<p>The use of recycled aggregates is limited in structural concrete applications because of the lack of guidelines in building codes and skepticism regarding their impact on the overall performance. Although recycled aggregate quality, reflected in parameters such as density, water absorption, porosity, attached mortar content and replacement rates are well documented in literature, limited studies considered the influence of structural scale on shear capacity of reinforced concrete (RC) beams without stirrups. An experimental program was conducted on three proportionally scaled RC beams incorporating either natural or recycled aggregates; the beam dimensions were 150 mm × 150 mm × 760 mm, 150 mm × 225 mm × 1230 mm, and 150 mm × 300 mm × 1600 mm while keeping the shear span-to-effective depth ratio equal to 2.5. Key properties including the first cracking load, ultimate shear load, ductility, and failure modes are determined to assess the size effect of beams made using natural or recycled aggregates. Numerical simulations were carried out using the ABAQUS and Cast3M finite element platforms to corroborate the experimental findings and to assess the behavior of RC beams at larger structural scales. The results were further examined through a critical comparison with the shear strength predictions prescribed by ACI 318. These findings provide valuable insight to structural engineers and consultants to provide additional insights on the adequacy of existing design codes and recommendations for structural concrete applications containing recycled aggregates.</p>

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Scale effect on shear strength of reinforced concrete beams made with natural or recycled aggregates—Experimental and numerical study

  • Ali Jahami,
  • Maria Ghannoum,
  • Emmanuel Daher,
  • Joseph Assaad

摘要

The use of recycled aggregates is limited in structural concrete applications because of the lack of guidelines in building codes and skepticism regarding their impact on the overall performance. Although recycled aggregate quality, reflected in parameters such as density, water absorption, porosity, attached mortar content and replacement rates are well documented in literature, limited studies considered the influence of structural scale on shear capacity of reinforced concrete (RC) beams without stirrups. An experimental program was conducted on three proportionally scaled RC beams incorporating either natural or recycled aggregates; the beam dimensions were 150 mm × 150 mm × 760 mm, 150 mm × 225 mm × 1230 mm, and 150 mm × 300 mm × 1600 mm while keeping the shear span-to-effective depth ratio equal to 2.5. Key properties including the first cracking load, ultimate shear load, ductility, and failure modes are determined to assess the size effect of beams made using natural or recycled aggregates. Numerical simulations were carried out using the ABAQUS and Cast3M finite element platforms to corroborate the experimental findings and to assess the behavior of RC beams at larger structural scales. The results were further examined through a critical comparison with the shear strength predictions prescribed by ACI 318. These findings provide valuable insight to structural engineers and consultants to provide additional insights on the adequacy of existing design codes and recommendations for structural concrete applications containing recycled aggregates.