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Abstract

In the present study, the effect of construction waste and pulverized lime on the strength of Shanghai clayey soil is investigated. The unconfined compressive strength and direct shear tests have been carried out on reinforced soils with different combinations of construction waste and pulverized lime over various curing periods. The results from unconfined compressive tests show that the compressive strength increases after introduction of construction waste and pulverized lime, and the longer the curing period the higher the strength of treated soil. The results from direct shear tests show that the shear strength parameters increase to different degree after mixing with construction waste and pulverized lime. The tests also show the increase in compressive strength is insignificant with the addition of construction waste alone, but ductility increases. The conclusions drawn from the present study are important not only for designing and construction of geotechnical engineering projects in practice, but also for making good use of waste material, sustainable development and environmental protection.

Abstract

In this paper, multiscale acoustic emission (AE) signal analysis was applied to acoustic emission data processing to classify the AE signals produced during the tensile process of C/SiC mini-composites. An established unsupervised clustering algorithm was provided to classify an unknown set of AE data into reasonable classes. In order to correctly match the obtained classes of the AE signals with the damage mode of the sample, three scales of materials were involved. Single fiber tensile test and fiber bundle tensile test were firstly performed to achieve the characteristics of AE signal of fiber fracture. Parameter analysis and waveform analysis were added to extract the different features of each class of signals in the In-situ tensile test of C/SiC mini-composite. The change of strain field on the sample surface analyzed by DIC (Digital Image Correlation) revealed the corresponding relationship between matrix cracking and AE signals. Microscopic examinationwas used to correlate the clusters to the damage mode. By analyzing the evolution process of signal activation for each class against the load, it also provided a reliable basis for the correlation between the obtained classes of the AE signals and the damage mechanism of the material.

Abstract

In view of the limitation of wide application of polypropylene(PP) with low strength, poor low-temperature brittleness and easy combustion, a kind of PP matrix nanocomposites was designed and prepared. Sb2O3 nanoparticles (nano-Sb2O3) modified by silane coupling agent of KH550 were dispersed into brominated polystyrene(BPS)-PP matrix by ball milling dispersion and melt blending method, respectively. And the nano-Sb2O3/BPS-PP composites samples were obtained by injection molding method. The effects of nano-Sb2O3 particles on mechanical properties of nano-Sb2O3/BPS-PP composites were investigated. The results showed that the surface of nano-Sb2O3 particles was successfully modified by the KH550 and the interfacial adhesion between nano-Sb2O3 and PP matrix was improved. With increasing of the mass fraction of nano-Sb2O3, the tensile strength and impact strength of nano-Sb2O3/BPS-PP composites were improved accompanying by increasing of crystallinity and refining grain of the composites. When the mass fraction of nano-Sb2O3 was 3 wt%, the tensile strength of nano-Sb2O3/BPS-PP composites was 43 MPa, which was 30.3% higher than that of PP. When the mass fraction of nano-Sb2O3 was 2 wt%, the impact strength of the composites was 44.19 kJ·m−2, which was 30.8% higher than that of PP.

Abstract

Increasingly high demands on environmental protection are intensifying the development of sustainable construction. Ventilated facades can provide an energy-efficient alternative to standard facades, that is, external thermal insulation composite systems (ETICS). The article compares standard facades, which was a reference, to ventilated facades in two variants: closed joints and open joints. The comparison was made by means of numerical simulations of computational fluid dynamic (CFD), under conditions of high outside temperature and high sunshine. The results showed great benefits of using ventilated facades in such external climate conditions. It was also observed that the selection of the variant of ventilated facade in the system of close or open joints has minimal influence on thermal efficiency of the whole partition.

Abstract

In this work, geopolymer foam composites containing waste basalt fibre (10, 30, and 50%wt) were exposed to elevated temperatures of 200, 400, 600, 800 and 1000C. With an increase in high temperature, the geopolymer foams material exhibits a decrease in compressive strength and bending strength. When heated above 600C, geopolymer foams materials exhibit a significant reduction in mechanical properties. It shows clearly with the naked eye that surface cracks in case of samples containing 10% of basalt filler. However, when increasing fillers with basalt fibres up to 30% and 50%, the cracking of the sample surface is no longer visible to the naked eye. Especially when the temperature increases, the mechanical properties also increase without decreasing in the sample of 50% by weighing to the binder. The results show that reinforcing the geopolymer foams with basalt ground fibre improves the mechanical properties at high temperatures.

Abstract

Polymer-based materials are mainly intended for structural applications in industries. Due to their competitive properties, they are used as a replacement for wood and other conventional materials. During their manufacture, fibres are reinforced into the polymer resin in different shapes as required. Among several available reinforcements, glass fibre in many researches showed the best in mechanical characters, ability to get reinforced in the matrix and handling ability. In contrast, bio-reinforcements from various natural sources are also used as an alternative and they provide an equal performance like the man-made reinforcements. When both the artificial fibre and natural fibre are used in a composite material, the composite attains the iconic characters of each reinforcement; thus, the material as a whole shows excellent characteristics. This chapter provides a clear picture on characterization of composites with glass reinforcement in sandwich form, and also shows various trends like the elevation or decline in their strengths, their possible reasons and the potential ways for elevating the characters of the composite.

Abstract

The requirement for structures with sustainable weight is in well progress nowadays. Filaments (fibres) with good capability and less weight are preferred. Sandwich consisting of fibre metal laminates replaces substantial solid metals in helicopters, air vehicles and so on. In this chapter, sandwich utilizing aluminium and glass fibre sheets with various fibre frameworks, for example, unidirectional, woven roving and chopped strand matrix, is manufactured. The composites are tested for tensile, flexural and impact. The outcomes revealed that the unidirectional glass fibre-reinforced polymer-Al stack performs better obstruction in contrast to cleaved strand and woven network under shifting stacking conditions. The cross-segment of the broken examples is seen under examined electron microscopy to dissect the holding quality among metal and fibre layers.

Abstract

Due to the unique characteristics, polymer matrix composites have been widely produced and used in various applications. In this chapter, the effects of synthetic fibres and polymers on the final characteristics of polymer composites, particularly glass fibre-reinforced polymer (GFRP), are discussed. Additionally, the influence of machining processes on the generation of delamination and development of defects in GFRP are elaborated. Finally, the delamination assessment as a major defect caused by machining processes is modelled by an algorithm. The proposed approach shows promising and can effectively interpret a large amount of data in a short period of time.

Abstract

Composite materials have extensive applications in creating products that we use in day-to-day life. However, due to the inhomogeneities present in the material in terms of reinforcement, the machining or processing of the same is extremely difficult. The underlying mechanisms involved in cutting such materials result in the generation of unbalanced cutting forces, rise in cutting temperature and excessive wear of the cutting tool. Such situations directly contributed to the inaccuracies in the machined feature. This chapter discusses the effects of two critical issues that occur during drilling of glass fibre-reinforced polymer composites, namely, heat generation and tool instability. Further different techniques that can be employed for quantifying heat generation, tool vibration and delamination are also discussed in brief.