Civil Engineering Infrastructures Journal
Volume:56 Issue: 2, Dec 2023

Full depth repair remains to be the favored pavement restoration method amongst the common rehabilitation and repair activities carried out for concrete pavements. This paper explores the prospects of utilizing behavioral benefits of Self-Compacting Concrete (SCC) with the inclusion of Wollastonite micro-fiber, for repair and rehabilitation of concrete pavements. Wollastonite was included in the study by replacing fine aggregates in concrete mix in proportions 10%, 20%, 30%, 40% and 50%. The mixes were investigated for their behavioral properties including flow ability, resistance to segregation, filling ability and mechanical properties i.e. compressive strength, flexural strength, water absorption and hardened density. The rehabilitation prospect of concrete pavements with SCC was studied by conducting a joint repair study on pavement prototypes specially designed and tested for the purpose. It was found that the concrete mix with Wollastonite were more cohesive and workable which is attributed to its acicular structure and lustrous appearance. During the rehabilitation study, prototypes representing a jointed section of concrete pavement were repaired with SCC mixes. The prototypes repaired with SCC having Wollastonite micro-fiber at levels of 10%, 20% and 30% reported better flexural strength in comparison to those repaired with conventional concrete or with plane self-compacting concrete mix.

In this research, a nonlinear model is presented to explore the seismic response of concrete arch dams. This model is much more simplified and efficient in comparison with plastic-damage models. It can represent softening, hardening and stiffness degradation of concrete due to load reversal. Additionally, it is able to predict the final and residual strength of the structure in softening with good accuracy. Employing different scale factors to monitor the failure of the dam, this model is used to analyze the nonlinear response of Morrow Point arch dam. The dam-reservoir interaction is considered with modified Westergaard’s approach, and the dam body is modeled with second order 20-node isoparametric elements. Moreover, two different damping algorithms are included to evaluate their impact on nonlinear analysis. It is concluded that the employed model can predict realistic crack patterns through the dam body, and it can be a good replacement for other time consuming and complicated models. In addition, it is shown that the damping algorithm plays a significant role in the nonlinear dynamic analysis of concrete arch dams.

Best Management Practices (BMPs) can play a vital role to control natural disasters like floods. In this paper, retention pond and vegetative swale are considered to restrain urban runoff. Storm water management modeling (SWMM) is used for runoff modeling. A piece of code is developed based on Non-dominated Sorting Genetic Algorithm (NSGA-II) in MATLAB to optimize the BMPs application. The aim is comparing the effect of roulette wheel, tournament and random selection operators to obtain the optimal location and area of BMPs. Minimizing the runoff volume and pollution in sub-catchments and the construction cost of the BMPs are three objective functions. Rafsanjan city located in southeast of Iran is selected as an appropriate case study. Estimating the best pressure of selection operator in roulette wheel and the best selection size in tournament operator and simultaneous quantitative and qualitative optimization using two BMPs are the innovations of this study. The results indicate that the pressure of the selection operator in roulette wheel which leads to the optimal answer is three and nine while the best size of selection in the tournament operator is nine. Optimum location, type, area and volume for each BMP are obtained after running the code.

Literature published TerraZyme stabilization case studies are analyzed rationally for evaluating the performance of TerraZyme as a stabilizer. As a measure of the degree of stabilization, the percentage variation in soil index and engineering properties induced by enzyme treatment for various soil types are investigated. The literature shows inconsistent enzyme stabilization results. The causes of the inconsistency in test results and factors affecting the effectivity of enzyme stabilization are elaborated. The effect of soil characteristics on the efficacy of enzyme stabilization is analyzed. The results of enzyme treatment on soil properties such as Atterberg limits and indices, optimum moisture content, maximum dry density, unconfined compressive strength and California bearing ratio, for various soil groups with different enzyme doses and conditions of curing are also studied. An attempt has been made to quantify the attribute variation of treated soils, establishing, the underlying reasons, for the effectivity of enzyme stabilization and its performance within and among various soil groups. The effect of enzymatic treatment on each soil group is also classified. The research emphasizes the necessity of an elaborate organized study on the enzyme and soil characterization, to have a better knowhow of the effectiveness of enzymatic stabilization.

