The impact of a pipeline by a dropped object has been considered to consist of four distinct impact components: the dropped object, pipeline protection, the soil bed and the pipeline itself. The effect of these components as energy absorbers and the effect on system response has been investigated. Quasi-static and dynamic testing has been earned out to investigate the interaction between the various impact components. Quasi-static testing has been widely used to develop initial predictions, since closer observation of interaction is easier. The validity of applying these predictions to dynamic situations has been addressed using results from dynamic impact testing. The Dropped Object: Two areas have been investigated which address the dropped object within the impact system: the dropped object's impact profile and its deformability. Testing has been carried out to study the effect of typical loading profiles. Research has shown that the dropped object profile significantly effects the pipe response; a cone shaped indentor generates deformation with far less energy than either a wedge or a patch shape. The applicability of a method to predict the interaction between two deforming structures, using a method of shared energy, has been investigated for quasi-static and dynamic loading. During quasi-static testing it was found possible to predict a combined response using individual responses. During dynamic testing prediction was not possible, since inertia effects where found to dominate the response. The Concrete Protective Coating: A programme of work carried out has qualified the role of a pipeline protective coating and assessed the effect of four different types of concrete reinforcement. Summary Although the study has not been exhaustive, it is clear that reinforcements, which hold the concrete coating to the pipe, allow the coating to continue its protection. Fibres added to a concrete mix were found to reduce the damage to the pipe. However mesh reinforcements were found to hold the concrete together most effectively and provided the greatest added protection. The Soil Support: All foundations absorb some energy. Tests have been carried out to investigate the effect of a soil bed on the response of a laterally loaded pipeline. During dynamic tests on sand supported pipes it was noted that no energy was absorbed during the initial deformation, possibly corresponding to local indentation of the pipe wall. After this the sand was seen to react and absorbed a proportion of the energy, depending on the hammer's drop height. The energy absorbed by the soil continued to increase until an energy plateau was reached, after which the soil absorbed no further energy. It was noted that the displacement at which this energy plateau was reached increased as the drop height increased. Two possible causes of the energy plateau have been discussed. The first cause questioned an assumption that the pipe would deform as if on simple supports. The second possible cause suggested a change from dynamic to quasi-static response and investigated the relationship between acceleration, velocity and reaction force. Of the possible causes of the energy plateau, the most likely is thought to be soil related. Investigation into the Deformation of Locally Loaded Pipes: The investigation into pipeline deformation has been carried out using experimental, numerical and theoretical analysis methods. Quasi-static test results have been used to investigate four pipeline parameters and their influence on energy absorbed by the pipeline, (length, L, wall thickness, t, diameter, D and material yield stress, ay). This investigation led to an empirical equation, which brought all energy-displacement (E-8) curves on to a common curve, for a wide range of these variables. This empirical relationship has been developed to predict deformation, for the range of parameters investigated. Dynamic results obtained were normalised using these empirical equations and data was seen to fall into two broad groups, one group comprising seam welded pipe and one group comprising cold drawn pipe. Strain rate effects were proposed as the most likely cause of this bi-grouping. Limitations in the experimentally derived empirical relationship have been identified, resulting from an insufficient range of pipe samples tested.

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The aim of this study was to investigate the diffusion of chloride ions into concrete samples that were exposed in scenarios that simulate the splash, tidal, atmospheric, and immersed portions of a marine structure. To study the atmospheric deposition, the project also investigated the relationship between chloride ion deposition on the wet candle and its accumulation into concrete samples. Results from the wet candle experiment indicated that between 2% and 45% of the chlorides deposited per square meter of exposed area could be found within the concrete samples. After 6 months, slag G1a blocks showed the most resistance to chloride penetration in the tidal and splash simulations. After 10 months of exposure, fly ash samples had the slowest rates of diffusion in the tidal simulation while the fly ash + silica fume samples and the slag samples measured similar rates of diffusion within the tidal zone. After 90 days of curing, cylinders composed of 20% fly ash & 8% silica fume measured the highest average resistivity values and were found to be less vulnerable to chloride ion penetration than the 20% fly ash and the 50% slag concrete through rapid migration tests. / by Victor Anthony Echevarria. / Thesis (M.S.C.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

