The design and selection of surface treatment binders in service is currently based on specifications that only account for the penetration and ductility of emulsion residues or the penetration and viscosity of hot-applied asphalt cements. These specifications consider neither the entire range of temperatures that the binders may be subjected to during production and in service, nor long-term aging behavior. A surface performance-graded (SPG) specification for the selection of surface treatment binders was developed as part of previous Texas Department of Transportation (TxDOT) and National Cooperative Highway Research Program (NCHRP) projects. The work performed under the TxDOT Project 0-6616 was the basis for this thesis. In this project, the SPG specification, which is performance-based and takes into account the physical properties of the binder at the temperature ranges in which the material will be used, was further validated. This was accomplished by standardizing the emulsion residue recovery method through the evaluation of two warm oven methods, exploring the exclusive use of the dynamic shear rheometer (DSR) for determining performance-based properties, and further field validating the thresholds for these properties. The laboratory and field results were used to revise the SPG specification for surface treatment binders in service. Binder samples collected from chip seal projects constructed on selected highway sections in Texas in summer 2011 were tested and graded according to the existing SPG specification developed in previous research projects. Two warm oven emulsion residue recovery methods were used and compared. New DSR tests, including the multiple stress creep recovery (MSCR) test and the frequency sweep test were evaluated for developing additional criteria in the SPG specification. The SPG grades of the surface binder samples evaluated from laboratory tests were compared with the actual field performance of the highway sections one year after construction. The SPG specification was found to be functional in terms of enabling the selection of binders to ensure adequate surface treatment performance. Moreover, the results obtained from the MSCR and DSR frequency sweep tests were compared with field performance to develop additional criteria in the specification. Further validation is recommended to investigate the effects of construction and quality control processes, as this study is limited to producing a revised SPG specification for properties that address stiffness and aggregate retention in service.

A dissertation submitted to the Faculty of Education in fulfillment of the Degree of Master of Education in the Department of Educational Psychology & Special Needs Education at the University of Zululand, 2017 / High rate of poor performance in matric level is a serious problem not only in uMkhanyakude district but in the whole world. One would say effective teaching and efficient management of schools is the answer to the problem and schools need more information about these two factors which form the summary of the findings. This study succeeded in getting the views from both learners and educators which means it is also important to understand what learners perceive as the factors of poor academic performance in the schools where they are as well. In this study Grade 12 learners perceptions were analysed. Learners in matric and educators teaching them from eight high schools participated in this study. The major factors contributing to poor matriculation performance according to learners are lack of resources, lack of support by parents in their learning, poverty, not being sure about group studying, not having a good command of a teaching and learning language and not prac-tising it. They seemed afraid to talk about their teachers .The educators perceptions tallied with those of educators, that is , lack of resources , focusing on Grade 12 instead of becoming serious from the lowest grades indicating poor management of schools, learners’ lack of mo-tivation and willingness to learn, lack of parental involvement, poor study skills in association with school readiness , lack of support by the district and circuit officials , CAPS concepts as not clear to simplify their teaching , qualifications seeming to be not at the level where the teacher would be in apposition to understand clearly the subject content he or she teaches. A culture of high expectancy on the part of educators, parents and managers at all levels may be the key to influencing the rates of success.

Evidence of the effects of indiscipline on the academic performance of grade 12 learners has been mixed. This study examined how indiscipline in the forms of disruptive, aggressive behaviour, alcohol and drug abuse affected levels of academic performance in a case study of public Senior Secondary Schools of the Libode Education District, Eastern Cape Province in the Republic of South Africa. A total of 25 teachers from two selected schools in the Libode District (10 men and 15 women) were randomly assigned to participate in both the quantitative and qualitative interview surveys conducted by the researcher. The study relied substantially on teacher ratings. The data were collected using interviews which were synthesized, analysed, presented and discussed within a specified time frame. The results adequately reflected on the three research questions of the study which were: To what extent do learners‘ aggressive and violent behaviour impede academic performance? Does imbibing alcohol and drugs influence learners‘ academic performance? To what extent does learners‘ disruptive behaviour affect their academic performance? It has been clearly indicated that disruptive, aggressive behaviour and alcohol and drug abuse have a negative impact on academic performance. The factors (disruptive, aggressive behaviour, alcohol and drug abuse) used in the analysis were identified as the main challenges to the educational development and academic achievement among learners; they pose a serious threat and have negative effects on students, teachers, the school environment and society. They originate from the same sources, however; these are mainly family background, society, cultural values, beliefs, technology, peer pressure and classroom management strategies employed by educators. Findings were discussed in the context of the main and sub research questions and recommendations were made.

