Browsing by Author "Ayad S. Aadi"

Now showing 1 - 3 of 3

Mechanical performance of eco-friendly self-compacting concrete (SCC) mixtures and two-way slabs partially containing cement kiln dust as cement replacement and internally reinforced with waste plastic mesh
(Elsevier, 2024-08) Nahla Hilal; Ayad S. Aadi; Sheelan Mahmoud Hama; Weiwen Li; Nadhim Hamah Sor; Walid Mansour
A large quantity of cement kiln dust (CKD) is produced annually during the production of Portland cement. The majority of the produced CKD remains unused except in specific cases related to soil stabilization projects. The current research investigates the production of self-compacting concrete (SCC) mixtures, in which CKD is used as a substitute for cement in different weight proportions, 3 %, 6 %, 9 %, 12 %, and 15 %. The hardened mechanical properties of SCC, such as compressive strength, splitting tensile strength, and flexural strength, as well as the fresh state characteristics (i.e., slump flow diameter, T500, V-funnel, and L-box tests), were recorded and compared with the control mixture which was entirely cast using cement. Results revealed that with an increase in the CKD content beyond 6 %, the slump flow diameter of SCC mixtures significantly decreased. Also, the increase ratios in the V-Funnel flow time for self-compacting concrete mixtures, when replacing cement with CKD ratios of 3 %, 6 %, 9 %, 12 %, and 15 %, were 13.3 %, 30 %, 46 %, 58 %, and 66.7 % respectively, compared with the reference mixture. Additionally, the impact behavior of two-way SCC slabs cast using CKD ratios ranging from 3 to 15 % and internally strengthened using various patterns of recycled plastic mesh was inves tigated. Strengthening the SCC slabs using two layers of recycled plastic grids proved to be effective in preventing the projectile from penetrating the whole thickness of the SCC slabs, regardless of the CKD content.
The Impact Resistance of Fire Shooting for Self-Compacted Concrete Slabs Containing Ceramic Powder and Reinforced by Novel Waste Nylon Fiber
(Annales de Chimie - Science des Matériaux, 2024-08-04) Nahla Hilal; Aseel S. Mansi; Ayad S. Aadi; Taghreed Khaleefa Mohammed Ali; Haider A. Abdulhameed
In the present study, nylon waste fibers (NWF) were utilized for the first time to improve the impact resistance of self-compacting concrete (SCC) slabs against pistol shooting. Six ratios of NWF were used in the range of (0.25- 1.5 at an increment of 0.25) % with three different lengths (50, 70, and 90) mm for each ratio. The fresh properties, compressive strength, and Utara sonic pulse velocity (UPV) of SCC were also measured. The results indicate the positive role of NWF in improving compressive strength. However, the fresh properties are affected negatively by using NWF. The best impact resistance of the slab occurred when 1% of NWF with a length of 90 mm was utilized.
The influence of waste polypropylene fibers on the behavior of sustainable reinforced concrete beams
(John Wiley & Sons, 2025-02-04) Nahla Hilal; Sulaiman Nayef Ahmed; Ayad S. Aadi; Mohammed Nawar; Salih Taner Yildirim; Nadhim Hamah Sor
Plastic waste has recently become one of the most important environmental issues. Plastic fibers in concrete provide a long-term solution to plastic waste management. Concrete is a rigid material and has superior compressive strength but has poor tensile strength. Using waste plastic fibers in concrete can address its brittleness and low tensile strength. In this study, waste polypropylene fiber (WPF) prepared from discarded plastic tapes in reinforced concrete (RC) beams was used. WPF of 5 mm width was added to the concrete at a volumetric percentage of 1%. The fibers were added at different lengths (50, 70, and 90 mm) individually, and then all lengths were mixed randomly. This study provides the results of laboratory tests conducted to evaluate the mechanical properties of the WPF-RC. Additionally, a comparison of RC beams with the same percentage of reinforcement but varying lengths of WPF in the tensile zone was provided. The criteria for the flexural test were determining the ultimate load, the yield, and the first cracking as well as the deflections associated with these loads. Evaluations of the energy absorption index, ductility, and failure modes were also carried out. The WPF enhanced the ultimate load by 5%, the deflection at the ultimate load by 33.26%, and the splitting tensile strength by 51.47% for the concrete. Additionally, the load– deflection relationships demonstrated that concrete beams reinforced with WPF tend to deflect more before failing. The energy absorption index capacity is increased by 94.36% and ductility by 25.83% for the beam reinforced with 1% WPF, mixed randomly at mixing randomly lengths. This possible enhancement of RC beam performance based on the WPF can promote the use of sustainable concrete in many structural applications based on the WPF.