Papers by Keyword: Water Absorption

Abstract: In this work, composition ratios of high-density polyethylene and polyolefin elastomer (HDPE/POE) for 60:40 and 40:60 were prepared with 10%, 20%, 30%, and 40% of corn husk fibre (CHF) by using an internal mixer. The effects of CHF content on mechanical properties, water absorption and morphology on the biocomposites were investigated. The tensile strength for the biocomposites 60:40 ratio displayed optimum at 20% of fibre content; while the biocomposites 40:60 ratio has decreasing tensile strength from 10% to 30% of fibre content. The more fibre is needed to hold the matrix in place for biocomposites with POE dominance. At all compositions, the tensile modulus for the biocomposites 60:40 and 40:60 HDPE/POE ratios exhibited increasing patterns. However, the results of impact strength and elongation at break for the 60:40 and 40:60 ratios showed declining trends. The results demonstrate the addition of CHF increases the stiffness of the HDPE/POE matrix while decreasing the composites' flexibility. The water absorption biocomposites 60:40 ratio was higher than 40:60 ratio at all compositions due to a better surface interaction in composition HDPE/POE with 40:60 compared to 60:40 ratio, and also revealed by morphological studies on fracture surface biocomposites by using field emission scanning electron microscopy (FESEM).

Abstract: The construction industry continually strives to enhance sustainability and reduce environmental impact. Developing innovative concrete materials that utilize recycled aggregates and alternative cementitious binders has gained significant attention in this context. This abstract presents a study on developing ultra-high-performance geopolymer concrete (UHPGC) by replacing fine aggregates with recycled materials. This research aims to develop UHPGC by incorporating recycled fine aggregate waste (RFAW) as a partial replacement for fine aggregate. Four different concrete mixes were prepared and tested to evaluate RFAW's influence on the performance of UHPGC, considering replacements of up to 30% of fine aggregate. The study examined the fresh properties and mechanical characteristics of the resulting material. The experimental outcomes demonstrated that adding RFAW enhanced the workability of fresh concrete, making it more easily manageable. However, the mechanical properties of the hardened concrete were slightly affected to some extent. Specifically, the compressive strength decreased from 119 MPa to 103 MPa when 30% RAW was added. Conversely, with lower replacement percentages of 10% and 20%, the concrete exhibited no reduction in strength compared to the 30% replacement levels. This reduction in strength could be attributed to a weaker bond between the geopolymer gel and the recycled fine aggregate particles. Additionally, it was observed that as the proportion of RFAW increased, the water absorption of the UHPGC also increased. This indicates that the concrete had a higher tendency to absorb moisture. Nevertheless, the findings suggest that RFAW waste could be a viable resource for producing environmentally friendly UHPGC with improved physical, mechanical, and durability properties with appropriate optimization. The outcomes of this study can promote sustainable construction practices by reducing the reliance on virgin materials and promoting the circular economy within the civil engineering industry.

Abstract: The adhesive strength and degradation behavior of the Al/resin interface was investigated under high temperature and high humidity conditions. The adhesive strength of the joint without aging was approximately 14 MPa. The value is the same as the Cu/resin joint. With progress of aging at 85°C in 85%R. H., the strength decreased rapidly in the early aging stage and decreased gradually by further aging. The strength of the Al/resin joint was inferior to that of the Cu/resin joint after aging. The fracture mainly occurred in the interface of the joint. The result of Fourier transform infrared spectroscopy analysis for the fracture surface showed that water absorption in the Al/resin joint occurs by aging and causes the degradation of the strength.

Abstract: In the present experimental research work hybrid composite is manufactured using hand lay-up technique, taking epoxy resin as matrix material and stainless-steel wire mesh along with alkaline treated and untreated pineapple leaf fiber as reinforcement. Mechanical characterization such as tensile, flexural, hardness and water absorption test were performed on the samples of developed composites as per ASTM standards. Mechanical characterization revealed that treatment of fiber is having significant effect on mechanical properties. Tensile strength and flexural strength of treated fiber reinforced composite is 132.12 % and 109.98% respectively higher than untreated fiber reinforced composite. Inclusion of wire mesh along with fiber enhanced the tensile strength by 11.22% whereas bending strength decreases by 8%. Analysis of fractured surfaces using scanning electron microscope revealed there is a lack of bonding between wire mesh and epoxy resin. Water absorption test revealed that treated fiber reinforced composite is having the least water absorption capacity of 6.63 %, wire mesh included composite is having water absorption capacity of 6.96 % and untreated fiber reinforced composite is having the highest water absorption capacity of 8.7 %.

