Performance Optimization of SBR-Modified PVA Fiber Reinforced Concrete

1. Effect of SBR Latex Dosage on Mechanical Properties

Studies have shown that the addition of styrene-butadiene rubber (SBR) latex to polyvinyl alcohol (PVA) fiber-reinforced concrete significantly enhances flexural and shear strength, while its impact on compressive strength is relatively moderate. For instance, a test found that with 9% SBR latex (by cement mass), the 28-day flexural strength increased by approximately 148% compared to unmodified concrete, with only an 8.6% reduction in compressive strength, still within acceptable limits. Other studies show that SBR contents ranging from 5% to 20% slightly reduce early-age strength but lead to significant improvements by 28 days. Overall, the optimal range of 3–10% SBR latex provides notable increases in ductility and flexural performance while keeping compressive strength manageable through proper mix design.

2. Synergistic Mechanism of SBR Latex and PVA Fibers

At both micro and nanoscale levels, SBR latex and PVA fibers demonstrate a strong synergistic effect in enhancing the fiber–matrix interfacial bond. Scanning Electron Microscopy (SEM), XRD, and FTIR analyses reveal that SBR forms a continuous polymer film within the cement matrix, filling microcracks and pores between the fibers and matrix. This densifies the interfacial transition zone (ITZ), improving bonding performance. Multiscale modeling and molecular dynamics simulations further indicate that SBR polymers increase the hydrogen bonding and van der Waals forces between PVA fibers and calcium-silicate-hydrate (C–S–H) gels, resulting in higher interfacial adhesion energy. In short, the polymer film provided by SBR acts as a flexible bridging layer, while PVA fibers bridge microcracks, together enhancing toughness and fracture energy.

3. Comparative Test Results

Compared to plain concrete (no fibers, no latex), the composite of PVA fibers and SBR latex shows significantly improved performance. Plain concrete exhibits brittleness and rapid crack propagation. With just a small dosage of PVA fibers (e.g., 1.8 kg/m³), compressive strength can increase by ~11.9%, with noticeable gains in toughness and crack resistance. Similarly, SBR-only modified concrete shows enhanced bond strength and flexural resistance, though excessive latex may reduce early compressive strength. Studies suggest that SBR compensates for the slight strength reduction often seen with fiber-only mixes. In sum, the dual modification offers superior shear and flexural strength and ductility compared to either individual modification alone.

4. Crack Resistance, Durability, and Waterproofing

The composite use of SBR latex and PVA fibers significantly enhances crack resistance and durability. PVA fibers reduce early-age shrinkage cracks and improve toughness, while SBR latex forms a polymer network that fills capillary pores, reducing shrinkage and permeability. This results in improved resistance to chloride ion penetration and corrosion. Research also indicates that fibers reduce pore size distribution and delay crack propagation, thereby extending service life. Furthermore, the hybrid mix shows strong resistance to freeze–thaw cycles, salt intrusion, and offers excellent waterproofing properties.

5. Application Potential and Limitations

SBR-PVA modified concrete offers high toughness and durability, making it suitable for critical applications such as bridge decks, tunnel linings, pavements, and industrial floors. However, there are limitations. The addition of fibers and latex increases material cost and complicates construction. Excess latex may slow early hydration, reducing early-age strength. High dosages may also affect workability, requiring adjustments with superplasticizers. Long-term performance and cost-effectiveness need further engineering validation. Nonetheless, the modified concrete's superior crack control, impermeability, and resilience make it highly promising for demanding infrastructure projects.

Lior

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