Fee escalation in construction refers to a boom in the price of an item inside the preliminary agreement or the bottom cost of an undertaking. racking production mission fees must be an ongoing procedure that must always be carried out on all projects, because the reasons for which the price will increase vary from project to project and due to the construction segment. The motive of this observation was to assess fee escalation, escalation factors and mitigation mechanisms in deciding on construction initiatives. From February 1 to 30, 2020, a questionnaire was administered to twelve workers and interviews with seven key informants were conducted for an in-depth look at four selected Jimma University construction projects, which were project A to project D. Relative importance index values were generated and ranked for the elements affecting fee escalation to see their relative significance. It was found that there has been a moderate degree of charge increase within the initiatives studied, from 12% to 21%. The mitigation modalities observed with the aid of the projects, particularly inserting escalation clauses in contractual agreements, making changes requiring funding and increasing time limits, seem to be inadequate, as they do not provide a foundation for choices and remedy of disputes instead of mitigating the escalation of tasks starting from 3.21% to 12%. KEYWORDS: Escalation, Mitigation, Price, Construction projects.
{"title":"Investigation of Price Escalation and Its Mitigation Mechanisms on Selected Building Construction Projects of Jimma University","authors":"Hamelmal Mekonen, Alemu Mosisa Legesse, Frikot Mulatu Ameya","doi":"10.14525/jjce.v17i2.03","DOIUrl":"https://doi.org/10.14525/jjce.v17i2.03","url":null,"abstract":"Fee escalation in construction refers to a boom in the price of an item inside the preliminary agreement or the bottom cost of an undertaking. racking production mission fees must be an ongoing procedure that must always be carried out on all projects, because the reasons for which the price will increase vary from project to project and due to the construction segment. The motive of this observation was to assess fee escalation, escalation factors and mitigation mechanisms in deciding on construction initiatives. From February 1 to 30, 2020, a questionnaire was administered to twelve workers and interviews with seven key informants were conducted for an in-depth look at four selected Jimma University construction projects, which were project A to project D. Relative importance index values were generated and ranked for the elements affecting fee escalation to see their relative significance. It was found that there has been a moderate degree of charge increase within the initiatives studied, from 12% to 21%. The mitigation modalities observed with the aid of the projects, particularly inserting escalation clauses in contractual agreements, making changes requiring funding and increasing time limits, seem to be inadequate, as they do not provide a foundation for choices and remedy of disputes instead of mitigating the escalation of tasks starting from 3.21% to 12%. KEYWORDS: Escalation, Mitigation, Price, Construction projects.","PeriodicalId":51814,"journal":{"name":"Jordan Journal of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48101666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Amjad Issa, Saleh Qanazi, E. Natsheh, Abdallah Rashed
This paper aimed at utilizing GIS software in calculating pavement condition index )PCI( values, using four different interpolation methods: IDW, spline, trend and kriging. The case study covers four major streets in Nablus city with a total length of about 6.50 km. The PCI values were calculated using the ASTM conventional method. The four streets were divided into equal 100- meter sections. The PCI values were also calculated for each point of defect in both directions of the streets. The results of the four methods (point by point of defects) were compared manually with the conventional method (ASTM procedure). The results showed that the spline method had a strong correlation with the conventional method in terms of multiple R and R-square calculation (multiple R for left 0.918, right 0.947 and R2 for left 0.843, right 0.897). This method also fitted the data better than the other methods, as seen from the linear regression model results, in addition to producing the minimum error value. The results indicated that by identifying the PCI value, it would be possible to select the proper pavement maintenance and corresponding cost for each point of defect. This in turn would help in prioritizing pavement sections. KEYWORDS: Pavement condition index (PCI), GIS, Interpolation, Distress, Maintenance, Spline.
