Journal of Rehabilitation in Civil Engineering
Volume:13 Issue: 1, Winter 2025

Utilization of landfills for possible construction projects requires investigation and improvement of geomaterials in these areas. In this research, the effects of lime on improving the behavior of soil materials in Isfahan landfill were investigated through a series of laboratory experiments. Unstabilized and stabilized samples with 3 %, 6 % and 9 % lime were tested. Direct shear tests under different overburden and falling head permeability tests were conducted. X-ray diffraction tests were also performed to check the structure of the samples. Also, the scanning electron microscope images of the tested samples were prepared and compared. The results indicate that the lime-stabilization improves the stress-strain behavior of the treated samples. At the strains greater than 1 %, the positive effect of lime-stabilization of treated soil samples is obvious. Tests results indicate that the optimal amount of lime for Isfahan landfill’s soil stabilization is 6 %. Stabilization of samples with 6% lime under vertical overburden stresses of 0.5, 1 and 2 kg/cm2 increases the maximum shear strength of the samples by 113.95 %, 30.95 % and 9.88 %, respectively. The results show that the permeability coefficient of stabilized samples decreases with the increase of lime content. Stabilization using 3 %, 6 % and 9 % lime has resulted in a decrease of 14.66 %, 84.83 % and 93.62 % of the permeability coefficient of the landfill soil samples compared to the unstabilized samples, respectively. The results also show that the decreasing rate of permeability coefficient is increasing up to 6 % of lime and beyond that has decreased.

Engineered cementitious composites (ECC) provide enhanced ductile behavior thanks to multiple-cracking arising from the synergistic optimization of fiber-matrix interface adhesion behavior. According to the micromechanics based design theory of ECC, there are two critical conditions that should be satisfied to guarantee the strain-hardening. According to the first condition fiber bridging strength should be greater than the cracking strength for any crack plane. Secondly, complementary energy of fiber bridging should be greater than the crack tip toughness. Both criteria are directly related with the fiber/matrix interface bonding parameters and critical for the success of ECC design. These interfacial bonding parameters are well documented for poly-vinyl alcohol (PVA) fiber reinforced ECC and poly-ethylene (PE) fiber reinforced ECC. However, interfacial bonding parameters need to be determined for the relatively new type of ECC known as high-tenacity polypropylene fiber reinforced ECC (HTPP-ECC). This study focuses on the effect of different curing conditions on HTPP fiber/matrix bonding parameters (frictional bond strength, slip hardening coefficient and chemical debond-related energy). These parameters have been experimentally determined by using a special single fiber pull-out test setup. Results showed that water curing or partial water curing at the initial periods of hydration has a positive influence on fiber/matrix frictional bond strength. The chemical debond-related energy and slip hardening coefficient values of HTPP-ECC interfaces were found excessively low and did not significantly affected from the curing conditions, which is reasonable for most of the hydrophobic fibers.

The accurate approximation is a benefit of the modern machine learning technique, which also disappeared the problems of traditional empirical methods, such as human and technical errors plus environmental pollution. Although there are many good samples on the state-of-the-art regarding the machine learning prediction of strength properties of steel fiber reinforced concrete, fewer articles are dedicated to proposing empirical formulations. This paper brings some novel empirical formulations to identify the strength properties of macro steel fiber-reinforced concrete. A 2650 multi-national data records are used to perform the regression, which is an exclusive dataset. This archive is the largest available dataset used in the state-of-the-art steel fiber-reinforced concrete prediction process, which is beneficial for supervised learning. Since the user must be careful regarding overtraining with such a vast resource, a successful strategy provided by the authors in previous research is utilized in which various machine learning techniques are compared to forecast the considered properties. So the Ridge, Lasso, and linear methods are used as regressors to predict the strength properties and the constants. Symbolic regression, a powerful tool for producing empirical formulations, is used for creating mathematical expressions regarding the strength properties. The performance is also evaluated based on well-known error analysis metrics. The formulations are presented for flat, waved, and hooked end fibers, the most common fibers used in construction engineering. The machine learning-driven formulations are exclusive due to the utilized strategy and the resources, and the precision of the relations are denoted, which presents the superiority to traditional methods.

\Masonry buildings remain popular worldwide due to their readily available materials, high compressive strength, ease of construction, and affordability. Therefore, understanding the impact of mortar on the compressive strength of masonry is essential. This study aimed to determine the compressive strength and failure patterns of masonry, focusing particularly on mortar. An experimental program was conducted, involving a total of 54 specimens: 27 cubes, 27 cylinders, and 9 masonry prisms. The cement-to-sand ratio (c/s) varied at ratios of 1:3, 1:4, and 1:5, while the water-to-cement ratio (w/c) remained fixed at 0.45. Each prism consisted of 5 bricks separated by a 10 mm mortar layer. Compressive strength data for cubes and cylinders were collected at 3, 7, and 28 days, while data for prisms were collected only at 28 days. The best results have been obtained at a c/s ratio of 1:3, with compressive strengths of 3555.5 psi for cubes, 3282.98 psi for cylinders, and a compressive force value of 129.33 kN for prisms at 28 days. The compressive strength of cubes and cylinders increases by approximately 68.19% and 64.61%, respectively, and the compressive force of masonry prisms increases by approximately 76.48% at 28 days when the cement-to-sand ratio is changed from 1:5 to 1:3. Stresses, graphs, and failure patterns have been analyzed and compared with the Bangladesh National Building Code (BNBC) 2020 and available literature, revealing a strong correlation.

