A K Sthapak, Mangdechu Hydroelectric Project Authority, Bhutan
Rajbal Singh, Central Soil and Materials Research Station, New Delhi

Six different grades of Self Compacting Concrete (SCC) varying from M15A20 to M35A20 were used in various components of Tala Hydroelectric Project in Bhutan in Himalayas. This paper deals with the mix design, application and performance of a wide range of SCC mixes used in gate grooves in dam, back fill and lining of surge shaft and pressure shafts of Tala Hydroelectric Project. In the present application, two important parameters viz. ease of placement and better filling ability of SCC without vibration weighed in favour of SCC despite its somewhat higher cost as compared to conventional concrete. In case of gate grooves, the space to be filled is vary narrow, in which reinforcement further obstruct the flow of concrete. Therefore, a rich mix with desired attributes was designed. In case of back fill, due to large dimensions, minimum possible cement content was used to avoid thermal problems. The SCC mixes were designed with and without viscosity modifying admixture without adding any fine powder. Under the given placement condition, the SCC was placed successfully without difficulty. The field performance was monitored by testing cubes, cores, beans etc.

Introduction

Tala Hydroelectric Project is a run of the river scheme, located 3 km downstream of the existing 336 MW Chukha Hydroelectric Project on river Wangchu in South Western Bhutan in Eastern Himalayas. The project has constructed a 92m high concrete gravity dam at Wangkha, three desilting chambers each of 250m x 13.90m x 18.5m size for removal of suspended sediments of 0.2mm and above size coming with the river water diverted through the intake structure; a modified horse shoe tunnel of 6.8m diameter and 23km in length, a surge shaft of 15m/12m diameter and 178m height; two pressure shafts of 4m diameter and 1.1km long each and an underground powerhouse (206m x 20.6m x 44.5m) for utilizing a gross fall of 861.5m. A tail race tunnel of 3.1 km length and 7.75m diameter discharges the water back into river Wangchu. The installed capacity of powerhouse is 1020 MW (6 x 170MW).

The project was taken up for execution from the zero level of infrastructure development from 1st October 1997 and its first unit was commissioned on 31st July 2006 and all six units were commissioned by March 2007. The project has been constructed by Tala Hydroelectric Project Authority (THPA), an autonomous body constituted jointly by the Government of India and the Royal Government of Bhutan.

The self compacting concrete (SCC) was used for backfill behind steel liners in pressure shafts, behind steel ribs in surge shaft, lining of surge shaft, and as second stage concrete in dam. The concrete grades of M15A20 and M20A20 were used for backfill in surge shaft and pressure shafts, respectively. M30 and M35 were used in lining of surge shaft. M25 with 10mm and 20mm MSA was used in gate grooves of stop log and radial gates in dam. Conventional pumped concrete could not properly fill all rock crevices and voids were noticed between two consecutive ribs when shutters were removed in surge shaft. Vibrating the concrete was practically difficult. Typically, SCC contains cementitious materials in the range of 400 to 600 kg/m3 including ultrafine inert materials (EFNARC, 2002). However, in the present application, an attempt has been made to produce SCC at a cement content of 310 to 360 kg/m3 with 20 to 25 kg/m3 micro silica content without any fine filler material by using viscosity modifying agent and a well suited proportioning of aggregates.

The mix design, application, and performance of various grades of SCC along with the advantages have been discussed in this paper.
This is a premium article available exclusively for our subscribers.
If you are already a subscriber, please Login
If not, subscribe now and get access to well researched articles & reports on infrastructure construction, equipment & machinery, innovations & technology, project reports, case studies, and more. All this by simply paying just ₹200/- for a month of complete portal access, or a discounted rate of ₹1000/- for a full year of access.
Concrete Rheology - Unveiling the Secrets of Concrete
Concrete is a heterogeneous composite complex material, and its hardened property is influenced by its fresh property. Concrete today has transformed into an advanced type with new and innovative ingredients added - either singly or in

Read more ...

ICRETE: Making Concrete Economical
ICRETE offers many benefits apart from reducing cement content and giving high grades saving to ready-mix concrete companies; it helps reduce shrinkage and permeability in concrete slabs, increases the durability of concrete, and also works

Read more ...

UltraTech Cement to implement Coolbrook’s RotoDynamic HeaterTM revolutionary technology for industrial electrification
UltraTech Cement Limited, India’s largest cement and ready-mix concrete (RMC) company, and Coolbrook, a transformational technology and engineering company, will jointly develop a project to implement Coolbrook’s RotoDynamic HeaterTM (RDH)

Read more ...

