Khalil, Sarah (2025) High-performance modified-weight concrete design using an optimal combined statistical experimental design methodology. Doctoral (PhD) thesis, Memorial University of Newfoundland.
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Abstract
This thesis has one primary and two secondary objectives. The primary objective of this research is to design and optimize High-Performance Modified-Weight Concrete (HPMWC) mixtures, investigating the application of the statistical mixture combined design methodology (SMCD). The concrete mixtures have six mixture components: metakaolin, cement, fine aggregates, normal weight coarse aggregates, lightweight coarse aggregate, and water; and one process variable: the maximum size of normal weight coarse aggregate. The 17 responses studied included various performance criteria of HPMWC, including fresh, mechanical, and durability properties. The study included the selection of the statistical design, logistical planning for execution, processing, and the analysis of the experimental runs. To minimize the number of runs and take into account the combined mixture and process variables, the KCV (Kowalski, Cornell, and Vining) model was used. Thirty-four experimental runs were required to model the responses studied. Prediction models were fitted for each response and validated. The results show that performance criteria prediction models accuracy ranges from very poor, such as Poisson’s Ratio and Tested MOR which result in negative predictive R2 values, to excellent, such as the Dry Bulk Density, with the others falling in between poor and excellent. A secondary objective of this thesis was the refinement of testing methodologies for evaluating HPMWC fresh concrete properties. It is recognized that the fresh properties have a critical influence on the final product, and an aim was to make recommendations on in-place workability testing. A detailed examination of existing workability tests, the Slump, K-Slump, and Kelly Ball tests were evaluated based on the fresh properties of the 34 concrete mixtures. The results obtained using the three testing methods were statistically compared and evaluated. The three workability techniques were shown to be statistically and positively correlated; however, Kelly Ball showed inconsistency with K-Slump and Slump tests in 4 workability measurements, reaching its limiting value. Thus, it was determined that among Kelly Ball and K-Slump in place tests, K-Slump has a potential of future improvement and use for in place workability assessment. The third objective of this thesis was to explore the abrasion resistance testing of HPMWC, considering its growing application in demanding environments such as bridges and offshore platforms. Two ASTM standard methods, one by sandblasting and one by rotating cutters, were employed to assess the abrasion resistance. These were supplemented by a novel laser-scanning techniques to measure the test results. A special focus was given to the topography of the abraded concrete surfaces resulted using Sandblasting approach, and to the inherent variability in abrasion mechanisms. An evaluation of ASTM C418-20 testing method was carried out and its modeling clay standard measurement method was statistically compared with the novel laser scanning measurement techniques. While no significant statistical difference at the 5% level between the results was found, the level of detail provided by each method was different and essential for test measurement choices. It was recommended that the laser scanning method should be used when the topographical information in relation to abrasion mechanism is required and when abrasion quantities are low. In summary, this thesis employed an advanced statistical method, specifically the SMCD approach and KCV model, to design and optimize HPMWC. It places emphasis on refining workability and abrasion resistance testing techniques to enhance the concrete's performance in demanding environments.
| Item Type: | Thesis (Doctoral (PhD)) |
|---|---|
| URI: | http://research.library.mun.ca/id/eprint/16968 |
| Item ID: | 16968 |
| Additional Information: | Includes bibliographical references (pages 228-261) -- Restricted until May 5, 2026 |
| Keywords: | SMCD, DOE, concrete, workability, abrasion |
| Department(s): | Engineering and Applied Science, Faculty of |
| Date: | May 2025 |
| Date Type: | Submission |
| Digital Object Identifier (DOI): | https://doi.org/10.48336/pbke-rg27 |
| Library of Congress Subject Heading: | Concrete--Design and construction; Concrete--Service life; Concrete--Testing; Concrete--Mechanical properties; High strength concrete |
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