الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Concrete is considered the most common construction materials in fire resistance because concrete’s excellent and proven fire resistance properties deliver protection of life, property and theenvironment in the case of fire. The aim of this thesis is to study the effect of the high temperatures on the conventional concrete and how to improve its resistance to high temperatures. For this target; silica fume, polypropylene fiber, steel fiber, limestone powder and bentonite were used as a partial replacement or additive to the cement content. On the other side, plastering using mortars may be used as the first line of defense against the high temperatures. Traditional (CEM I) and modified mortars using (limestone Portland cement, ceramic powder, melamine powder, bentonite and brick clay powder) were utilized. It should be noted that all the mixtures were made by limestone aggregate This thesis contains the following parameters that were considered for all the concrete mixtures at different elevated temperatures:
1- Compressive strength.
2- Flexural strength.
3- Weight loss.
4- Thermogravimetric analysis (TGA/DTG).
5- Scanning electron microscope (SEM).
6-The effect of elevated temperatures on small scale reinforced concrete slabs.
7- Visual inspection.
Some anomaly parameters were considered for the traditional concrete (CEM I only)at high temperature such as: Splitting tensile strength, the effect of water cooling regime on the residual compressive strength, the effect of concrete cover thickness on the protection of the reinforcement inside the concrete and the deceitful pull out test.
Whilst, the parameters of mortarsthat were considered beside the compressive strength, weight loss, (TGA/DTG), SEM; include studying the effect of the mortars (as an external protection)on theresidual compressive strength of the conventional concrete after heating to 600°C for 2 hrs and its role in reinforcement’s preservation from elevated temperatures. As a part of the experimental program, a case study on the 4x2m reinforced concrete slab of the room was done, as a real fire practice.Finally, two models using artificial neural network (ANN) have been conducted on estimating the steel temperatures inside small scale concrete slabs with different concrete cover thickness and furthermore, estimating the residual compressive strength of the concrete mixtures at different elevated temperatures. The results obtained from these experiments show that the high temperatures have an adverse effect on all mechanical properties of the traditional concreteespecially at 600°C thatconsidered the critical temperature.The results also showed that the temperature of the reinforcement inside small scale traditional concrete slabs was reduced by about 58% as increasing the thickness of concrete cover from 1 inch to3 inch. The applications of the thermo gravimetric analysis (TGA/DTG) have a significant effect on studying the mineralogy of the concrete depending on the temperature of component decomposition.As an important estimation from TGA test, it iseasyto draw curvesthat can be used to estimate the degree of the temperature and its duration, by knowing either of them, depending on TGA total weight loss of the sample taken from the heated concrete.The experimental resultshave also indicated that,most of the additive materials improve the properties of concrete at elevated temperatures. Silica fume concrete is more sensitive to high temperatures than the ordinary cement concreteat 600ºC. Polypropylene fibers can enhance residual strength at low temperatures and reducing the explosion spalling effect. Moreover, the presence of steel fibers and the limestone powder as 10 and 15% additive to cement content areconsidered to have the best results on the enhancement of concrete high temperature resistance. Limestone powder has a visible effect on reducing the surface cracks of the concrete. The addition of bentonite, as a 10%cement replacement shows a stable reduction in residual compressive strength at all elevated temperature and a good effect on reducing the surface cracks of concrete. Scanningelectron microscope (SEM) confirmedthe former results obviously.The plastering has a considerable effect on protecting the concrete against high temperatures; the residual compressive strength of the covered concrete is increased by about 20% at 600°C compared with the uncovered concrete. The results obtained from the experiments on the mortar have revealed that limestone portland cement mortarand replacing a part of cement content by (ceramic powder and melamine powder) enhance the properties of the mortars at high temperature. SEM shows the presence of ceramic, melamine and bentonite particles in the mortars numerously up to 600°C. The presence of brick clay powder may have insignificant effects on the mortar, if it exposed to high temperatures.Numerical modeling using neural network shows good prediction for steel temperatures and compressive strength for concretesamples subjected to high temperatures where the minimum value of R² is 0.90for testing set ANN.