Hard-burnt magnesium oxide (MgO) has been successfully used in large volume concrete, mainly dam construction in China, for thermal shrinkage reduction since the 1970’s. At ~4% addition to the cement by weight, it is much simpler than conventional shrinkage measures and in particular, reduces the quantity of crack control reinforcement used. The mechanism is similar to conventional ettringite-based and lime-based expansive admixture relying on their expansion to offset concrete shrinkage. In other words, the tensile stresses induced by concrete shrinkage are offset by the compressive stresses induced by MgO expansion under a restrained condition so that shrinkage and cracking can be reduced. While there are technical specifications in China for this application, the production of MgO is not robust enough to produce specified MgOs, and thus specific performance cannot be specified or guaranteed. In addition, there has been very little rigorous scientific research work in the literature on the performance mechanisms and controlling variables. These issues have hindered the application of the unique designable expansion characteristics of MgO and have limited the application in thermal shrinkage reduction. Hence, this PhD study aims to investigate the expansive characteristics of a number of commercially available MgOs used as an additive and evaluate their shrinkage reduction in cement and concrete. This work also presents a literature review of MgOs, particularly from Chinese sources, and a thorough evaluation of the expansion characteristics and shrinkage reduction capabilities of MgOs with different reactivities in both cement paste and concrete. To this end, four different reactivity MgOs obtained from seawater, brine and magnesite were tested. First, cement paste and concrete prisms - both cured in water - were used for correlating MgO reactivities with expansion characteristics under unrestrained and restrained conditions. The changes in length in cement paste and concrete prisms showed that the MgO expansion rate and magnitude increased with MgO content and reactivity as well as water content. Provision of restraint in prisms both decreased the magnitude and rate of expansion. Highly reactive MgOs showed higher early age expansion and plateaued in a relatively short period while less reactive MgOs exhibited delayed expansion. Temperature increase accelerated all MgOs hydration activation. In particular, less reactive MgOs displayed rapid expansion at an early age instead of delayed expansion. With regards to unrestrained compressive strength development, it was found that the higher the MgO expansion, the greater the compressive strength reduction. Microstructural analyses confirmed the existence of MgO hydration product brucite which contributed to the expansion. While the brucite quantity increased in cement paste systems, it had an insignificant influence on cement paste pH and thus potential reinforcement corrosion resistance. Similar expansion characteristic was found in the PC-Slag cement pastes containing different reactivities of MgOs as compared to that of PC cement paste except that the PC-Slag cement pastes displayed a slightly higher expansion than PC cement at an early age but lower ultimate expansion. One high reactivity MgO (MgO-N50) and one medium reactivity MgO (MgO-92/200), with distinct expansion characteristics, were selected for evaluating the shrinkage reduction performance of cement paste in autogenous and drying curing conditions. Autogenous shrinkage of unrestrained cement paste prisms was measured using laser sensors and length comparator at an early age (< 24 hours) and long-term respectively. The results showed that autogenous shrinkage in the cement paste containing the MgOs was reduced and further decreased with MgO reactivity, content, as well as water content. Compared to PC, the slower strength development in PC-Slag cement resulted in smaller autogenous shrinkage reduction. Drying shrinkage reduction was observed at an early age in both PC and PC-Slag unrestrained cement paste containing the MgOs at water-to-bonder (w/b) ratio of 0.5, although the long-term shrinkage was higher than the control. To further investigate the benefit of early age MgO expansion in drying shrinkage reduction, the final part of the study focused on restrained concrete specimens using the restrained ring test. The results showed that drying shrinkage was reduced in PC concrete with the addition of the highly reactive MgO-N50 when the w/b ratio was increased from 0.40 and 0.50. On the contrary, drying shrinkage reduction was not observed in the PC concrete with the less reactive MgO-92/200. Neither MgOs in PC-Slag concrete showed drying shrinkage reduction. The results reaffirmed the earlier findings that MgO expansion is dependent on strength development. The combination of pre-compressive stresses, delay in tensile stress development and smaller modulus of elasticity of MgO concrete contributed to a lower stresses-to-strength ratio and thus higher resistance to cracking caused by drying shrinkage. From an engineering point of view, the high reactivity MgO-N50 characterised by early age expansion can be used for reducing concrete autogenous shrinkage as it is used for drying shrinkage effect. The less reactive MgO-92/200 with delayed expansion can be utilised in mass concrete to address thermal shrinkage.

