Drying shrinkage behavior of base restrained high strength concrete walls

Abstract EN

In this study, reduced scale wall models (which are believed to resemble as much as possible field conditions) were used to study the shrinkage behavior of high strength concrete base restrained walls.

Two sets of base restrained HSC walls were cast; Winter set which consists eight walls in different length/height ratios with and without reinforcement and Summer set which consists two reinforced walls in two length/height ratios.

These walls were base restrained by steel base frame to hinder the shrinkage movement in the concrete base.

The mechanical properties of high strength concrete investigated were; compressive strength between ( 50 – 90 ) MPa, splitting tensile strength between ( 5.5 – 7) MPa, flexural tensile strength ( 6 – 8.6) MPa, static modulus of elasticity ( 32 – 44 ) GPa.

Based on the observations of this work, it was found that the cracks did not develop in the reinforced and unreinforced high strength concrete walls with L / H (1, 2, 4 and 6) during 90 days period of drying conditions.

Also, the shrinkage values increase toward the edges.

Based on the results of this work, the increasing in maximum shrinkage values in Summer were (73٪, 61٪) of the maximum shrinkage values in Winter for length/height ratios (4,6) respectively.

The use of horizontal reinforcement (0.2٪) led to reduce in the maximum shrinkage values with increasing of length/height ratio where this reduction ratios were (12 ٪, 14٪, 20٪, 28٪) of the maximum shrinkage values in the unreinforced walls for length / height ratios (1, 2, 4, 6) respectively.

The experimental observation in end restrained beams showed that the Summer free shrinkage (at date of cracking) was higher than of Winter free shrinkage by about (27٪), the Summer tensile strain capacity (at date of cracking) was higher than of Winter by about (30٪), the Summer elastic tensile strain capacity (at date of cracking) was higher than the Winter elastic tensile strain capacity by about (44٪).