The successful production of high-strength concrete which meets the desired strength and durability is dependent on optimising its rheological (or flow) properties and reducing its loss of workability during the transportation, placing and compaction stages. The research presented in this thesis aimed to: 1. Determine whether mix stability and compactability can be adequately described by the two Bingham parameters of yield value and plastic viscosity. 2. Reduce the uncertainties in material selection with regards to the performance of superplasticizers and cement replacement materials. 3. Examine how the two Bingham parameters vary at different degrees of compaction by vibration. 4. Determine how these influence the strength development characteristics in the hardened state. 5. An additional aim was to carry out any modifications to the test apparatus and methods which experience makes necessary. Measurements with Tattersall's MH two-point workability test apparatus indicated that mix stability correlates more closely with the yield value than with plastic viscosity, whilst the opposite is true with respect to compactability under self-weight. The performance of conventional and new-generation superplasticizers (based on SMF, SNF, MLS, Vinyl and Acrylate polymers) was evaluated with different dosages, mixing procedures and cements. The SNF superplasticizer produced slightly lower initial workabilities than the Acrylate superplasticizer, but the longest workability retentions of the superplasticizers tested. Partial cement replacements by CSF in binary blends produced lower superplasticizer dosage demands, higher initial workabilities and longer workability retentions than those due to PFA and GGBS. When used in ternary blended cements, CSF enhanced the performance of mixes containing PFA or GGBS at w/b ratios of 0.30-0.22. A novel method developed to assess the vibration response of fresh concretes has, for the first time, demonstrated that both the yield value and plastic viscosity decrease during compaction. The method has also demonstrated that the maximum compressive strengths and densities of concretes compacted for different vibration durations/amplitudes coincide with the attainment of zero yield value. Continuous reductions in plastic viscosity during vibration mainly reduced the homogeneity of concrete compacted in short columns.

Charles University, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical technology Supervisor: doc. PharmDr. Zdeňka Šklubalová, Ph.D. Consultant: Ing. Hana Hurychová Student: Eliška Dostálová Title of Thesis: Study of bulk and consolidation properties of size fractions of anhydrous lactose The bulk and consolidation behaviour of pharmaceutical excipients belong to their important properties. Properties of five size fractions of anhydrous lactose having the particle size in the range of 1-400 µm were studied in this thesis. The measurement was carried out by using static and dynamic pharmacopoeial methods. The bulk density and the tapped density, the angle of repose were evaluated as well as the true density of particles by using the gas pycnometry. The mass flow rate through the orifice of a model conical hopper by the force of gravity was estimated for the individual size fractions. The discharge rate through the orifice having the diameter in a range of 0.6-1.5 cm was modelled with the Beverloo et al and Jones & Pilpel power regression equations; the precision of the flow rate prediction was about 3 %. The best bulk properties were detected for the particle size fraction 246 µm. The results of the evaluation of the consolidation dynamic during the tapping of powder bed permitted...

Králové doc. PharmDr. Zdeňka Šklubalová, Ph.D. Ing. Hana Hurychová, Ph.D. Monika Hnatková The objective of this diploma thesis was to evaluate the flow and consolidation behaviour of the size fractions of lactose for direct compression - Tabletose® 80 in a range of 80-400 μm obtained by sieving. The nonlinear influence of the particle size on the flow rate was detected; the fractions of Tablettose® 80 with the mean size of 245 and 346 µm showed the best flowability. The influence of the diameter of the hopper opening on the flow rate was modeled using the Beverloo and/or Jones & Pilpel flow equation; the latter described the results better. The assessment of volume changes by gravitational tapping allowed to observe dynamics of consolidation and to express porosity factor for the powder bed, which enabled an estimation of the angle of internal friction.

Twelve field projects were studied where fortyour locations were evaluated to assess the cause or causes of asphalt concrete that exhibits ‘tender zone’ characteristics and to investigate the tendency of these mixes to be susceptible to moisture damage. Data was collected during construction and samples were obtained to conduct laboratory tests. Field and laboratory data was used to develop multiple regression equations to predict final in place air voids and moisture susceptibility. The overall conclusion was that compactability appeared to be predicted in a reasonable manner while moisture susceptibility did not. The Methylene Blue test appears promising when used in conjunction with cold feed and/or mix moisture as a means of providing guidance for achieving higher in place density. The tensile strength ratio (TSR) test as performed in this research on laboratory compacted specimens was found to be questionable in terms of its ability to predict field moisture susceptibility.

