Modelling the fresh properties of self compacting concrete utilizing statistical design of experiment techniques


Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2007

Öğrenci: LEVENT EROĞLU

Eş Danışman: İSMAİL ÖZGÜR YAMAN, MUSTAFA TOKYAY

Özet:

Self compacting concrete (SCC) is first developed in Japan in the late 1980s in order to overcome the consolidation problems associated with the presence of congested reinforcement. It is also termed as a high performance concrete, as it can flow under its own weight and completely fill the formworks. As the fresh properties of SCC are quite important, mix design of a SCC is performed by considering various workability related fresh properties. Therefore, a well designed SCC should satisfy all requirements of a hardened concrete, besides its superior workability properties. The aim of this research is to assess the effects of some basic ingredients of SCC on the fresh properties of SCC. This will be performed by applying design of experiment techniques and obtaining significant statistical models, which will give valuable information about the effects of the model parameters on the rheology and fresh state characteristics of SCC. In this research program, four different variables; use of fly ash replacement, use of high range water reducing admixture (HRWRA), use of viscosity modifying admixtures (VMA) and water-cementitious material ratio, are considered as the variables of the experimental design. Central Composite Design (CCD), a design of experiment technique, is employed throughout the experimental program and a total of 21 mixtures of concrete are cast. Slump flow, V-funnel, L-box, sieve segregation, initial and final setting time tests are performed, furthermore; to investigate the effects of these variables to the rheology of SCC, relative plastic viscosity and relative yield stress, which are the parameters of Bingham Model are measured with the help of a concrete rheometer. As a result of the experimental program, the fresh state properties of SCC are expressed by mathematical equations. Those equations are then used in order to explain the effects of fly ash replacement, HRWRA and VMA concentration, and the w/cm ratio on the fresh state properties of SCC. According to the derived models, it is stated that the water-cementitious material ratio of the concrete mixture is the most effective parameter on the flowability and passing ability of SCC beside the other parameters utilized in this research as its coefficient was the highest in the related models.