When damaged, military airfields must be repaired quickly so that flying operations can resume. Due to their rapid-setting and high-strength properties, epoxy-based polymer concretes (PC) may provide a good alternative to the portland cement concrete (PCC) rapid repair mixes currently used by the United States Air Force (USAF) for their Rapid Airfield Damage Recovery (RADR) operations. Epoxy-based PCs use epoxy polymers in place of portland cement to bind together aggregate and form the composite concrete. A commercially available epoxy-based PC, referred to as Commercial Product "B" in this thesis, was tested according to the procedures stated in the Tri-Services Pavements Working Group (TSPWG) Manual M 3-270-01.08-2. This manual defines testing protocol to be used for rapidsetting rigid repair materials intended for use on rigid airfield pavement spall repairs. These tests include various ASTM standards for compressive strength, flexural strength, slant-shear bonding strength, modulus of elasticity, coefficient of thermal expansion, and slump. Commercial Product "B" was not able to set and cure within the time limits set by the TSPWG manual, but otherwise surpassed final compressive strength, flexural strength, slant-shear bonding strength, and slump requirements. However, its modulus of elasticity was below the acceptable range, and its coefficient of thermal expansion was several times higher than the maximum allowed value. In addition, a second epoxy-based PC currently under development by Luna Labs and D.S. Brown was tested for compressive strength and, in most mix designs, surpassed the minimum requirements. This PC was also field tested in a series of four (4) 2-feet by 2-feet by 8-inch deep patches placed within an 8-inch thick PCC slab. Three of these patches did not meet minimum compressive strength requirements and none of them exhibited good bonding between the PC repair material and the original PCC slab. Finally, the effect of the surface moisture content of PCC on the bonding strength and chloride ion penetration resistance when PCC is bonded to PC was tested by casting Commercial Product "B" against ordinary PCC under two different moisture conditions: surface saturated dry (SSD) and PCC that had been conditioned at 10% relative humidity (RH) for 48 hours. The bonded samples underwent three- and four-point bond flexural testing and rapid chloride penetration testing (RCPT). The bond flexural testing showed that Commercial Product "B" bonds to PCC better when the PCC has been conditioned at 10% RH rather than being at SSD conditions. No statistically significant difference was detected for RCPT between bonded samples cast under the two surface moisture conditions, but did show that samples of PCC bonded with Commercial Product "B" are less susceptible to chloride ion penetration than samples comprised entirely of PCC. The results of this thesis show that PC may be useful to the USAF for repair airfields as short term repairs, but further work is required to ensure they meet all standards set by TSPWG for rapid repair materials. They also demonstrate that, when possible, a PCC repair surface should be dried completely before PC repair material is cast against it. / Master of Science / When damaged, military airfields must be repaired quickly so that flying operations can resume. Due to their rapid-setting and high-strength properties, epoxy-based polymer concretes (PC) may provide a good alternative to the portland cement concrete (PCC) rapid repair mixes currently used by the United States Air Force (USAF) for their Rapid Airfield Damage Recovery (RADR) operations. Epoxy-based PC use epoxy polymers in place of portland cement to bind together aggregate and form the composite concrete. To test whether epoxy-based PC can be used for RADR or other airfield repair operations, a commercially available epoxy-based PC, titled Commercial Product "B" in this thesis, underwent a battery of tests as specified for potential rapid repair materials in the Tri-Services Pavements Working Group (TSPWG) manual for testing protocol for rapid-setting rigid repair materials. Commercial Product "B" was not able to set and cure within the time limits set by the TSPWG manual but otherwise surpassed final strength, bonding, and workability requirements. However, it is not nearly as stiff as ordinary PCC and it expands and contracts far more than PCC when it undergoes temperature changes. In addition, a second epoxy-based PC currently under development by Luna Labs and D.S. Brown was tested for compressive strength and, in most mix designs, surpassed the minimum requirements. This PC was also field tested in a series of four (4) patches placed within a PCC slab. Three of these patches did not meet minimum compressive strength requirements and none of them exhibited good bonding between the PC repair material and the original PCC slab. Finally, the effect of the surface moisture content of PCC on the bonding strength and resistance to chloride ions, often found in de-icing agents, when PCC is bonded to PC was tested by casting Commercial Product "B" against ordinary PCC under two different moisture conditions: surface saturated dry (SSD) and PCC that had been conditioned at 10% relative humidity (RH). The bonded samples underwent bond flexural testing and rapid chloride penetration testing (RCPT). The bond flexural testing showed that Commercial Product "B" bonds to PCC better when the PCC has been conditioned at 10% RH rather than being at SSD conditions. No statistically significant difference was detected for RCPT between bonded samples cast under the two surface moisture conditions but did show that samples of PCC bonded with Commercial Product "B" are less susceptible to chloride ion penetration than samples comprised entirely of PCC. The results of this thesis show that PC may be useful to the USAF for repair airfields as short term repairs, but further work is required to ensure they meet all standards set by TSPWG for rapid repair materials. They also demonstrate that, when possible, a PCC repair surface should be dried completely before PC repair material is cast against it.

