H=Hyatt Regency Dallas; U=Union Station
100 Year Anniversary of the Slump Cone, Part 1 of 2
Sunday, October 23, 2022 8:00 AM - 10:00 AM, H-Reunion A
The slump cone has been used for the past 100 years to assess the consistency and workability of fresh concrete. The objective of this session is to reflect on the slump test and provide perspective on how it and other tools can be used to assess fresh concrete properties today as well as in the future. Academic and industry researchers, practitioners and students should attend this session to gain a historical perspective on the slump cone.
(1) Discuss how the slump test has evolved;
(2) Identify what information can be obtained;
(3) Discuss the limitations of the slump test;
(4) Review different workability test methods for different classes of concretes.
This session has been AIA/ICC approved for 2 CEU/PDH credits.
Evolution of the Slump Test: A Perspective
Presented By: Denis Beaupre
Affiliation: Command Alkon
Description: Who would have predicted that a simple empirical test such as the slump cone would have last more than a century? The consistency test has been used for two main purposes, both implies by its definition: to assess 1) the concrete workability and 2) the repeatability of the production from load to load. There are now so many different types of concrete that using a minimum, maximum or both slump limit is not enough. This paper presents a short history of the slumps test but also describes several alternatives. From portable rheometer to truck mounted sensor several replacements to the slump test are presented along with a discussion on what considerations are needed for a wide adoption of either or any of these substitutes. It may still take more time to replace the slump test but interesting options are now available.
Rheology Assessment and Improvement for Concrete Mixtures in Flat Work Applications
Presented By: Lesley Suz Chung Ko
Affiliation: Master Builders Solutions US LLC
Description: Customer surveys have indicated existing challenges associated with placing, pumping, and finishing industrial flooring applications. This is especially true when various materials, such as different cements, slag, manufactured sand and/or fibers are used as concrete constituents. To address these challenges, a new generation of water reducers has been developed based on an innovative polymer technology. In addition to providing the targeted slump measured by traditional slump cone, this new technology can modify rheological properties of concrete mixtures, such as lowering plastic viscosity, static yield stress and thixotropy compared to typical water reducers. These properties are related to ease of handling, placing, and finishing characteristics of concrete. Various laboratory methods have been employed to assess rheological behavior of mortar or concrete, such as the commonly used ICAR rheometer, an
analytical rheometer, a sliding pipe rheometer, and other novel equipment including vibrating L-box and lab-scale finishing machine. Field applications using rheology modified concrete has demonstrated positive impact on those pain points which can lead to more efficient use of equipment, manpower and increase construction speed.
Measuring Workability, from Pavement Concrete to UHPC
Presented By: Jiong Hu
Affiliation: University of Nebraska-Lincoln
Description: Appropriate fresh concrete workability is essential to ensure successful concrete construction and structures with sufficient mechanical properties and durability. However, depending on the application, the requirement of the workability of concrete could be very different. With different types of concrete, appropriate test methods and criteria are needed for fresh concrete workability. This presentation includes examples of workability test methods and results for different classes of concrete, from slipform pavement concrete to fiber-reinforcement concrete and ultra-high-performance concrete. Aspects including the role of vibration, fiber stability, and rheological properties of different types of concrete are also discussed.
Vibration Energy Transfer and Slump of Concrete - Then and Now
Presented By: Jae Hong Kim
Description: No other tests except the slump test have been used for such a long time. We keep on evaluating the workability and quality of concrete using the test, and so it is possible to compare the fresh properties of concrete now and then. The current mix proportion of concrete is quite different from that of concrete 50 years ago (very conservatively). We need adding more water in concrete 50 years ago to increase its slump (very conservatively). We needed to add more water in concrete 50 years ago to increase its slump, but now superplasticizer allows us to get a high slump at the minimum water content. The difference in the water content would result in affecting the vibrating energy transfer in the process of consolidation. We measure the intrinsic attenuation of concrete assuming a cylindrical wavefront and exponential decay for P-wave propagation. As a result, it is found that the attenuation coefficient of modern concrete is distributed from 1 to 3 m -1. The notional power density, the maximum energy level imposed by a conventional vibrator, is 100 to 300 W/m excluding the instability of near-field liquefaction.