Articles in This Issue
Abstract
In recent years, a number of researchers have adopted the wet packing (WP) approach to design different types of concrete mixes. Particle grading is a key to the optimization of the wet compactness density; for that reason, all empty spaces that exist in between large-size particles need to be completely filled with particles of smaller size. Previously-conducted studies in this field have been focused on measuring the particle size distribution’s packing density (PD) of the of granular matrices is the purpose of investigating how to increase the PD of cementitious materials. Thus, literature lacks models capable of predicting the optimal PD value. The current study collected and analyzed 216 datasets in order to construct a model for accurate prediction of PD. The main datasets were organized into two categories: modeling datasets and validation datasets. To configure the model in the best way, a hybrid gravitational search algorithm-artificial neural network (GSA-ANN) was also developed in this study. The findings confirmed ANN as an effective alternative for measuring the ultimate PD of cementitious pastes. ANN provided high levels of accuracy, practicality, and effectiveness in the process of predicting the PD value. Based on the final results, the implementation of the hybrid GSA-ANN technique causes a significant decrease in the number of tests conducted on experimental samples, which results in not only saving time and money, but also reducing the CO2 emission volume.
Abstract
One of the most significant aspects of developing any region is establishing a viable road network and determining the relationship between landscape use and road networks. Adequate connectivity and direction are essential for the proper construction of any network. However, the Al-Ramadi road network has received far less attention and appraisal. As a result, the purpose of this study was to evaluate the current road network link in Al-Ramadi city. In addition, the GIS application was used in this study to show the city's primary features. The Alpha index, Beta index, Gamma index, and Eta index were utilized to evaluate the road network in this research. The primary goal of this research is to evaluate how successful the road network is in containing current road traffic and to make recommendations for the future traffic management efficiency to accommodate increase. The findings show that immediate upgrades, such as the construction of new roadways, are essential.
Abstract
The frequency of accidents, as well as statistical models of accident frequency, are often used as a foundation for prioritizing improvements to roadway safety by several transportation organizations. However, the use of accident severities in safety programming has frequently been restricted to the locational assessment of accident fatalities, with little or no emphasis being placed on the full severity distribution of accidents (slight damage, serious damage) which is required in order to properly evaluate the advantages of several competing efforts aimed at improving safety. Within the scope of this research, we provide a sufficient modeling technique that may be used to get a better understanding of the accident severity level that occur on highway segments, as well as the influence of traffic characteristics such as annual daily flow, percentage of heavy vehicle and free flow speed. The modeling approach that used in this research (random parameters model) provides the possibility that the estimated values of the model parameters might differ from one road segment to another to account the heterogeneity of the independent variables. The estimated random parameters models are developed using accident severity data and traffic characteristics data that obtained from Fallujha – Al-Qaeam rural multilane road in Al-Anbar province, Iraq. The results of the estimated results suggest annual daily flow, percentage of heavy vehicle and free flow speed all have significant effect on the accident severity level. For the purpose of prioritizing highway safety improvements, a number of government transportation authority’s base their decisions on accident rates and statistical models of accident rates. The random parameters models have been shown to have significant potential for use as a sufficient method in the programming of highway safety.
Abstract
Slurry infiltrated fiber concrete (SIFCON) is a relatively new high performance material and can be considered a special type of fiber concrete (FRC) with high fiber content. The matrix consists of a flowing mortar or cement slurry that must penetrate well through the network of fibers placed in the mold. SIFCON has excellent mechanical properties combined with high ductility and toughness values. SIFCON a relatively new material, is composed of mud (cement or cement and sand), water, a plasticizer (water reducer), and fibers. All previous studies have used waste steel fibers, steel fibers and other fibers, but in this study, plastic fibers were made from polyethylene terephthalate (PET) by cutting carbonated beverage bottles. The main objectives of this study are: Determination the effect of the waste plastic fiber volume ratio on the strength and deformation of (SIFCON) samples under the influence of bending loads. Both flexural strength and toughness properties were determined by testing samples (100×100×400) mm at 28 and 56 days of age. The results obtained from these tests were compared with those performed on conventional tests. Aspect Ratio equal to (36.8) and three volume ratios (3%, 5% and 7%) of the total volume of the concrete mixture were used to add fibers with different volume ratios. A conventional concrete mix was created as a reference for comparison. Bending strength and fresh concrete tests were performed. And compared with the reference mixture and according to the analysis of the results. The results showed an improvement in bending strength .It was found through the flexural examination that the flexural strength of the mixture containing fiber percentage (7%) achieved the highest strength compared to the rest of the ratios used, compared with the reference mixture (Ref.) by (32.25, 27.5)% for ages (28, 56), respectively.
Abstract
The present study, the effect of changes that developed in concrete structures with time is presented. Two way slab investigated experimentally by [1]was analyzed using finite element method by ANSYS commercial program. Many parameters studied such as length to thickness ratio, reinforcement ratio and ultimate load ratio. The slab with dimension (2360*2360*63) mm and reinforced with different types of materials such as steel bars ,GFRP and CFRP (fiber reinforced polymer) bars . The results show that the strain increase gradually with time after apply the load. It can see that the strain in steel model increase with ratio of 19.98% when the load increase from 75% to 90%,and decrease with ratio 50% when the load decrease from 75% to 50% .That is, the change by increasing the strain is less and slower than the change by decreasing the strain, since the strain when dropping the load is less than the strain when lifting the load, because the structure has not undergone and its stiffness is still high and it is trying to recover its original shape. It increases significantly at the beginning, and then the difference decreases or stabilizes approximately after 330 days.
Abstract
This paper presents and discuses some properties of self-compacting concrete SCC containing optimum contents of different types of cement replacement materials CRMs like fly ah, silica fume and limestone powder. The purpose is to evaluate the performance of SCC mixtures to choose the best one for strengthening purposes of corroded reinforcement concrete beams. In a preliminary work, the theoretical optimum contents of the above materials were specified using statistical program (Minitab) and they were verified experimentally. This verification based on checking fresh properties such as slump flow, T500, L-box and segregation resistance as well as compressive strength. The optimum contents of CRMs: 14% fly ash, 19% limestone, 18% silica fume plus fly ash and 11% silica fume were selected and studied. Compressive, tensile, and flexural strengths were examined, as well as the modulus of elasticity, water absorption and porosity (which reflect the related durability properties) were examined. Test results show that the optimum verified theoretical percentage of a combination of fly ash and silica fume, at 18% by weight of cement with a fixed water-binder ratio of 0.33 showed the best overall performance. It was deduced that this SCC mix gave the highest mechanical properties and the lowest porosity and water absorption. For example, the compressive strength increased by 36.25% as compared to SCC mix containing limestone powder. Further, the porosity and water absorption decreased by 120.8% and 164% respectively as compared to the above same SCC mix. Thus, it could be used for strengthening purpose of corroded RC beams.