CORE TORSION STRENGTH OF CONCRETE

Abstract

Methodology Invention: The test methodology consists of applying torsion or torque to a core formed within the structure until failure occurs at the base of the core. The torsion value is correlated with the concrete's strength using torque-strength graphs previously calibrated in the laboratory. Core Making Equipment Saw Drill Guide Invention: The core making equipment consists of a drill and a saw drill guide. The saw drill guide consists of a tubular metal housing that, via bearings, houses and rotates a shaft connected to a diamond saw drill. The saw drill guide rests on the surface of the structure, and the rotation imparted by the drill causes the saw drill to shape or create the core. The saw drill guide includes its shaft, housing, base with drains, and water inlet nozzle.Invention of the Core Torsion Testing Equipment Insertion Tube: In core torsion testing equipment, the Insertion Tube, inserted vertically into the manufactured core and secured to it by means of its clamp, is firmly gripped and fastened to the core. This allows torque to be applied using the handle connected to the torque wrench. With both properly positioned, the core base is then subjected to failure. The maximum torque value that produces this failure at the core base is the torque value recorded by the torque wrench, and this value is correlated with the material's strength. Once the test is completed, resulting in the core being torn or extracted from its base, the core is removed from the insertion tube using the extraction screw inserted into the hole at the top of the tube. The screw, upon penetration, dislodges the core.The Insertion Tube invention includes the slotted tube with its 19 mm hexagonal nut, its 6 mm threaded top hole, its extractor screw, and clamp. Torque-Strength Graphs Invention: The torque value obtained in the core torsion test is compared with the torque [Nm]-strength [MPa] graphs to obtain the material's strength value. The graphs are obtained by pre-calibrating the torque obtained in the laboratory on prismatic concrete specimens measuring 150 x 150 x 600 mm for torsion tests and on standard cylinders measuring 150 mm in diameter x 300 mm in height tested under compression, both made from the same material mix. Tests were performed on concretes of varying strengths to obtain a range of values ​​and plot their values ​​on the graphs.The invention of torque-resistance graphs includes the geometry of the resulting curves according to the laboratory results obtained and their respective equations as a function of torque, T, for concretes with coarse aggregates from crushed limestone and rounded siliceous gravel.