Investigation of self-compacting concrete by using non-linear fracture mechanics methods

Over a century, concrete has been used as a construction material all over the world, and its application areas increases and becomes commonplace each day. Moreover, concrete is expected to have distinct performances according to application area or the construction used. These expectations could be met only by special concretes. Today, one of the mostly used special concrete types is self-compacting concrete (SCC).SCC is a special concrete type which places itself in densely-equipped narrow and deep sections with its own weight, tightens without any vibrations, has high resistance or durability characteristics and performances, and has a very fluid- consistency. Its most important difference from conventional concrete is that powder materials and super plasticizer are used in its compound. Although SCC is denser than the conventional concrete, it includes such defects as cavity and fracture as it has.Fracture Mechanics Science searches for defects like notch, fracture and cavity available in the material increases strain mass and the damage caused by these. These damages are also valid for concrete and reinforced concrete constructions. As concrete has a heterogenic structure, it has been determined that it could not be analyzed by Linear Elastic Fracture Mechanics (LEFM) Principles. Therefore, researchers have developed nonlinear fracture mechanics models that attend to fracture process zone. It is possible to classify these models as Cohesive Crack Models (Work-of-fracture Method, Size Effect Model and Variable-Notch One-Size Specimen Method) and Effective Crack Models (Two-Parameter Model, Peak-load Method and Effective Crack Model).In this thesis, self-compacting concretes which have different compounds has been obtained by using marble powder, silica fume, fly ash. Self-compacting concrete beams produced as notched or unnotched were subjected to three-point bending tests. With the aid of sample maximum loads obtained, by using Size Effect Model Gf ve cf; by using Variable-Notch One-Size Specimen Method Gf ve cf, by using Peak-load Method Kıc ve CTODc fracture parameters were determined. When the results of the tests were evaluated, it was seen that powder material types (puzolanik or inert) are effective on SCC?s fracture parameters. In addition, it was determined that fracture parameters of SCCs that have the same compound level as different powder materials vary according the age of the concrete.Keywords: Self-Compacting Concrete, Fracture Mechanics, Two-Parameter Model, Peak-Load Method, Size Effect Method.