<p>This study investigates the effectiveness of shaft grouting in enhancing the axial bearing capacity of bored piles under varying grout injection rates in sandy soil conditions at the Thao Truong Tan Uyen site. Bored piles with dimensions of 400&#xa0;mm in diameter and 3.3&#xa0;m in length were constructed, and grout was injected at three different rates (<i>IR</i> = 20, 35, and 50&#xa0;L per square meter). Static load tests were conducted according to ASTM D1143 to evaluate the effect of grouting on pile performance. The results reveal that grouting significantly enhances the load-bearing capacity of piles and reduces settlement across all loading conditions. A two-phase response to increasing <i>IR</i> was observed. In the first phase (<i>IR</i> = 0 to 35&#xa0;l/m²), load capacity increased sharply, with a 90% improvement compared to non-grouted piles. In the second phase (<i>IR</i> = 35 to 50&#xa0;l/m²), the rate of improvement diminished, with only a marginal 5% increase in capacity. This suggests that an <i>IR</i> of 35&#xa0;l/m² is optimal for maximizing pile performance while maintaining cost efficiency. Visual inspections following the excavation of surrounding soil showed that grouted piles had significantly more soil adhesion, enhancing shaft friction and soil-pile interaction. This finding aligns with previous studies, further validating the effectiveness of grouting in improving pile performance, particularly in sandy soil.</p>