{"title":"Assessment of Existing Pavement Distresses Utilizing ArcMap-GIS: The Case of Nablus City","authors":"Amjad Issa, Saleh Qanazi, E. Natsheh, Abdallah Rashed","doi":"10.14525/jjce.v17i2.07","DOIUrl":"https://doi.org/10.14525/jjce.v17i2.07","url":null,"abstract":"This paper aimed at utilizing GIS software in calculating pavement condition index )PCI( values, using four different interpolation methods: IDW, spline, trend and kriging. The case study covers four major streets in Nablus city with a total length of about 6.50 km. The PCI values were calculated using the ASTM conventional method. The four streets were divided into equal 100- meter sections. The PCI values were also calculated for each point of defect in both directions of the streets. The results of the four methods (point by point of defects) were compared manually with the conventional method (ASTM procedure). The results showed that the spline method had a strong correlation with the conventional method in terms of multiple R and R-square calculation (multiple R for left 0.918, right 0.947 and R2 for left 0.843, right 0.897). This method also fitted the data better than the other methods, as seen from the linear regression model results, in addition to producing the minimum error value. The results indicated that by identifying the PCI value, it would be possible to select the proper pavement maintenance and corresponding cost for each point of defect. This in turn would help in prioritizing pavement sections. KEYWORDS: Pavement condition index (PCI), GIS, Interpolation, Distress, Maintenance, Spline.","PeriodicalId":51814,"journal":{"name":"Jordan Journal of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49653569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Permanent ground deformations (PGDs) induced by slope failures cause catastrophic damage to buried pipelines. This paper presents a 2D plane-strain numerical analysis of the behavior of a 800 mm water transport pipeline buried in the Aine-Tine slope (Mila, Algeria) subjected to shallow PGD, as it could be triggered by the recent earthquake of August 07th, 2020 (M= 4.9). The analysis is carried out through the application of an incremental displacement to simulate the soil-pipeline interaction while focusing on the effect of (1) the magnitude of the PGD and (2) the rigidity of the pipeline on the structural response of the pipeline. The elasticperfectly Mohr-Coulomb model was used to simulate the soil behavior and the elastic model was used to simulate that of the steel pipe. Pipeline deformations (i.e., translation and ovalization) and radial internal forces’ (i.e., axial forces F, shear forces Fୗ and bending moments M) results highlighted that shallow PGD can exert additional loads on pipelines that are proportional to the magnitude of the PGD. It has been found that the soil deformations as well as the internal forces induced on the pipeline ring are higher for rigid pipelines. Moreover, the results indicated that rigid pipelines are more effective than flexible ones as far as ovalization-serviceability limit state is concerned. In effect, for PGD magnitudes of 0.5, 1 and 2 m, the ovalization values of the flexible pipeline are, respectively, higher by 23%, 21% and 18% than those calculated for the rigid pipeline. Through a simplified linear numerical simulation such as that presented in this study, engineers and planners could be guided to foresee the possible causes of pipeline leaks and the mechanisms of ruptures that lead very often to severe disruption of pipelines’ normal operation. KEYWORDS: Soil-structure interaction, Slope failure, Permanent ground deformation, Pipelines, Radial internal forces, Ovalization
{"title":"Numerical Investigation on Buried Pipelines Subjected to Permanent Ground Deformations Due to Shallow Slope Failure","authors":"Mohammed Bouatia, R. Demagh, Z. Derriche","doi":"10.14525/jjce.v17i1.07","DOIUrl":"https://doi.org/10.14525/jjce.v17i1.07","url":null,"abstract":"Permanent ground deformations (PGDs) induced by slope failures cause catastrophic damage to buried pipelines. This paper presents a 2D plane-strain numerical analysis of the behavior of a 800 mm water transport pipeline buried in the Aine-Tine slope (Mila, Algeria) subjected to shallow PGD, as it could be triggered by the recent earthquake of August 07th, 2020 (M= 4.9). The analysis is carried out through the application of an incremental displacement to simulate the soil-pipeline interaction while focusing on the effect of (1) the magnitude of the PGD and (2) the rigidity of the pipeline on the structural response of the pipeline. The elasticperfectly Mohr-Coulomb model was used to simulate the soil behavior and the elastic model was used to simulate that of the steel pipe. Pipeline deformations (i.e., translation and ovalization) and radial internal forces’ (i.e., axial forces F, shear forces Fୗ and bending moments M) results highlighted that shallow PGD can exert additional loads on pipelines that are proportional to the magnitude of the PGD. It has been found that the soil deformations as well as the internal forces induced on the pipeline ring are higher for rigid pipelines. Moreover, the results indicated that rigid pipelines are more effective than flexible ones as far as ovalization-serviceability limit state is concerned. In effect, for PGD magnitudes of 0.5, 1 and 2 m, the ovalization values of the flexible pipeline are, respectively, higher by 23%, 21% and 18% than those calculated for the rigid pipeline. Through