×
The submission system is temporarily under maintenance. Please send your manuscripts to
Go to Editorial ManagerIn recent decades, the need for strengthening and repairing reinforced concrete structures has increasingly arisen. One common method is the use of concrete jackets. Slurry Infiltrated Fiber Concrete (SIFCON), a newly developed material, offers superior mechanical properties, making it a preferred choice for strengthening and repairing concrete structures. However, there is limited understanding of its bonding performance when used as an overlay on a Normal Strength Concrete (NSC) substrate. This study conducted a direct Shear Test (DST) to evaluate the bond performance using reinforced NSC cubes externally bonded with SIFCON jackets subjected to direct shear. Eighteen reinforced cubes were strengthened with various bonding systems to investigate how different factors affect the bond performance between the NSC substrate and SIFCON overlay. The parameters studied included surface preparation methods, binder types, jacket configurations, bonding conditions (fresh overlay on hardened substrate and hardened overlay on hardened substrate), dowel placement, and bonding mechanisms. The results show that using bonding agents significantly improved bond strength, with epoxy proving more effective than latex. Specimens prepared by chipping showed better bonding performance compared to those prepared through diamond cutting. Chipping increased bond strength by 8.91% to 13.84% over diamond cutting in the case of fresh SIFCON overlay on hardened substrate. Using dowels in the bonding systems also improved bond performance by 10.89% to 16.97%. Applying jackets to three sides instead of two increased the ultimate failure load by 31.76% when dowels were used in both the two-sided and three-sided strengthened samples, and by 35.45% in the absence of dowels in both types of strengthened specimens. The cast-in-situ specimens demonstrated superiority over those strengthened with precast jacket layers.
In this investigation, the bond stresses between the reinforcement and concrete was studied by using non-material interface elements that are able to produce the bond stresses for the reinforced concrete beam gradually loaded from zero to failure. Depending on (Jawad) program, which is a non-linear analysis program of plain and reinforced concrete beams through a discrete-crack approach by using the finite element method. The stiffness matrix derivation of the interface element and the way of non-linear treatment were explained. The distribution of bond stress drawings along the steel reinforcement for different values of loading was achieved before and after cracking.
Adhesives have been around for millennia. Nevertheless, this technique for joining has only seen significant development within the past 70 years. Professional technical engineering applications primarily use adhesives derived from synthetic polymers, a development that dates back to the mid-1940s. Its characteristics facilitate their strong adhesion to most substrates, as well as their ability to transfer substantial loads. This paper presents an extensive assessment of the current knowledge in the field of adhesives and related technologies, with a focus on adhesion theories and their parameters, as well as designing, joint configuration, geometric aspects, and failure modes. The paper also explores the interplay between research and development efforts, industrial standards, and regulatory aspects, with the goal of fostering collaboration between academia and industry. Over the past years, the development of new materials, methods, and models has resolved many of the shortcomings. Nonetheless, it is still possible to evaluate and estimate the optimal combination of aspects that will give the greatest efficiency and performance for adhesive bond joints (ABJs).
Polyethylene terephthalate (PET) was prepared from (PET) flakes and 25% of NaOH solution were added to in tri-neck flask, the reaction run for six hours at temperature (100-130) oC and the precipitate was reacted with ethylene glycol at temperature (130-160) oC. IR spectrophotometer was used for the diagnoses of (PET). Differential scanning calorimeter (DSC) is used to indicate glass transition temperature Tg, the melting temperature Tm and the heat absorbed. Part hundred ratios (phr,s) of (PET) rather than dosage of PET in gms. To concrete cubes were added to study its effect on concrete properties. Additives of (phr,s) impart performance such as increased cement dispersion, and enhance the performance of concrete which was appeared in maintaining a lengthening or slow the setting time that meets product and job needs. Maximum and minimum compressive strength is 43.7 MPa and 30.0 MPa at 0.3 gm. and 0.1 gm. respectively.
A composite beam is an accumulation of different materials so as to form a single unit to exploit the prominent quality of these materials according to their position within the cross-section of the composite beam. The present study investigates the structural behavior of six simply supported composite beams, in which a reinforced concrete T-beam is connected together with a steel channel located at the bottom of a T-beam by means of headed stud shear connectors. The used degrees of shear connection are (100%, 75%, 50%, and 38%). Three dimensional nonlinear finite element analysis has been used to conduct the numerical investigation for the general behavior of beams which are subjected to central point load. ANSYS 12.1 program code was used to estimate the ultimate loads, deflections, stresses, strains, end slip. Concrete was modeled by brick element (SOLID65), while the steel channel was modeled as brick element (SOLID45). Two-node discrete elements (LINK8) are used to represent the steel reinforcement and shear connectors. Perfect bond between the reinforcing rebars and the concrete was assumed. The load on beams was applied monotonically in increments up to failure. The reduction of the degree of shear connection from 100% to 38% causes increasing of strain, mid span deflection and end slip with an average of 3.95%, 13%, and 111% respectively, while the ultimate load decreases with an average of 7.3%. In order to observe the efficiency of the 3-D model, a comparison was made with available experimental work. Good agreement was obtained throughout this work between the finite element and available test results.
The polyethylene terephthalate (PET) was prepared from PET flakes of empty local water drinking bottles and diagnosis by infrared spectroscopy (IR). The glass transition temperature, melting temperature T m and heat capacity were indicated by differential scanning calorimeter (DSC). Part hundred ratios (phr , s) of (PET) were added to study its effect on concrete properties. Additives of (phr) impart performance such as increased cement dispersion, enabling drastically reduced water requirements. Enhance the mortar cubes performance; depend on the compatibility of cement with PET. Porosity of mortar cubes with cement, sand and added PET products were calculated. Maximum and minimum Compressive strength were calculated 58.76 MPa, and 24.0 MPa at phr 0.04 and 0.07 of PET with cement. And PET with cement and sand were calculated 16.5 MPa and 4 MPa at dosages 0.03 gm. and 0.08 gm. The relative dosages in calculating porosity percentages are (0.06, 0.1 and 0.3) gm.