podstawowym dążeniem projektantów i technologów jest opracowanie trwałych i przyjaznych środowisku technologii drogowych, które z powodzeniem mogą być stosowane na obszarach przyrodniczo cennych. W artykule przedstawiono wybrane nowoczesne rozwiązania materiałowo-technologiczne stosowane do budowy nawierzchni na obszarach podlegających szczególnej ochronie (np. Natura 2000). Przykładem nowoczesnych proekologicznych rozwiązań technologicznych w budownictwie drogowym są: nawierzchnie asfaltowe z dodatkiem gumy ze zuży-tych opon samochodowych, nawierzchnie asfaltowe z mieszanek o obniżonej emisji substancji lotnych, „ciche” nawierzchnie, nawierzchnie z wykorzystaniem materiałów z recyklingu, nawierzchnie z materiałów lokalnych, nawierzchnie „biologicznie czynne” (przepuszczalne warstwy mineralne). W Politechnice Warszawskiej, od wielu lat realizowane są projekty badawcze dotyczące tematyki nowoczesnych i ekologicznych nawierzchni drogowych. Jednym z nich jest projekt mający na celu zidentyfikowanie głównych kierunków w jakich rozwijać się będzie technologia budowy dróg w perspektywie 30 lat, ze szczególnym uwzględnieniem zasad zrównoważonego rozwoju i ochrony środowiska. W ramach realizowanych obecnie dwóch projektów, zostały wykonane odcinki doświadczalne nawierzchni z dodatkiem gumy oraz odcinki doświadczalne w technologiach ograniczających hałas, które poddawane będą wieloletniemu monitoringowi.Właściwy dobór materiałów i technologii drogowych na obszarach przyrodniczo cennych nie pogorszy trwałości nawierzchni, komfortu użytkowania i bezpieczeństwa na drogach a jednocześnie poprawi bezpieczeństwo ekologiczne, nie zakłócając funkcjonowania cennych ekosystemów

Flexible pavement rehabilitation with continuously reinforced concrete slab with HFRP bars - mechanistic analysis

Asphalt road pavements are subject to damage under the influence of loads from the traffic of vehicles and of the environmental factors. One of the ways to strengthen damaged flexible pavements is to apply a cement concrete overlay with continuous reinforcement. The purpose of this paper is to analyze the road structure with concrete overlay with continuous reinforcement HFRP composite bars, which is laid on the existing cracked asphalt layers of a typical flexible road of KR3 traffic category. In HFRP bars some of the basalt fibers have been replaced with carbon fibers with the addition of resin binders. This do the possibility of making concrete slabs with increased resistance for environmental aggression, with good mechanical properties, which is especially important in the case of road constructions. An analysis of fatigue life of the strengthened asphalt pavement with a concrete slab with continuous reinforcement of HFRP bars was carried out, implementing the mechanistic model of the pavement structure. The stress analysis in the structure under the action of static loading was determined by the Finite Element Method using the Abaqus/Standard program. The maximum value of stress caused by temperature gradient in the concrete slab was calculated from the Westergaard’s formula for infinite slab. It has been shown that strengthening the analyzed road pavement with a continuous reinforcement is a technology that ensures an increase in fatigue life and reinforcement with HFRP bars further increases durability due to the negative impact of environmental factors

Prognozowanie rozwoju technologii drogowych na podstawie metody delfickiej – wybrane zagadnienia