This study identifies the cause of unstable vibrations that sporadically occur in decanting centrifuges as being caused by a combination of internal bearing clearance, conveyor unbalance and low bearing loads. These centrifuges are different from other rotating equipment common in industry (pumps, fans, compressors, electric motors) in that they are dual rotor systems – one rotor inside the other. Unbalance in either rotor can produce severe vibration of the whole machine when the running speed is close to a mode of vibration – that is, running at or near a critical speed. The external rotor, called the bowl, is subjected to an internal pressure generated by the centrifugal force of the product being separated. The internal rotor is supported from the bowl and is in the form of an auger screw. The main supporting bearings are subjected to forces from both the bowl and the auger - the liquid end bearing also supports the gearbox. Being able to predict critical speeds through numerical or computational analysis is a necessary step in the design process or for troubleshooting vibration problems. As part of the study, the main rolling element bearings were replaced by oil-film journal bearings to assess the viability of their use. Journal bearings are simpler, of lower cost and generate less noise than their rolling element counterparts. However, instability in running above the first critical speed can result due to oil film forces and internal hysteresis of the rotor assembly. The auger is asymmetric so instability in running is possible at around half the first critical speed. This study was undertaken to understand the dynamics of decanting type centrifuges and develop a methodology for identifying their critical speeds and cause of unstable vibration. In the longer term this will assist in the generation of new designs that are quieter, use less energy and have better separation efficiencies.

Given the increasing consumption of plastic materials their reuse becomes a very topical issue. Recycling the single-cleaned plastic waste is simple, these products can be used as raw material or additive in the manufacture of new products. The problem remains the energy, economic and environmental demands in sorting, cleaning and eventual regranulation of waste to a suitable feedstock. This problem can be solved using technology that is able to handle multiple-type waste thermoplastics in further useful products.

Fibre reinforced polymer (FRP) composites have been used for strengthening concrete structures since early 1990s. More recently, FRP has been used for retrofitting concrete structures for high energy events such as impact and blast. Debonding at the FRP-to-concrete interface is one of the predominant failure modes for both static and dynamic loading. Although extensive research has been conducted on the static bond behaviour, the bond-slip mechanics under high strain rates is not well understood yet. This thesis is mainly concerned with the FRP-to-concrete bond behaviour under dynamic loading. Because debonding mostly occurs in the concrete adjacent to the FRP, the behaviour of concrete is of crucial importance for the FRP-to-concrete bond behaviour. The early emphasis of this thesis is thus on the meso-scale concrete modelling of concrete with appropriate consideration of static and dynamic properties. Issues related to FE modelling of tensile and compressive localization of concrete are first investigated in detail under static condition using the K&C concrete damage model in LS-DYNA. It is discovered for the first time that dilation of concrete plays an important role in the FRP-to-concrete bond behaviour. This has led to the development of a model relating the shear dilation factor to the concrete strength based on the modelling of a large number of static FRP-to-concrete shear tests, forming the basis for dynamic modelling. Concrete dynamic increasing factor (DIF) has been a subject of extensive investigation and debate for many years, but it is for the first time discovered in this study that mesh objectivity cannot be achieved in meso-scale modelling of concrete under high strain rate deformation. This has led to the development of a mesh and strain rate dependent concrete tension DIF model. This DIF model shall have wide applications in meso-scale modelling of concrete, not limited to the topic in this thesis. Based on a detailed numerical investigation of the FRP-to-concrete bond shear test under different loading rates, taking on the above issues into careful consideration, a slip rate dependent FRP-to-concrete dynamic bond-slip model is finally proposed for the first time. The FE predictions deploring this proposed bond-slip model are compaed with test results of a set of FRP-to-concrete bonded specimens under impact loading, and a FRP plated slab under blast loading, validating the model.

