Reshoring and Early-Age Building Behavior-Early-Age Concrete Properties and their Effect on Shoring-Reshoring (PDF)

Early-Age Concrete Properties and their Effect on Shoring-Reshoring (PDF)

Pdf Summary

The document discusses the early age properties of concrete, focusing on their implications for shoring and reshoring operations. It highlights the importance of early age compressive strength, the modulus of elasticity, and shrinkage properties in ensuring the stability and durability of concrete structures. Proper engineering analysis must be conducted before the removal of temporary supports (shores or reshores) to prevent structural failures such as deflections or severe cracking.<br /><br />Premature removal of shores can lead to significant structural issues, emphasizing the need for accurate prediction of concrete properties. The document identifies several factors that influence these properties, including curing methods and pozzolanic material content. Traditional methods to estimate concrete properties may not always be reliable, necessitating specific testing for concrete mixtures.<br /><br />The modulus of elasticity is particularly crucial, and incorrect estimation can result in permanent deflections or catastrophic failure. This study examined various methods to measure the elastic modulus and found that different curing methods significantly impact the modulus over time. The document notes that traditional prediction equations, like those from ACI 363, sometimes inaccurately estimate the elastic modulus, especially for high pozzolan content mixes.<br /><br />The maturity method is discussed as an effective tool for estimating compressive strength at early ages, although discrepancies can occur when comparing cylinder testing with real-time slab performance. The maturity method relies on the correlation between concrete hydration rates and temperature history to determine strength.<br /><br />The document concludes by emphasizing accurate measurement of properties like the modulus of elasticity and controlled shrinkage to avoid structural failures like punching shear. It highlights the necessity of tailored approaches such as on-site measurements and the use of the maturity method to ensure structural integrity when removing supports.

Keywords

early age properties

concrete

shoring

reshoring

compressive strength

modulus of elasticity

shrinkage

structural stability

maturity method

pozzolanic materials