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With an increase in global energy demands, the importance of well integrity and the oilfield cements has become more important than ever as it guarantees the continuous supply of fossil fuel to fulfill the requirement of the world. Drilling operations in recent years have gone into much deeper depths to meet the global demands in hydrocarbons, geothermal, gas storage and carbon sequestration purposes. In well integrity, cement plays a crucial role as it seals/isolates the troublesome formation or thief zone meanwhile protect the casing from corrosion and giving structural support to it. Therefore, it is necessary that cement slurry characteristics should be designed according to the subsurface environment, thus a proper characterization of the mechanical properties of cement in the laboratory is mandatory get to know its behavior when exposed to downhole conditions, and cubes and cylinders are the most commonly used shapes to characterized the mechanical properties, nevertheless, American Petroleum Institute (API) does not have a recommendation for cylinders, moreover, a review of American Society for Testing and Materials (ASTM) and British standards (BS) for the UCS is given, hence a study to determine if a correlation between cubes and cylinders can be achieved is studied. Though there are many conventional additives in the market but unconventional additives like Gilsonite and Microcellulose is not extensively studied. Gilsonite is a naturally occurring additive that is derived from hydrocarbons classified as asphaltite. It has been used in water-based drilling fluid and sometimes with an oil base mud as a treatment for filtration and sloughing shale problems. Given the useful properties of Gilsonite such as impermeability, low specific gravity and its great corrosive and acidic resistance it has been used as a loss of circulation material in cement applications. Micro-cellulose (MC) has been reported as a great additive in geothermal well fluid loss curing solutions. Given the recent success of using Micro-Cellulose in curing loss circulation and providing Wellbore Strengthening, addition of some amount to the cement slurry could inevitably be an option for cement fluid loss cure. However, the Micro-Cellulose can change the hydration process on the cement due to its natural characteristics, decreasing the compressive strength of the cement at the early stages; this phenomenon will be further described in the paper This paper shows the results of more than 100 tests conducted on cement cubes and cylinders to determine if a correlation between cubes and cylinders can be obtained, cubes and cylinders samples of class H cement at room and elevated temperature were prepared, and an investigation of more than 500 test was performed to show the effect of age (up to 120 days) and temperature (23c and 75c) on class H neat, H + 4% Microcellulose and 4% Gilsonite to investigate the effect of those additives in the mechanical properties of the cement. It was observed that variation in the results existed in the UCS when cubes are compared with the cylinder, which raises the importance of the development of the new standard. The results showed the high compressive strength of the cube as much as 50% and 35% for the sample cured at high and room temperature respectively. Moreover, no correlation existed between the cylinder cured at high temperature and UCS or UPV. Whereas the cube sample was able to give a logarithmic or exponential correlation for all the testing scenarios. Hence a better understanding of the cylindrical sample is needed and the data from this research can help to compare the results from these two geometries. This research also focuses on the evaluation of mechanical properties of Gilsonite and Microcellulose (MC) cement composite and compared with neat Class H cement. The compressive strength of the cement is measured through a direct and indirect method. Samples were cured at high temperatures (75°C) and at ambient conditions for the period of 1, 3, 7, 14, 21, 28, 35, 60, 90 and 120 days. It was found that at high temperature (HT) the development of compressive strength in 4% Gilsonite cement composite was very rapid with the UCS going as high as 42MPa within three days of curing. Whereas 4% MC shows an identical behavior as Gilsonite at room temperature, but a decrease in strength at HT when compared to Gilsonite or neat class H cement.

Dynamic Mechanical Analysis (DMA) is an important experimental characterization technique for the mechanical properties of polymers. In this paper, we translate such a technique into a Molecular Dynamics (MD) simulation workflow capable of outputting properties from DMA within a much wider frequency and temperature range than what can be experimentally observed. We also introduce metrics for convergence of simulation runtime and DMA straining size that are not discussed in comparable computational literature but that drastically affect the accuracy of results. We validate the efficacy of the work by comparing our obtained storage and loss modulus data on Polyvinylidene Fluoride (PVDF) with previous computational literature and indicating performance and accuracy improvements for such study based on our convergence metrics. Finally, we perform a complete workflow run at GHz-range frequencies on PVDF utilizing the All-Atom Optimized Potential for Liquid Simulations (OPLS-AA). With this, we hope to validate and justify this forcefield as a good standard for high-throughput analyses on other polymers with the workflow and to compare our data with experimental results employing the Time-Temperature Superposition (TTS) method.

