Experimental Investigation on the Mechanical Properties of Polypropylene Hybrid Fiber-Reinforced Roller-Compacted Concrete Pavements

To explore the effect of multi-scale polypropylene fiber (PPF) hybridization on the mechanical properties of roller-compacted concrete (RCC), the early-age (3, 7, 14, 28 days) compressive strength, splitting tensile strength and uniaxial tensile test of RCC reinforced with micro-, macro- and hybrid polypropylene fibers were investigated. Then, the tensile stress–strain curve of polypropylene fiber-reinforced roller-compacted concrete (PFRCC) and the corresponding tensile parameters were obtained. The uniaxial tensile constitutive equation of PFRCC and fiber hybrid effect function was also proposed. Finally, the enhancement mechanism of fiber hybridization on mechanical properties of RCC was analyzed. The results indicated that the strength and toughness of PFRCC improved with the incorporation of PPF, showing obvious plastic failure characteristics of PFRCC. Before curing the concrete for 7 days, micro-PPF played a major role in strengthening RCC, while macro-PPF played a major role in reinforcing concrete after that. Moreover, the tensile strength and toughness indexes of multi-scale PFRCC performed the best, indicating the positive hybridization of three types of PPF. The proposed PFRCC uniaxial tensile constitutive equation and fiber hybrid effect function based on existing researches were also well matched with the experimental results.

Mechanical Properties of Hybrid Fiber Reinforced Rubber Concrete

Orthogonal experiments were designed for hybrid fiber rubber concrete (HFRC). The mechanical properties of HFRC were tested and compared with ordinary concrete. The effects of basalt fiber volume ratio (VBF), PVA fiber volume ratio (VPF) and rubber volume ratio (VR) on the compressive strength, splitting tensile strength and flexural strength of HFRC were analyzed. The results show that the strength of HFRC is the best when the volume ratio of basalt fiber is 0.3%, the volume ratio of PVA fiber is 0.2% and the volume ratio of rubber is 5%. Basalt fiber has the greatest influence on the strength of HFRC. The strength of HFRC mixed with hybrid fiber is greatly improved, which reflects the good fiber “positive hybrid effect”. With the increase of rubber volume ratio, the strength of HFRC decreases gradually. With the help of SEM and EDS, the toughening and cracking resistance mechanism of the fiber to HFRC was analyzed. Finally, the strength of HFRC was predicted by model.

The Impact of Local Parties on Party System Institutionalisation in Post-Conflict Aceh

While there has been a flurry of research on party system institutionalisation (PSI) and regionalist parties, very little research has been conducted on their imbrication. This study aims to fill this gap by analysing the impact of local parties on the party system in post-conflict Aceh, Indonesia. It contends that the presence of local parties in Aceh has had a hybrid effect on the institutionalisation of the party system. Similar to national parties, local parties in Indonesia have weak societal roots and party organisations that obstruct PSI in Aceh. That notwithstanding, local parties in post-conflict Aceh have assisted in solidifying the party system by improving the legitimacy of parties and elections and by creating a less fragmented party system. This hybrid effect is also strongly influenced by Aceh’s long wartime history and its post-conflict status.

Processes Developed Based on Friction Stir Welding Process

Considering the remarkable results obtained by using friction stir welding process (FSW), ISIM Timisoara has developed research programs for the knowledge and development of processing processes based on the FSW process principle.The paper presents a synthesis of the researches and the results obtained within some of research projects carried out by ISIM Timisoara, regarding possibilities of using some of processes derived from the FSW process, which has focused mainly on two directions (areas): surface engineering (materials surface processing) and joining by friction riveting. In the field of surfaces engineering, there are presented some results that represent own contributions of ISIM Timisoara, regarding: friction stir processing as well as coating with functional layers from lightweight alloys of steel substrates (by friction with consumable tool).Regarding friction riveting, two methods are presented: classic friction riveting, respectively friction riveting with hybrid effect (mechanical grip and friction welding).The paper shows very good results obtained to FSP processing (for cast aluminum alloys), to friction riveting with hybrid effect (for aluminum and copper alloys) and to friction riveting (for aluminum alloy), but also some limitations of these friction processing methods.Also in the paper are presented new research directions that are currently being addressed, respectively that will be addressed in the next period at ISIM Timisoara, regarding new variants of application of FSW welding.