Copyright © 2018 Authors. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. International Journal of Engineering & Technology, 7 (4.20) (2018) 602-607 International Journal of Engineering & Technology Website: www.sciencepubco.com/index.php/IJET Research paper Behavior of Plastic Tubular Specimens Filled with Brick-Aggregates Concrete Under Compressive Loads Haider Sadiq Al-Aasam 1 *, Ruaa Yousif Hassan 2 , Riyadh Jawad Aziz 3 1 Al-Esraa University College, Baghdad, Iraq. 2 Al-Esraa University College, Baghdad, Iraq. 3 Al-Esraa University College, Baghdad, Iraq. *Corresponding author E-mail: haider.sa@gmail.com Abstract This study represents results of an experimental test to investigate the effect on the compression strength of gravel and recycled brick aggregates concrete specimens confined using plastic tubes. Plastic tubes used to confine concrete which is produced using river gravel or broken brick as a replacement for river gravel. A compressive load was applied to the specimens gradually up to failure. The results have indicated that as concrete compressive strength increased from (21.0 to 27.5)MPa, an increase in peak load of (3-46)% was achieved. Moreover, the brick aggregates concrete specimens have lower peak load as compared to gravel concrete and the peak load of confined specimens increased (3-6) times as compared to unconfined. Also, when the ratio of (height/diameter) of the concrete specimen increases from (2-4) the peak load decreased by about (2-12)%. The use of brick aggregates as a replacement to river aggregates results in significant decrease in weight and cost of concrete members. As well, the use of plastic tubes as a concrete form is superior to other construction materials such as wood or steel forms, since plastic tubes reduce the cost of forms and time of construction, and it protects concrete used for underground construction. Keywords: Broken Brick; Concrete Column; Confinement; PP-R Pipes; Strength. 1. Introduction The continuous decadence in piers and piles of structures, especially those constructed in harsh environments such as piles of bridges, has raised the request for repairing and modifying existing concrete columns in building and passway substructures [1]. It is needful to repair the decadence and damaged concrete columns to raise their carrying capacity and ductility to get better durability and realization [2]. A composite system such as Concrete-Filled Tube (CFT) may be used for such rehabilitation and retrofitting. For many years, different types of confined columns had been used such as steel or FRP (fiber-reinforced polymer) pipes as the confinement material. But these types of materials are facing a lot of difficulties due to a number of factors such as abrasion resistant of steel when used in under-sea piling, and the high cost of industrialization FRP material [4]. An alternative to the use of composite materials tubing is to use plastic pipes. The pipes are corrosion resistance and are rather cheap as compared to the steel and FRP [4]. The plastic jacket also acts as permanent formwork. Formwork methods must be capable of carrying its own weight, the weight developed by fresh concrete, also live loads associated with the construction operation and equipment. The formwork that stay-in- place has been lately used as an alternative to the conventional formwork methods. Stay-in-place formwork methods are mainly assembled on site, hence facilitate the construction operation and reducing the construction time as the removal proceedings are eliminated. Furthermore, many of the stay-in-place formwork methods are made of lightweight and prefabricated materials [5]. Recently, many research efforts have been conducted to study the structural behavior of confined concrete columns using the commercially available UPVC plastic pipes. Thus this study focused on investigating the behavior of columns concrete filled in tubular made from plastic using Polypropylene random copolymer (PP- R) pipes. Due to good and important physical properties of PP - r such as properties of mechanical resistance, inertia to chemical aggression impact strength, corrosion resistance and higher working temperature and has general properties of low density, good balance of stiffness to toughness, low tendency to stress cracking and is easy to process and installation. PP-r becomes the most popular material used in the world’s market as a construction material. [11]. The normal weight of concrete (self-weight) varies from (2200 to 2600) kg per cubic meter. And this is one of the main disadvantages of traditional concrete as this heavy-weight concrete makes it uneconomical construction material. For increase the efficiency of concrete as a construction material, attempts have been made to minimize its weight per cubic meter. A type of Concrete having self-weight ranging from (300 to 1850) kg per cubic meter is called light-weight concrete. Recently years, lightweight concrete has become more popular due to various advantages it offers over the traditional concrete [6]. Recycled aggregates (from construction, demolition and excavation wastes) are increasingly used as partial replacements of natural aggregates. Concrete can be successfully produced using recycled materials. The use of recycled aggregate concrete (RAC) has steadily increased during the last two decades and its current field of applications includes: lightweight concrete, lightweight aggregate, asphalt concrete, concrete exposed to high temperatures and road