Materials Science Forum Vol. 987

Abstract: Windy accumulated sand samples are collected in the main desert (Sandy land) in China, they are carried out the comparative tests by heavy-typed compaction and surface vibrated compression method. The results show that the effect of surface vibrated compression is stronger than that of heavy-typed compaction in general, especially when the water content is approaching to 0 or the saturation state, the former is greater than the latter by about 1g/ cm³; When the water content is about ranging from 1 % to 5 %, the former is still mostly higher than the latter, yet not much and the most is under 0.3 g/ cm³, even the former is slightly lower than the latter sometimes; When the water content is within other intervals, it shows a transitional situation. The main reason is the influence of false cohesion arising from the capillary water. In view of this, when determining the compression standard (maximum dry density) for the construction of wind-accumulated sand base, the surface vibrated compression method should be adopted, especially when it is dry compression or full water compression.

Abstract: In a conventional wharf design, batter piles are incorporated in the design as a primary lateral resistance element, however in recent years it is mostly discouraged to use batter piles in the design of wharf structure, especially in higher seismic zone. The use of seismic isolation in the design of wharf structure has been introduced since 2005 in UFC 4-152-01 code as an alternative design for wharf structure, from several studies it is shown that the usage of seismic isolation systems in wharf design has offered many benefits either in new design or structure retrofitting design. The objective of this research is to study the application of seismic isolation system on wharf structure with batter piles, with study case of the wharf design on Kendari, Sulawesi Tenggara, Indonesia. This objective will be achieved by comparing the length per width (L/W) ratio of wharf structure model to evaluate base reaction, natural period and deflection of structure, from these results, a clearer understanding about the advantages of seismic isolation system in wharf structure, so it will be encouraging the application of seismic isolation systems.

Abstract: The article presents the results of the study of the properties of the sol of silicate paint. The chemical structure of the polysilicate solutions obtained with the addition of glycerol was studied by IR spectroscopy. It is shown, that the interaction of potassium liquid glass and glycerol is weak and due to the partial replacement of hydrogen ions by potassium ions.

Abstract: Where suitable rock of only a limited size is scarce, asphalt grouting can be used to provide an impermeable armour layer of greater resistance to wave action than the component rock alone. Asphalt-grouted stone revetments provide a flexible and durable cover layer which can resists abrasion, is indifferent to chemical attack by salt water etc.The paper presents the research on the relationship between the depth of asphalt grouting penetration with the diameter of stone and asphalt viscosity to apply for designing asphalt-grouted stone revetments to protect sea dykes.

Abstract: Delayed Ettringite Formation (DEF) is an internal sulfate attack caused by heat-induced decomposition and/or prevention of normal ettringite formed during the initial hydration of cement at elevated temperature (above about 70°C) and its re-crystallization in the hardened matrix. This reaction is a physico-chemical phenomenon inducing an expansion of the cement paste that could lead to cracking of cementitious matrix. These cracks result in a decrease in the mechanical performances and durability parameters of the material. However, the internal sulfate attack is characterized by a very slow reaction kinetics and therefore it is difficult to study it in laboratories. This research developed an accelerated method focused on mortar specimens; it is based on electrochemical techniques in order to speed the leaching of alkalis that could be accelerated the DEF.

Abstract: The experimental work presented in this article examines the possibility of lowering the economic cost of UHPC. The UHPC were designed using the Linear Packing Density Model. After 7 days, the UHPC compressive strength exceeded 120 MPa. Level of compressive strength after 90 days reaching 150 MPa had been obtained with a lower dose of cement (700 kg/m³) and with the use of secondary raw materials (fly ash), without the use of dispersed reinforcement. The successful design and production proved that the use of secondary raw materials is possible, thereby decreasing the economic cost of UHPC production.

Abstract: Abrasion is the physical wear of a surface due to cyclically recurring dynamic forces and shifts. Therefore, abrasion resistance can be defined as the ability of a surface to resist wear due to friction. The paper deals with the issue of the resistance of concrete surface layers to the effects of abrasion. The research focused on monitoring the influence of different types of aggregate on increasing the abrasion resistance of concrete surfaces. Concrete surfaces with three different types of aggregate were tested: amphibolite, granodiorite and psammite. The concrete class was C35/45. Abrasion was tested using the Böhme method. The highest abrasion resistance after 28 days of maturation was found in concrete surfaces with amphibolite aggregate.

Abstract: Natural rubber is an elastomeric material to make rubber products such as toys, households, automobiles, wheel tires, medical and health care products. Natural rubber compound is one kind of polymer matrix composites (PMCs) composed of natural rubber compound acted as a matrix phase and filler acted as a dispersed or reinforcement phase. There are many kinds of fillers used in the PMCs in terms of particles, fibers, and structural sheets. Adding organic/inorganic fibers into the natural rubber composites can increase the mechanical-thermal-physical properties and sound absorption. The natural rubber embedded fiber composite samples were prepared via the vulcanization process at the curing temperature 150°C by the two-roll mill. The amount of whisker alumina (Al₂O₃), coconut coir and water hyacinth fiber were varied from 0 to 50 phr on 100 phr of natural rubber in a sulfur curing system. The obtained rubber composite samples were of good mechanical properties, low thermal conductivity and good acoustic-sound absorption, suitable for various applications such as automobile, insulation and storage tank. The obtained rubber composite with 10 phr whisker alumina added (NR-Al-10) possessed the tensile strength, Young’s modulus, elongation at break and thermal conductivity values equal to 14.38 ± 1.95 MPa, 545.63 ± 25.67 MPa, 1038.4 ± 41.45% and 0.02527 ± 0.0003 W/m.K, respectively. Furthermore, the sound absorption value of natural rubber composite added 10 phr whisker alumina (NR-Al-10) is equal to 45.09% in the range of 3000‒4000 Hz of acoustic sound level better than the pure natural compound without adding filler.

Abstract: A new multi-chamber detonation accelerator (MCDS) was applied to fabricate ZrB₂–MoSi₂ composite coating containing 20 mol.% of MoSi₂ on carbon/carbon composites. Phase composition and microstructure of the coating were characterized by X-ray diffraction and scanning electron microscopy. The ZrB₂–20MoSi₂ coating displayed compact and lamellar microstructure with porosity lower than 1%, where SiO₂ phase was uniformly distributed in the ZrO₂ matrix. The coating was well-adhered with carbon/carbon composites. Silica, m-ZrO₂, and small amount of Zr(MoO₄)₂ were formed.