# Flexural Fracture Behavior and Mechanical Properties of SAP-PVA Fiber-Reinforced Concrete

## TL;DR

This study examines how adding super-absorbent polymers and PVA fibers affects the strength and crack resistance of concrete.

## Contribution

The paper introduces a systematic analysis of SAP-PVA fiber-reinforced concrete's fracture behavior and mechanical properties.

## Key findings

- PVA fibers significantly increase residual flexural tensile strength by 4.5–42%.
- SAP particles slightly reduce concrete strength by about 6%.
- Higher initial crack-height ratios increase crack opening displacement but do not affect fracture toughness.

## Abstract

To investigate the fracture behavior of super-absorbent polymer (SAP) internally cured polyvinyl alcohol (PVA) fiber-reinforced concrete (SAP-PVAC), three-point bending tests were carried out. This study systematically examined the effects of (1) PVA fiber content and (2) initial crack-depth-to-beam-height ratios (a0/D) on the failure modes, fracture toughness (KIC), and residual flexural tensile strength (fR,1) of SAP-PVAC beams. The test results demonstrate that SAP particles have a weakening effect on concrete strength (reduce about 6%). Still, the addition of PVA fibers can effectively improve the crack-resistance performance of SAP-PVAC and significantly increase the residual flexural tensile strength by 4.5–42%. The softening performance of the concrete is affected by the initial crack-height ratio. An increase in a0/D leads to an obvious increase in the crack opening displacement but has little impact on the fracture toughness, while the fracture energy shows a downward trend. SEM microscopic analysis reveals that the synergistic effect of SAP and PVA fibers exhibits a positive promoting effect on the toughening and crack resistance of SAP-PVAC specimens. These results establish a theoretical framework for SAP-PVAC fracture assessment and provide actionable guidelines for its shrinkage-crack mitigation structure engineering applications.