Abstract
This research undertook an experimental exploration focusing on geogrid-reinforced bottom ash concrete beams and strip foundations to examine how the positioning of geogrid reinforcement and the quantity of bottom ash influence the load-bearing capacity of concrete strip foundations. Four different concrete mixtures were formulated for this investigation. The initial mixture represented conventional concrete, while the remaining three mixtures involved the substitution of fine aggregate with bottom ash at different proportions, namely 20%, 40%, and 60%.
Samples were made from the specified mixtures in three different forms: Concrete Cubes (CC) measuring 100 mm, Concrete Beams (B) with dimensions of 150 mm depth×150 mm width × 700 mm length, and Concrete Slab Strips (SS) sized at 150 mm depth × 700 mm width × 1200 mm length. The beams and slab specimens were reinforced with bi-axial geogrid positioned at different depths from the concrete base, namely 30 mm, 40 mm, and 60 mm. A total of six bottom ash concrete cubes and eighteen geogrid reinforced ash concrete beams and slabs were testes, and these results were compared with those obtained from six unreinforced specimens made of conventional concrete. The beams underwent examination through a four-point bending test, whereas the slabs were subjected to evaluation by positioning them atop a testing box with plan dimensions of 1500 mm × 800 mm and a height of 600 mm. The box was filled with sand having a maximum dry density of 2053 kg/m³. The specimens were analyzed for compressive strength, flexural strength, ultimate load-carrying capacity, deflection, and crack patterns.
According to the test outcomes, the most favorable performance, with respect to compressive strength, flexural strength, and load-carrying capacity, was obtained when the replacement of bottom ash was confined to 40 % with the geogrid placement at approximately 1:3.75 for the ratio of sample height to geogrid’s location from the bottom of the sample. Findings from tests conducted on fully supported slab strips indicated a significant enhancement in load-carrying capacity during the post-cracking stage for geogrid-reinforced slabs, exhibiting a maximum strength gain of 318%. The presence of geogrids in the specimen led to a significant slowdown in crack propagation, providing the section with increased strength and post-cracking ductility. A comparison between the laboratory test results and the Prokon software analysis revealed discrepancies ranging from 6% to 37% for the tested slabs. These differences in results are
STABILITY ANALYSIS OF GEOGRID REINFORCED ASH CONCRETE STRIP FOUNDATION
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attributed to limitations in the software, which hindered its ability to depict support and boundary conditions accurately and to conduct precise simulations of model tests, particularly in 3D modelling.
As a result, this discrepancy affected the overall behavior of the beam-foundation system, consequently influencing the analysis outcomes.