The master’s thesis by the student (Saif Ibrahim Hendi) was discussed in the Department of Civil Engineering on the research entitled (Effect of Hybrid Fibers on some Properties of Reactive Powder Concrete Containing Sustainable Materials) on Thursday, 16-5-2024, under the supervision of
Prof. Dr. Nada Mahdi Fawzi AL-Jalawi
The discussion committee was formed of:
- Prof. Dr. Zena K. Abbas University of Baghdad/College of Engineering (Chairman)
- Prof. Dr. Layth Abed Al-Jabari University of Al-Mostansyria /College of Engineering (Member)
- Assist. Prof. Dr. Mohammed Zuhair AL-Mulali University of Baghdad/College of Engineering (Member)
- Prof. Dr. Nada Mahdi Fawzi AL-jalawi University of Baghdad/College of Engineering (Supervisor)
ABSTRACT
The emphasis these days has to be on finding high sustainability and minimizing environmental problems issues. This thesis uses reactive powder concrete (RPC) to accomplish these objectives. Numerous investigations have reported that the use of fiber reinforcing can increase the capacity of RPC at higher temperatures.
The primary goal of this research is to produce reactive powder concrete with high mechanical qualities and benefits for the environment and economy. There were two kinds of fibers used. The use of 1% (volume of concrete) with recycled copper fibers (RCF) and micro steel fibers (MSF). Five distinct combinations were utilized in varying proportions: [(1:0), (0:1), (0.5:0.5), (0.4:0.6), (0.3:0.7)] of MSF and RCF, respectively. Sustainable resources were also employed in place of cement, to examine how the mechanical properties of RPC changed. All mixtures had the same proportion of fundamental components, which were selected by previous research: the total weight of binders is 1100 kg/m³ with 10% silica fume by the weight of cement and 18% quartz powder of the weight of cement and the dosage of superplasticizer used was 1% of cementitious materials. MSF and RCF were used singly in the mixture and in a hybrid form, the warm water curing regime adopted in the rest of the tests, through which optimal results were obtained at 35℃. All mixtures were compared to the reference mixture (M1), which contains (1%) of Micro steel fibers (synthetic).
Compressive and flexural strength of the mixture (M2) including recycled copper fiber reactive powder concrete (RCRPC) with a percentage of 1% volume of fibers when compared with M3 reduced by (6.9, 19.7) % respectively after 28 days. The dry bulk density increased by 0.8% after 28 days. While the Flow increased by 5.9%. The fresh density increased by 4.7 %. The toughness index and ductility index increased compared to the reference mixture (M1) while the resilience decreased to 0.3.
The mixture M3, which contains 0.5% RCF and 0.5% MSF, produces the best compressive strength and density for concrete with hybrid fibers. When comparing the results of M3 with M1, the compressive strength and flexural strength slightly decreased by (3.4, 5) %, respectively, while the dry bulk density increased by (0.37) % after days. Fresh density increased by (1.7) % while the flow of concrete increased by (1.3%). The toughness index and ductility index increased compared to the reference mixture (M1) while the resilience decreased to 0.5, which results are very close to that of M1. The rate increases in shrinkage using Hybrid fibers in reactive powder concrete compared to M1 was (7.6, 9.6, 8.6, and 9.3) % at (7,30,60, and 90) days respectively. The rate increases in the creep test using Recycled Copper Fibers in reactive powder concrete compared to RPCMSF was (15.6, 19.8, 21.7, and 17.2) % at (7,30,60, and 90) days respectively.
Based on the information above, we can say that the mechanical qualities of M1 performed better than hybrid mixtures and mixtures of recycled copper fibers.