a simplified linear numerical simulation such as that presented in this study, engineers and planners could be guided to foresee the possible causes of pipeline leaks and the mechanisms of ruptures that lead very often to severe disruption of pipelines’ normal operation. KEYWORDS: Soil-structure interaction, Slope failure, Permanent ground deformation, Pipelines, Radial internal forces, Ovalization","PeriodicalId":51814,"journal":{"name":"Jordan Journal of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42912671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carbon dioxide can react with alkaline carbonate substances in cement-based materials, which harms the durability of the concrete structure. The carbonation reaction is a process of releasing water, resulting in an increase in pore water saturation, which was always neglected by previous studies. In this paper, a transient pore water saturation equation is proposed and introduced into the classical carbonation reaction kinetic model, which is simulated by finite-element software with a typical ordinary Portland cement. The model was verified by two classical empirical equations for carbonation-depth prediction. The simulation results indicated that the increment of pore water saturation originated by carbonation-produced water will weaken the CO2 diffusivity and enhance the carbonation resistance. Besides, the growth rate of carbonation depth is slightly faster without considering the produced water and with higher initial saturation, the difference will be more significant. If the influence of carbonation water is ignored, the predicted carbonation depth of unsaturated concrete may be less accurate. This study can provide some reference for theoretical and experimental studies on concrete carbonation. However, future work is still needed including more realistic effects in the model such as the mesoscale modeling of concrete and the integration of stress states. KEYWORDS: Ordinary Portland concrete, Carbonization reaction, Carbon-dioxide transport, Finite-element method, Pore saturation.
{"title":"Study of Carbonation-depth Prediction of Unsaturated Concrete Considering Carbonation-produced Water","authors":"J. Long, Zhigao Peng, Haoxiong Feng, Aocheng Yang","doi":"10.14525/jjce.v17i1.08","DOIUrl":"https://doi.org/10.14525/jjce.v17i1.08","url":null,"abstract":"Carbon dioxide can react with alkaline carbonate substances in cement-based materials, which harms the durability of the concrete structure. The carbonation reaction is a process of releasing water, resulting in an increase in pore water saturation, which was always neglected by previous studies. In this paper, a transient pore water saturation equation is proposed and introduced into the classical carbonation reaction kinetic model, which is simulated by finite-element software with a typical ordinary Portland cement. The model was verified by two classical empirical equations for carbonation-depth prediction. The simulation results indicated that the increment of pore water saturation originated by carbonation-produced water will weaken the CO2 diffusivity and enhance the carbonation resistance. Besides, the growth rate of carbonation depth is slightly faster without considering the produced water and with higher initial saturation, the difference will be more significant. If the influence of carbonation water is ignored, the predicted carbonation depth of unsaturated concrete may be less accurate. This study can provide some reference for theoretical and experimental studies on concrete carbonation. However, future work is still needed including more realistic effects in the model such as the mesoscale modeling of concrete and the integration of stress states. KEYWORDS: Ordinary Portland concrete, Carbonization reaction, Carbon-dioxide transport, Finite-element method, Pore saturation.","PeriodicalId":51814,"journal":{"name":"Jordan Journal of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45323420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Swelling in compacted soils may lead to some damages to structures and buildings. For the sake of reducing such damages, soil swelling should be determined, so as to make the structures exhibit adequate resistance against such a phenomenon. For most cases, fully non-linear relations have been observed between soil swelling and the parameters contributing to swelling in compacted soil. As such, soil swelling should be determined via either experimentations or prediction models. However, being extremely timely, swelling tests require special expensive equipment. Accordingly, there is a need for models which can use available data to theoretically give swelling estimations of a relatively high accuracy without getting busy with swelling tests and associated issues. Investigated and evaluated in this research are the ability and application of an adaptive neuro-fuzzy interference system (ANFIS) developed by subtractive clustering and fuzzy c-mean clustering to determine and predict swelling in compacted soils. The results along with the obtained values of root mean squared error (RMSE), mean absolute error (MAE) and coefficient of correlation (R) indicated that the proposed ANFIS model succeeded to predict swelling in compacted soils at a good level of accuracy. Therefore, ANFIS models can be used to predict swelling without getting busy with swelling tests and associated issues. KEYWORDS: Swelling of compacted soil, Subtractive clustering, Fuzzy c-mean clustering, ANFIS, Prediction.
