Al-Hdabi, A (2014) HIGH STRENGTH COLD ROLLED ASPHALT SURFACE COURSE MIXTURES. Doctoral thesis, Liverpool John Moores University.

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Abstract

Cold Bituminous Emulsion Mixtures (BEMs) means manufacturing of asphalt at ambient temperature using bitumen emulsion as the binder. It has been widely utilised in many countries such as the USA and France. The use and development of BEMs were not brought forward in the UK due to the country’s relatively wet/cold climatic conditions, which are not favourable to the application of cold BEM in terms of the long curing process and low early strength.
Decreasing wastes from aggregate production processes, reducing land-filling and reducing CO2 emissions during hot bituminous mixture production and laying are the main target schemes for the environmentally friendly processes. Cold BEM is one of the attractive methods of producing bituminous mixtures to tackle the mentioned disadvantages when incorporating some waste and/or by-product materials individually or collectively into these mixtures. Recently, researchers have shown an increased interest in incorporating supplementary cementitious materials (SCM) in production of BEMs in the UK and around the world. Three benefits can be stated when using SCM in BEMs; these are upgraded mechanical properties, gaining economic advantage and the ecological advantage factor.
Mainly due to some inherent problems associated with the performance of the pavement produced by the BEMs process, they are regarded as “inferior” to conventional HMA. The major problems with this kind of application are the long curing time (evaporation of trapped water) required to achieve the required performance, the weak early life strength (because of the existence of water) and high air voids content. The full curing in the field of these mixtures may occur between 2−24 months depending on the mixture’s ingredients and weather conditions.
Considering the above disadvantages, this study investigated the possible ways of developing a new BEM/s with gap graded mixtures similar to the conventional Hot Rolled Asphalt (HRA) gradation. HRA is extensively used for surfacing major roads in the UK because it provides a dense, impervious layer, resulting in a weather-resistant durable surface able to endure the demands of today’s traffic loads and providing good resistance to fatigue cracking. The mentioned new product is termed Cold Rolled Asphalt (CRA).
The main aim of this study was to investigate producing high strength, fast curing and sustainable CRA mixtures for heavily trafficked road and highway surfacing layers by using different waste and by-product materials (normally used as SCM) individually and/or collectively as a replacement for conventional mineral filler. To achieve the above aim, four SCMs have been used which were: Waste Paper Sludge Ash (WPSA), which has high lime and gelenite content, Poultry Litter Fly Ash (PLFA), which has high alkali components, Silica Fume (SF), and Rice Husk Ash (RHA), which is high silica content and cost-plus material, collectively instead of conventional mineral filler. In addition, besides the production of the new high-quality CRA mixtures, the research includes a detailed comparison study of conventional HRA mixtures, CRA mixtures containing conventional mineral filler and CRA mixtures containing hydraulic filler, i.e. Ordinary Portland Cement (OPC).
This laboratory study was conducted by utilising different types of testing and curing and conditioning methods to characterise the mechanical properties and durability of the produced CRA mixtures. Indirect Tensile Stiffness Modulus (ITSM), Uniaxial Compression Cyclic Test (UCCT), Four Point Bending fatigue test on prismatic shaped specimens (4PB) and Semi-Circular Bending monotonic test (SCB) were used to assess the mechanical properties of these mixtures while Stiffness Modulus Ratio (SMR) and Long Term Oven Aging (LTOA) were used to investigate the main durability features, i.e. water sensitivity and long-term aging, respectively. Furthermore, Scan Electron Microscopy (SEM) technique and X-Ray Diffraction (XRD) analysis have been used to investigate the reasons behind the improvement in the mechanical properties of the novel mixtures.
By means of ITSM results, four high-qualities CRA mixtures have been optimised which are: CRA-WPSA (containing 6% WPSA), CRA-BBF (containing 4.5% WPSA+1.5% PLFA), CRA-TBF-1 (containing 3.75% WPSA+1.25% PLFA+1% SF) and CRA-TBF-2 (containing 3.375% WPSA+1.125%PLFA+1.5% RHA).
Stiffness modulus of CRA mixtures increases significantly by replacing the conventional mineral filler with WPSA, BBF, TBF-1 and TBF-2, especially in the early curing time (less than 7 days), which is the main disadvantage of the cold BEMs. Also, the target stiffness modulus, which is the ITSM for 100/150 HRA (approximately 2000MPa), was achieved after 4 hours for the produced fast-curing CRA mixtures, i.e. CRA-TBF-1 and CRA-TBF-2, under the normal curing method (24 hours in the mould then leave the samples at 20 ºC). In addition, the replacement of conventional mineral filler with WPSA, BBF, TBF-1 and TBF-2 greatly improves the permanent deformation resistance and fatigue life when compared with the control CRA and the traditional HRA mixtures.

Item Type:	Thesis (Doctoral)
Subjects:	Q Science > QD Chemistry T Technology > TE Highway engineering. Roads and pavements
Divisions:	Civil Engineering & Built Environment
Date Deposited:	03 Nov 2016 16:13
Last Modified:	03 Sep 2021 23:27
DOI or ID number:	10.24377/LJMU.t.00004576
Supervisors:	Al Nageim, Hassan, Ruddock, Felicite and Seton, Linda
URI:	https://researchonline.ljmu.ac.uk/id/eprint/4576

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