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theses

Self-consolidating concrete (SCC) has been used for repairs due to its ability in overhead applications and hard to access areas such as condensed reinforcement. However, due to its high content in cementitious and supplementary materials, SCC is subjected to shrinkage cracking. To overcome this aspect, fibers were used in the SCC mixtures to form what is known as fiber-reinforced self-consolidating concrete (FR-SCC). Experimental and analytical programs were carried out to investigate the use of the FR-SCC as a repair material. The experimental program included the flexural behavior of 10 beam specimens made of FR-SCC using different volume fractions of two types of supplementary cementitious materials (silica fume (SF) and slag (SL)) and two types of fibers (steel fiber (STF) and polypropylene fiber (PPF)). The main reinforcement for the control beams consisted of #5 reinforcing bars, while the main reinforcement for the repaired beams was either #4 or #3 reinforcing bars that were introduced to simulate 35 % and 65 % loss in rebar areas due to corrosion, respectively. The goal of the repair scheme is focused on extending the service life of the structural elements for about 5-10 years. The analytical part of this research included the development and validation of a finite element model (FEM) that can be used for the analysis and prediction of the structural behavior at various load points. Additionally, results from the experimental program were compared with predictions of the structural properties of all the beams using various code provisions. Results from tests on the fresh and hardened mechanical properties demonstrated that the optimized FR-SCC mixtures were efficient repair materials and can develop adequate bond strength to existing concrete. The flexural test results showed that the repaired beams have higher cracking capacities compared with the control beams. A maximum percentage increase of 29 % was achieved for the beam repaired with 10SF50S compared to the average cracking load for the two control beams. This demonstrated that the repair material markedly improves the repaired area properties, especially the tensile strength. Such improvement is vital in extending the life of the repaired structure under the service loads. The ACI 318, CSA A23.3, and AASHTO-LRFD were non-conservative in estimating the cracking load as well as the deflection in both control and repaired beams, while the ACI 544 equations were conservative and provided a safe prediction for both cracking and ultimate loads. The developed finite element models (FEMs) were effective in producing good prediction in the elastic and plastic ranges of the applied load but did not produce the ultimate deflections (i.e., ductility) exhibited during the tests. Nonetheless, FEM could be used as a tool to further investigate the behavior of repaired and unrepaired concrete beams under static loading.

ETD_8665

Ph.D.

Includes bibliographical references

by Haider Adel Abdulhameed

doi:10.7282/T3HT2SH1

ETD doctoral

The author owns the copyright to this work.