Experimental Investigation of Sandwich Panels with Different Types of Coarse Aggregate

تمثل الالواح الساندويجية الخرسانية شكل انشائي مبتكر يتكون من طبقتين او أكثر من الخرسانة مفصولة بطبقة خفيفة الوزن .في العمل الحالي , الالواح الساندويجية تتكون من طبقتين من الخرسانة الخفيفة الوزن بينهما طبقة من الفلين , تربط الطبقتين الخرسانية الخارجية بواسطة قضيب حديدي على شكل قفص .البرنامج العملي يتكون من اربعة سقوف , واحد منها يكون سقف صلد بينما السقوف الثلاث الأخرى هي سقوف ساندويجية. المتغير الرئيسي للدراسة الحالية كان نوع الركام الخشن المستخدم في طبقتا الخرسانة الخارجية . فحصت الالواح بوضعية بسيط الأسناد تحت تأثير خطين من الحمل المسلط . بينت النتائج العملية ان استخدام السقوف الساندويجية يحسن الكثير من الخواص مثل المتانة والليونة والقيمة العظمى للهطول.بالأضافة الى الفائدة الرئيسية وهي تقليل الوزن الأجمالي للألواح , وكذلك اختلاف انواع  الركام الخشن يؤثر بشكل كبير على التصرف الانشائي للألواح .Concrete sandwich panel [CSP] is an innovative structural construction system. It is two or more layers of concrete separate by lightweight layers. The present work, the one-way sandwich panels are comprised of two lightweight concrete layers, between them a layer of cork, the dimensions of the slabs were (1100mm total length × 400 mm width × 90mm thickness). The outer concrete layers were connected by steel bar in the shape of truss. An experimental program was carried out on four slabs, one of them was solid slab while the three other slabs were sandwich slabs. The main variable of this study was the type of course aggregate which used in the outer concrete layers. The slabs have been tested as a simply support span under two points load. Experimental results proved that the using of sandwich panels will have enhanced many properties such as toughness, ductility and maximum value of deflection, in addition to the main benefit is a total weight reduction. The differ in the type of coarse aggregate considerably influences the structural behavior of the panels

Finite Element Modeling of Reinforced Concrete Slabs Strengthened in Flexural with NSM-CFRP

        This study is devoted to investigate the behavior and performance of R.C. slabs strengthened with near surface mounted (NSM-CFRP). A system of computer program (ANSYS V.12.1) is used for analysis at this study. The ordinary reinforced concrete is modeled by 8-node isoparametric brick elements, while the steel reinforcing bars is modeled as axial members (bar elements) connecting opposite nodes in the brick elements with a full interaction assumption. The NSM CFRP strips were modeled by shell element. The effect of some selected parameters (thickness and shape) is studied. It is found that the ultimate load increased efficiently with increasing the thickness of NSM (87% & 123% for slabs S1 & S2 respectively). Concrete strength of R.C. slabs tested is (fc’ 18.85). The maximum increment in terms of the slab load carrying capacity is limited by the concrete crushing.

Behavior of Concrete Beams Internally Cured with Clay Brick Waste

In this research, the long-term potential cracking of normal concrete internally cured with clay brick waste as a sustainable approach was investigated. 10% and 15% volume of sand was substituted with corresponding quantity of pre-saturated clay brick waste to enhance the hydration of cement and improve properties of concrete. Four beams internally cured were compared with two control beams. The use of clay brick waste can improve the compressive and splitting tensile strength and also a significant reduction in cracks were observed. Depending on the recorded results, it is demonstrated that the exemplary percentages of clay brick waste to natural fine aggregate was found to be 15%, which developed greatest compressive and splitting tensile strength, and reduce the crack by means of flexural test