الفهرس 
General StatementOnly 14 pages are availabe for public view
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Abstract
In this work, all the data of field observation, geochemical, geological, petrographical,
mechanical, physical data and concentrated laboratory works have been collected and create
to extract the following conclusions:
1- characterization of the engineering properties of metavolcanics rocks can provide a base
for a more rational approach to use these rocks in civil engineering works.
2- characterization of the physical and mechanical properties can be helpful both for early
selection for building stone.
The selected areas in the Central Eastern Desert embraces Ambagi and Sid areas and in
Southern Eastern Desert are Shadli and Idfu Marsa Alam area are made up of porphyritic
metabasalt, olivine metabasalts, basaltic meta-andesite , meta-andesite, metadacite and
metarhyolite. Chemical analysis (XRF) was carried out to define the mineral composition
and to know the nature and degree of alterations of the various rock units from the selected
area.
Geochemically, the different types of metavolcanics from four location represent tholeiitic
characterization. Slightly down of K2O and enrichment of Na2O occurred in the mafic units.
The mafic rocks are also medium in MgO (<9.5%) and P2O5 and TiO2 which might signify
highly developed magma from deep mantle sources. Related to plate tectonic theory, the
different types of metavolcanics located in island arc with tholeiitic characterization
The physical and mechanical properties (porosity, density, uniaxial compressive strength,
water absorption, flakiness and elongated index and specific gravity) of the metabasaltic
rocks indicated these rocks could be used as cobblestone, masonry stone and slabs for
sidewalks.
There is also a direct relation between the compressive strength and density of rock
aggregates. On the other hand, the relation between the porosity, water absorption and
compressive strength is indirect relationship. Metabasalt rocks have low porosity with high compressive strength compared to metarhyolite, metadacite and meta-andesite. The
relationship between the compressive strength and normative mafic minerals contents is
direct relation.
The Ambagi metabasalts are also excellent building stones as much as physical and
mechanical properties are concerned.
Relating to aggregate properties, every rock unit has its specific properties subject upon its
petrological and textural characteristics. Flakiness and Elongation indices are generally
measured to be a characteristic property of the rock itself depending mainly upon its
petrological, texture and structure; and partly on the crushing methodology/techniques. The
Flakiness index ranges from 15% to 44% while the elongation index ranges from 15% to
32%. However, most metabasalt samples fall in the range from 15% to 29% which meet the
ASTM D4791 specifications as concrete aggregates. The highest compressive strength
values, are measured from the Ambagi and the lowest one measured from metarhyolite in
Shadli area so, the Ambagi basalt is the main source of aggregates to be utilized in concrete
in the area of study and can be used as crushed aggregate for concrete mix in large sized
buildings, bridges and roads.
After mixing aggregates with cement and water for concrete, The compressive strength of
different metavolcanics aggregate type effect on the compressive strength, flexural tensile
strength were investigated using constant mixture proportions. Five different aggregate types
(metabasalt, basaltic meta-andesite, meta-andesite, metadacite and metarhyolite) were used
in the concrete mixtures. The results of the investigation showed that aggregate strength and
texture influenced the compressive strength, flexural tensile strength of concrete. A
relationship was existed between aggregate compressive strength of concrete and
compressive strength of aggregates with correlation coefficients R² = 0.44. A good
relationship was existed between aggregate compressive strength and flexural tensile
strength with correlation coefficients R² = 0.541. There is a good relationship was existed
between concrete strength and Bulk density of concrete, with correlation coefficients o
R²=0.926. A relationship was existed between concrete strength and porosity, with
correlation coefficients R² = - 0.795. A strong relationship existed between tensile strength
for concrete and bulk density for concrete with correlation coefficients R²= 0.7134 .Ultrasonic waves are a very effective tool for quantifying mechanical changes in concrete.
Sonic tests (P-wave velocity and the shear wave velocity) on metavolcanic concrete pastes
gave a quantitative valuation of the degree of development achieved through the cement
addition in terms of strength gain.
There is a good relationship was existed between uniaxial compressive strength for concrete
(UCS) and shear modulus for concrete by ultrasonic with correlation coefficients R²=0.6378.
A good relationship was also existed between ultrasonic p waves and the dynamic elastic
modulus with correlation coefficients R²= 0.9981
SEM and EDX were approved for qualitative understanding the strength minerals formed
during stabilization. The formation of the cementitious compounds containing calcium
hydroxide CaOH2 and calcium silicate hydrated (CSH). These remarks show that a good
mixing between metavolcanics aggregates and cement additives might have resulted. The
procedure for formation the cementing materials may be formed by the reaction of the silica
and alumina from the metavolcanics aggregates and the calcium hydroxide from cement.
This process increases the strength by formation additional cementitious materials, which
increase the interparticle bonding.
Recommendations for future work
So far, the Ambagi, Sid, and El Sukkari metabasalts and Shadli metabasalt have been used
as building material. For selection of aggregate in concrete production without any physical
and mechanical characterization, this leads to failure of the engineering structures before the
design life. The present study identified important physical, chemical and mechanical
properties of the selected areas in general. However, the following recommendations are
given for future consideration:
1- There is an incorrect thought that accepts all basaltic rocks are considered as very good
source of aggregates for concrete and asphalt mix; however this is totally wrong, instead
attention should be attentive on the mineral constituents of the rocks to identify
deleterious components
2- Aggregate identification, quarrying, storage and handling should be done professionally.