The goal of this research is to investigate the behavior of polymer concrete confined with a carbon fiber sleeve used as a pile foundation. To evaluate the behavior of a confined polymer concrete pile in this research, four steps was considered. The first step of this investigation considered the mix design of polymer concrete, polymer concrete is a new material which is a combination of epoxy resin and aggregate. Instead of using a traditional mix of cement and water to make concrete, epoxy resin is used. Three dissimilar varieties of aggregate are mixed with different ratios in order to reach the maximum bulk density to obtain the maximum strength. After discovering the optimum ratio which gives the maximum bulk density, several samples of the aggregate are mixed with different ratios of epoxy resin. Next, the samples are investigated in a compression test to observe which ratios have the maximum strength and this ratio is used for a polymer concrete mix design to create a pile foundation. The pile is a built using a cast in place method and confined with a sleeve of carbon fiber. The second part of this investigation determined the structural mechanical properties of confined polymer concrete pile material. The unconfined and confined polymer concrete was tested in compression to determine compressive strength and stress-strain behavior. Similar tests were conducted on unconfined and confined cement concrete for comparison between these materials. Additional tension tests were conducted on unconfined polymer concrete. Then, a carbon fiber sleeve was tested in compression test to determine tensile strength and tension stress-strain behavior. After these tests, the confined polymer concrete is modeled in the computer program MATTCAD which is used to calculate the theoretical bending moment capacity and load-displacement curve. Finally, the confined polymer concrete is tested with the MTS 311 Load Frame in three point load flexure test to determine the experimentally bending moment capacity, load-displacement curve and compare with theoretical results. Confined polymer concrete was tested in one and two way cyclic loading to observe the ductility behavior of this material as laterally loaded piles and compared with cement concrete results in cyclic loading. The third part of this investigation determined the geotechnical mechanical properties of confined polymer concrete pile material. Cyclic Multi Degree of Freedom (CYMDOF) device was used to determine interface reaction and friction angle between confined polymer concrete and soil with interface shear test theory method. Furthermore, the same device was used to determine the friction angle of soil with direct shear test theory, and compare the friction angle results together. The last part of this investigation considered the behavior of different sized confined polymer concrete pile in different types of soil. A confined polymer concrete pile was modeled into PLAXIS and OPENSEES PL computer software to analysis pile in axial load and lateral load respectively. Furthermore, a cement concrete pile was modeled with similar software and conditions to compare these two materials.

Fiber reinforced polymer (FRP) composites have been increasingly used inconcrete construction. This research focused on the behavior of concrete columnsreinforced with FRP bars, or prestressed with FRP tendons. The methodology was basedthe ultimate strength approach where stress and strain compatibility conditions andmaterial constitutive laws were applied.Axial strength-moment (P-M) interaction relations of reinforced or prestressedconcrete columns with FRP, a linearly-elastic material, were examined. The analyticalresults identified the possibility of premature compression and/or brittle-tension failureoccurring in FRP reinforced and prestressed concrete columns where sudden andexplosive type failures were expected. These failures were related to the rupture of FRPrebars or tendons in compression and/or in tension prior to concrete reaching its ultimatestrain and strength. The study also concluded that brittle-tension failure was more likelyto occur due to the low ultimate tensile strain of FRP bars or tendons as compared to steel.In addition, the failures were more prevalent when long term effects such as creep andshrinkage of concrete, and creep rupture of FRP were considered. Barring FRP failure,concrete columns reinforced with FRP, in some instances, gained significant momentresistance. As expected the strength interaction of slender steel or FRP reinforcedconcrete columns were dependent more on column length rather than material differencesbetween steel and FRP.Current ACI minimum reinforcement ratio for steel (pmin) reinforced concretecolumns may not be adequate for use in FRP reinforced concrete columns. Design aidswere developed in this study to determine the minimum reinforcement ratio (pf,min)required for rectangular reinforced concrete columns by averting brittle-tension failure toa failure controlled by concrete crushing which in nature was a less catastrophic and moregradual type failure. The proposed method using pf,min enabled the analysis of FRPreinforced concrete columns to be carried out in a manner similar to steel reinforcedconcrete columns since similar provisions in ACI 318 were consistently used indeveloping these aids. The design aids produced accurate estimates of pf,min. Whencreep and shrinkage effects of concrete were considered, conservative pf,min values wereobtained in order to preserve an adequate margin of safety due to their unpredictability.