Plastic Shrinkage and Cracks in Concrete
Plastic shrinkage cracking occurs when fresh concrete is subjected to a very rapid loss of moisture. It is caused by a combination of factors such as air and concrete temperature, relative humidity, and wind velocity at the surface of concrete. These can cause

Read more ...

Mechanised way of plastering with spray Plaster Machine
This paper covers the research work carried out on cement plastering process for internal and external building wall by using spray plastering machine. Objective of study is to experiment and compare the plastering activity by conventional way and

Read more ...

Construction Defects Investigation & Remedies
In recent years, the speed of construction has increased very fast; buildings which used to take 3-5 years are now getting completed in 1-2 years. There is a race to complete projects faster, but due to this speedy construction, the quality of construction is often

Read more ...

Challenges in usage of Hydrogen in Cement Industry
With its zero-emission characteristics, hydrogen has become a promising decarbonization path for the cement industry. While there are several issues that need to be resolved in the use of hydrogen, there are also many advantages, so much so that the growth

Read more ...

Enhancing Corrosion Resistance of Steel Bars in Reinforced Concrete Structures
Reinforced concrete is a composite material which is made using concrete and steel bars. Concrete takes the compressive forces and steel bar takes tensile forces. Concrete around the steel bar protects it from corrosion by providing an alkaline environment

Read more ...

Moving toward workability retention to rheology retention with low viscosity concrete technology
Amol Patil, Sr. Specialist - General Manager (Admixture and Specialty Products), Master Builders Solutions (India), and Nilotpol KAR, Managing Director, Master Builders Solutions (South Asia), present a paper on the concept of low viscosity concrete in

Read more ...

Cement industry innovating eco-friendly packaging
Cement companies are constantly innovating to meet global sustainability standards and improve logistics, shelf life, and utility of cement, while reducing wastage. Thei aim is to reduce their environmental impact without compromising their product

Read more ...

IIT Madras uses Solar Thermal Energy to Recycle Waste concrete
Researchers at the Indian Institute of Technology Madras have developed a treatment process using solar thermal energy to recycle construction and demolition debris. Waste concrete from demolition was heated using solar radiation to produce recycled concrete

Read more ...

Textile Reinforced Concrete - A Novel Construction Material of the Future
As a new-age innovative building material, TRC is especially suited for maintenance of existing structures, for manufacturing new lightweight precast members, or as a secondary building material to aid the main building material. Textile Reinforced Concrete

Read more ...

Technological Innovation for Use of Bottom Ash by-product of Thermal Power Plants in the Production of Concrete
The day is not far for the adoption of this innovative, eco-friendly, and cost-effective bottom ash – concrete process technology by construction agencies undertaking road/infrastructure project works, real estate developers, ready mix concrete (RMC) operators

Read more ...

Headed Bars in Concrete Construction
Using headed bars instead of hooked bars offer several advantages like requirement of reduced development length, less congestion, ease of transport and fixing at site, better concrete consolidation, and better performance under seismic loads.

Read more ...

Sustainability of Cement Concrete - Research Experience at CRRI on Sustainability of Concrete from Materials Perspective
It can be said that ever since the publication of the document of World Commission on Environment and Development [1], the focus of the world has diverted towards sustainability. Gro Harlem Bruntland [1] defined sustainable development as “development

Read more ...

Shrinkage, Creep, Crack-Width, Deflection in Concrete
The effects of shrinkage, creep, crack-width, and deflection in concrete are often ignored by designers while designing structural members. These effects, if not considered in some special cases such as long span slabs or long cantilevers, may become very

Read more ...

Concrete Relief Shelve Walls - An Innovative Method of Earth Retention
Relief shelve walls are a unique concept that use only conventional construction materials like PCC / RCC / steel reinforcements, and work on a completely different fundamental to resist the lateral load caused due to soil. Information on the various dimensions

Read more ...

Carbon Neutrality in Cement Industry A Global Perspective
Increasing energy costs, overcapacity, and environmental pollution are the top concerns of the cement industry, which is one of the major contributors to CO2 emissions. Dr S B Hegde, Professor, Department of Civil Engineering, Jain College of Engineering

Read more ...

Finnish company Betolar expands to Indian concrete markets with a cement-free concrete solution
Betolar, a Finnish start-up, and innovator of geopolymer concrete solution Geoprime®, has expanded its operations to Europe and Asian markets including India, Vietnam and Indonesia. Betolar’s innovation Geoprime® is the next-generation, low carbon

Read more ...

Why Fly Ash Bricks Are Better Than Clay/Red Bricks
It is estimated that in India each million clay bricks consume about 200 tons of coal and emit around 270 tons of CO2; on the other hand, with fly ash bricks production in an energy-free route, there are no emissions. Dr. N. Subramanian, Consulting

Read more ...