Interfacial strength development in thermoplastic resins and fiber-reinforced thermoplastic composites

An experimental program to develop test methods to be used to characterize interfacial (autohesive) strength development in polysulfone thermoplastic resin and graphite-polysulfone prepreg during processing is reported. Two test methods were used to examine interfacial strength development in neat resin samples. These included an interfacial tension test and a compact tension (CT) fracture toughness test. The interfacial tensile test proved to be very difficult to perform with a considerable amount of data scatter. Thus, the interfacial test was discarded in favor of the fracture toughness test. Interfacial strength development was observed by measuring the refracture toughness of precracked compact tension specimens that were rehealed at a given temperature and contact time. The measured refracture toughness was correlated with temperature and contact time. Interfacial strength development in graphite-polysulfone unidirectional composites was measured using a double cantilever beam (DCB) interlaminar fracture toughness test. The critical strain energy release rate of refractured composite specimens was measured as a function of healing temperature and contact time

Influence of different factors to the strength development of the cement slurry with aplite as a pozzolanic material.

This study has 18 experiments which were performed in order to see the influence of different factors to she strength development of cement slurry containing Aplite. Aplite is a pozzolanic material consisting mainly from silica. It provides beneficial strength development for cement slurries curing above 110ºC, more environmental friendly than cement and more cost effective. Experiments showed that Aplite has a pozzolanic effect and prevent cement slurry from strength retrogression at the temperatures higher than 110ºC. Also it was discovered that proportional re-placement of Aplite by cement has a positive effect to the strength development. Experiments showed that curing under high pressures has positive effect to the strength development. Tem-perature has also positive effect to the strength development, but in a different way for the slur-ries curing above and under 110ºC

Strength Development and Pore Structure Characterisation of Binary Alkali-activated Binder Based on Tungsten Mining Waste

The mineralogical properties of tungsten mining waste mud (TMWM) make its valorisation and re-usage as an alumino-silicate source material to produce an alkali-activated binder without calcination is a challenge. Moreover, the dissolution of silicate and alumina species from TMWM is very slow. Despite the crystallinity of TMWM, this study demonstrates that its combination with other sources of the alumino-silicate source was the materials–such as red clay brick waste(RCBW),ground granulated blast furnace slag (GGBFS) and electric arc furnace slag (EAFS) – improved the compressive strength and the pore structure of the alkali-activated matrix.Thecombinedprecursors (90 vt.%TMWM+10 vt.%RCBW, 90 vt.%TMWM+10 vt.%GGBFS, and 90 vt.%TMWM+10 vt.%EAFS) were activated using a combination of alkaline activator solutions (sodium silicate and sodium hydroxide) with the ratio of 1:3(66.6wt.%sodiumsilicatecombined with 33.33 wt.% of NaOH 10M). The results show that the compressive strength increased from11.23MPa at 28 days to reach 24.98MPawhentheTMWMwaspartially replacedby10vt.%RCBW. In addition,this study shows that the interconnected porosity decreased where the critical pore size was reduced from 21.28 µm to 0.55 µm for the tungsten mining waste-based alkali-activated binder and the binary alkali-activated binder based on TMWM and RCBW. Keywords: Mining Waste, Alkali-activated, Microstructure, MIP, Metakaoli

Factorial Design Applied to Waste Immobilisation in Geopolymer-based Systems

Concentrated alkali, ground glass and air pollution control residues were mixed in various proportions and cured for up to 28 days. These blocks were tested in strength and analysed by thermal gravimetric analysis to assess the success of the geopolymerisation process. A Taguchi factorial design approach was then adopted to investigate the effects of different variables upon the strength development of these blocks