An objective of this research project is an analysis of development directions of new materials, technologies and pavement structures used in road industry, taking into account special environmental conditions and sustainable development rules. Results of the first round of conducted study based on the foresight method are described in this paper. Such results are helpful to provide support for making a long term strategy decisions by the government. Selected results and analysis in the scope of identification of the main research areas and hypothesis connected with developments of road technology are shown in this paper with a special focus on the construction of the durable pavements. It was found that the most important task is related to developments of the asphalt and cement pavements technology providing at least 30 years durability period. The construction of such pavements is possible only when high quality of work is provided and there is further road technology development as a result of the science and industry cooperation.  Celem realizowanego projektu badawczego jest analiza kierunków rozwoju nowych materiałów, technologii i konstrukcji nawierzchni stosowanych w budownictwie drogowym z uwzględnieniem szczególnych uwarunkowań środowiskowych i zasad zrównoważonego rozwoju. W artykule przedstawiono wyniki pierwszej rundy badania eksperckiego w którym wykorzystano metodę foresightu. Badania studialne przydatne są w informowaniu decydentów politycznych oraz środowisk opiniotwórczych o pożądanych kierunkach długoterminowego rozwoju i zmian. W niniejszym artykule przedstawiono wybrane wyniki badań i analiz w zakresie identyfikacji głównych obszarów i tez badawczych związanych z prognozowanymi kierunkami rozwoju budownictwa drogowego. Omówiono zidentyfikowany obszar badawczy dotyczący technologii budowy trwałych nawierzchni drogowych w Polsce. Wykazano, że najważniejszym obecnie zadaniem w zakresie budowy nawierzchni drogowych jest prowadzenie prac nad rozwojem technologii asfaltowych i z betonu cementowego, które zapewnią co najmniej 30-letnią trwałość nowo budowanym nawierzchniom. Stwierdzono, że budowa trwałych nawierzchni drogowych jest możliwa tylko w przypadku zapewnienia wysokiej jakości wykonawstwa robót oraz rozwoju badań w ramach współpracy jednostek naukowych z szeroko pojętą gospodarką

Advanced adenoid cystic carcinoma (ACC) is featured by SWI/SNF chromatin remodeling complex aberrations

Abstract Purpose Adenoid cystic carcinoma (ACC) is a rare neurotropic cancer with slow progression occurring in salivary glands and less frequently in other body parts. ACC is featured by hyperchromatic nuclei and various mutations in genes encoding chromatin-related machineries. The ACC treatment is mainly limited to the radical surgery and radiotherapy while the chemotherapy remains ineffective. As the knowledge about molecular basis of ACC development is limited, we investigated here the molecular features of this disease. Patients and methods This study included 50 patients with ACC. Transcript profiling of available ACC samples vs normal salivary gland tissue, quantitative real-time PCR (qRT-PCR) transcript level measurements and the immunohistochemistry (IHC) for SWI/SNF chromatin remodeling complex (CRC) subunits and androgen receptor on surgery-derived paraffinembedded samples were performed. Results Transcriptomic study followed by Gene Ontology classification indicated alteration of chromatin-related processes, including downregulated transcript levels of main SWI/SNF CRC subunits and elevated expression of BRM ATPase-coding SMARCA2 gene in ACC. Subsequent IHC indicated broad accumulation of BRM ATPase and several SWI/SNF subunits, suggesting affected control of their protein level in ACC. The IHC revealed ectopic, heterogeneous expression of androgen receptor (AR) in some ACC cells. Conclusions Our study indicated that ACC features aberrant expression of genes controlling chromatin status and structure. We found that the balance between SWI/SNF classes is moved towards the BRM ATPase-containing complex in ACC. As BRM is known to be involved in chemoresistance in cancer cells, this observation may be the likely explanation for ACC chemoresistance

Rheological properties of materials used in bridge asphalt pavement structures

One of the elements that determine the durability of bridge structures is the bridge pavement. The durability of"br" bridge pavements depends on two main factors: traffic load and climatic conditions. Bridge deck surfaces might"br" exceptionally become exposed to extreme low and high temperature conditions. Stresses and strains in this type"br" of construction are different from those of the road surfaces located on the soil. Bituminous binders and asphalt"br" mixtures are thermoplastic components of waterproofing layers and surfacing. Their properties vary depending on"br" the temperature. This paper presents the laboratory test results of rheological properties of asphalt mixtures for"br" bridge pavements. The research plan included typically used asphalt mixtures - asphalt concrete (AC), stone mastic"br" asphalt (SMA) and mastic asphalt (MA). A new type of mixtures, stone mastic asphalt with high grit content SMAMA,"br" were also tested. Paper presents test procedure for determining the stiffness of asphalt mixtures on cylindrical"br" samples. Samples preparation and test method of direct tension–compression on cylindrical specimens (DTC-CY)"br" were discussed. The selected results of dynamic modulus and phase angle at different temperatures and varied"br" frequencies were presented. These parameters describe the visco-elastic properties which determine the durability"br" of bridge pavements. The results were presented as a leading curves, black curves and Cole-Cole graphs. A"br" comparison of the results of asphalt mixtures with the results of binder in dynamic shear rheometer DSR was"br" performed. The functional evaluation of the asphalt mixtures was extended for fatigue life test and rutting"br" resistance. The results of conducted research proved that the types of asphalt mixture affect the viscoelastic"br" properties and durability of bridge pavements