Recent Advances in Civil Engineering

The service life of reinforced concrete structures is decreasing day by day without serving its designed life. This is caused to a variety of factors, including structural deterioration, which renders the structure unsafe for users. Deterioration of structures may be caused due to change in use or functionality, adverse environmental effects and addition in loading on the structure due to vertical development. The demand for commercial and residential space is increasing drastically and due to high land value vertical development is the only option left with necessary precautions considered against the capacity of foundations. It is important for structural members to have adequate strength and deformation capacity for stable performance of structures during its entire life, hence repairing, retrofitting and upgrading the structure for enhanced load carrying capacity and displacement capacity is necessary. In present experimental study, newly cast reinforced concrete (RC) beams were strengthened by attaching RC precast segments and followed by carbon fibre reinforced polymer (CFRP) wrapping. Further to increase bonding between the CFRP and concrete, CFRP anchors were installed to anchor the CFRP wrapping layers on the surface of concrete beam. From the experimental investigation, it can be observed that the beams strengthened with the help of precast segments and CFRP wrapping show considerable increase in load carrying capacity. The CFRP anchors have increased the bond between CFRP wrapping and concrete surface.

Rapid urbanization has led to high consumption of natural river sand as an aggregate as well as higher generation of pond ash due to the high demand for energy. Pond ash, a waste generated in thermal power plants during the coal combustion process, is detrimental to the environment, directly or indirectly demanding a large area of land for disposal. The properties of pond ash, however, also make it suitable to serve as an alternative to river sand as fine aggregates in concretes and mortar. The use of pond ash as fine aggregates in mortar helps to solve two pressing problems at the same time without much risk. This paper focuses on investigation on fresh and hardened mortar with varied percentages of pond ash as natural aggregate in different cement: sand proportions. The properties are assessed as per the standard test procedures. Flow table test is conducted to assess the workability characteristics, while compressive strength test is conducted for its strength behaviour. The results show that the workability and compressive strength of the mixes are lesser for higher percentage of replacement and for leaner mix. This can be attributed to the shape of pond ash and higher fine aggregate content. The investigation showed that higher water content was necessary at higher replacement percentages of sand with pond ash, to contribute to increased workability, which may be the reason for decreased compressive strength. The bleeding of water on the flow table may be due to the higher water absorption of pond ash particles and lesser water retentivity at later point of time. The compressive strength, even after reduction is still in the range of requirements as per the standard set by the BIS. The flowability of mortar shows that the mortar mixes are workable at all levels of replacements of sand with pond ash. The investigation recommends using mortar for masonry works without compromise in its wet properties and also compressive strength. However, the study highlights the scope of future research to address the water absorption properties of porous particles of pond ash so as to use the pond ash in large scale for sustainable construction activities, solving problems of sand deficiency and problem of disposal of pond ash.

Soil, a widely used building material is most effective and economic form of material for housing construction. About one-third of population around the world lives in a structure built using earth as per UN report. The use of the earth in construction is significant throughout human history. In addition to the creation of simple shelters, many of the world’s great monuments of construction involved mud or dust. The present study focuses on development of bamboo mud panel using locally available materials. The basic requirement of roof panel decides the materials / process to be adopted. The objective of present study is to provide a suitable ecofriendly process which consumes lower level of energy and uses locally available materials. The raw materials such as bamboo, soil, lime, chicken mesh, cement and stone dust are carefully chosen for the experimental work. The experimental work involves casting of mud roof panel using above-mentioned raw materials. The panel was tested for flexural strength, and two types of mud roof panel were made with whole bamboo and split bamboo. The panel made with whole bamboo performed better than split bamboo.

The purpose of this research is to investigate the seismic response of RC buildings with re-entrant corners of height G + 10, Square, I, U, and Y-shapes. ETABS-2019 software was used to perform the modeling and analysis. The equivalent static method and the response spectrum method are used to study the seismic zone III with soil type II (medium soil) defined in IS 1893:2016(Part-1). Different responses like maximum storey displacement, storey stiffness, storey drifts, and time period are plotted in order to compare the results of both the equivalent static analysis method and the response spectrum method for all the configurations.

The present-day problems faced by the modern world revolve mainly around environment, natural resources management, and sustainability. The demand for construction of various projects has increased due to population growth, rapid industrialization, and urbanization. The construction Industry plays a significant role in polluting environmental indirectly or directly. The current study focuses on the comprehensive use of processed recycled aggregates as a replacement material to natural resources in concrete as rigid pavement material with two different grades of M40 and M60. A rational conclusion is drawn with the study of strength aspects for recycled materials applications.

In RC structures either to increase the load carrying capacity of a column or to strengthen a deteriorated column, one of the methods of strengthening used is Fibre Reinforced Polymer (FRP) wrapping. The use of FRP which is a composite material for confining reinforced concrete columns is increasing rapidly due to its ease of application, high strength to weight ratio and less requirement of time of execution for retrofitting of concrete structures. Design of these FRP confined concrete columns requires an accurate estimate of the performance enhancement due to the confinement mechanism. Therefore, the key issue is to develop a confinement model, which relates the confined concrete strength with the unconfined concrete strength. In the present study, a three-dimensional finite element model of rectangular column converted to elliptical shape by attaching precast concrete segments followed by Carbon Fibre Reinforced Polymer (CFRP) wrapping under different eccentricities of compressive loads has been developed using ANSYS—a software for Finite Element Method of Analysis. Effect of important parameters, namely, aspect ratio of elliptical cross section, eccentricity of loading and number of layers of CFRP wrapping on load carrying capacity of compression members has been studied. From the results obtained it is seen that the load carrying capacity of elliptical compression members increases with number of layers of CFRP. Also it decreases with increase in eccentricity of loading and increase in aspect ratio of cross section.

In present scenario of deterioration of concrete elements or requirement of addition load carrying capacity is due to various reasons like seismic activity, environmental attack, poor design, change in utilization, addition of storeys, etc. There is demand for appropriate retrofitting or strengthening technique. Over several years research and practices have found external FRP wrapping for effective confinement of concrete as very effective, fast-growing method of strengthening technique, although confinement effectiveness can highly depend on geometrical parameters. However, there is a lack of proper formulation and codal provision except from a few countries till date. The present study deals with attaching microconcrete precast segments of required size and shape around the original RC member and then wrapping them together with Carbon Fibre Reinforced Polymer (CFRP). The experimental work presents the procedure of casting and attaching four microconcrete precast segments, each corner which is ground to get circular shape and wrapped the segments around a square RC compressive member. The study compares the load carrying capacity of RC compressive member under concentric load, load with an eccentricity of 0, 15 and 25 mm with or without the CFRP. The experimental values are compared with that obtained by analysis using ANSYS 14.5, a FEA tool. The results of experimental and analytical studies are discussed and concluded.