<p>The aim of this thesis was to identify some functionality related characteristics of pharmaceutically relevant solid materials and to study the effect of their variation on processing behaviour and product performance. For this purpose, particles with different characteristics were prepared under a variety of conditions by crystal agglomeration, wet granulation and spray drying. The effect of particle size distribution on the evolution of the tablet microstructure during and after compression was investigated. The compression behaviour of particles with different nominal strength and degrees of agglomeration was studied and the influence of the surfactant concentration of amorphous particles on the compression behaviour was examined. The response of the powders to compression was described with the help of various techniques characterising the microstructure and tensile strength of the tablets produced. </p><p>Furthermore, a method suitable for observing drug release from single matrix granules was developed and used to study the effect of granule porosity and compaction pressure on the drug release process. </p><p>The particle size distribution did not influence the evolution of the tablet porosity or the tensile strength during compression, but it could have an effect on the evolution of the tablet microstructure during short-term storage, depending on the instability mechanism. The compression behaviour of particles prepared by crystal agglomeration and wet granulation was dependent on their degree of agglomeration and their failure strength. For particles with similar solid state properties and compression behaviour, the surface energy appears to have an effect on the bonding strength of adsorption bonds acting at interparticulate junctions. Using the method developed to observe the drug release from single matrix granules, reproducible data was obtained enabling the drug release process to be characterised. Depending on the type of matrix and the compaction pressure, the drug release rate could be enhanced or retarded. </p>

The aim of this thesis was to identify some functionality related characteristics of pharmaceutically relevant solid materials and to study the effect of their variation on processing behaviour and product performance. For this purpose, particles with different characteristics were prepared under a variety of conditions by crystal agglomeration, wet granulation and spray drying. The effect of particle size distribution on the evolution of the tablet microstructure during and after compression was investigated. The compression behaviour of particles with different nominal strength and degrees of agglomeration was studied and the influence of the surfactant concentration of amorphous particles on the compression behaviour was examined. The response of the powders to compression was described with the help of various techniques characterising the microstructure and tensile strength of the tablets produced. Furthermore, a method suitable for observing drug release from single matrix granules was developed and used to study the effect of granule porosity and compaction pressure on the drug release process. The particle size distribution did not influence the evolution of the tablet porosity or the tensile strength during compression, but it could have an effect on the evolution of the tablet microstructure during short-term storage, depending on the instability mechanism. The compression behaviour of particles prepared by crystal agglomeration and wet granulation was dependent on their degree of agglomeration and their failure strength. For particles with similar solid state properties and compression behaviour, the surface energy appears to have an effect on the bonding strength of adsorption bonds acting at interparticulate junctions. Using the method developed to observe the drug release from single matrix granules, reproducible data was obtained enabling the drug release process to be characterised. Depending on the type of matrix and the compaction pressure, the drug release rate could be enhanced or retarded.

Asphalt joints are potentially weakest parts of every pavement. Despite of their importance, reliable tools for measuring their mechanical properties for design and performance assessments are still scarce. This is particularly true for cold joints when attaching a new hot pavement to a cold existing one as in case of large patches for pavement repair. In this study, three static fracture testing methods, i.e. indirect tensile test (IDT), direct tension test (DTT) and 4 point bending (4PB), were adapted and used for evaluating different laboratory made joints. The results suggested that joints with inclined interfaces and also the ones with combined interface treatments (preheated and sealed) seemed to show more promising behaviors than the vertical and untreated joints. It was also confirmed that compacting from the hot side towards the joint improved the joint properties due to imposing a different flow pattern as compared to the frequent compaction methods. The latter finding highlighted the importance of asphalt particle rearrangements and flow during the compaction phase as a very little known subject in asphalt industry. Studies on compaction are of special practical importance since they may also contribute to reducing the possibility of over-compaction and aggregate crushing. Therefore, in this study, a new test method, i.e. Flow Test (FT), was developed to simulate the material flow during compaction. Initially, asphalt materials were substituted by geometrically simple model materials to lower the level of complexity for checking the feasibility of the test method as well as modeling purposes. X-ray radiography images were also used for capturing the flow patterns during the test. Results of the FT on model materials showed the capability of the test method to clearly distinguish between specimens with different characteristics. In addition, a simple discrete element model was applied for a better understanding of the test results as a basis for further improvements when studying real mixtures. Then, real mixtures were prepared and tested under the same FT configuration and the results were found to support the findings from the feasibility tests. The test method also showed its potential for capturing flow pattern differences among different mixtures even without using the X-ray. Therefore, the FT was improved as an attempt towards developing a systematic workability test method focusing on the flow of particles at early stages of compaction and was called the Compaction Flow Test (CFT). The CFT was used for testing mixtures with different characteristics to identify the parameters with highest impact on the asphalt particle movements under compaction forces. X-ray investigations during the CFT underlined the reliability of the CFT results. In addition, simple discrete element models were successfully generated to justify some of the CFT results. / <p>QC 20151104</p>