Strength development of fly ash based composite material

The term „fly ash‟ is often used to describe any fine particulate material precipitated from the stack gases of industrial furnaces burning solid fuels. The amount of fly ash collected from furnaces on a single site can vary from less than one ton per day to several tons per minute. The characteristics and properties of different fly ashes depend on the nature of the fuel and the size of furnace used. Pulverization of solid fuels for the large furnaces used in power stations creates an immediate, urgent problem; dry fly ash has to be collected from the stack gases and disposed of quickly and safely. Fly ashes generally fall into one of two categories, depending on their origin and their chemical and mineralogical composition. Combustion of anthracite or bituminous coal generally produces low-calcium fly ashes; high-calcium fly ashes result from burning lignite or sub-bituminous coal. Both types contain a preponderance of amorphous glass. Composite material made of fly ash is used in many ways and is subject to a variety of different loading conditions, and so different types of stress develop. The compressive strength of concrete, one of its most important and useful properties and one of the most easily determined, is indicated by the unit stress required to cause failure of a specimen. In addition to being a significant indicator of load-carrying ability, strength is also indicative of other elements of quality concrete in a direct or indirect manner. In general, strong concrete will be more impermeable, better able to withstand severe exposure, and more resistant to wear. On the other hand, strong concrete may have greater shrinkage and susceptibility to cracking than a weaker material. Finally, the concrete-making properties of the various ingredients of the mix are usually measured in terms of the compressive strength

Fatigue tests on big structure assemblies of concorde aircraft

Fatigue tests on structural assemblies of the Concorde supersonic transport aircraft are reported. Two main sections of the aircraft were subjected to pressure, mechanical load, and thermal static tests. The types of fatigue tests conducted and the results obtained are discussed. It was concluded that on a supersonic aircraft whose structural weight is a significant part of the weight analysis, many fatigue and static strength development tests should be made and fatigue and thermal tests of the structures are absolutely necessary

Modelling the effects of waste components on cement hydration

Ordinary Portland Cement (OPC) is often used for the Solidification/Stabilization (S/S) of waste containing heavy metals and salts. These waste componenents will precipitate in the form of insoluble compounds onto unreacted cement clinker grains preventing further hydration. In this study the long term effects of the presence of contaminants in solidified waste is examined by numerically simulating cement hydration after precipitation of metal salts on the surface of cement grains. A cement hydration model was extended in order to describe porewater composition and the effects of coating. Calculations were made and the strength development predicted by the model was found to agree qualitatively with experimental results found in literature. The complete model is useful in predicting the strength and leaching resistance of solidified products and developing solidification recipes based on cement

An Investigation of the Influence of Shearing Forces on Pulp Strength

This thesis attempts to determine the importance of shearing forces in the strength development of a pulp. Theoretically, if these shearing forces are able to flex the fibers and thereby reduce their stiffness, it follows that more intimate fiber to fiber contact will result with a related higher bonded area and consequent increased paper strength. The pulp was subjected to the shearing forces in a Day sigma blade kneader at a high consistency. The treatment time was increased in sequence in an attempt to obtain the maximum strength development these shearing forces could produce. The work certainly demonstrated that shearing forces can play an important role in strength development of a pulp. This does not mean to imply that they necessarily do in the conventional processes, however, for other possibly dominating factors in stock preparation such as fiber bruising may affect the strength development before the shearing forces have had ample opportunity

Physico-mechanical properties of polymer concrete containing micro-filler of palm oil fuel ash

Objective of this study is to present a research conducted on ground (fine) and unground (coarse) POFA in polymer concrete (PC) followed by determination on the physico-mechanical properties of PC. Physical properties of micro-fillers and mechanical properties of produced PCs were characterized. Calcium carbonate and silica sand were also used as micro-fillers for comparison purpose. The samples were subjected to compression and flexural. Morphology images of the particles were captured under morphology test to support the findings. Results showed that fine POFA micro-filler has a highly promising potential in becoming PC filler compared to coarse micro-filler. Additionally, its produced PC had comparable strength to PC with calcium carbonate. From the strength development and sustainability stand point, fine POFA has demonstrated its capability to produce quality and sustainable P