Differential characteristics of concrete in centrifugally spun and vibrospun building structures

Structural mechanics

This paper presents research into the variatropic structural characteristics of experimental circular-section concrete specimens as well as the related differential (varying depthwise) structural characteristics of concrete subjected to centrifugal spinning and vibrospinning. The researchers sought to assess how the production technology (centrifugal spinning or vibrospinning) could affect the differential (varying depthwise) characteristics of concrete: density; cube and prism axial compressive strength; ultimate axial compressive strain; axial tensile strength and tensile bending strength; ultimate axial tensile strain; the elastic modulus; the strain-stress curve for compression and tensioning. The researchers made and tested six basic centrifugally spun and vibrospun circular-section specimens that had an outer diameter D of 450 mm, an inner diameter d of 150 mm, and a total height H = 1200 mm. The manufacturing technology differed in the experiments, as the team used both centrifugal spinning and vibrospinning. Experimental research into the differential characteristics of centrifugally spun and vibrospun concrete aged 7, 28, and 180 days as exposed by compression and tension revealed that the outer concrete layer had the best characteristics, while the inner layer was the worst. The experiments thus back the three-layer model of the variatropic structure in centrifugally spun and vibrospun concrete. The following differentiation was observed in variatropic concrete: the outer layer had the best strength and elastic modulus, while being less deformable; the inner layer had the least strength and elastic modulus, while being more deformable; the mid-layer concrete was average in terms of everything. Stress-strain curves of centrifugally spun and vibrospun concrete did differ by layer, too, further proving that such concrete had a variatropic structure. The curves showed the greatest strength for the outer layer and the lowest for the inner layer, while the mid layer had average values.