Low-temperature cracking (LTC) is a critical form of pavement distress in cold regions. The fracture toughness in the semicircular bending (SCB) test serves as an indicator of LTC growth. Firstly, this study evaluated the effect of adding nano Al2O3 on the improvement of hot mix asphalt (HMA) fracture toughness. Another goal of the paper was to investigate the influence of different parameters, such as temperature (-5, -15, and -25 °C), loading mode (I, II, and I/II), crack geometry (vertical and angular cracks), and nano-modification, on the fracture toughness of HMA by using machine learning technique. An artificial neural network (ANN) was employed to quantify the impact of these parameters. The findings of this research clearly show that although asphalt mixtures in cold region are prone to thermal cracks, the addition of nano Al2O3 improves their resistance by 12% in comparison with control mixtures. The ANN analysis identified loading mode is the most significant factor affecting fracture toughness (48% contribution). Temperature followed with a 28% contribution, while crack geometry and nano Al2O3 modification each contributed 12%.

Incineration is the most commonly employed alternate disposal strategy of biomedical waste across the globe, which produces Biomedical Waste Incinerated Fly Ash (BMWIFA). BMWIFA is often disposed of in landfills to prevent environmental contamination. Due to limited space and the high cost of land disposal, recycling methods and ash reuse in various systems have been developed. Therefore, the present study evaluates the performance of BMWIFA and Ordinary Portland Cement (OPC) blends as stabilizing agents for the base layers of low-volume roads (LVRs). Different trial mixes of crushed aggregate (CA), BMWIFA, and OPC were tested to find the optimum mix. The stabilizer content was considered to be 3.0%, 5.0%, and 7.0% of the total dry weight of the mix, in which the BMWIFA (a)/OPC (c) ratio is taken as 100/0, 80/20, 60/40, 40/60, 20/80, and 0/100 in each percentage of stabilizer. Optimum values of compaction characteristics were used for strength evaluations of mixes in terms of unconfined compressive strength (UCS) and indirect tensile strength (ITS) at 7, 14, and 28 days of air curing. The mix proportions 97% CA, 95% CA, and 93% CA stabilized with 3% (a/c = 20/80), 5% (a/c = 40/60), 7% (a/c = 60/40) binders respectively, satisfied the 7-day UCS requirements (3MPa) according to the Ministry of Rural Development (MoRD) for LVR cement-treated bases and were found durable. Furthermore, the Toxicity Characteristics Leaching Procedure (TCLP) analysis for various heavy metals reveals that the CA, BMWIFA, and OPC compositions were non-hazardous materials. Finally, this study's findings recommend the use of BMWIFA and OPC blends as stabilizers in low-volume road construction.

Concentric bracing systems are a popular solution for strengthening moment frames due to their high lateral stiffness, ease of installation, and low cost. However, buckling in compression members can result in sudden loss of strength and less deformability. Researchers have suggested using steel slit dampers to increase deformability and energy dissipation in this system by directing damage away from bracing members. In this study, 265 finite element models were analyzed in ABAQUS software based on previous experimental investigations and the installation configuration of the combined elliptical slit elements with Chevron bracing system in a moment frame. The effects of varying each geometric parameter of the element, including thickness, width, height, and number of slits, as well as the minor diameter of the elliptical slit, on the behavioral characteristics have been investigated in a three-dimensional parametric space. These characteristics are such as elastic stiffness, ductility, force capacity, and cyclic energy dissipation. Finally, and based on conducted numerical analysis, suitable ranges for each geometric parameter have been proposed to facilitate optimal design of the element.

The safety evaluation of retaining structures, especially in cases of potential instability or disaster, frequently depends on empirical methods that apply overall safety factors. In this article, an innovative approach employing probabilistic methods to assess the reliability of gravity retaining walls, considering uncertainties in parameters and their inherent variability, has been introduced. This study applies First Order Reliability Method (FORM) to assess the influence of construction defects and soil-structure friction on gravity wall reliability. his approach represents notable progress over traditional empirical methods, which rely on total safety factors and frequently manage uncertainties arbitrarily. The paper is indeed novel as it integrates probabilistic methods into the analysis of gravity retaining wall stability, offering a more nuanced understanding of the reliability of these structures. This contribution seeks to enhance safety assessments and rehabilitation strategies in civil engineering practices, with a focus on addressing uncertainties in geotechnical parameters and construction defects.

