Shrinkage and Mechanical Properties of Self-Compacting SFRC With Calcium-Sulfoaluminate Expansive Agent

Abstract

With the premise of ensuring workability on a fresh mixture, the volume stability of hardened self-compacting steel fiber reinforced concrete (SFRC) becomes an issue due to the content of cementitious materials increased with the volume fraction of steel fiber. By using the expansive agent to reduce the shrinkage deformation of self-compacting SFRC, the strength reduction of hardened self-compacting SFRC is another issue. To solve these issues, this paper performed an experimental investigation on the workability, shrinkage, and mechanical properties of self-compacting SFRC compared to the self-compacting concrete (SCC) with or without an expansive agent. The calcium-sulfoaluminate expansive agent with content optimized to be 10% mass of binders and the steel fiber with a varying volume fraction from 0.4% to 1.2% were selected as the main parameters. The mix proportion of self-compacting SFRC with expansive agent was designed by the direct absolute volume method, of which the steel fibers are considered to be the distributed coarse aggregates. Results showed that rational high filling and passing ability of fresh self-compacting SFRC was ensured by increasing the binder to coarse-aggregate ratio and the sand ratio in the mix proportions; the autogenous and drying shrinkages of hardened self-compacting SFRC reduced by 22.2% to 3.2% and by 18.5% to 7.3% compared to those of the SCC without expansive agent at a curing age of 180 d, although the expansion effect of expansive agent decreased with the increasing volume fraction of steel fiber; the mechanical properties, including the compressive strength, the splitting tensile strength, and the modulus of elasticity increased with the incorporation of an expansive agent and steel fibers, which met the design requirements.

Effect of Curing Methods on Shrinkage Development in 3D-Printed Concrete

“…A very small increase in deformations, resulting from autogenous shrinkage in the material, can be observed between the first and seventh days of measurement. The gradients of all of the graphs are convergent, which confirms that the cause of deformation was autogenous shrinkage (to a large extent dependent on the amount of binder in the mix [38][39][40]). In the seven day period analysed, in comparison to the base concrete, the 2% and 4% additions of SRA caused 7% and 23% reductions in shrinkage, respectively.…”

Bond Behaviors of Steel Fiber in Mortar Affected by Inclination Angle and Fiber Spacing

“…With short and random distributed steel fibers, a composite material is produced to be the steel fiber reinforced concrete (SFRC) [ 1 , 2 , 3 ]. This promotes the post-cracking performances of conventional concrete [ 4 , 5 , 6 , 7 ]. From the viewpoint of meso-mechanism, the bond of steel fiber is essential to the reinforcement effect, and the steel fibers bridging cracks of concrete matrix enhance the post-cracking performance of SFRC [ 2 , 4 , 7 ].…”

Experimental study on dynamic compressive and splitting tensile properties of high strength expansive concrete

“…(Shen et al, 2020) investigated the combined use of lightweight aggregate and an EA in UHPC and found that the expansive UHPC exhibited high levels of expansion and high mechanical properties. (Li et al, 2020) found that the compressive strength, splitting tensile strength and elastic modulus of self-compacting steel-fibre-reinforced concrete increased when an EA was incorporated. (Cao et al, 2017) observed that the compressive strength of expansive self-consolidating concrete was improved at 7 days when an EA was added.…”