Sustainable Structures and Materials, An International Journal

Improvement of Strength and Permeability Attributes of Silty Sand Type of Soils using Enzyme Induced Calcite Precipitation

Muhammad Muneeb Nawaz — 2023-03-17

ABSTRACT

Enzyme Induced Calcite Precipitation (EICP) is one of the soil stabilization techniques based on microbiological activity. In this technique, urea decomposes with the aid of urease enzymes in the presence of calcium chloride and produces calcite, which acts as a bio-clogging and bio-cementing material. In this study, test tube experiments are performed to assess the optimal amount of calcium chloride, urea, and urease enzymes to be used for engineering applications. The silty sand type of soil is treated with different proportions namely; P1 (0.1g urease enzymes, 0.375g urea, 0.9g CaCl₂), P2 (0.2g urease enzymes, 0.75g urea, 1.8g CaCl₂), and P3 (0.4g urease enzymes, 1.5g urea, 3.6g CaCl₂), to analyze their effect on strength and permeability attributes of soils after 14 days of curing time. It was observed that an increase in EICP content causes a substantial increase in shear strength particularly cohesion due to the bio-clogging phenomenon induced in soil particles by EICP which eventually leads to a decrease in permeability and inhibits the activity of urease. Overall, P3 yields higher cohesion (48 kPa) than P1(40 kPa), P2 (43kPa), and untreated soil samples (31 kPa). Furthermore, P3 causes a significant decrease in permeability as compared to P2, P1, and untreated soil samples tested after 14 days of the curing period. The findings of the study suggest the successful implementation of EICP for soil stabilization.

Key Words: Enzyme Induced Calcite Precipitation (EICP); permeability; shear strength; bio-clogging; bio-cementation.

MANAGEMENT AND CLASSIFICATION OF CONSTRUCTION AND DEMOLITION WASTE IN INDIA

Ojha P N — 2023-03-17

Construction and Demolition (C&D) waste have a huge potential to replace virgin materials. However, due to lack of management, its utilization has not been optimized. Issues like sharing of responsibilities among various stakeholders and classification of C&D waste are some of bottleneck on part of effective implementation of C&D waste management in India. This paper illustrates quantity and quality of C&D waste generation in India, regulatory framework, policy interventions and R&D work carried out to classify C&D waste aggregate for production of concrete. Experimental studies were carried out using two different sources of recycled concrete aggregates; one batch of aggregates are obtained from Burari Plant located in New Delhi and another batch of aggregates were created in laboratory by crushing concrete cubes of 20- 30MPa. Thereafter, recycled concrete aggregates were classified on basis of their physical properties like specific gravity and water absorption and their performance in concrete have been evaluated in terms of fresh properties like workability, air content, bleed water percentage and mechanical properties like compressive and flexural strength. Study indicates that air content in concrete mixes prepared from recycled coarse aggregate (RCA) is 5-20 % higher than that of corresponding control mix whereas admixture requirement for concrete mixes prepared with RCA was found to be slightly higher in comparison to that of control. Experimental study indicates that compressive strength as well as flexural strength of concrete mixes prepared with recycled concrete aggregate has been reduced drastically in comparison to control mixes without recycled coarse aggregate.

IoT Based Real Time Early Age Concrete Compressive Strength Monitoring

Fahad Iqbal — 2023-05-11

Concrete Strength determination has been an expensive and hectic job due to its orthodox methodology of measuring concrete strength where cylinders are filled with concrete. Its strength is measured using the crushing of concrete (Compression Test). A significant amount of waste is generated while performing this test multiple times during the execution of the project. The present study proposes a new IoT-based framework comprising a low-cost sensor and a window dashboard to estimate and monitor the real-time early-age concrete strength. This system will significantly help the construction industry to avoid the onsite laboratory testing of concrete for strength. In this study, a temperature sensor, along with an ESP32 microprocessor, is used to acquire and transmit the recorded temperature in real time to a cloud database. The window application developed load data from the cloud database and presented it as figures and graphs related to concrete strength with time. The strength calculated using the developed sensor was compared with the actual strength determined using a compression test for the same mix design, which showed a significant match. The project is a contribution toward the non-destructive testing of concrete. By knowing the concrete strength of any structural member in advance, the practitioners can make decisions well before time to avoid delays in the project.