Aditivos têm sido incorporados ao ligante asfáltico no intuito de melhorar o desempenho dos pavimentos. O enrijecimento do ligante asfáltico provocado pelos aditivos, aumenta a resistência à deformação permanente das misturas asfálticas, mas ainda não se sabe qual o efeito deles sobre a resistência à fadiga e ao trincamento térmico dos ligantes asfálticos. Um dos produtos modernos mais promissores para modificação de ligantes asfálticos é o ácido polifosfórico (PPA). No entanto, o mecanismo de modificação com PPA depende fortemente da composição química do ligante asfáltico de base. Para avaliar o impacto da adição de PPA em ligantes asfálticos de diferentes fontes, dois ligantes asfálticos 50/70 (REDUC e LUBNOR), de diferentes PGs e composição química foram modificados por quatro proporções de PPA (0,5, 1,0, 1,5, 2,0%). As frações de saturados, aromáticos, resinas e asfaltenos (SARA) dos ligantes asfálticos puros e modificados foram determinadas por meio da cromatografia de camada fina. Para avaliar o efeito da adição de PPA sobre as propriedades reológicas dos ligantes asfálticos, foram analisados a viscosidade, o grau de desempenho, a rigidez, a elasticidade, a recuperação elástica, a compliância não-recuperável e o comprimento de trinca na ruptura. A viscosidade dos ligantes asfálticos e as temperaturas de usinagem e compactação aumentaram com o aumento do teor de PPA. A temperatura alta do PG aumentou com a proporção de PPA em intensidades diferentes, dependendo do ligante asfáltico de base. A adição de PPA aumenta a rigidez, a elasticidade e a recuperação elástica e diminui a compliância não-recuperável dos ligantes asfálticos. Em termos de tolerância à fadiga, a adição de PPA e o envelhecimento provocaram um aumento na tolerância à fadiga dos ligantes asfálticos. Os resultados apresentados destacam a importância da composição química do ligante asfáltico de base no grau de modificação provocado pela adição de PPA. Recomenda-se a adição de teores baixos de PPA para o LUBNOR (até 1%) e de teores altos de PPA para o REDUC (superiores a 1,0%). / Additives have been incorporated to asphalt binder in order to improve the performance of pavements. The stiffening of asphalt binders induced by additives should increases the rut resistance of asphalt concrete, unclear how PPA affects the resistance to fatigue and thermal cracking of asphalt binders. One of the most promising new products for asphalt binders modification is the polyphosphoric acid (PPA). However, the mechanism of PPA modification depends strongly on the chemical composition of the base asphalt binder. To evaluate the impact of the PPA modification in asphalt binders from different sources, two asphalt binders 50/70 penetration grade (REDUC and LUBNOR) from different crude source with different performance grades and chemical composition have been modified by four proportions of PPA (0.5, 1 0, 1.5, 2.0%). Saturated aromatics, resins and asphaltenes (SARA) fractions of neat and modified asphalt binders were determined using the thin-layer chromatography. To evaluate the effect of PPA addition on the rheological properties of asphalt binders it was analyzed the viscosity, the performance grade, the stiffness, the elasticity, the elastic recovery, the non-recoverable compliance and the crack length at failure. The viscosity of asphalt binders and the mixing and compaction temperature increased with increasing levels of PPA. The high temperature of PG increased in different magnitude with the ratio of PPA, depending on the base asphalt binder. The addition of PPA increases the stifiness, the elasticity and the elastic recovery and decrease the non-recoverable compliance of asphalt binders. With regard to the fatigue tolerance, the addition of PPA and the thermo-oxidative aging induced an increase in the fatigue tolerance of asphalt binders. The presented results show the importance of the chemical composition of the base asphalt binder on the extent of modification caused by the addition of PPA. It is recommended to use low levels of PPA to modify the LUBNOR (to 1%) and high levels of PPA to modify the REDUC (over 1.0%).

