A STUDY OF CEMENT MODIFIED BITUMEN EMULSION MIXTURES
Earlier studies have demonstrated the beneficial effects of adding Ordinary Portland Portland Cement (OPC) to bitumen mixtures. These effects were confirmed for some dense graded mixtures based on recipes currently used for hot mix in the UK and being considered for use in cold mix. Laboratory tests included stiffness modulus, resistance to permanent deformation and resistance to fatigue cracking. In order to obtain a clearer understanding of the mechanisms causing the improvements in properties, some basic studies were carried out. These included measurement of the rate at which coalescence of bitumen droplets developed and adhered to the aggregate particles, since this is the initial mechanism by which mechanical properties of the mixture are developed. The study was ten extended to obtain an understanding of the properties of emulsion blended with OPC, hydrated lime or limestone filler. This was done since it was thought that a contribution to "binding" of the aggregate in mixtures came for the hydration of cement as well as from the coalesced bitumen. Dynamic Shear Rheometer tests were used on various blends demonstrating the stiffening effects of both OPC and hydrated lime and that filler had little influence. The emulsifying process was also shown to have no effect on the characteristics of the base bitumen. Electron microscopy was sued to study the crystalline structures of fully cured mixtures with and without OPC addition. Expert interpretation considered that some of the characteristics of cement hydration effects were present in those mixtures incorporating OPC. The study concluded that the improvements to key properties of cold mix by the addition of OPC can be explained by a range of mechanisms, including improved rate of emulsion coalescence after compaction, cement hydration and enhancement of binder viscosity.
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Corporate Authors:
Association of Asphalt Paving Technologists (AAPT)
400 Selby Avenue, Suite I
St Paul, MN United States 55102 -
Authors:
- BROWN, S F
- NEEDHAM, D
- Conference:
- Publication Date: 2000
Language
- English
Media Info
- Features: Figures; References; Tables;
- Pagination: p. 92-121
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Serial:
- Volume: 69
Subject/Index Terms
- TRT Terms: Binders; Bituminous mixtures; Deformation; Emulsions; Lime cement
- Subject Areas: Highways; Materials; I31: Bituminous Binders and Materials;
Filing Info
- Accession Number: 00805936
- Record Type: Publication
- Files: TRIS, ATRI
- Created Date: Feb 1 2001 12:00AM