الفهرس 
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Abstract
The continuous development of ornamental stone industry
in Egypt due to the increasingly great demand of the Egyptian stones, led to a continuous and
increasing accumulation of huge quantities of wastes in different forms. In the area of Shaq El –
Thoaban only, about 70 % of these wastes is generating. The majority of these wastes are generated
in the form of sludge (semi liquid) which has a hazardous effect on the surrounding environment and
the sustainable development.
In the present study we used the term “marble” as a commercial name comprising the whole class of
carbonate rocks amenable to sawing and polishing for decorative purposes and economically valuable.
The main objective of the present study is to characterize the marble and granite sludge wastes
chemically, mineralogically and physically to demonstrate their possibility as a cement substitute
rather than natural aggregates in cement and concrete production besides, the suitability of using
the marble sludge wastes in quicklime manufacturing.
The properties of cement composites, manufactured concrete products and prepared quicklime were
investigated chemically, mineralogically and physico-mechanically.
Regarding cement composites pastes, the marble and
granite sludge were substituted for cement binder separately up to 40 % and combining up to 50% at
certain proportions of 0% (control), 10%, 20%, 30%, 40% and 50%. The chemical, mineralogical,
physical and mechanical properties of both fresh and hardened cement composites pastes including
these wastes were determined at 3, 7 and 28 days curing according to standard
test methods (ASTM and/or ECP) and the results were compared
with the specification requirements of these standards.
Concerning the concrete mixtures, the marble sludge waste was only used as a cement replacement at
certain proportions of 0%, 10%, 20%, 30% and 40% and the hardened concrete units so produced were
tested for the physical and mechanical properties after 28 days curing according to standard test
methods (ASTM and/or EN BS) and the results were compared with the specification requirements of
these standards.
With respect to quicklime, the marble sludge was fired at 1000ºC for three soaking times (15, 30
and 120 min.). The quality of prepared quicklime samples was determined in terms of available lime
index and lime reactivity and the results were compared with the specification requirements of
these standards.
The test results showed that the addition of marble and granite sludge as cement replacement in
cement composites led to an insignificant increase in water absorption and apparent porosity and
decrease in compressive strength up to 20% replacement, which becomes observable at higher
replacement levels compared to the control. The physical and mechanical properties of cement
composites were found to conform to the standard (ASTM and ESS).
The test results of hardened concrete products showed that the addition of up to 20% marble sludge
as cement replacement improved the physical and mechanical properties where water absorption and
porosity decreased while the compressive and flexural strengths, abrasion resistance and
freeze-thaw durability increased. At higher replacement levels these properties were affected
negatively. The results showed also that the physical and mechanical properties of concrete units
were found to conform
with the standard (ASTM, EN BS and ESS) that enable them to be used in construction and building
sectors.
The results of prepared quicklime showed that the
calcinations of marble sludge wastes at 1000°C for 30 min. soaking time is considered the optimum
condition for quicklime production of higher available lime index more than other soaking times,
consequently higher lime reactivity.
All the aforementioned results indicated that the using of marble and granite sludge waste have a
significant effect on the properties of cement composites, concrete products and quicklime
production, meanwhile reduce their hazardous effect on the environment.
The present study suggests a concrete mix comprising: marble powder waste (70 Kg/m3), Ordinary
Portland cement (280 Kg/m3), coarse aggregate (1163 Kg/m3), fine aggregate (682 Kg/m3) and water
(178 Kg/m3). Such mix was prepared on the production line of “The Engineering Company for Concrete
Products” (Techno-Crete) and tested.