Moisture Impact on Static and Dynamic Modulus of Elasticity in Structural Normal-Weight Concretes

Area of Science:

• Civil Engineering
• Materials Science
• Structural Health Monitoring

Background:

• Static modulus of elasticity (E) is crucial for structural analysis.
• Ultrasonic pulse velocity (UPV) method is commonly used to estimate E.
• Existing methods often neglect concrete moisture's influence on E.

Purpose of the Study:

• To investigate the impact of moisture content on the static secant modulus of elasticity (E) in normal-weight structural concrete.
• To compare the moisture sensitivity of E measurements obtained through static and dynamic (UPV) methods.
• To validate existing formulas for estimating E under varying moisture conditions.

Main Methods:

• Dynamic modulus of elasticity (E) was measured using the ultrasonic pulse velocity method.
• Static secant modulus of elasticity (E) was determined through direct tests on drilled cores.
• Two normal-weight concretes with compressive strengths of 51.6 MPa and 71.4 MPa were tested under different moisture conditions.
• Results were compared with previously obtained data for lightweight aggregate concretes.

Main Results:

• Moisture content significantly affected the dynamic modulus of elasticity (E) primarily in the weaker concrete (51.6 MPa).
• The impact of moisture on the static modulus of elasticity (E) was less pronounced than expected and often insignificant, contrary to some literature.
• Discrepancies in moisture impact between static and dynamic moduli were attributed to concrete's dense structure and measurement sensitivity.
• Established formulas for estimating E were verified, showing varying degrees of accuracy under different moisture conditions.

Conclusions:

• Concrete moisture's effect on static modulus (E) is complex and depends on concrete strength and measurement method.
• The UPV method may be more sensitive to moisture variations than direct static tests for certain concrete types.
• The study highlights the need for considering moisture content in structural concrete assessments, particularly for weaker mixes.
• Findings provide valuable data for refining models used in structural health monitoring and concrete property estimation.