{"title":"Swelling Prediction in Compacted Soils Using Adaptive Neuro-Fuzzy Inference System","authors":"M. Jokar, S. Mirassi, Meisam Mahboubi","doi":"10.14525/jjce.v17i1.09","DOIUrl":"https://doi.org/10.14525/jjce.v17i1.09","url":null,"abstract":"Swelling in compacted soils may lead to some damages to structures and buildings. For the sake of reducing such damages, soil swelling should be determined, so as to make the structures exhibit adequate resistance against such a phenomenon. For most cases, fully non-linear relations have been observed between soil swelling and the parameters contributing to swelling in compacted soil. As such, soil swelling should be determined via either experimentations or prediction models. However, being extremely timely, swelling tests require special expensive equipment. Accordingly, there is a need for models which can use available data to theoretically give swelling estimations of a relatively high accuracy without getting busy with swelling tests and associated issues. Investigated and evaluated in this research are the ability and application of an adaptive neuro-fuzzy interference system (ANFIS) developed by subtractive clustering and fuzzy c-mean clustering to determine and predict swelling in compacted soils. The results along with the obtained values of root mean squared error (RMSE), mean absolute error (MAE) and coefficient of correlation (R) indicated that the proposed ANFIS model succeeded to predict swelling in compacted soils at a good level of accuracy. Therefore, ANFIS models can be used to predict swelling without getting busy with swelling tests and associated issues. KEYWORDS: Swelling of compacted soil, Subtractive clustering, Fuzzy c-mean clustering, ANFIS, Prediction.","PeriodicalId":51814,"journal":{"name":"Jordan Journal of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48565099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qasim M. Shakir, Yahya M. Al-Sahlawi, Baneen B. Abd, Sara A. Hamad
The inclusion of D-regions within a reinforced-concrete member may affect largely the general behavior of the structure. Different techniques and approaches were proposed to control the behaviour of D-regions, such as the shear-friction approach and the STM model. Such proposals may not be applicable for all types of Dregions. The current work presents a nonlinear finite element model using the ANSYS software, that is adopted to study three types of D-regions, which are dapped ends, deep beams with openings and beams with loaded openings. The results revealed that the proposed FE model predicted adequately the effects of the inclusion of D-regions in RC beams. It is found that reducing the hanger or the nib reinforcement of a dapped end by 25% resulted in reducing capacity by 15% and 32%, respectively. Also, the results showed that for these deficiently reinforced dapped ends, reducing a/d ratio from 1.5 to 0.75 improved capacity by 23% and 36%. For the deficiently shearreinforced flanged deep beams, it was found that the inclusion of large openings within the shear span resulted in a capacity drop by (41-49) %. An enhancement of 23% was obtained when using stirrups of 12mm on both sides of the openings. Moreover, it is confirmed that the optimum location of the openings is under the diagonal path. Furthermore, it has been concluded that for loaded openings, the use of T-rolled sections within the bottom chord of the opening yielded an enhancement of 23% relative to the rhombus-shaped configuration. KEYWORDS: Dapped ends, T-deep beams with openings, Loaded openings, Hanger reinforcement.
