oa Civil Engineer in South Africa - Elasticity of plain concrete and mortar specimens in flexure and compression
The elasticity of concrete and mortar is assessed by means of cylinder and prism compression teats, and beam bending tests. A comparison between the elastic moduli measured in the different tests shows that higher moduli are measured in the smaller beams and prisms than in the larger cylinders. A statistical 'weakest link' theory may qualitatively assist in explaining the results, and it is proposed that specimen size effects are important in stiffness measurements. Beams show better stress-strain linearity under load than do cylinders. A relationship is derived for the flexural tensile stresses and strains in a plain beam, and shown to be similar to previous relationships for compression. It appears that transverse strain gradients exercise a greater crack-modifying effect on concrete in tension than in compression.
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