Correlation of Uni-axial Tensile and Flexural Properties of Recycled Glass Fiber Reinforced Cement Composite

Abstract

Industrial growth of developed and developing countries is at peak and construction industry is one of them. Cement based composite materials (i.e. concrete, mortar and repair material) is one of the majorly used construction material. Mechanical and durability properties of construction material plays the major role to make the structure sustainable and durable. It is well known that the compressive strength of cement composite is very good nevertheless its tensile strength is low. The use of fiber reinforced cement composite is increased in structural application to reduce shrinkage crack and increase tensile strength. In this study the glass fiber reinforced acrylic (GFRA) waste is recycled to get the recycled glass fibers. The Crushed waste is collected from sanitary industry and mechanical method is used to reclaim glass fibers from the waste and to produce fine powder of PMMA. Reclaimed glass fibers are used to produce glass fibers reinforced cement composites. The scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analysis is performed on the recycled as well as on the raw glass fiber to get the physical property and the chemical property respectively. It is observed that recycled glass fibers are in bundle form and they are not alkali resistant. The SEM and EDX analysis of MV5, MR5, CV3 and CR3 is also performed and formation of calcium sulphate hydrates is observed in the MR5 and CR3. Mortar mix having 0.2%, 0.3%, and 0.5% of recycled as well as raw glass fibers by volume is used for the experimental work. Concrete mix is prepared which has 0.1%, 0.2%, and 0.3% of recycled as well as raw glass fibers by volume of concrete, the slump of concrete is maintained in between 130mm to 165mm using high water reducing admixture(HWRA). It is noted that the high amount of high water reducing admixture (HWRA) is required for raw glass fibers which shows that the fibres used in experiment are hydrophilic. The cube specimen are tested for the compressive strength and compression of results is discussed. The briquette samples of mortar having recycled and raw glass fibers are tested for the uni-axial tensile strength and it is observed that the uni-axial tensile strength is increases as the percentage of recycled as well as raw glass fiber is increase to 0.5%. SEM and EDX analysis show that recycled glass fibers are in the bundle form in the mortar and raw glass fibers are dispersed homogeneously. The compressive strength and split tensile strength of various mix are also investigated, the significance increase in compressive strength of recycled glass fiber reinforced concrete and the compressive strength of raw glass fiber reinforced concrete is decreasing as the percentage of dosage increases. The split tensile strength is higher compare to the control concrete for both recycled as well as raw glass fiber reinforced concrete. The influence of fiber dosage in flexural strength of concrete is investigated by the flexural test using fore point bending method and closed loop system. The flexural strength of concrete having both recycled and raw glass fibers is increases as the percentage of dosage increases to 0.3%. SEM and EDX analysis show the formation of the calcium sulfate hydrates in recycled glass fiber concrete which improves the compressive strength. In order to correlate the uni-axial tensile and the flexural property of the cement composite the back calculation method has been used. In the back calculation method the closed form equation are used to produce the tensile stress-strain model and compressive stress-strain model by simulating the load-defalcation curve from the flexural test. The tensile strength before cracking is higher for GFRC having 0.3% of recycled glass fibers nevertheless the tensile strength after cracking is higher for the GFRC having 0.3% of raw glass fibers. The comparison tensile stress-strain model of concrete and the uni-axial tensile strength of mortar is also discussed in this study.