{"title":"Nonlinear Finite Element Analysis of High-strength Reinforced Concrete Beams with Severely Disturbed Regions","authors":"Qasim M. Shakir, Yahya M. Al-Sahlawi, Baneen B. Abd, Sara A. Hamad","doi":"10.14525/jjce.v17i1.03","DOIUrl":"https://doi.org/10.14525/jjce.v17i1.03","url":null,"abstract":"The inclusion of D-regions within a reinforced-concrete member may affect largely the general behavior of the structure. Different techniques and approaches were proposed to control the behaviour of D-regions, such as the shear-friction approach and the STM model. Such proposals may not be applicable for all types of Dregions. The current work presents a nonlinear finite element model using the ANSYS software, that is adopted to study three types of D-regions, which are dapped ends, deep beams with openings and beams with loaded openings. The results revealed that the proposed FE model predicted adequately the effects of the inclusion of D-regions in RC beams. It is found that reducing the hanger or the nib reinforcement of a dapped end by 25% resulted in reducing capacity by 15% and 32%, respectively. Also, the results showed that for these deficiently reinforced dapped ends, reducing a/d ratio from 1.5 to 0.75 improved capacity by 23% and 36%. For the deficiently shearreinforced flanged deep beams, it was found that the inclusion of large openings within the shear span resulted in a capacity drop by (41-49) %. An enhancement of 23% was obtained when using stirrups of 12mm on both sides of the openings. Moreover, it is confirmed that the optimum location of the openings is under the diagonal path. Furthermore, it has been concluded that for loaded openings, the use of T-rolled sections within the bottom chord of the opening yielded an enhancement of 23% relative to the rhombus-shaped configuration. KEYWORDS: Dapped ends, T-deep beams with openings, Loaded openings, Hanger reinforcement.","PeriodicalId":51814,"journal":{"name":"Jordan Journal of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45016458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Waste management is of great concern in today’s world. Every year, an enormous amount of solid waste is generated from different industrial activities, especially the waste which is produced by iron industries in a particular form of slag. The major issue of emission of carbon dioxide (CO2) from cement industries is a serious problem for the earth's environment and the surrounding area. Thus, in this study, the waste iron slag obtained from nearby iron industries was used as a partial substitute for cement. The cement was replaced with iron slag (IS) at the substitution levels of 7.5%, 15%, 22.5%, 30% and 37.5% by weight of cement. The doses of superplasticizer for every mix were taken based on the essential workability requirements for the reinforcedconcrete work. Performance of control and blended mixes was evaluated by workability evaluation, compressive strength test, flexural strength test, water permeability test, water absorption evaluation, rapid chloride penetration test (RCPT) and carbonation test. Scanning electron microscopy (SEM), X-ray diffraction (XRD) technique and thermogravimetric analysis (TGA) technique were used to assess the micro-structural changes and to evaluate the chemistry of the blended mixes. The results obtained from this study were encouraging in terms of compressive and flexural strengths. The maximum compressive and flexural strengths were recorded at a 22.5% replacement level of slag. The results obtained at 30% replacement were also better compared to the control mix. The resistance of slag-made concrete mixes against adverse conditions; i.e., CO2 penetration, chloride penetration and water penetration was far better than that of conventional ones. The results obtained from TGA indicated that the productivity of calcium silicate gel of slag concrete is better than that of control concrete. KEYWORDS: Concrete, Slag, Carbonization, RCPT, XRD, TGA, SEM.
{"title":"Impact of Waste Iron Slag on Mechanical and Durability Properties of Concrete","authors":"K. Jain, D. Sharma, R. Choudhary, S. Bhargava","doi":"10.14525/jjce.v17i1.05","DOIUrl":"https://doi.org/10.14525/jjce.v17i1.05","url":null,"abstract":"Waste management is of great concern in today’s world. Every year, an enormous amount of solid waste is generated from different industrial activities, especially the waste which is produced by iron industries in a particular form of slag. The major issue of emission of carbon dioxide (CO2) from cement industries is a serious problem for the earth's environment and the surrounding area. Thus, in this study, the waste iron slag obtained from nearby iron industries was used as a partial substitute for cement. The cement was replaced with iron slag (IS) at the substitution levels of 7.5%, 15%, 22.5%, 30% and 37.5% by weight of cement. The doses of superplasticizer for every mix were taken based on the essential workability requirements for the reinforcedconcrete work. Performance of control and blended mixes was evaluated by workability evaluation, compressive strength test, flexural strength test, water permeability test, water absorption evaluation, rapid chloride penetration test (RCPT) and carbonation test. Scanning electron microscopy (SEM), X-ray diffraction (XRD) technique and thermogravimetric analysis (TGA) technique were used to assess the micro-structural changes and to evaluate the chemistry of the blended mixes. The results obtained from this study were encouraging in terms of compressive and flexural strengths. The maximum compressive and flexural strengths were recorded at a 22.5% replacement level of slag. The results obtained at 30% replacement were also better compared to the control mix. The resistance of slag-made concrete mixes against adverse conditions; i.e., CO2 penetration, chloride penetration and water penetration was far better than that of conventional ones. The results obtained from TGA indicated that the productivity of calcium silicate gel of slag concrete is better than that of control concrete. KEYWORDS: Concrete, Slag, Carbonization, RCPT, XRD, TGA, SEM.","PeriodicalId":51814,"journal":{"name":"Jordan Journal of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42806648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The coupled heat and moisture actions could easily cause deformation, cracking and corrosion problems in the slab ballastless track under operational conditions via China Railway Track System (CRTS) Ⅱ. In this paper, two one-quarter-scaled models of CRTS Ⅱ slab ballastless track under hygro-thermal environment were tested in a testing chamber, respectively. To study the effect of constrained conditions on the structural performance of track structure, temperature distribution, stress and displacement of two scaled models with constrained and free boundary conditions were also compared. Then, the temperature and stress field of the track structure was investigated by establishing a finite-element model. The results showed that the temperature transfer between layers has a temperature-lag effect. The positive and negative temperature gradients between the lower part of the track slab and the cement asphalt (CA) mortar layer of the constrained specimen are smaller than those of the free specimen. The longitudinal displacement of the track slab for the free specimen is significantly affected under the hygro-thermal environment and the longitudinal displacement of the concrete base and the track slab forms a displacement difference. Numerical-analysis results showed that the bottom of the concrete base is prone to produce a high-temperature core and that the temperature inside the track structure forms an agglomeration effect. KEYWORDS: Slab track, Hygro-thermal environment, Structural performance, Scale model, Finiteelement model.