Tunnels are used for numerous purposes; therefore, proper evaluation and prediction of tunnel behavior, influenced by the surrounding environment's characteristics, is of great concern for civil engineers. In this regard, two water convey and railway tunnels in rock medium were modelled to investigate the influence of various constitutive models on tunnels’ behaviors prediction. The tunnel convergence predicted by each constitutive model was compared with the reported monitoring data. Then, the most appropriate constitutive models for tunnel analysis in each rock category were proposed according to the strength of each category’s rocks. The results indicated that the Mohr-Coulomb criteria for very weak rocks, the Generalized Hoek-Brown for weak rocks and the Generalized Hoek-Brown with the residual parameter criteria for modelling medium rocks, had more reliable predictions of tunnel convergence. Also, utilizing shear strength parameters correlated from rock mass specific parameters to analyze tunnels in weak and medium rocks was not satisfactory.

The stability of a structure could be achieved either by adopting strong foundation or by improving the strength of the soil. This study is an attempt to investigate the behavior of a raft foundation (U-RF) upon reinforcing with geogrid (RF-R-Gr) and reinforcing with geocell (RF-R-Gc). The results of the study showed that optimal depth for placement of geogrid was found to be 0.3B (B is width of raft) while optimal depth for geocell varied from 0.1B to 0.15B. It was also found that the Bearing Capacity Ratio (BCR) for RF-R-Gr was typically six times higher than U-RF, while for RF-R-Gc it was eleven times higher than U-RF. Further, the outcomes of experimental study were modeled using Artificial Neural Networks (ANN) to predict the settlements. It was found that ANN models predicted settlement with higher values of correlation coefficient (r) as 0.9996 for RF-R-Gr and 0.9995 for RF-R-G.

Bituminous mixes are prepared with aggregates, filler and bitumen as binder. Ageing of bitumen due to oxidation reduces the durability of such mixes. Various research efforts are therefore put in to decrease the ageing potential of binders and use of anti-oxidants has shown substantial success. In this research, Irganox 1010 has been identified as an anti-oxidant which has been found to be economical and yet of limited use in the field of pavement engineering. Various physical and rheological tests were conducted to determine the influence of Irganox 1010 on short-termed as well as long termed aged binders and results were analyzed. Softening Point Index (SPI) and Viscosity Ageing Index (VAI) were determined to understand the influence of Irganox 1010 on bituminous mixes. It was observed that Irganox 1010 significantly reduce ageing potential with usage of 0.6% by weight of bitumen. It has been found to be cost-effective due requirement of small quantities and being of comparatively lesser cost. This material has the potential of large scale usage to increase durability of bituminous mixes.

Chemical admixtures are widely used for the production of high-performance concrete, but they are responsible for environmental pollution and health issue during construction because of their chemical nature. Also manufactured admixtures are expensive, on this base recently, researches and attempts are focused to find alternatives, and using different natural or bio admixtures for concrete is a good choice. In this study, the impact of Grape Extract (GE), a natural additive, on the properties of concrete was investigated. Various GE percentages were used to investigate the properties of fresh and hardened concrete. The results show that there is a continuous workability enhancement and continuous splitting tensile strength loss with GE increase.  Improvement of 28 days compressive strength by 18.5% was observed on using 0.22% GE, while no compressive and flexural strengths loss was observed with GE addition up to 0.55%. Finally, the results of the study showed that GE dosages can strongly impact the fresh properties and mechanical strength of concrete mixtures. So there is a chance to produce self-compacting concrete using GE natural admixture instead of chemical admixture but there is a need for further experimental tests.

