Date of Award
Master of Science (MS)
Dr. Laura Redmond
Dr. Weichiang Pang
Dr. Brandon Ross
Reduction in structural mass, improvement in thermal performance, and reduction in shrinkage cracking through internal curing are some of the reasons that lightweight (LW) aggregates have been used in structures and pavements for decades. However, lightweight grout is still not permitted for use in reinforced masonry construction by the TMS 402/602-16 code. In order to realize the benefits of lightweight grout in U.S. reinforced masonry construction, a codified procedure for its use is required which must be informed by experimental testing.
This research is a pilot project directed to characterize the performance of LW grout in comparison to normal weight (NW) grout by conducting anchor bolt tests, modulus of rupture tests, diagonal tensile strength tests, and lap splice tests. Two types of lightweight aggregates, expanded clay aggregates (EC) and expanded slate (ES) aggregates, are separately used to make the lightweight grout mixes. Firstly, the appropriate mix designs are obtained through a number of trial batches which indicate that proper grout mixes cannot be obtained through the volume proportions suggested by ASTM C476, hence recommendations for the mix design criteria have been made in this research. The grout mix designs adopted in the tests comply with the strength and slump requirements of ASTM C476. For the anchor bolt tests, two types of fully grouted wall assemblies, half with EC grout and half ES grout are made. Half of them are tested in static out-of-plane tension and the other half are tested in static in-plane shear, in accordance with ASTM E488. A reduction factor for the TMS 402-16 equations does not appear necessary for anchor bolts in tension in LW grout based on the results of this study but further research would be required to corroborate these findings. The performance of anchor bolts in shear in LW grout specimens seem similar to the performance in NW grout specimens, but additional testing involving different bar diameters would be helpful to determine the consistency of the results. Modulus of rupture tests in compliance with ASTM E518 are conducted in grout prisms and the results support the higher tensile capacities of the ES grout found in the anchor bolt test in tension. For the lap splice test, two lap splice configurations are tested using masonry assemblies constructed with EC and ES grout. Regression analysis is used to compare this dataset to historical data of lap splice specimens with NW grout. Finally, three types of wall panels, each fully grouted with either EC grout, expanded slate ES grout, or NW grout, are constructed and tested in accordance with ASTM E519. Modification factors are found to be necessary for both the lap splice capacity and diagonal tensile strength capacity of assemblies with LW grout compared to the predictive equations for capacities in NW grout. In addition to the discussion of the datasets, parallels are drawn between the relative performance of LW grout specimens and NW grout specimens and the relative performance of LW versus NW concrete specimens from the literature.
Shrestha, Rumi, "Development of Lambda Factors for Masonry Design with Lightweight Grout" (2021). All Theses. 3689.
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