Engineering and Technology Journal

This scientific research was carried out within the framework of contributing to the recovery different of natures of waste, and making it possible to minimize using of natural aggregates in the field of construction, in order to place an eco-self-consolidating concrete (eco-SCC). Crushed demolition waste mainly of concrete had been studied as a substitute for natural sand. As well as the effect of replacing fines with crushed eggshell waste was assessed. So this present work fits in these contexts. Therefore the main objective of this study is to improve current knowledge on the behavior of studied concretes in the fresh state: slump-flow test, and hardened state: mechanical resistances in compression and in bending, as well as water absorption by capillarity test, absorption by total immersion, and porosity accessible to the water of SCCs designed from different types of waste, recycled sand, and eggshell fines. Also, the method of assessing mixes were affected by the sort of chemical attack, namely the (NaCl) attack was investigated. In light of the obtained results, it was found that the addition of eggshell fines in adequate quantity, can improve the properties of SCCs, in this study a volume of 30% was sufficient, increasing the volume added to 60% introduced an opposite effect. Using recycled sand in this study did not contribute to a significant effect on the mechanical properties of the mixtures studied, although an improvement in workability was observed.

This study deals with durability characteristics and unconfined compressive
strength of clayey soil stabilized with lime. The tests comprises of unconfined
compressive strength for samples stabilized with the optimum lime percent (4%),
and subjected to cycles of the wet-dry, dry-wet and freeze-thaw durability tests as
well as, long-term soaking and slake tests.
The results indicated that, the efficiency of the lime in the improvement of
unconfined compressive strength of clayey soil is of negative effect in the long
term durability periods The wetting-drying cycles showed greater reduction in
unconfined compressive strength than drying-wetting cycles, while the volume
change of samples which subjected to drying at first, was greater than those
conducted with wetting. On the other hand, freezing-thawing cycles causes a
decreasing in the unconfined compressive strength values, and the reduction ratio
was greater than wetting and drying cases. But, during soaking tests it was found
that at early soaking periods, the lime stabilized samples continuously gaining
strength, but beyond this the strength decreased with increasing soaking period.
Finally, the stabilized samples with (4 and 6%) lime becomes more durable
against the cycles of wetting and drying.

The failure of polymer matrix composite upon exposure to the environment
conditions has been assessed in the present study. Glass fabrics and unsaturated
polyester resin were selected to fabricate 8-layer laminates cross ply [(0/90)8]
arranged in symmetric and antisymmetric stacking sequence. Environmental
conditioning using Sea and Tap water with humidity exposure and Ultraviolet
radiation was conducted to investigate the vibrations characteristics of symmetric
and antisymmetric composite samples. After exposure time to the conditions
above for 500, 1000 and 2000 hr, laminates were subjected to three point bending
testing, in order to study their flexural properties (stiffness and strength) before
and after these exposures. Then a finite element analysis using the package
program ANSYS (version 10) was used for the analysis of free vibration
characteristics. The object was to obtain the natural frequency for each case of
environmental conditions at different exposure times. The results showed that
natural frequencies of cantilever laminate plates decreased with the increased
exposure time for the different environmental conditions.

The Biometrics recognition systems act as an efficient method with broad
applications in the area of: security access control, personal identification to humancomputer
communication. From other hand, some biometrics have only little variation
over the population, have large intra-variability over time, or/and are not present in all
the population. To fill these gaps, a use of multimodal biometrics is a first choice
solution [1].
This paper describes a multibiometrics method for human recognition based on
new teacher vector identified as spectrum eigenface, and spectrum eigenpalm. The
proposed combination scheme exploits parallel mode capabilities of the fusion feature
vectors in matching level and invokes certain normalization techniques that increase its
robustness to variations in geometry and illumination for face and palmprint. The
correlation distance is used as a similarity measure. A threshold value is used to
prevent the imposter for being recognized. Experimental results demonstrate the
effectiveness of the new method compared to the unimodal biometrics for spectrum
eigenface/eigenpalm.

The applications of a mineral admixture, or a zinc coating to steel surface, or a
combination of both are methods used for the corrosion prevention of ferrocement
element in this study. Results of a study to evaluate many corrosion protection systems
with metakaolin and/or galvanized steel mesh are presented in six U-shaped specimens.
Specimens were built to simulate exposure conditions typical for marine environment.
Laboratory data collected along duration of 40 weeks of exposure were used in
modeling the cover depth as a function of time to corrosion initiation of the investigated
corrosion prevention methods. Methods used to assess the condition of specimens
included chloride concentration measurements, and corrosion rates. Model predictions
show that the ferrocement specimen of high-performance mortar with metakaolin
provides much better level of protection against moisture and chlorides than the
conventional specimen, by delay rate of chloride ingress. Application of a galvanized
steel mesh causes an elevation of the chloride threshold resulting in an additional
increase in the predicted time to corrosion initiation.