Browsing by Author "Sander, Zara Rose"

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    Fire behaviour of plastic bottle ecobricks as an infill building material
    (Stellenbosch : Stellenbosch University, 2022-04) Sander, Zara Rose; Walls, Richard Shaun; Babafemi, Adewumi John; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
    ENGLISH ABSTRACT: A global increased awareness of plastic pollution, and the consequences of not addressing said problem, has led to increased interest and adoption of ecobricks as a building material. Ecobricks consist of any size plastic beverage bottle, densely filled with dry, non-recyclable plastic. As a result, places such as schools, shops and crèches around the world are collecting them and using them as an infill material in the construction of private and municipal projects. Construction projects incorporating ecobricks involve placing the plastic bricks inside a timber or reinforced concrete frame. The frame is sometimes covered with steel mesh (“chicken wire”) and plastered with various plaster-mixes. Ecobrick structures have gained popularity, with over 200 schools in Guatemala having been built using ecobricks. With plastics being highly flammable, it is important that the construction and fire engineering industries understand how they may perform when exposed to fire. The problem this thesis aims to answer is: how do ecobrick walls behave when exposed to fire, and how can they be built to ensure that they are safe? As construction using ecobricks is relatively new, minimal research has been done regarding fire safety. Two of the most common methods for constructing homes out of ecobricks were identified. One consists of laying ecobricks horizontally between cob (a clay-straw-sand-mortar mix). The alternative was to stack them vertically and encase them with a mesh and plaster. In this work, various plaster systems were tested, including, (a) traditional cement-sand mortar, (b) lime mortar, and (c) cob. This thesis investigates the placement of bottles, the application of plaster, and the use of mesh layers in relation to the thermal performance of ecobricks in a standard fire test. Six wall samples were built to represent the two different construction methods and three different plasters. The samples were tested in a large-scale furnace where the temperatures were measured through the cross-section of each wall. The temperatures were then compared against 2D thermal modelled wall samples to understand the thermal behaviour of the plaster and ecobricks. The plaster of each wall sample proved to be critical in the fire behaviour of the samples. The most favourable ecobrick and plaster combination, a cob plaster of 40 mm on the horizontal ecobrick wall sample, was able to achieve a one-hour fire rating, where the ecobricks did not melt or ignite. Samples tested with a vertical ecobrick and cement mortar experienced severe flaming and failed after 56 minutes, with some samples failing significantly faster. The lime plaster delaminated early on resulting in rapid failure. Preliminary guidelines for ensuring suitable fire behaviour are presented.