Speed of production of units/structural elements and efficient use of resources are key driving forces in the precast/prestressed concrete industry and these factors significantly influence the concrete mixtures used by precast producers. For example, the production efficiencies provided by self-consolidating concrete (SCC) led to its rapid and widespread adoption in the precast industry. The development of newer high-performance concretes, such as ultra-high-performance concrete (UHPC), a continued shortage of skilled labor and societal demands with respect to sustainable concrete construction have increased the need for innovative concreting materials, in particular, chemical admixtures to address operational issues regarding concrete mixtures. Some of these issues include mixing time, flowability and flow retention, a high-quality surface finish, and very high-early strength development. In this paper, the authors present and discuss the use of innovative admixtures to address some of these performance issues; specifically, new high-range water-reducing admixtures that, respectively, provide fast wet-out of binder materials and rheology modification, nanotechnology-based strength-enhancing admixtures and a novel workability-retaining admixture.

Many of the papers presented in this volume were included in the two-part session Nanotechnology for Improved Concrete Performance, sponsored by ACI Committee 241, Nanotechnology of Concrete at the ACI Convention in Philadelphia, PA, on October 26, 2016. In line with the practice and requirements of the American Concrete Institute, peer review, followed by appropriate response and revision by authors, has been implemented.

In recent years, there has been significant research and product development in the field of nanotechnology – using particles of approximately 1 and 100 nm in size. From medicines, to electronics and coatings, the answers to ‘big problems’ are being provided by ‘tiny solutions.’ In the cement and concrete field, nano‐structural models of Calcium Silicate Hydrate (C‐S‐H), have allowed researchers to develop particles to improve and increase C‐S‐H formation. Additionally, micro particles have the ability to address durability issues that have plagued concrete for decades. The practical challenge continues to be how to introduce these micro‐ and nanoscale particles into the concrete matrix. A logical option is in the form of a liquid admixture added to the concrete mixture during batching. This paper will focus on the current and emerging micro‐ and nanoscale particulate‐based admixture technologies for concrete and their effects on the hydration process and long‐term durability of concrete. The information to be presented will show that the use of these particulate‐based liquid admixtures offer different options for modifying and improving the fresh, hardened and durability properties of concrete.

Editors: Mohammad Pour-Ghaz, Aali R. Alizadeh, and Jason Weiss

With the recent quest for developing sustainable infrastructure materials, there is a need for more advanced material characterization techniques at different length scales that can provide insight to the nature and fundamental behavior of the new classes of cementitious materials as they are becoming available. These methods can be used to predict the mechanical properties, microstructural aspects, and long-term performance of different cementitious systems. Examples of these novel techniques that have been recently used for material characterization include nuclear magnetic resonance spectroscopy, nano- and micro-indentation, X-Ray tomography, and atomic force microscopy. Recently, major progress has also been made in the development of novel cement-based systems such as C-S-H/polymer nanocomposites and self-healing materials. This Special Publication aims at providing a treatise on the current research in the areas related to innovative characterization methods and analytical techniques used in the cement and concrete research, as well as the development of novel basic and composite cementitious materials. This Special Publication is developed to honor the significant contributions made by Dr. James J. Beaudoin over the past four decades to the advancement of cement and concrete science. Dr. Beaudoin, a Researcher Emeritus, Fellow of the Royal Society of Canada, and Fellow of the American Ceramic Society, has authored more than 500 publications, including five books, 20 book chapters, encyclopedia contributions, more than 270 research journal papers, 17 patents, and numerous discussions and book reviews. He is the recipient of numerous prestigious awards, including the Della Roy Lecture Award on applications of nanotechnology in cement science (American Ceramic Society, 2005), the Wason Medal for Materials Research (American Concrete Institute, March 1999) and the Copeland Award (American Ceramic Society, 1998). The papers included in this Special Publication were presented in two sessions in ACI Fall 2014 Convention, Oct 26-30, 2014.

This CD-ROM consist of 9 papers sponsored by ACI Committee 236, at the Fall 2009 Convention in New Orleans, LA, in November 2009. The papers included cover a broad range of subjects related to the nanotechnology and material science of concrete with focus on nanostructure characterization, synthesis, design, and modeling of cement based materials, as well as application of nano-materials in concrete technology. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-267