Top of the Pile

Continuous Flight Auger (CFA) technology might well be on its way to becoming the most user-friendly and cost-effective alternative in the piling industry, reveals Sanjoy Chakrabarty, Managing Director, Soilmec India.India, as we know, has progressed by leaps and bounds in the infrastructure sector, and a lot of the credit goes to recent, persistent advancements in the piling industry. Indeed, the industry has come on par with European standards, in terms of the technology used, and the focus is increasingly shifting toward machines offering even better productivity.With an astronomical increase in the number of projects and growing demand within the industry, there is a crying need for a user-friendly and eco-friendly technology. Contractors and private infrastructure project developers are increasingly demanding foundation equipment, which is highly productive as well as safe to operate. Introduction of the internationally acclaimed CFA (Continuous Flight Auger) technology has taken care of their needs to a large extent.Advantage CFAPatronised by a majority of European nations, CFA is a technology trusted primarily for its stability, minimal operating costs and a unique ability to operate with ease in almost every kind of soil. Globally referred to as dry pile, CFA increases functional productivity at work sites, along with added environmental benefits such as an exponential reduction in sound emissions, and other pollutants. Significantly, it can perform in every kind of soil without the use of bentonite, helping cut down the requirement for allied machinery such as tanks, as well as overall piling costs. CFA is less manpower intensive and quite safe, environmentally speaking, considering that the extracted soil is not contaminated with bentonite.Tools and techniquesCFA equipment typically consists of a flanged or tubular type of leader, depending on the pile depth, and a crawler unit on which the leader is mounted. The actual drilling is performed by a helicoidal steel plate welded to a central hollow stem, which is provided with teeth on the lower part to help penetration into the ground. A disposable cap, fitted as a plug at the end of the stem, prevents soil from entering when the auger string is driven down into the ground. During operation of this technology, the ground is partially pressed sideways by auger penetration, resulting in compaction of the soil all around the shaft.The drilling method allows excavating in a wide variety of soils, including dry or water-logged or loose or cohesive, and penetrating through low capacity or soft rock formations such as loamy clays, limestone, sandstone, etc. During the drilling process, no shocks or vibrations are induced. As per requirements under the law, the equipment is fully soundproof, making CFA the most convenient piling method for construction in town centres.As CFA can be executed with almost any kind of soil, it allows working close to existing structures. As bentonite is not required, there need be no provision of space for the side plant. With reduced volume of soil brought up to the surface, there is less amount of excavated material that needs transportation to the point of disposal.Road aheadCFA was used for the first time in India at a site in Rajpura, where the execution of the piling was done up to a depth of 18 m, using a diameter of 600 mm, taking piling to the next level in the country. The dynamic and physical load tests of these experimental piles give strength to the belief that there are great expectations from CFA to become the most acceptable and economical piling technology in many parts of the country.All said, while CFA might well be the future of foundation engineering technology, it must be coupled with availability of spare parts and strong technical help made available by the suppliers in order for it to become the most user-friendly and cost-effective alternative in the  piling industry.If you have a new and innovative technology to share, email us at feedback@ASAPPmedia.com