Enhancing the Mechanical Properties of Concrete and Self-Healing Phenomena by adding Bacteria, Silica fume and Fibres

Rana Ehtisham — 2023-05-11

Concrete which is the most useable material in the world after the water has flaws, it is susceptible to cracking over time. These cracks occur in the form of shear cracks, flexural cracks, tension cracks, shrinkage cracks etc. With these cracks, some hair-like cracks also occur in concrete which are not visible during the visual inspection. The propagation of these cracks in concrete allows the water and many other chemicals to seep inside the concrete and leads to a decrease in its properties. Such properties include decreasing durability, erosion of rebars, and progressive failure in the concrete strength. Therefore, the repair of hair-like cracks is also essential for the long-term safety of structures. In the present study the Silica fume, and Polypropylene fibres are added to a rich concrete along with the bacteria named Bacillus Subtilis and Calcium Lactate for enhancement of its mechanical properties and self-healing phenomena. The effect of bacteria in the healing phenomenon and other properties is compared to normal concrete by casting the cylinders and beams. The slump, compressive strength, tensile strength, and self-healing phenomena are tested and found the increase in mechanical properties of concrete. The self-healing phenomena of cracks is observed by the Scanning Electron Microscope (SEM).

Recycling of Steel Scraps as a Strength Enhancement Material in Concrete

Asad Ur Rahman — 2023-05-11

The cement industry is very energy consumptive and produces CO2 and also generates greenhouse gases which are the major cause of global warming. The production of cement and the use of concrete are both rising daily. So, to protect the environment, alternate materials are required. The construction industry has several constructional byproducts and wastes as a variant of traditionally used products. In the process of production and working with steel, steel chips are formed as waste material. The best way to reduce environmental pollution and improve waste recycling is to partially replace concrete with steel chips. Due to these factors and the abundance of material, steel chips were used as a partial cement replacement at 0.5%, 1%, 1.5%, and 2% by the volume of cement. The properties such as compressive strength, split tensile strength, flexural beam strength, and modulus of elasticity are checked after 7, 14, and 28 days. Comparing these qualities to those of control molds showed that by raising the percentage of steel chips in the concrete up to 1.5%, mechanical characteristics are improved; however, when the percentage is increased to 2%, mechanical properties are also affected.

Seismic Performance Assessment of Deteriorating Reinforced Concrete Box Culvert

Zahoor Khan — 2023-05-11

A culvert is a crucial component of highways whose proper operation is connected indirectly to the state's economy and the effectiveness and safety of road transportation. Therefore, it is crucial to assess the culvert structure's safety. In this work, a seismic assessment of undamaged and damaged reinforced concrete box culverts is performed. The deterioration in culvert slab thickness over time due to corrosion is considered. The structure was subjected to seismic loading along with standard static loading to observe the performance of a box culvert. The results show that the seismic response of culverts would be influenced by aging and deterioration of slab thickness from its original conditions. The finding of this study highlights the importance of considering the effect of corrosion on the slab thickness when assessing the seismic performance of culverts, as it can have a significant impact on the structure's safety.

Utilizing Chat GPT for Automation of Material Supply in Construction Projects using Programming and Primavera P6 Scheduling

Areeba Ashiq — 2023-05-11

Construction Industry (CI) is considered as the backbone of a country’s economy. Despite the fact, it experiences high fragmentation and reduced productivity, delays, cost overruns and lack of innovation from the start till the end of a project. It has been identified that material deliveries often affect productivity at site therefore this study focuses on the development of Automated Materials Supply (AMS). Supply chain in construction being automated presents a feasible solution to late material deliveries and cost and time overruns on a project by proposing a framework for information transfer by using primavera schedule and OPEN AI among stakeholders of the project to avoid material overruns on-site and reducing human effort. The result of this study leads to the development of a framework that executes the information transfer among various stakeholders of a project to automate the material delivery process.

Regression Model for Predicting Soaked CBR from UCC

Zakir ullah — 2023-05-11

ABSTRACT. Flexible pavement is a multi-layered structure with a subgrade layer acting as the pavement structure’s foundation. The performance and strength of soil for its use as a subgrade are ascertained by its California Bearing Ratio (CBR) value. CBR test is a technically extensive and labor-intensive mechanism that could cause delays in carrying out construction projects, which would raise the construction cost. Therefore, highway engineers need to design a predictive model for quick assessment of the CBR of subgrade soil. In this research, eight specimens of disturbed soil were obtained from Rawalpindi Division, Pakistan. All soil samples were subjected to laboratory testing and categorized according to the AASHTO soil Classification System. The specimens were subjected to soaked CBR, and unconfined compression tests based on Maximum Dry Density (MDD) and Optimum Moisture Content (OMC) values, acquired from the Modified Proctor Compaction test. An empirical correlation between soaked CBR and unconfined compressive strength test is developed by the Suitable Trend-Line Method in Microsoft excel. From the single linear regression model, the value of the coefficient of correlation is found (0.98) indicating a very good correlation between soaked CBR and UCC strength test.

