Assessment on the Utilization of Recycled Hollow Block as Asphalt Mastic Material

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Addis Ababa University


In road construction, different kinds of filler materials are used. Among them the very common are stone dust, cement, lime, crushed concrete, flay ash and crushed glass fines. These materials have their own drawbacks such as high cost and availability Therefore, the theme of this thesis is to assess the rheological property of recycled hollow block to use it as mastic asphalt(blends of binder and recycled hollow block), as it is easily available from the wastes of building construction and also from hollow block manufacturing companies. The objective of this research is hence to identify the availability of Hollow Block waste material from construction sites and manufacturing companies, to study the basic engineering properties of recycled Hollow Block before blending (as filler material) and to characterize the rheological property of mastic. i.e. Linear Visco Elastic (LVE) range, master curve and Multiple stress creep recovery(MSCR) of mastics. To meet the objectives, to know the availability of waste Hollow Blocks questionnaires were distributed to different real estate companies, construction companies and Hollow Block manufacturing companies. A chemical composition test was performed to check on the chemical properties .For the Hollow block as a filler material specific gravity test, sieve analysis and plasticity index test were done. After having performed the filler tests, recycled hollow block was blended with the bitumen at 15%, 25% and 35% of the binder. After doing so, different tests for the binder and the mastic were performed to check on penetration, ductility, softening point, loss on heating. The rheological properties of both the binder and mastic were checked by different tests such as amplitude sweep test, Frequency sweep test, Performance grade determination and MSCR were performed by Dynamic Shear Rheometer (DSR). Prior to performing Frequency Sweeps Test (FST), Amplitude Sweep Tests (AST)was performed to establish the linear viscoelastic range of the mastics performed at different temperatures at 10 rad/s. After completing the AST based on LVE range, frequency sweeps for a range of temperatures and frequencies were performed on all the samples. Frequency sweeps are used to measure the complex shear modulus (G*) and the phase angle δ at different temperatures by applying a defined strain and a sweep of frequencies allowing construction of the master curves for the binder under consideration. While adding recycled hollow block in the binder will make the asphalt material stiff, the LVE Range decrease with increasing the content of recycled hollow block and increase with increasing temperature. The FST results show that, in the low frequency region (high temperatures) and high frequency region (Low temperatures), the rheological behavior of the unaged and Aged mastics differs from the neat binder and increase the stiffness which is directly related to the durability. Furthermore, Based on the MSCR test as the content of recycled hollow block increased the non-recoverable compliance decrease at 0.1 kPa and 3.2 kPa shear stress levels, this notify as the rutting resistance is good . The research concludes that adding recycled hollow block in Asphalt materials improves the performance of mixtures and increases the life of pavement. Furthermore, the fact that waste is being utilized meets advantage in reducing usage of virgin material and environmental pollution.



Recycled Hollow Block, Assessment, Asphalt Mastic Material