{"title":"Experimental and Numerical Investigations of Structural Performance of Slab Track under Hygrothermal Environment","authors":"Anxiang Song, G. Yao, Xuanrui Yu, Yuerui Wang, Qingkang Guo, Rui Zhou","doi":"10.14525/jjce.v17i1.11","DOIUrl":"https://doi.org/10.14525/jjce.v17i1.11","url":null,"abstract":"The coupled heat and moisture actions could easily cause deformation, cracking and corrosion problems in the slab ballastless track under operational conditions via China Railway Track System (CRTS) Ⅱ. In this paper, two one-quarter-scaled models of CRTS Ⅱ slab ballastless track under hygro-thermal environment were tested in a testing chamber, respectively. To study the effect of constrained conditions on the structural performance of track structure, temperature distribution, stress and displacement of two scaled models with constrained and free boundary conditions were also compared. Then, the temperature and stress field of the track structure was investigated by establishing a finite-element model. The results showed that the temperature transfer between layers has a temperature-lag effect. The positive and negative temperature gradients between the lower part of the track slab and the cement asphalt (CA) mortar layer of the constrained specimen are smaller than those of the free specimen. The longitudinal displacement of the track slab for the free specimen is significantly affected under the hygro-thermal environment and the longitudinal displacement of the concrete base and the track slab forms a displacement difference. Numerical-analysis results showed that the bottom of the concrete base is prone to produce a high-temperature core and that the temperature inside the track structure forms an agglomeration effect. KEYWORDS: Slab track, Hygro-thermal environment, Structural performance, Scale model, Finiteelement model.","PeriodicalId":51814,"journal":{"name":"Jordan Journal of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48521482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Self-compacting concrete (SCC) is a high-performance concrete widely used as a building material. The present investigation examines the effects of age and cooling type (air-cooled and water-cooled) of SCC after being exposed to elevated temperatures and compares them to those of normal conventional concrete (NCC). Two types of concrete; i.e., NCC and SCC, were developed and studied for early-age and residual strengths. SCC was developed with three different types of admixtures; namely, fly ash (FA), silica fume (SF) and metakaolin (MK) as binder materials, by replacing the cement. The mechanical characteristics of FA- and SF-blended SCC before heating show similar results, whereas MK-based SCC possesses greater strength than other mixes. In the case of specimens exposed to high temperature of 1000℃, MK-blended SCC produced the lowest residual strength compared to FA- and SF-based mixes. Further microstructural investigation was conducted to examine the internal structure of the specimens exposed to various heating temperatures. From the results, it is concluded that the higher the strength gain upon aging, the greater the strength loss upon temperature rise. KEYWORDS: Self-compacting concrete, Fly ash, Silica fume, Metakaolin, Residual strength, Microstructure.
