Laboratory Evaluation of a Vertical Vibration Testing Method for an SMA-13 Mixture

In order to simulate the on-site compaction conditions of a Stone Matrix Asphalt (SMA) mixture, The Vertical Vibration Testing Method (VVTM), Superpave Gyratory Compactor (SGC), and Marshall method are used to test the SMA-13 mixture, and the physical and mechanical properties of the asphalt mixture designed by these three methods are tested. Subsequently, the influences of the molding method on the mechanical properties are compared. The influence of vibration compaction time on the volume parameters of the SMA mixture is studied. Following the heavy traffic compaction standards, the vibration compaction time of the SMA mixture is determined. The results show that the densities of the heavy Marshall specimen, VVTM specimen, and SGC specimen are 1.018 times, 1.019 times, and 1.015 times greater than that of the standard Marshall specimen, respectively. The passing rate of the 4.75 mm aggregate of the standard Marshall specimen is 29.9%, and that of the VVTM specimen and SGC specimen is 31.1% and 30.5%, respectively, while that of the heavy Marshall specimen is 34.5%. The mechanical strength of the specimen can be greatly improved as the density increases. On the other hand, by the same compaction work, the mechanical strength of the VVTM specimens can be increased by at least 7% compared with the heavy Marshall specimen. The mechanical strength of the VVTM specimen is increased by at least 22% compared with the standard Marshall specimen. The results also show that under the optimal asphalt-aggregate ratio and the same compaction work, the compressive strength and shear strength of the VVTM specimens are increased by at least 6% and 9%, respectively, compared with the Marshall specimens. In summary, the performance of the asphalt mixture designed by the VVTM is superior, providing a wider choice for future asphalt mixture design.

Research of Preparation of Defect Cocoons for Unreeling and Technology for Producing Silk-Raw With High Linear Density

The article examines the yield of defective cocoons according to the feeding season of the silk moth and hybrids, determines the increase in the yield of defective cocoons in the second and third season by 2 and 6% compared to the first season. It is proved that in order to obtain raw silk of grade 4A; cocoons must be unwound separately by grades. Determining the indicators of defective cocoons after processing, the possibilities of unwinding with a speed of 110-130 m / min were revealed. Studying the time of filling cocoons in a rose while regulating leukemic density, the compaction time was determined for raw silk with a high linear density and it was recommended to use the obtained raw silk for the production of silk carpets.

Experimental Study on the Mechanical Properties of Biomass Briquettes from a Mixture of Rice Husk and Pine Sawdust

In search of guaranteeing global energy requirements, waste from different agricultural, forestry and industrial sources is presented as a renewable and sustainable energy source. The manufacture of solid fuels from biomass based on the densification of this to improve its mechanical and energy properties is one of the mechanisms of viable energy production from the technical-economic point of view. The biomass mixture is one of the topics currently researched, in which various factors can affect the final behavior of the briquettes. In this research the influence on the mechanical properties of briquettes obtained from the mixture between two biomasses is studied: rice husk and pine sawdust. A mixed factorial experimental factorial design is used, in which the process temperature, the proportion of the rice husk biomass over the total mass, and the compaction time are defined as experimental factors. Experimental statistical models are obtained that partially explain the behavior of several responses that characterize the mechanical properties of the briquettes based on the selected independent parameters. It was found that the mechanical durability of the briquettes is higher than 97.5%, meets the existing standards, like German Institute for Standardization (DIN) 51731, Theological Institute Batista Ebenézer (ITEBE) SS187120 or International Organization for Standardization (ISO) 17225-2, for a compaction temperature of 110 °C and a proportion of rice husk that does not exceed 60% of the total biomass mixture in the briquette. The compaction time was also statistically significant to achieve a briquettes density and an appropriate elasticity modulus in the briquettes. The results of this research are of interest and can serve as a starting point for the design of the industrial process of densification of these two mixed biomasses.

Shrinkage Characteristics and Modeling of Cement Stabilized Road Pavement Bases: A Compaction Delay Investigation

One of the main failure modes of a cement-stabilized road pavement base is the shrinkage cracking which could lead to negative consequences up to the failure of road pavements. The compaction time delay and cement content inherently affect to the shrinkage characteristics of the cement stabilized base course. This research aims to investigate the shrinkage characteristics with respect to the compaction time delay of a cement-stabilized base material through laboratory experiments. A series of shrinkage tests were performed on cement stabilized base samples with varying 3%, 4% and 5% of cement contents under controlled compaction delay periods varied from 0.5 hours to 1 day. The results of this study showed that shrinkage values of the study cement stabilized base increase with longer compaction time delay periods and cement contents. In addition, during an early stage (1-14 days) of shrinkage tests, shrinkage sharply increases before reaching the stage of a relatively constant rate after 14 days of testing. It would also be further notice that around 80% of the maximum shrinkage values from all tests gains in a test period between 14-21 days out of 42 days of a total shrinkage measurement period. Finally, the mathematic shrinkage model was formulated based on the test results of the study. In the model, the main factors of compaction delay time, cement content, and curing periods were used as the model variables. Shrinkage values can be predicted with a reliability of the R2 value of 0.6755.

Cassette Installation with Active Working Body in the Separating Partition

The article explores the vibration form for forming single-type Ferro-concrete products, where the partition walls as an active working body has the opportunity to be involved in resonance oscillations, which allows to reduce the compaction time and reduce the energy costs for manufacturing products. Partitions dynamic characteristics the as well as the effect of the partitions oscillations on the sealing medium are studied mathematically.