Acidic Rocks as Aggregates in Concrete: Engineering Properties,Microstructures and Petrologic Characteristics |
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| Authors: | A I M Ismail D Sadek Ghabrial |
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| Institution: | (1) Geological Science Department, National Research Centre, Dokki, Cairo, Egypt |
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| Abstract: | In this research, the possibility of replacing different portions of the normally used aggregate by acidic rocks was investigated.
These rock types outcrop at the northern part of Eastern Desert, southwest Ras Gharib area where large quantities of good
quality acidic rocks are available their. Portland cement concrete is a composite material made up of the hydrated cement
matrix, fine aggregate and coarse aggregate. The scanning electron microscope equipped with an energy dispersive X-ray analysis
system (EDX) has been applied to investigate several aspects of Portland cement concrete microstructure. The topics investigated
so far include the influence of aggregate composition on the development of the cement paste-aggregate interface and the formation
of calcium silicate hydrate CSH/calcium silicate aluminate CSA formation. The silicate gel coated the aggregates in the concrete
paste and crystallized into well defined needle like shape, cotton shape as well as euhedral to subhedral crystals of silicate/alumiante
and ettringite minerals with free lime librated from the hydrolysis process. The free lime can react again with the aggregates
leading to the formation of cementing materials which increase strength and durability of the concrete paste by increasing
the interfacial bonds between the used aggregates. |
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| Keywords: | Acidic aggregates Microstructure Strength Durability |
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