{"title":"Mechanical Properties and Microstructure Characteristics of Self-compacting Concrete with Different Admixtures Exposed to Elevated Temperatures","authors":"B. Kanagaraj","doi":"10.14525/jjce.v17i1.01","DOIUrl":"https://doi.org/10.14525/jjce.v17i1.01","url":null,"abstract":"Self-compacting concrete (SCC) is a high-performance concrete widely used as a building material. The present investigation examines the effects of age and cooling type (air-cooled and water-cooled) of SCC after being exposed to elevated temperatures and compares them to those of normal conventional concrete (NCC). Two types of concrete; i.e., NCC and SCC, were developed and studied for early-age and residual strengths. SCC was developed with three different types of admixtures; namely, fly ash (FA), silica fume (SF) and metakaolin (MK) as binder materials, by replacing the cement. The mechanical characteristics of FA- and SF-blended SCC before heating show similar results, whereas MK-based SCC possesses greater strength than other mixes. In the case of specimens exposed to high temperature of 1000℃, MK-blended SCC produced the lowest residual strength compared to FA- and SF-based mixes. Further microstructural investigation was conducted to examine the internal structure of the specimens exposed to various heating temperatures. From the results, it is concluded that the higher the strength gain upon aging, the greater the strength loss upon temperature rise. KEYWORDS: Self-compacting concrete, Fly ash, Silica fume, Metakaolin, Residual strength, Microstructure.","PeriodicalId":51814,"journal":{"name":"Jordan Journal of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48939755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sajjad Rezaei, M. Khabiri, Hamed Abshari, Behzad Pezeshk, Mojtaba Movahed, Amir Khakbazan
The effectiveness of weight ratio of mineral filler to effective bitumen in the fatigue performance of asphalt mixture with integral granules was investigated based on experiments on bitumen mastic (mixture of bitumen and mineral filler passed through sieve grade 200). The experiments included a dynamic shear rheometer, elastic recovery, linear amplitude sweep tests and other performance tests on asphalt mixture, such as fatigue of indirect tensile and resilient modulus test for assessing the medium temperature with various mineral fillerto- bitumen ratios of: 0.4, 0.6, 0.8, 1.0, 1.2, 1.4 and 1.6 for bitumen 70-16 PG. Based on this project, the weight ratio of mineral filler to effective bitumen according to Iran Management and Planning Organization (IMPO234) and SHRP-A407 standard and based on fatigue performance of asphalt mixture was separated and modified. So, to control and modify the medium temperature, the maximum weight ratio of filler to effective bitumen should be considered, which is equal to 0.8. The results of this research showed that for controlling the fatigue performance, the rheological behavior of bitumen mastic should be considered beside the asphalt mixture performance and the bitumen rheological behavior. KEYWORDS: Asphalt mixture, Bitumen mastic, Ratio of filler to bitumen, Performance, Fatigue
{"title":"Effectiveness of Weight Ratio of Mineral Filler to Effective Bitumen in the Asphalt-mixture Fatigue Performance","authors":"Sajjad Rezaei, M. Khabiri, Hamed Abshari, Behzad Pezeshk, Mojtaba Movahed, Amir Khakbazan","doi":"10.14525/jjce.v17i1.12","DOIUrl":"https://doi.org/10.14525/jjce.v17i1.12","url":null,"abstract":"The effectiveness of weight ratio of mineral filler to effective bitumen in the fatigue performance of asphalt mixture with integral granules was investigated based on experiments on bitumen mastic (mixture of bitumen and mineral filler passed through sieve grade 200). The experiments included a dynamic shear rheometer, elastic recovery, linear amplitude sweep tests and other performance tests on asphalt mixture, such as fatigue of indirect tensile and resilient modulus test for assessing the medium temperature with various mineral fillerto- bitumen ratios of: 0.4, 0.6, 0.8, 1.0, 1.2, 1.4 and 1.6 for bitumen 70-16 PG. Based on this project, the weight ratio of mineral filler to effective bitumen according to Iran Management and Planning Organization (IMPO234) and SHRP-A407 standard and based on fatigue performance of asphalt mixture was separated and modified. So, to control and modify the medium temperature, the maximum weight ratio of filler to effective bitumen should be considered, which is equal to 0.8. The results of this research showed that for controlling the fatigue performance, the rheological behavior of bitumen mastic should be considered beside the asphalt mixture performance and the bitumen rheological behavior. KEYWORDS: Asphalt mixture, Bitumen mastic, Ratio of filler to bitumen, Performance, Fatigue","PeriodicalId":51814,"journal":{"name":"Jordan Journal of Civil Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45912541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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