This study evaluates the intake tower's effect on the buttress dam responses, considering the access bridge and reservoir under seismic loading in ANSYS using the finite element model. Wimbleball dam in England is assigned as a case study to assess the effects of different characteristics of the system components on seismic responses. Some parameters were applied, such as the presence of the intake tower and access bridge, reservoir water level, intake tower height, and internal water level. Nine cases with and without intake towers and access bridges have been studied by raising the reservoir water level, intake tower height, and internal water level, resulting in three-dimensional seismic analyses. Circular frequencies, crest displacements, and heel stresses of the dam have been presented for current cases. The interaction between the reservoir, dam, and intake tower can alter the case's stiffness and consequently change its frequencies. The modal analysis responses presented that the case's frequencies were reduced by raising the reservoir water level by up to 40% and increasing the intake tower height by up to 19%. The seismic results show that the heel stresses of the middle buttress increase by raising the reservoir water level by up to 39%. For constant water levels in the reservoir and tower, displacements and stresses of the middle buttress increased by increasing the intake tower height by up to 3% and 43%, respectively.

The published researches on the mechanical behaviour of granular soils reinforced with crushed glass particles from recycled glass waste is notably limited compared to studies involving glass powder. The disposal of waste glass presents significant environmental challenges, highlighting the need for innovative recycling solutions. This study investigates the use of crushed waste glass as a reinforcement material for sand to enhance its mechanical properties, offering a sustainable solution in geotechnical engineering. To achieve this goal, a series of direct shear experiments were conducted on three categories of river sand, each with a different mean particle size (D50 = 2.00 mm, 1.00 mm, and 0.63 mm). These sands were mixed with varying amounts of crushed waste glass (CWG = 0, 10, 20, and 30%) and subjected to three various normal stresses: 50, 200, and 400 kPa. The obtained data demonstrated clearly the combined impact of crushed waste glass and mean particle size on the angle of repose, internal friction angle, peak and residual friction angles, as well as the excess and maximum dilatancy angles for the sand-CWG mixtures. The results showed that as the crushed waste glass content (CWG) and mean particle size (D50) increased, the sand-CWG mixtures exhibited higher values of repose and internal friction angles. The study concludes that crushed waste glass can effectively reinforce sand, benefiting both waste recycling and construction material performance. These findings support sustainable civil engineering practices by reducing the environmental impact of waste glass and improving sandy soil performance. Future research should investigate the long-term durability and environmental impacts of using crushed glass in various geotechnical applications.

Nowadays, concrete is one of the most commonly used building and pavement materials. The type of concrete that has been used more than the other types is the concrete reinforced with steel. Due to the disadvantages of reinforcing concrete with steel such as corrosion, heavy weight, high cost and high-energy production, Glass Fiber Geogrid Mesh (GFGM) is chosen in this study for investigating the flexural reinforcement in the concrete beams. Fifty concrete beams in dimensions of 65 cm × 15 cm × 15 cm with different layers of GFGM, placements, curing times (28 and 90 days) and various concrete mixing designs (25 and 30 MPa) were reinforced in order to be compared with the unreinforced concrete beams (control beams). Then, the beams were tested under three-point bending test using displacement control mechanism. The results showed that the peak load capacity increased at most to 48.6 % in comparison with the Control Beams. Furthermore, a complete bonding between the GFGM and the concrete was indicated. It was also observed that the deflection at the midspan of the specimens reinforced with different Geogrid placements did not follow a specific pattern.

Recent seismic incidents in Turkey have raised concerns among engineers about the potential performance of existing buildings in earthquakes. Due to its location in a somewhat active seismic region, Bangladesh is susceptible to experiencing catastrophic damage if a heavy to moderate earthquake hits. Therefore, the assessment of the seismic capacity of existing buildings is essential to investigate potential risks. Before this, Bangladesh did not have a seismic assessment or retrofitting guideline. However, the Public Works Department (PWD) of Bangladesh has now adopted the seismic assessment procedure from the Japan Building Disaster Prevention Association Manual (JBDPA, 2001) and published it as CNCRP (2015). On top of that, the building design code of Bangladesh (BNBC) has been updated, and the calculation of seismic demand has also changed. This study aims to assess an existing RC building located in Bangladesh for local seismic loads and retrofit it if found vulnerable. A six-storeyed RC building was assessed in detail. The building's seismic capacity was calculated using the suggestions of the CNCRP seismic assessment manual (2015), which depends on the strength and ductility capacity of structural members. The storey collapse mechanism was considered; therefore, the capacity of each storey was computed by considering the lateral capacities (both strength and ductility) of all columns in that storey. The columns were classified according to tributary area, and their failure mechanism was identified. The seismic index was computed utilizing the strength and ductility correlations. After evaluation, some floors were found vulnerable, and the necessary reinforcement specifications were computed following the CNCRP retrofit manual (2015). The retrofit design was established, and a comprehensive re-examination was conducted. Ultimately, the building was found safe according to the CNCRP seismic assessment manual (2015) after the retrofit.