Mega Structure 4 - Chenani – Nashri Tunnel

Prime Minister Narendra Modi on Sunday dedicated Asia's longest bi-directional road tunnel on the Jammu-Srinagar National Highway to the nation. The Chenani-Nashri tunnel will cut down travel time between Jammu and Srinagar by two hours.

Modi was accompanied by Road Transport and Highways and Shipping Minister Nitin Gadkari and Minister of State for PMO and MP from Kathua-Udhampur constituency, Jitendra Singh.

The Rs 2,519-crore all-weather tunnel is equipped with world-class safety features and has been built in a record four years on the hilly terrain of Jammu and Kashmir, Road Transport and Highways Minister Nitin Gadkari had said earlier.

"This state-of-the-art 10.89-km tunnel between Udhampur and Ramban in Jammu and Kashmir, an engineering marvel on the most difficult terrain of the Himalayas, was built in a record four years," the minister had said.

Mixing and Batching of Mortar And Concrete Ingredients

ABSTRACT:
A concrete plant, also known as batch plant is device that combines various ingredients to form concrete. In general, it is a process of combining all ingredients of concrete as per the mix design. Batching and mixing are extremely important parts of mortar and concrete manufactures they influence properties of concrete both in plastic as well as in hardened stages. Also, it is one of the important processes, which is to be done to obtain a quality concrete. Many processes are carried out in various parts of the world with many changes and different equipment. There are various types of batching and mixing equipment and methods that is to say from manual to most sophisticated computerized batching and mixing. Mechanization improves quality of batching and mixing, its speed and thereby can most often result in economy.There are number of factors which are to be considered while doing the process which are discussed in this paper. Moreover, the machinery, which is to be required while making concrete or for batching process and discharging and unloading of the mixture, are also discussed in brief.

1.0 INTRODUCTION:

Concrete is the most widely used construction material in the world. This material is not going to be easily replaced by any other material on account of its economical as well as the technical advantage.This material is generally produced at the site in our country and therefore needs to be carefully supervised and controlled in order that it performs the way it is technically expected to perform.

Concrete is made from raw materials such as cement, natural and manufactured aggregates, water and at times concrete additives (chemicals). It is worth noting that cement and aggregates are manufactured or obtained from natural solid stone, which is quarried, crushed, screened and processed to give the required physical and chemical properties.

This paper covers the batching and mixing process of concrete manufacture. The processes of batching and mixing of concrete or mortar materials are very similar to preparations of a dish in cookery as per a recipe wherein various ingredients depending on their individual properties have to be mixed in correct proportions to give the required flavour and taste.

Plastic Cracking of Concrete

1.0 INTRODUCTION:
Cracking is one of the major issues in concrete. Since concrete has various physical and chemical properties it is prone to cracking. Its elimination is not possible totally but it can be restricted or reduced to a certain extent. Mostly, cracking goes on a microscopic scale and does not appear visibly as a fault. If the cracking goes on a macroscopic scale it can result in loss of strength, stability and durability. It can also cause decrease in sound insulation and overall efficiency besides affects aesthetics to a greater extent.

The main causes of cracking are as follows:

• Ageing – Carbonation
• Foundation problems
• Weathering Actions
• Improper or modified use of the structure
• Poor maintenance
• Progressive loading
• Deficiencies in design
• Poor quality of concrete material
• Improper concrete mix
• Movement of concrete arising from physical properties
• Poor workmanship and negligence
• Over troweling and impermeable formwork
• Reduced continuity of the structural member
• Defects and errors in construction practices
• Improper structural repairs or modification
• Chemical attacks by Chlorides and Sulphates
• Differential thermal stress – Heat of hydration of cement

Since, prevention is better than cure it is always preferable to prevent cracking to a certain or a possible extent than to think of repairs in the future due to various reasons. One of the frequent occurrences of cracking of concrete is due to plastic shrinkage of plastic settlement. This paper deals with various aspect of these types of cracking.

2.0 OCCURRENCE OF PLASTIC CRACKING:

Both plastic shrinkage and plastic settlement cracks occur within a few minutes or hours of concrete placing and finishing. They occur when concrete is still in plastic state and has not fully hardened. They can be seen as early as 10 minutes from the time of placing and finishing to as late as 3 hours after placing.

The plastic cracks are of two types:
1. Plastic settlement Cracks
2. Plastic shrinkage Cracks

The Effect of Bagasse Ash and Rubber Tyre Waste in Concrete

Abstract
The utilization of industrial and agricultural waste produced by industrial process has been the focus on waste reduction research for economical, environmental and technical reasons. SCBA is a fibrous waste product of the sugar refining industry, along with ethanol vapour. Bagasse ash mainly contains aluminium ion and silica. The use of SCBA as a pozzolonic material for producing high strength concrete. OPC is partially replaced with finely SCBA. At present the disposal of waste tyre is becoming a major waste management problem in the world. In this project, the bagasse ash has been chemically and physically characterized and partially replaced in the ratio of 0%, 5%, 15% and 25% by weight of cement in concrete. The mix proportion for M30 grade concrete was derived. Rubber tyre waste has been used as coarse aggregate with replacement of conventional coarse aggregate and it is taken as constant of 10%.

INTRODUCTION 
Ordinary Portland cement is the most extensively used construction material in the world. Portland cement is the conventional building material that actually is responsible for about 5%-8% of global CO2 emissions. This environmental problem will most likely be increased due to exponential demand of Portland cement. Today we are focusing on ways of utilizing either industrial or agricultural waste, as a source of raw materials for industry. This waste, utilization would not only be economical, but may also result in foreign exchange earnings and environmental pollution control. Several researchers and even the Portland cement industry are investigating alternatives to produce green building materials. Industrial wastes, such as blast furnace slag, fly ash and silica fume are being used as supplementary cement replacement materials. Agro wastes such as rice husk ash, wheat straw ash, hazel nutshell and sugarcane bagasse ash are used as pozzolanic materials for the development of concrete. Currently, there has been an attempt to utilize the large amount of bagasse ash, the residue from an in-line sugar industry and the bagasse-biomass fuel in electric generation industry. When this waste is burned under controlled conditions, it also gives ash having amorphous silica, which has pozzolanic properties. Solid waste is concerned with waste tyres, has become a problem of interest because of its non-biodegradable nature. Tyre rubber wastes represent a major environmental problem of increasing significance. Most of the waste tyre rubbers are used as a fuel in many of the industries such as thermal power plant, cement kilns and brick kilns etc. this material can also be used for non load-bearing purposes such as noise reduction barriers. Investigations about rubber waste concrete show that concrete performance is very dependent on the waste aggregates. Further investigations are needed to clarify for instance which are the characteristics that maximize concrete performance.