In-situ Concrete Compressive Strength of Residential, Public and Military Structures
L. Mazılıgüney1, F. Azılı2, İ.Ö. Yaman1
1Department of Civil Engineering, METU, Ankara, Turkey
2Project Coordination Unit, İstanbul, Turkey
In this article, using the databases of private firms working for Ministry of Defense and Ministry of Public Works and Settlement, compressive strength of 4647 core specimens taken from 693 buildings, mostly in İstanbul are analyzed. Analyses include the distribution of concrete compressive strengths of military, public and residential buildings. The correlation of concrete compressive strengths found by testing cored specimens and Schmidt hammer rebound readings is also sought. The effects of several factors on the concrete compressive strength of existing reinforced concrete structures; origin, construction date, number of stories, and the correction factors utilized in several standards, and the reliability of the Schmidt hammer rebound testing compared by destructive test methods are also discussed.
Keywords: concrete, core strength, strength variation, Schmidt hammer
1 Introduction Identifying the in-situ strength properties of the concrete and reinforcing bars used in the structural system of an existing reinforced concrete building, is one of the first problems that a civil engineer encounters. In general, the compressive strength of concrete is determined either separately or, often, simultaneously; i) through destructive test methods such as drilled core specimens, and ii) through nondestructive test methods such as the Schmidt hammer test method. Many parameters affect the strength of a concrete material because of its composite and complex nature. Its ingredients, mixing procedure, curing conditions, age, temperature and other environmental factors are only few examples of these parameters [1, 2]. These parameters cause a certain variation in the strength of in-situ concrete. On the other hand, to drill the...