High-density polyethylene is a common recyclable plastic that has a large potential as an additive manufacturing material due its economic and environmental benefits. However, high-density polyethylene has undesirable thermal properties that cause the material to shirk and not adhere to the printing bed during an additive manufacturing processes. Researchers have attempted to combat these thermal properties but have only created novel filaments of high-density polyethylene without being able to create 3D printed specimens for mechanical property testing. This paper presents several methods to create 3D printed specimens with pure high-density polyethylene filament on a fused filament fabrication type 3D printer. The methods show that using a plastic bag composed of highdensity polyethylene on the printing bed in conjunction with clamps can be used to 3D print high-density polyethylene specimens consistently. These methods were used to create specimens for tensile, compression, impact, flexural, and shear mechanical property tests. The results of this study showed that following the recommended methods for 3D printing with high-density polyethylene presented in this paper will yield consistent specimens and data for mechanical property testing on a fused filament fabrication type 3D printer.

Abstract: With growing concern over global warming and greenhouse gas emissions, research must be undertaken to reduce the environmental footprint of buildings. Cellular concrete provides good strength to weight ratios and good thermal insulation because of its cellular structure. This makes it suitable for reducing the energy demands of buildings constructed with this material. However, the Portland cement currently used in cellular concrete releases large amounts of CO2 during its production. Alternative materials to Portland cement can provide lower carbon footprints. Alkali activated materials can fully replace Portland cement with an alumino-silicate source which is reacted with an alkaline solution. Common alumino-silicate sources are often industrial by-products, so the use of alkali activated materials both reduces the need for Portland cement and diverts by-products from landfills. Renewably sourced ashes also have potential for replacing Portland cement. Ash from the burning of hog fuel in the pulp and paper industry can be used to partially replace the Portland cement in concrete mixes. Applying these more environmentally friendly materials to cellular concrete will produce a material with low carbon emissions for production and high environmental performance for buildings constructed using them. In this thesis, cellular concretes are prepared with cast densities from 100 kg/m3 to 1400 kg/m3 out of alkali activated fly ash, and out of Portland cement blended with up to 20% wood ash. The mechanical, thermal, and acoustic properties of these cellular materials are characterised, and the effects of the differing cementitious materials on these properties are analysed. The cellular structure of the materials is characterised through the use of image analysis, and relationships between the structure and the thermal and acoustic properties of the materials are analyzed.

Studies focusing on materials used in Cultural Heritage conservation projects are becoming increasingly important. In this paper, the pore structure and mechanical properties of lime–cement mortars are evaluated in order to analyze their potential use, because this kind of mortar could reduce the disadvantages presented by both lime-based mortars and cement-based mortars. The microstructure of these blended mortars is studied taking into account porosity, pore size distribution and surface fractal dimension. Compressive and flexural strengths are discussed as a function of several parameters: curing time, binder composition and B/Ag (Binder/aggregate) ratio. The mechanical strength versus the deformation of the material is also evaluated, by analysis of Young's modulus, as well as the elastic and plastic zones. Unlike cement-based mortars, blended mortars with a high percentage of lime present a large plastic zone, which could be useful in the service-life of these mortars as a result of their ability to absorb strains caused by wall movements.

The increasing use of lime-based mortars for the restoration of historic buildings and structures justifies the research on these materials. The focus of this paper is the effect of technological variables on pore structure and mechanical properties of lime-based mortars. The influence of curing time, binder:aggregate ratio, aggregate attributes and porosity is discussed. Mortars prepared with aerial lime, varying aggregate types and binder:aggregate ratios ranging from (1:1) to (1:5) by volume were tested. Compressive and flexural strength measurements, as well as X-ray diffraction and thermal studies, were performed after 3, 7, 28, 91, 182 and 365 days. A strong increase in strength of mortar mixtures after 365 curing days (as compared to 28 curing days) is found. In spite of the fact that larger amounts of binder increase the total porosity, the strength of these mixtures is also increased. A good interlocked structure is obtained as binder contents increase. Also, higher porosities allow better portlandite carbonation. A relationship between mechanical properties and pore structure was established. However, in case of binder excess, the increase in voids leads to a strength reduction. The use of calcareous aggregates improves strength more as compared to the use of siliceous aggregates. Factors as grain size distribution and grain shape of the aggregates have also been considered.

Studies have investigated and dismissed the effect of freeze-thaw cycles on both skeletal muscle and on trabecular bone, but have failed to properly address the effects of these storage methods on the integrity of articular cartilage. Preventing cartilage injury is important in minimizing the long term debilitating effects of osteoarthritis. Accurate subfracture injury prediction must take into account the possible effects that freeze thaw cycles may have on the mechanical properties of cartilage tissue. This paper addresses this concern with matched pair testing of various low temperature storage techniques against fresh control groups. Controlled mechanical indention tests were performed on bovine articular cartilage-on-bone specimens to compare stiffness, peak stress, and loading energy of the cartilage. Findings showed that a slow freeze thaw or flash freeze cycle caused cartilage stiffness to decrease by 37% and 31% respectively. Compressive stress at this strain was also lowered by 31% with a single freezing process. These results may be indicative of a weakened extracellular matrix structure caused by the freeze-thaw process. It is still unclear whether these changes in mechanical properties will result in a change in injury susceptibility for articular cartilage.