"Pumping is an easy method to move concrete while keeping stability. It is worldwide accepted as one of the principal methods for concrete placement, as it accelerates construction. Typically, concrete acceptance in terms of fresh quantitative empirical properties (i.e. slump/slump flow and air content) are performed prior to the pumping process. However, empirical measurements have the drawback that they only measure 1 point. Rheology is better tool to evaluate the behavior of concrete. Pumping is a process that induces considerable shearing in the concrete that can impact its rheological properties. Therefore, the magnitude of these changes in fresh properties depends on a combination of mix design, flow rate, boom length and configuration, and concrete drop height. This research work evaluates the interaction between fresh concrete properties and pumping parameters on several mixtures with different workability levels and air contents. Large scale concrete batches were produced with different types and contents of admixtures and subjected to different pumping conditions. The tests used to address the workability changes were slump/slump flow, T50, air content (pressure method), unit weight, segregation resistance and rheology. The results showed that the fresh concrete properties are affected in diverse ways by pumping, with the results being dependent on the concrete fresh properties, and pumping parameters. Additionally, an attempt was performed to reverse engineer the composition of the so called 'lubrication layer' through the science of rheology. Main results indicated a composition of purely paste"--Abstract, page iii.
Civil, Architectural and Environmental Engineering
M.S. in Civil Engineering
Missouri University of Science and Technology
xxi, 162 pages
© 2019 Alexis Salinas, All rights reserved.
Thesis - Open Access
Electronic OCLC #
Salinas, Alexis, "Changes in fresh properties of flowable concrete induced by pumping and composition of the lubrication layer" (2019). Masters Theses. 7922.