Aditivos têm sido incorporados ao ligante asfáltico no intuito de melhorar o desempenho dos pavimentos. O enrijecimento do ligante asfáltico provocado pelos aditivos, aumenta a resistência à deformação permanente das misturas asfálticas, mas ainda não se sabe qual o efeito deles sobre a resistência à fadiga e ao trincamento térmico dos ligantes asfálticos. Um dos produtos modernos mais promissores para modificação de ligantes asfálticos é o ácido polifosfórico (PPA). No entanto, o mecanismo de modificação com PPA depende fortemente da composição química do ligante asfáltico de base. Para avaliar o impacto da adição de PPA em ligantes asfálticos de diferentes fontes, dois ligantes asfálticos 50/70 (REDUC e LUBNOR), de diferentes PGs e composição química foram modificados por quatro proporções de PPA (0,5, 1,0, 1,5, 2,0%). As frações de saturados, aromáticos, resinas e asfaltenos (SARA) dos ligantes asfálticos puros e modificados foram determinadas por meio da cromatografia de camada fina. Para avaliar o efeito da adição de PPA sobre as propriedades reológicas dos ligantes asfálticos, foram analisados a viscosidade, o grau de desempenho, a rigidez, a elasticidade, a recuperação elástica, a compliância não-recuperável e o comprimento de trinca na ruptura. A viscosidade dos ligantes asfálticos e as temperaturas de usinagem e compactação aumentaram com o aumento do teor de PPA. A temperatura alta do PG aumentou com a proporção de PPA em intensidades diferentes, dependendo do ligante asfáltico de base. A adição de PPA aumenta a rigidez, a elasticidade e a recuperação elástica e diminui a compliância não-recuperável dos ligantes asfálticos. Em termos de tolerância à fadiga, a adição de PPA e o envelhecimento provocaram um aumento na tolerância à fadiga dos ligantes asfálticos. Os resultados apresentados destacam a importância da composição química do ligante asfáltico de base no grau de modificação provocado pela adição de PPA. Recomenda-se a adição de teores baixos de PPA para o LUBNOR (até 1%) e de teores altos de PPA para o REDUC (superiores a 1,0%). / Additives have been incorporated to asphalt binder in order to improve the performance of pavements. The stiffening of asphalt binders induced by additives should increases the rut resistance of asphalt concrete, unclear how PPA affects the resistance to fatigue and thermal cracking of asphalt binders. One of the most promising new products for asphalt binders modification is the polyphosphoric acid (PPA). However, the mechanism of PPA modification depends strongly on the chemical composition of the base asphalt binder. To evaluate the impact of the PPA modification in asphalt binders from different sources, two asphalt binders 50/70 penetration grade (REDUC and LUBNOR) from different crude source with different performance grades and chemical composition have been modified by four proportions of PPA (0.5, 1 0, 1.5, 2.0%). Saturated aromatics, resins and asphaltenes (SARA) fractions of neat and modified asphalt binders were determined using the thin-layer chromatography. To evaluate the effect of PPA addition on the rheological properties of asphalt binders it was analyzed the viscosity, the performance grade, the stiffness, the elasticity, the elastic recovery, the non-recoverable compliance and the crack length at failure. The viscosity of asphalt binders and the mixing and compaction temperature increased with increasing levels of PPA. The high temperature of PG increased in different magnitude with the ratio of PPA, depending on the base asphalt binder. The addition of PPA increases the stifiness, the elasticity and the elastic recovery and decrease the non-recoverable compliance of asphalt binders. With regard to the fatigue tolerance, the addition of PPA and the thermo-oxidative aging induced an increase in the fatigue tolerance of asphalt binders. The presented results show the importance of the chemical composition of the base asphalt binder on the extent of modification caused by the addition of PPA. It is recommended to use low levels of PPA to modify the LUBNOR (to 1%) and high levels of PPA to modify the REDUC (over 1.0%).