Solid State Phenomena Vol. 329

Abstract: A molecular dynamic (MD) simulation, which is used for estimating mechanical properties of both microscopic and mesoscopic materials during loading/unloading processes. Understanding the deformation mechanisms of material's internal structure, shape and volume is a key step to enhance its strength and rigidity. Novel nanostructures, nanoparticles and nanocomposites, more efficient, selective, and environmental friendly can be developed and suggested. At the moment, few experimental methods can characterize molecular mechanisms due to their time-consuming and cost-intensive. Therefore, MD simulation allows to gain understanding in structure-to-function relationships involved in the low-dimensional materials. Specifically, MD simulation can be performed on the time scale of nanoseconds, and in three dimensions, it is thus sufficient for the study of the mechanical behaviors and deformation mechanisms at a molecular level. This work reviews the progress in MD simulation of the mechanical properties and structure deformations for various tubular nanomaterials including silicon, carbon and III-V compound nanotubes (NTs), respectively. In particular, we have a detailed description and analysis of the impacts of environmental and structural factors on material strength for the present nanostructures. It is hopeful that this review can provide certain reference for the follow-up research.

Abstract: The contact between the original and the new concrete layer is important from the point of view of the load-bearing capacity of the composite cross-section. In practice, we encounter that when reinforcing a concrete element with a new layer of concrete, the element is considered as a single cross-section, so no slippage between the individual layers is assumed. This article deals with numerical modeling of two contact variants. The first alternative is modeling according to the im-plemented module which contains the 3D program ATENA Cervenka Consulting and the second is using an intermediate layer and subsequent comparison of modeling methods with a real experiment.

Abstract: Asphalt mixtures have a dominant position in road construction in most countries. The choice of asphalt mixture type and surface depends mainly on the traffic loading and climatic conditions. The stiffness of asphalt mixture is one of important parameters that determines how road pavement performs and what pavement response to traffic loading. The stiffness modulus of the asphalt mixture changes during its service life, it tends to increase. During this process the mixtures in pavement age and degrade. Aging of asphalt mixtures has a significant effect on changes in the properties of individual mixtures. Presented research was focused on monitoring the change in the stiffness modulus of two asphalt mixtures AC11 50/70 and AC11 PMB 45/80-75 by the effect of aging. The asphalt mixtures have been exposed to the effects of short-term and long-term ageing by the conditioning of loose mixture method. After aging of the asphalt mixtures, the stiffness modulus of compacted asphalt mixture samples was measured. The stiffness modulus was determined using the IT-CY method at temperature of 10 °C, 20 °C and 30 °C and showed an increase after exposure of the mixture to short-term and long-term aging.

Abstract: Scrap tyres disposal revival the environmental concern except if recycled in an eco-friendly way. The inclusion of waste tyre crumb rubber (WTCRs) as a partial replacement of natural aggregate can be possible solutions for those concern. Thus, this study investigates the effect of using WTCRs at various contents (5, 10, 20 and 30% of volume) as a replacement agent of fine or/and coarse aggregate on water absorption, carbonation depth and chloride ion penetration rubberised concrete prepared with 20% ground blast furnace slag (GBFS) as Portland cement (OPC) replacement. Twelve batches are prepared by mixing the industrial wastes of GBFS and WTCRs. The results shown that modified rubberised containing 5% WRTCs as a substitute to natural aggregate, provided high durable performance such as lower water absorption, carbonation depth and chloride ion penetration compared to control specimen of traditional concrete. However, the rubberised concrete durability performance slightly trends to decrease with increasing WRTCs content from 5% to 30%, these proposed mix designs have a high potential for a wide variety of concrete industrial applications, especially in acid and sulphate risk.