Abstract: Natural fibers possess the advantage of low cost, abundant in quantity and biodegradability. Rising awareness about green products and supportive government regulations are likely to propel the growth in the field of green composite. In this current research, a comparative study of mechanical characteristics and water absorption behaviour of green composites incorporating Aloe Vera and pineapple leaf fibers in biodegradable matrix (polylactic acid) has been experimentally examined. Composite has been developed using compression molding technique. The effect of surface modification of fibers on mechanical properties and water absorption behaviour of developed composite was investigated. Surface treatment was done using alkaline solution of sodium hydroxide having concentration of 5%. Treatment of fiber enhanced tensile, flexural, microhardness and impact properties of developed green composite and reduces water absorption capacity. Moreover, experimental results show that Aloe Vera reinforced composites have better mechanical properties in comparison to Pineapple leaf fiber reinforced composites. Thereby having potential to be used in various engineering applications

Abstract: This paper studies the effect of both perlite and pozzolan powders as cement substituents. First, it addresses the mechanical properties of pozzolanic mortar in the short term, i.e., with a schedule of 7, 14 and 28 days. Next, in order to extend the analysis related to the porosity of the designed mortars, the water absorption is studied. The provided results indicated that the compressive strengths of the pozzolanic mortars were lower than those of the reference mortar. However, among the tested pozzolanic mortars, those containing 10% of perlite displayed superior strengths. Additionally, while the water absorption values for pozzolanic mortars were higher than those of the reference mortar, the inclusion of 10% of perlite in the mortar resulted in lower water absorption compared to the other pozzolanic mortars.

Abstract: There are the results of studies on increasing the sedimentation stability of cement-mineral suspensions intended to fill hollow spaces in fractured rocky soils and strengthen dispersed soils, as well as to prevent filtration processes in soils.To ensure the sedimentation stability of cement-mineral suspensions, it is proposed to use the water solutions of hydroxyl-containing polymers prone to swelling as a dispersion medium (mixing water): water solutions of polyvinyl alcohol (PVA) in 4% - 8% concentration. The concentration range of polymer solution from 4% to 8% was established in order to prevent coagulation during storage and to ensure the production of polymer films from water PVA solutions.The research results showed that polyvinyl alcohol provides the high kinetic sedimentation stability of cement-mineral systems determined by hydrodynamic factors as follows: the viscosity and density of the water polymer solution. The higher the viscosity and density of the water solution of polyvinyl alcohol (concentration), the higher the sedimentation stability of cement-mineral suspensions.

Abstract: This article focuses on the moister sorption by laminated composites. Moisture sorption was carried out on layered polymer composite materials consisting of layers of basalt fabric and fiberglass based on epoxy-diane resin. It is shown that the process of moisture absorption for glass fiber-reinforced polymers is more intense and with a higher concentration of moisture in comparison with basalt fiber-reinforced polymer. Curves of the sorption processes of moisture absorption and water absorption are obtained. The diffusion coefficients for the corresponding processes are calculated. Alteration in the surface structure of polymer composite materials were recorded using surface topography and REM images before and after exposure in the climate of Yakutsk (Russia).

Abstract: With the wide application of hydrogel materials in agriculture, forestry, flexible electronics, electronic information engineering, environmental detection, flexible electronics, information science, technology and so on, the development of various new functional hydrogel materials has gradually become one of the research hotspots. At present, the research on hydrogel materials is mainly focused on the preparation of various functional hydrogels by experimental methods, there is no fundamental understanding of the relationship between the “stimulus-response” and its inner microstructures. In this paper, the author uses the molecular dynamics simulation method to study the evolution of the hydrogel’s microscopic network structure, the relationship between microstructure and water absorption of hydrogels in the processes of water swelling and “stimulus-response”. The next generation of new super absorbent, high toughness, high strength and other functional hydrogels could be synthesized by the guide of this study, and these new hydrogels have a promising future to apply in new fields of technology such as flexible electronics, and biological medicine.

Abstract: A research on the influence of non-functional organosilicon compounds (OSC) - polyorganosiloxanes on the hydrophysical properties of cement systems has been carried out. Two groups of polyorganosiloxanes with the most typical structure (linear, cyclolinear, and three-dimensional) have been studied: polyorganylsilsesquioxanes and polydiorganylsiloxanes. Within the group of polyorganylsilsesquioxanes the polyphenylsiloxane (PPS) and polyvinylsiloxane (PVS) differing in the type of radical and degree of structure completion were studied. Within the group of polydiorganylsiloxanes the polydimethylsiloxane liquid (PMS-6) and dimethylsiloxane rubber (SKTN) differing in molecular weight were studied.It has been established that non-functional organosilicon compounds (polydiorganylsiloxanes, polyorganylsilsesquioxanes) are able to hydrophobize the cement systems when introduced by the method of mechanical activation. At the same time, SKTN is a powerful agent for efflorescence formation, preventing the removal of calcium hydroxide Ca (OH)₂ out of the cement stone.