i-manager's Journal on Civil Engineering (JCE)


Volume 10 Issue 2 March - May 2020

Research Paper

Assessment of Subgrade Soils through California Bearing Ratio (CBR) on Gilgit-Skardu Road (Pakistan): Techniques for Improvement of Subgrade Soil Properties

Muhammad Bilal Sadiq* , Syed Husnain Ali Shah **, Abdullah Khan ***, Aneel Ahmed ****
*-**** COMSATS University Islamabad, Abbottabad Campus, Pakistan.
Sadiq, M. B., Shah, S. H. A., Khan, A., and Ahmed, A. (2020). Assessment of Subgrade Soils through California Bearing Ratio (CBR) on Gilgit-Skardu Road (Pakistan): Techniques for Improvement of Subgrade Soil Properties. i-manager's Journal on Civil Engineering, 10(2), 1-6. https://doi.org/10.26634/jce.10.2.16619

Abstract

Quality and stiffness of subgrade soils play a crucial part in performance of the pavements subjected to overwhelming traffic stack. To evaluate the quality of road subgrades, a test known as California Bearing Ratio (CBR) was developed by California State Highways Department. CBR is regularly utilized for flexible highway and airport pavements and occasionally for other development purposes to assess the strength of earth materials. To assess the values of CBR, Standard Proctor Compaction, and Moisture Content and Atterberg Limits, the collected subgrade soil samples were taken to the laboratory. Standard test methods of ASTM were followed for carrying out different tests. The CBR of the samples ranges from 4 – 16% and the plasticity index (PI) values extend from 13-17% which demonstrates the expansive behavior of the subgrade soils. The examination of different results portrays that the subgrade soils from the study area are of destitute quality, thus these soils don't qualify to be utilized as subgrade concurring to the National Highway Authority (NHA) specification. From the study, it can be concluded that the performance of the examined material ought to be upgraded for utilization as subgrade. After checking on the financial contemplations, evacuation of the existing subgrade soil upto 0.6m and stabilization with a natural waste material such as granite cutting waste and fly ash etc. has been proposed as a subgrade soil enhancement strategy. The other suggested soil advancement strategy involves the introduction of an additional base layer.

Research Paper

Performance Evaluation of SCC Made with Commercially Available Construction and Demolition Waste

S. Girish* , Sasha Azimi**
*-** Department of Civil Engineering, B.M.S. College of Engineering, Bangalore, India.
Girish, S., and Azimi, S. (2020). Performance Evaluation of SCC Made with Commercially Available Construction and Demolition Waste. i-manager's Journal on Civil Engineering, 10(2), 7-17. https://doi.org/10.26634/jce.10.2.17151

Abstract

Large amounts of Construction and Demolition (C&D) waste materials are generated by construction projects and there is a wide scope for reusing or recycling them. Presently, due to continuous global demand for infrastructure due to persistent increase in population growth has led to large consumption of aggregate and cement for concrete production. This would eventually lead to more extraction and depletion of natural resources and increased carbon emission. This study aims at providing an exhaustive comparison using natural aggregates and recycled aggregates to produce Self–Compacting Concrete (SCC), which is a high-performance concrete. Totally twenty one mixes were investigated. The Girish method of mix design, which is based on absolute volume concept starting with a volume of paste, was advantageously used to develop the mixes with less number of trials. The paste and the total powder content used in this study have a wide range considering the field requirements and the unfavourable aggregates used. The water to cement ratio varied widely from 0.38 to 0.67, total powder content from 455 kg/m3 to 672 kg/m3 and volume of paste from 0.37 to 0.43. Tests were carried out to assess the fresh properties as well as the compressive strength and split tensile strength of concrete. The 28 day compressive strength ranged from 22 MPa to 51 MPa. The study clearly demonstrates that an increase in paste content both for natural and recycled aggregates leads to increase of the compressive strength of SCC. However, the increase has optimality at Vp 0.43 for the materials used in this study and this can be one of the factors to be considered in the mix design. The volume of paste ranging from 0.37 to 0.43 can be successfully used for developing SCC for both natural and recycled aggregates.

