Impact of Service Penetrations on Concrete Strength: A Study of Longitudinal Circular Holes

The integration of longitudinal circular holes (LCH) in structural concrete elements has become a common practice to facilitate embedded services such as electrical conduits, plumbing, and HVAC systems. However, these voids can significantly alter the stress distribution and reduce the compressive strength. This study presents an investigation of the compressive strength of concrete with longitudinal circular holes (LCHC). A total of 72 concrete cubes (150 mm × 150 mm × 150 mm) were cast using two mix ratios (1:2:4 and 1:1.5:3) and a constant water–cement ratio of 0.5. Specimens were produced with centrally placed longitudinal holes of 25, 50, and 75 mm in diameter. Compressive strength tests were conducted after 7, 14, and 28 days of curing for each specimen. The results demonstrated a consistent reduction in compressive strength ranging from 4.61% to 27.92% with increasing hole diameter. This study highlights the structural implications of voided concrete and underscores the importance evaluating the hole dimensions and concrete quality in the design. Although LCHs are functionally necessary in modern construction, their unregulated inclusion may significantly compromise structural integrity. It is recommended that service conduits embedded longitudinally in load-bearing concrete elements be limited to 8–10% of the cross-sectional area.