Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 2

Search results for: Ndabenhle Sosibo

2 Assessing the Suitability of South African Waste Foundry Sand as an Additive in Clay Masonry Products

Authors: Nthabiseng Portia Mahumapelo, Andre van Niekerk, Ndabenhle Sosibo, Nirdesh Singh

Abstract:

The foundry industry generates large quantities of solid waste in the form of waste foundry sand. The ever-increasing quantities of this type of industrial waste put pressure on land-filling space and its proper management has become a global concern. The South African foundry industry is not different when it comes to this solid waste generation. Utilizing the foundry waste sand in other applications has become an attractive avenue to deal with this waste stream. In the present paper, an evaluation was done on the suitability of foundry waste sand as an additive in clay masonry products. Purchased clay was added to the foundry waste sand sample in a 50/50 ratio. The mixture was named FC sample. The FC sample was mixed with water in a pan mixer until the mixture was consistent and suitable for extrusion. The FC sample was extruded and cut into briquettes. Water absorption, shrinkage and modulus of rupture tests were conducted on the resultant briquettes. Foundry waste sand and FC samples were respectively characterized mineralogically using X-Ray Diffraction, and the major and trace elements were determined using Inductively Coupled Plasma Optical Emission Spectroscopy. Adding purchased clay to the foundry waste sand positively influenced the workability of the test sample. Another positive characteristic was the low linear shrinkage, which indicated that products manufactured from the FC sample would not be susceptible to cracking. The water absorption values were acceptable and the unfired and fired strength values of the briquette’s samples were acceptable. In conclusion, tests showed that foundry waste sand can be used as an additive in masonry clay bricks, provided it is blended with good quality clay.

Keywords: foundry waste sand, masonry clay bricks, modulus of rupture, shrinkage

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1 The Effect of a Theoretical and Practical Training Program on Student Teachers’ Acquisition of Objectivity in Self-Assessments

Authors: Zilungile Sosibo

Abstract:

Constructivism in teacher education is growing tremendously in both the developed and developing world. Proponents of constructivism emphasize active engagement of students in the teaching and learning process. In an effort to keep students engaged while they learn to learn, teachers use a variety of methods to incorporate constructivism in the teaching-learning situations. One area that has a potential for realizing constructivism in the classroom is self-assessment. Sadly, students are rarely involved in the assessment of their work. Instead, the most knowing teacher dominates this process. Student involvement in self-assessments has a potential to teach student teachers to become objective assessors of their students’ work by the time they become credentialed. This is important, as objectivity in assessments is a much-needed skill in the classroom contexts within which teachers deal with students from diverse backgrounds and in which biased assessments should be avoided at all cost. The purpose of the study presented in this paper was to investigate whether student teachers acquired the skills of administering self-assessments objectively after they had been immersed in a formal training program and participated in four sets of self-assessments. The objectives were to determine the extent to which they had mastered the skills of objective self-assessments, their growth and development in this area, and the challenges they encountered in administering self-assessments objectively. The research question was: To what extent did student teachers acquire objectivity in self-assessments after their theoretical and practical engagement in this activity? Data were collected from student teachers through participant observation and semi-structured interviews. The design was a qualitative case study. The sample consisted of 39 final-year student teachers enrolled in a Bachelor of Education teacher education program at a university in South Africa. Results revealed that the formal training program and participation in self-assessments had a minimal effect on students’ acquisition of objectivity in self-assessments, due to the factors associated with self-aggrandizement and hegemony, the latter resulting from gender, religious and racial differences. These results have serious implications for the need to incorporate self-assessments in the teacher-education curriculum, as well as for extended formal training programs for student teachers on assessment in general.

Keywords: objectivity, self-assessment, student teachers, teacher education curriculum

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