The durability of Reinforced Concrete (RC) structures in the Marine environment is causing serious concern in the structural infrastructure. Reinforced concrete structures, exposed to aggressive environments, are expected to last with little or no maintenance for long periods of time. However, one of the most serious environmental exposures that causes degradation is Chloride Diffusion, due to shrinkage, atmospheric corrosion, and tide-induced wet and dry conditions at the air-water interfaces of coastal structures. Therefore, chloride diffusivity, which correlates with the electrical resistivity, has a significant impact on the durability of concrete. Concrete chloride diffusivity has been experimented by multiple agencies and researchers on sound concrete, but there is a considerable need for investigation of the durability of cracked concrete in the marine environment. The two test methods carried out are presented: Standardized American Society for Testing and Materials (ASTM) C1202 for Rapid Chloride Permeability (RCP) and ASTM D257 for Surface Resistivity (SR), and Nordtest (NT) Build 492 for Rapid Chloride Migration (RCM) and Bulk Resistivity (BR) for both sound (uncracked) and cracked (micro and macro) concrete. The limitations of the ASTM method, due to measurements before the steady-state migration is reached, does not account for leakage in cracked concrete, and the heating of the specimen due to higher current that increase the conductivity are indicated. The Rapid Chloride Migration test provides for the non-steady state of diffusion. Again, Bulk Resistivity, in contradistinction to Surface Resistivity is more accurate for cracked concrete. The correlation betweeen RCM-BR are plotted. Chloride Permeability/Migration is an important parameter that governs the Durability of Concrete. The principal contribution is the highlighting of the inadequacy of the current widely used standard ASTM C1202 for diffusivity testing, and the need for revision with further investigation. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

This study combined research available through literature with extensive experimental studies and substantial physical modelling to estimate the remaining ultimate life of large offshore reinforced concrete structures. Although much research has focussed on concrete degradation due to chloride ingress, corrosion of permanently submerged concrete is regarded as negligible due to the long-assumed apparent worst case of tidal or splash zone exposure. Around 350 specimens were tested with a further 200 exposed for further testing by future research groups. Specimens ranged in size from standard cubes to various beam lengths up to 1.5 metres, allowing for material and structural properties to be assessed. My original contribution to knowledge in the sector enhances the fundamental understanding of corrosion in subsea concrete, challenging the generally held belief of negligible corrosion. Results and modelling provides an improved ability to ultimately estimate the longevity of fully submerged offshore reinforced concrete. Throughout this thesis, the results from experimental works, carried out as a direct result of the lack of data or information in literature, are reported, assessed and then utilised to provide updated ultimate life estimations. With the current offshore concrete structures currently coming to the end of their service life, and the likelihood of further offshore development using concrete for the renewables sector, understanding the long-term degradation is vital in determining the most effective decommissioning and derogation options. The research carried out directly provides detailed information of the likely time-to-failure, allowing for an informed decision to be made on operational and decommissioning plans. Experimental work was carried out over four main phases; corrosion initiation due to bulk diffusion of chlorides (Phase I), corrosion propagation in low oxygen environments (Phase II), corrosion in statically and dynamically cracked sections (Phase III) and structural response of heavily corroded individual and lapped bar sections (Phase IV). Phase I work shows a marked difference between submerged exposures to seawater as opposed to NaCl solution, the unsuitability for accelerated testing with seawater and the likelihood of rapid initiation in offshore structures. Further experimental works through Phases II and III found that although exposed to low oxygen concentrations, reinforcement corrosion continued at significant rates. A variation between anode sizes on the reinforcement is noted, but critically the cross sectional area of the steel was still reduced, albeit in fewer locations. Corrosive products were visibly different, with fewer expansive products, if any, present. Additionally, this study further highlights the importance of cracking on corrosion, currently ignored by recent model codes, such as the fib Model Code 2010, up to 0.2mm crack width. A linear relationship was found between crack width and corrosion rates, with cracking above 0.1mm considered significant. The loss of cross sectional area due to propagation was determined for the given environment, and consequently further studies were initiated in an attempt to determine the relationship between this corrosion propagation and the reduced serviceability or ultimate life of concrete beams. Serviceability, defined by beam stiffness, was reduced due to bond loss along reinforcement. Most importantly, however, results prove that the loss of cross sectional area to be the critical influence on loss of ultimate life. Initial estimates on the remaining ultimate life of the large offshore structures support early rough work that the structures would last centuries. This thesis, however, has shown this is due to the ability of concrete structures with such large volumes of steel to continue to ultimately withstand loading at high corrosion percentages and not due to negligible corrosion, or long initiation periods, commonly suggested in submerged, low oxygen environments.