Research Paper

A Study on the use of Microorganisms in the Enhancement of Compressive Strength and Influence of Temperature Variations on the Performance of Bio Concrete

S. Girish* , T. Soumya **, Ananya Girish ***
*-** Department of Civil Engineering, B.M.S. College of Engineering, Bangalore, Karnataka, India.
*** MVJ Medical College and Research Hospital, Bangalore, Karnataka, India.
Girish, S., Soumya, T., and Girish, A. (2020). A Study on the use of Microorganisms in the Enhancement of Compressive Strength and Influence of Temperature Variations on the Performance of Bio Concrete. i-manager's Journal on Civil Engineering, 10(2), 18-26. https://doi.org/10.26634/jce.10.2.17132

Abstract

Bacterial concrete is a self-remediating biomaterial. Under favorable conditions, bacteria can precipitate calcite in concrete. Calcite precipitation plays an important role in mitigating the micro cracks there by increasing the long-term structural integrity and durability of concrete. The present study focuses on the addition of favorable microorganisms to improve the compressive strength of concrete. The microorganisms selected were Pseudomonas and Klebsiella, which microbiologically induce the mineral precipitation. Both the beneficial microorganisms were studied at different cell concentrations ranging from 101 to 108 . The study shows a positive influence on the property of compressive strength of concrete, with an approximate increment of 18% to 22% in strength possibly due to densification of micro pores due to the growth of fibrous and calcium precipitation thereby strengthening the pore structure. The study also reveals the importance of culturing medium and selection of microorganisms, as revealed by the good results by using Klebsiella over Pseudomonas. In addition, concrete cubes were tested with Pseudomonas and Klebsiella at elevated temperature and there was no improvement in the strength possibly due to the mobility of microorganism.

Research Paper

A Static approach for Determining Rheological Properties of Self-Compacting Concrete (Powder and VMA Type) by using Direct Shear Box Test Method

N. Ajay* , S. Girish **, Ashwin M. Joshi ***
*, *** Infrastructure Construction and Management, RASTA, Bangalore, India.
** Department of Civil Engineering, B.M.S. College of Engineering, Bangalore, India.
Ajay, N., Girish, S., and Joshi, A. M. (2020). A Static approach for Determining Rheological Properties of Self-Compacting Concrete (Powder and VMA Type) by using Direct Shear Box Test Method. i-manager's Journal on Civil Engineering, 10(2), 27-33. https://doi.org/10.26634/jce.10.2.17128

Abstract

To provide better understanding of the behavior of the fresh concrete and to enhance the quality of concrete, the Selfcompacting concrete (SCC) is characterized by its rheological properties, by a more scientific approach to overcome the limitations of the existing empirical test methods. In this study, SCC mixes (Powder and Viscosity Modifying Admixture type) were developed by using Portland Pozzalana Cement (PPC), ground granulated blast slag (GGBS) as a filler material, M-sand as a fine aggregate, natural angular crushed granite as coarse aggregate and with superplasticizer (SP) and Viscosity Modifying Admixture (VMA). About 12 different SCC mixes with more than 100 trials, were developed with varying cement contents (300, 375 and 450 kg/m3) and water contents (185 and 205 /m3) along with varying filler contents. The experimental results show that direct shear box can be effectively used to determine the Bingham parameters of fresh SCC under static condition following an unique procedure. The result also shows the importance of volume of paste (Vp) in making the mix robust.

Review Paper

A Review on Textile Reinforced Mortar and Fiber Reinforced Polymer Composites for Structural Applications

H. R. Priyanka* , Madhavi K.**
*-** Department of Civil Engineering, RV College of Engineering, Bengaluru, India.
Priyanka, H. R., and Madhavi, K. (2020). A Review on Textile Reinforced Mortar and Fiber Reinforced Polymer Composites for Structural Applications. i-manager's Journal on Civil Engineering, 10(2), 34-46. https://doi.org/10.26634/jce.10.2.17363

Abstract

Fibre reinforced composites are being used to strengthen the structural components. Fibre Reinforced Polymer which consists of organic matrices are widely used for structural retrofitting due to its high strength to weight ratio. The use of fibre reinforced cementitious mortar (FRCM) is gaining popularity due to their ability to evade the problems associated with fibre reinforced polymer (FRP) systems. The advantages of FRCM are (i) mortar used in FRCM system is more compatible with the concrete and masonry substrate compared to epoxy; (ii) high thermal conductivity; (iii) fire resistance and (iv) can be applied on wet surfaces. Recycled materials can be incorporated in FRCM systems leading to a sustainable product with less impact on the environment. Therefore, the use of FRCM is becoming attractive for retrofitting of structures than FRP which are being widely used. This paper addresses the application of textile reinforced mortar (TRM) composites over FRP in strengthening of structural members.