This work describes the construction of polymer - concrete frame of a machine tool. In particular it deals with the proposal of cast iron frame for the surface grinding machine BHP from the company KMS Brno, which should at all point replace the original cast iron frame of the same machine. The whole work is divided into two sections. First section consists of the research including a brief mention of the grinding technology in the reference to the construction of the frame of the grinding machine. Further the work deals with the theoretical knowledge regarding construction of frames of the machine. Finally it describes issues related to the technology of polymer – concrete and the production technology of parts from this material. Second section of the work consists of an engineering proposal of polymer – concreted frame considering the requirement of the main functional dimensions related from the structural measures. Subsequently the system approach and the principals for transition to the polymer – concrete construction of the grinding machine are made. The work concludes with the analysis and comparison of the two concepts (cast iron frame and polymer – concrete) in the terms of the Finite element method.

yes / A numerical method for estimating the curvature, deflection and moment capacity of FRP reinforced concrete beams is developed. Force equilibrium and strain compatibility equations for a beam section divided into a number of segments are numerically solved due to the non-linear behaviour of concrete. The deflection is then obtained from the flexural rigidity at mid-span section using the deflection formula for various load cases. A proposed modification to the mid-span flexural rigidity is also introduced to account for the experimentally observed wide cracks over the intermediate support of continuous FRP reinforced concrete beams. Comparisons with experimental results show that the proposed numerical technique can accurately predict moment capacity, curvature and deflection of FRP reinforced concrete beams. The ACI-440.1R-06 equations reasonably predicted the moment capacity of FRP reinforced concrete beams but progressively underestimated the deflection of continuous ones. On the other hand, the proposed modified formula including a correction factor for the beam flexural rigidity reasonably predicted deflections of continuous FRP reinforced concrete beams. It was also shown that a large increase in FRP reinforcement slightly increases the moment capacity of FRP over-reinforced concrete beams but greatly reduces the defection after first cracking.

The objectives of this research were to 1) compile a synthesis of information about polyester polymer concrete (PPC) from the literature; 2) conduct a scanning tour to observe PPC construction, inspect in-service PPC overlays, and discuss topics related to PPC; 3) revise the existing Utah Department of Transportation (UDOT) PPC specification; 4) document a PPC field demonstration project; and 5) perform laboratory characterization of the material properties of field-mixed PPC. The scope of the research included a scanning tour, field testing, and laboratory experimentation. The objectives of the scanning tour included observation of a PPC overlay placement, inspection of existing overlays, and discussion of selected topics related to PPC. The scanning tour comprised a 3-day visit to California. Items related to material properties, mixture and overlay design, laboratory testing, and construction and field testing were investigated. Several recommendations relevant to Utah bridge deck preservation practice were developed based on the findings and then incorporated into a revised UDOT PPC specification. The objective of the field testing was to evaluate specific aspects of construction, quality assurance, and performance of PPC overlays on concrete bridge decks. The scope of the project included testing of a PPC test section overlay and three PPC bridge deck overlays during and after construction. Hardness tests were performed on the test section placements, and hardness, skid resistance, impact-echo, impedance, and resin content determination tests were performed on each of the bridge deck overlays. The field testing yielded valuable information about PPC overlays. Recommendations regarding hardness testing, skid resistance testing, patching, and surface preparation were developed based on the findings. The objectives of the laboratory experimentation were to characterize several material properties of field-mixed PPC sampled from actual bridge deck overlay placements in Utah and compare them to properties of laboratory-mixed PPC reported in the literature. Laboratory testing was conducted on a typical PPC mixture. Properties that were measured include density, modulus of elasticity, coefficient of thermal expansion, hardness, unconfined compressive strength, splitting tensile strength, rapid chloride permeability, and resin content. Measured properties were consistent with typical ranges cited in the literature.

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