This research was conducted to better understand the corrosion propagation stage on dry-cast reinforced concrete pipes (DCRCPs) while exposed to high moisture conditions and chlorides. Corrosion initiation and propagation were studied in instrumented specimens obtained from segments of dry-cast reinforced concrete pipes. All specimens were subjected to accelerated chloride transport by the application of an electric field. Corrosion of the steel wire mesh initiated after a few days to a few months rather than several years. The specimens were then transferred to high moisture environments (immersed in water, high humidity and/or covered with wet sand) during the corrosion propagation stage. Reinforcement potentials, linear polarization resistance (LPR) and Electrochemical Impedance Spectroscopy (EIS) measurements were carried out periodically. During the propagation stage in different exposures, reinforcement eventually reached negative potentials values (< –-0.55 Vsce), which suggest mass transfer limitations. These specimens showed no visual signs of corrosion such as cracks or corrosion products except the ones exposed to high humidity and laboratory environments; where some corrosion products have reached the concrete surface. Moreover, the apparent corrosion rate values obtained suggest high corrosion rates. No crack appearance on specimens exposed to other conditions could be explained by the porosity of the specimens; the corrosion products moved into saturated pores. It is speculated that although there might be mass transfer limitations present, the current demanded by the anode is being balanced by a larger cathode area due to macrocell effects since the high moisture conditions likely reduced the concrete resistivity and increased the throwing power. The corrected polarization resistance (Rc) was calculated by subtracting the solution resistance from the apparent polarization resistance measured. The Rc values measured over time were used to obtain the calculated mass loss (using Faraday’s Law). Most specimens were forensically analyzed and the measured mass loss compared to the calculated mass loss. The forensic examination includes the measurement of the actual corroding areas. The measured corroding areas were used to obtain corrosion current density (icorr) values. A comparison was made of the calculated corrosion current densities obtained using the linear polarization resistance method (LPR) and the extrapolation method from cyclic polarization tests. It was evident that most of the specimens’ corrosion rates were significantly high. The corrosion products filled the wet-pores inside the concrete and provide an explanation for no cracks or corrosion bleed outs being visually observed on the specimens. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

This thesis explores the past and present of concrete poetry with the purpose of finding out whether concrete poetry is still being produced in its original form, or whether it has changed. Concrete poets were not the first ones to create picture poems and similar texts. In chapter I an overview of earlier picture poetry is given. It and other precursors of concrete poetry are discussed and their possible contributions evaluated. Chapters II and III deal with the definition of concrete poetry of the mid-fifties and sixties ( pure, classic c.p.). They focus primarily on German, Austrian and Swiss poets. Manifestos are examined and individual poems are discussed in detail. The many different kinds of concrete poetry that developed after 1970 are mentioned without any further discussion.

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This study concerns the strength and behaviour of low-rise shear walls made from high-strength concrete under reversed cyclic loading. The response of such walls is often strongly governed by the shear effects leading to the shear induced or brittle failure. The brittle nature of high-strength concrete poses further difficulties in obtaining ductile response from shear walls. An experimental program consisting of six high-strength concrete shear walls was carried out. Specimens were tested under inplane axial load and reversed cyclic displacements with the test parameters investigated being longitudinal reinforcement ratio, transverse reinforcement ratio and axial load. Lateral loads, lateral displacements and the strains of reinforcement in edge elements and web wall were measured. The test results showed the presence of axial load has a significant effect on the strength and ductility of the shear walls. The axially loaded wall specimens exhibited a brittle behaviour regardless of reinforcement ratio whereas the specimen with no axial load had a lower strength but higher ductility. It was also found that an increase in the longitudinal reinforcement ratio gave an increase in the failure load while an increase in the transverse reinforcement ratio had no significant effect on the strength but influenced the failure mode. A non-linear finite element program based on the crack membrane model and using smeared-fixed crack approach was developed with a new aggregate interlock model incorporated into the finite element procedure. The finite element model was corroborated by experimental results of shear panels and walls. The finite element analysis of shear wall specimens indicated that while strengths can be predicted reasonably, the stiffness of edge elements has a significant effect on the deformational results for two-dimensional analyses. Therefore, to capture the deformation of walls accurately, three-dimensional finite element analyses are required. The shear wall design provisions given in the current Australian Standard and the Building Code of American Concrete Institute were compared with the experimental results. The comparison showed that the calculated strengths based on the codes are considerably conservative, specially when there exists the axial load.