Cement Energy and Environment

f The possibility of a merger between ACC and Ambuja Ce– ments has been the talking point among industry players for a long time. However, both the companies have denied this. Brokerage JP Morgan noted that the purchase of the additional equity by Holcim, by which it would have the majority holding, had resu lted in speculation that a merger would follow. That had resulted in the shares of both entities trading at valuations significantly above those of their peers. Courtesy: The Financial Express Mumbai, ffh May 2011 TECHNOLOGY UPGRADATION Quality & Standards CHALLENGES AND OPPORTUNITIES FOR CONCRETE RESEARCH IN THE NEW MILLENNIUM In the past 50 years, significant changes have taken place in the properties of concrete. During the 1940s, 1950s, and 1960s, substantial basic research conducted around the world resulted in a thorough understanding of the properties of concrete materials ' such as cement and aggregates, and the effect of these materials on the plastic and hardened properties of concrete. Material standards and specifications, mix-design and ingredient proportions, test procedures, and construction techniques were developed on the basis of this knowledge. In recent years, strong emphasis is being placed on high early-strength and high– performance concrete and on shorter construction times. In response to this cha llenge, research has been focussed on producing changes in the properties of the basic ingredients of concrete, such as cement, and on developing new ingredients to achieve better quality, higher strength, and more durable concrete. Several generations of concrete admixtures have been developed with the aim of altering a wide range of plastic and hardened properties of concrete to achieve high-early– strength and high-performance concrete. Use of admixtures has allowed a dramatic reduction in the water- cementitious materials ratio (w/cm) in the concrete m· IX, which in turn has resulted in higher-strength and more– durable concrete. Significant research has also been done on the development and use of cementitious and pozzolanic materials, such as fly ash, silica fume, and slag, to replace or supplement the cement content in the concrete mixture. These ~aterials have significantly Improved the durability of concrete by reducing its permeability. To day it is not un common for five or more admixtures and cementitious and pozzolanic materials to be included in a mixture in addition to the standard concrete ingredients. Such complex concrete mixtures are significantly different from the simple mixtures produced in the 1950s and 1960s. Yet many specifications and construction practices developed in accordance with basic research of the 1950s are still being applied to today's ·concrete materials and construction. In addition, there are still unresolved problems and many unanswered questions associated with today's concrete. For example, excessive shrinkage and shrinkage cracking are being observed in many of the high– performance and high-strength concretes. These unintended consequences impact the durability of the concrete and . thus tend to defeat the purpose of using such mixtures. Another important set of issues with 3