Keywords: Regression Model, Correlation Coefficient, California Bearing Ratio (CBR), UCC strength.

To study the procurement process and develop a conceptual framework model in the Pakistani construction industry

Muhammad Umair — 2023-05-11

Procurement of equipment and materials in any construction project holds a tremendous significance for the project to be completed on time and within the budget. In this research, procurement in the Pakistan’s construction industry has been studied and a conceptual framework in terms of e-procurement portal has been suggested to smoothly execute the process of e-procurement by mitigating the barriers involved in the concerned process. A questionnaire survey form has been developed and 100 responses have been recorded to take the input from industry experts on the proposed procurement framework. A total of 84 respondents out of 100 thought that the proposed framework will be a better way to solve the problems that come up during the procurement process. Furthermore, it was also found that the main reason for procurement delays in construction projects is lack of communication and coordination among different departments within an organization, to which the suggested framework can be used as a potential tool to deal with.

An overview on use of waste plastic for soil stabilization

Attique Ur Rehman — 2023-05-11

There have been various environmental concerns recently as a result of the huge increase in the use of plastic products like polypropylene (PP) and polyethylene (PE) bottles. Therefore, it's critical to develop strategies for managing these wastes without endangering the environment. Utilizing waste plastic as soil stabilizer materials is one of these techniques. Waste plastic, after some treatment or recycling, has been reported to be used in different forms as construction materials. However, its use for soil stabilization has not exclusively been reported. Thus, the goal of the current literature research is to have a comprehensive review of the literature about the potential of waste plastic for soil stabilization. This is done by focusing on articles published in highly reputable journals in the last decade. The major benefit, however, is that it is incredibly cost-effective because it has demonstrated a significant improvement in soil qualities. It offers a good stabilization approach as opposed to more expensive alternatives. Waste Plastic production is steadily increasing, which has resulted in several poor disposal techniques, such as burning, and a variety of environmental and pollution issues. As a result, finding secure and effective disposal techniques is essential for protecting our environment and the future of the following generations.

Model Updating of a Full-Scale Building Structure Under Train Induced Vibration

Muhammad Saqib — 2023-05-24

Structure health monitoring (SHM) system is a method of monitoring and evaluation of structural health. Finite element method is extensively use to model the dynamics properties of a structure as it is believed to be an authentic tool for providing accurate results. To adopt a more precise dynamic properties of a structure, model updating technique involve updating a finite element model of a structure. However, due to many imaginary assumptions in the finite element (FE) model generation, the practical behaviour of full-scale structures contradicts the model results. It may be due to uncertain boundary conditions, poorly defined material properties of the structure or because of the simplified modeling of complicated structural systems. In this paper, six storey frame structure building has been investigated for dynamic model updating. The building was subjected to train induced excitation. Four accelerometers were employed to measure the response. Manual updating of building FEM model is carried out as per design parameters of the finite element model (elastic modulus and boundary constraints) to diminish the inconsistencies between the field measurement and the results of finite element model. For the subject building the supposition of semi-rigid joints (rotational area springs) can most precisely depict the dynamic properties of the subject building. The modified parameters obtained from the updated model are logical having meaningful interpretation.

Performance of Partially Bonded Engineered Cementitious Composites (ECC) In Concrete Block Masonry

Fahim Abbas — 2023-05-24

The objective of this study is to examine the behavior and determine the potential implications of Engineered Cementitious Composites (ECC) to strengthen the concrete block masonry by using a unique method of partially bonding the tension face as tension strengthened beam under the out of plane loadings. The specimens under investigation were comprised of two categories i.e. un-strengthened concrete block masonry beams and tension strengthen beams with different thicknesses of ECC layers. All the specimens were experimented under the four point loadings to evaluate the flexural performance of fabricated beams. The current study reveals that the partially bonded ECC strengthening of concrete block masonry beams has significantly improved the strength and deformability.