Geopolymer Concrete (GPC) are known as green and nature-friendly concretes. In the current research, GPC based on Granulated Blast Furnace Slag (GBFS) was used with 0-2% Polyolefin Fibers (POFs) and 0-8% Nano Silica (NS) to improve its structure. After curing the specimens under dry conditions at a temperature of 60 °C in an oven, then subjected to permeability test, water absorption test and Uultrasonic Pulse Velocity (UPV) test at the ages of 7, 28 and 90 days. On the other hand, NS reduced the amount of water absorption and water permeability in concrete by 24 and 44%, this is due to the property of filling the pores with NS. Moreover, by conducting the ultrasonic, X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), and Scanning Electron Microscope (SEM) tests, a microstructure investigation was carried out on the concrete samples. In addition to their overlapping with each other, the results indicate the GPC superiority over the regular concrete. Besides, it demonstrated the positive influence of NS addition on the UPV and microstructural properties concretes against the heating treatment at the age of 90 days. Heat caused a drop in the results by destroying the concrete microstructure.

The demolishing of roads for repair and reconstruction produces an ample amount of Recycled Asphalt Pavement (RAP) which, if not utilized, may cause depletion of aggregate sources and pollution. The use of RAP in the plain cement concrete (PCC) is sustainable use of road waste material. However, the potential of incorporating RAP to replace natural aggregate needs to evaluate. This research targets the evaluation of mechanical properties of PCC made with extracted RAP materials through laboratory experiments and to achieve the optimized replacement of natural aggregate for rigid pavement composite design. The Virgin Coarse Aggregate (VCA) in PCC was replaced with RAP at 0:25:100 percent by weight. Results show that incorporating RAP in PCC causes a gradual decrease in mechanical properties. However, the decrease in compressive strength is more (57%) than the flexural and splitting tensile strength. RAP up to 25% was found as an optimum allowable replacement with VCA in the rigid pavement. From the Modulus Of Elasticity (MOE), it was detected that with the incorporation of RAP the ductility of PCC improved slightly.

Ultra-High Performance Concrete (UHPC), known for its superior mechanical and durability properties, is an appropriate material for different applications such as building and bridge construction. Investigating the possibility of UHPC production using available materials is an engineering challenge. This paper evaluates the applicability of some materials in making UHPC and the effectiveness of several parameters on the compressive strength of UHPCs. Then, by choosing the mixture yielding the highest compressive strength, the durability and mechanical properties of the mixture with 0-2.5% crimped steel fiber are investigated. The tests include compressive strength, flexural and tensile parameters, length change, rapid chloride ion migration, sorptivity, porosity, and sulfate resistance. The results reveal that the pozzolanic activity of silica fume and its synergetic effect with glass powder lead to the highest compressive strength. Moreover, it makes it possible to easily obtain a strength higher than 150 MPa. Utilization of 2.5% crimped steel fiber in UHPC mixtures remarkably enhanced mechanical performance so that the flexural and tensile strength were increased by about 95% and 25% compared to the plain UHPC, respectively. However, the incorporation of fibers increased the UHPC permeability.

In this study, nonlinear dynamic response of 4, 7, and 10-story moment frame steel structures is investigated under seismic ground motions. An incrementally increasing intensity is accounted for to evaluate the collapse fragility curves of the same buildings under different values of torsional eccentricity. The site soil of the buildings is assumed to be composed once of a firm and then of a soft soil. As a distinction of this study, the realistic maximum possible value of eccentricity ratio for moment frames, including both stiffness and mass eccentricities, is shown to be 10-15% that is much less than peak values of the past studies. Because of the three-dimensional aspect of the study, the eccentricity is selected to be bi-directional and the horizontal components of the earthquake motion are applied concurrently. It is exhibited that while torsional eccentricity lowers the median collapse probability of the studied buildings, it does not have a sensible effect up to the eccentricity ratios not larger than 10%. Besides, the taller structures on the firm soil are affected more strongly from torsional eccentricity, as the median collapse acceleration decreases up to 46% for the 10-story building suffering from 15% eccentricity ratio on the firm soil.