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ACI 2005 Concrete Projects Competition Winners

 

1st Place:
Lightweight Concrete Modulus of Elasticity
Author:
Cadet Eileen Stiffey, United States Military Academy, West Point, New York
Advisor:
LTC Colonel Karl F. Meyer
Abstract:
This report presents the results of a study conducted to determine a new equation to more accurately predict the modulus of elasticity (MOE) for lightweight concrete.  Current equations specified in the ACI 318-Structural Building Code and the ACI 363-Guide for High Strength Concrete are not good predictors of MOE.  Results from approximately 500 MOE tests were collected and analyzed in this study.  Data was collected based on aggregate type, but was analyzed collectively to determine a new equation that more accurately fits the data.
This study considered Dr. Adrian Pauw's research from over 40 years ago that suggested the use of a cube root of the compressive strength versus the currently specified square root.  By adjusting the current equations to use a cube root of the compressive strength, and adjusting other terms in the equations, the average percent difference was driven to zero from upwards of 68%. 
This report proposes a new equation to predict MOE.  When compared to the current ACI equations, the proposed equation is a better predictor of MOE as the average percent difference between experimental and predicted values is significantly lower.
In addition to proposing a new MOE equation for lightweight concrete, this report also examines the new equation for use on normal weight concrete.  The proposed equation did not prove as accurate for use on normal weight concrete.  However, with some slight modifications, a more accurate equation for normal weight concrete was also proposed.
Further research must be conducted to more thoroughly verify the proposed equation for use on lightweight concrete incorporating all types of lightweight aggregates.  It is also necessary to further test the proposed equation against other normal weight data to determine the feasibility that only one equation is accurate for use on both lightweight and normal weight concrete.
 
2nd Place:
Concrete Flatwork Methods
Author:
Cory Hart, Southern Illinois University at Edwardsville, Edwardsville, IL
Advisor:
Luke M. Snell
 
3rd Place:
Smart Concrete
Author:
Ryan Taylor, Southern Illinois University at Edwardsville, Edwardsville, IL
Advisor:
Luke M. Snell