Browsing by Author "Rudman, Chantal"

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    Aspects of self-cementation when applied in roads
    (Stellenbosch : Stellenbosch University, 2019-04) Rudman, Chantal; Jenkins, Kim J.; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
    ENGLISH ABSTRACT: Worldwide, the growing volumes of traffic have led to the increase in an expanding infrastructure that must be continually maintained. Congruent with these developments are undesirable environmental consequences, including depletion of natural resources. Given the fact that the construction industry is responsible for more than 40% of extracted materials [Fadiya et al., 2014], and subsequently generates large amounts of construction waste, it is ominous that the roads industry should be a key player in implementing austerity measures. These actions should include progressing to more efficient construction practices and the reuse of materials to alleviate the strain on already overburdened natural resources. Many initiatives and developments have been implemented towards this goal and conventional road construction materials replaced with alternative options such as construction demolition waste – better known as recycled concrete aggregate (RCA) and recycled crushed masonry (RCM). The Netherlands, for example, has been processing RCA and RCM for use in road layers as common practice since the late 1970s and has developed industry norms towards successful utilisation within the construction industry. These applications have been highly satisfactory. It has been reported that mix compositions of RCA and RCM exhibit self‐cementing characteristics. These characteristics could be beneficial to road design. Unfortunately, they are also associated with unforeseen challenges that become more complex when considering mechanisms such as self‐cementation, which manifests over time and potentially influences the performance of such a material. The long‐term performance of this type of self‐cementing, secondary material is not fully understood and long‐term behaviour is often difficult to predict. The change in response of governing mechanisms brought on by self‐cementing could lead to a change in failure behaviour. Potentially, the material could transform between characteristics of an unbound material, governed by rutting and permanent deformation failure, to that of a bound material, in turn governed by fatigue and subsequent cracking behaviour. These could lead to undesired defects, which may appear randomly in terms of severity and therefore require an assessment of the scope of what the long‐term physical, mechanical and durability performance of these materials could entail. Often these changes and associated risks are minimised through decreasing variability of the material when processed in a formalised industry. In emerging markets, characteristic of many developing countries, risk is increased due to informal practices. The current research investigates the range of variability in which the behavioural response of the materials can manifest. It includes the way in which self‐cementing manifests in the micro‐ and macrostructure and the short‐ and long‐term structural performance associated with self‐cementation of RCA. Additionally, the intrinsic and extrinsic factors associated with durability concerns manifesting as a result of the potential transforming nature of RCA, between characteristics of an unbound to a bound layer, are investigated. The research in this regard includes the consequences of carbonation as well as the modelling of test data and its potential for shrinkage crack patterning as a result of fatigue failure behaviour. The results reveal that some benefit can be derived from exploiting the self‐cementing characteristics of the material, but that caution should be exercised in curtailing risk during application of the material within road layers. Finally, guidelines are proposed that account for the factors that may affect the long‐term performance of this material, so that it can be incorporated into normal practice. These considerations include aspects concerning the structural and durability performance of the material (especially in informal markets where standardised processing of materials is not the norm) and the application in construction practices and design considerations.
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    Investigation into the structural behaviour of portal frames
    (Stellenbosch : University of Stellenbosch, 2009-03) Rudman, Chantal; Dunaiski, P. E.; Pahl, P. J.; University of Stellenbosch. Faculty of Engineering. Dept. of Civil Engineering.
    An established procedure for analysing perforated plates is based on treating material as an equivalent elastic constants. In this steel plates thickness to with ligament pitch ratios solid material investigation, efficiencies of of 0.648 were the stress in the perforated with modified thin perforated 0.074 and plate tested. The effective Young's moduli and determined for these perforated existing recommendations.