A Modified Tensile Test to Study the Behaviour of Cementitious Materials

Abstract

We investigate the tensile behaviour of two fibre reinforced repair mortars by two direct tensile testing configurations. In the first configuration, a ball-joint loading fixture is developed such that an ideal hinge boundary condition is guaranteed. This technique allows to access to mechanical properties of the material such as the modulus of elasticity and the failure stress. However, it does not allow studying the post-peak behaviour of the materials. A new post-peak tension test is adopted using a metallic bar within the fibre reinforced repair mortar hollow sample. Bar constitute a crack stabiliser by providing extra stiffness. It can minimise or eliminate the strain energy release from the testing machine, so that a stable post-peak response can be obtained. The test method uses a digitally controlled closed-loop testing electromechanical machine and three control channels: crosshead displacement and two extensometers mounted on the test sample. A complete stress-strain curve is obtained by this method if adaptive control and test setup are chosen appropriately.KEY WORDS: adaptive control, fibre reinforced mortar, post-peak tensile test, tensile test Ó

Strain and Displacement Controls by Fibre Bragg Grating and Digital Image Correlation

“…The relation between the wavelength and strain, present in each FBG included in the system, is outlined in (5) cf. Equation (1). If no additional measurements from the I-MON interrogator are required (6), the programme is stopped (7).…”

Anisotropic model of damage for geomaterials and concrete

“…Onset and propagation of defects in material are assumed to be associated with positive strain field 21–25. Thus, the positive part of volumetric strain is affected by a coefficient function of the state damage.…”

“…This function depends on three positive additional parameters a, b and γ. Damage threshold K ( D ) is not built on physical arguments but allows to obtain realistic results regarding concrete and geomaterials behavior observed in some experimental tests 24–26.…”

Çi̇mento Esasli Malzemeleri̇n Çekme Dayanimlarini Bulabi̇lmek İçi̇n Yeni̇ Bi̇r Yöntem Öneri̇si̇: Üçgen Plaka Yöntemi̇

“…Genellikle doğrudan çekme, yarmada çekme, eğilmede (üç veya dört nokta yükleme) çekme testleri gibi tek eksenli doğrudan veya dolaylı çekme test düzenekleri kullanılarak belirlenmektedir. Doğrudan tek eksenli çekme testi daha doğru ve güvenilir sonuçlar sağlasa da, dolaylı testler (silindir yarma ve eğilmede çekme testleri) doğrudan tek eksenli çekme deneyinin yapma zorluğu nedeniyle, çimento bazlı malzemelerin çekme dayanımını belirlemek için yaygın olarak kullanılır [2,3]. Bilindiği üzere tek eksenli çekme deneyi düzeneğinin hazırlanması ve deneyin gerçekleştirilmesi çok zordur.…”