Experimental and numerical analysis of effect of curing time on mechanical properties of thin spray-on liners


Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Mining Engineering, Turkey

Approval Date: 2014

Student: DOĞUKAN GÜNER

Supervisor: HASAN ÖZTÜRK

Abstract:

This research study investigates the effect of curing time on elastic material properties (Young’s modulus, Poisson’s ratio) and tensile, compressive strength of thin spray on liners (TSL). TSLs are fast curing, comparatively thin (3-5mm) and widely used rock support system in mining and civil engineering excavations. They have advantages of low volume, rapid application and low operating cost. The major ingredients of current TSLs are divided as polyurethane/ polyurea or Portland cement based latex products. One of the important parameters that control the support mechanisms of TSLs’ is the tensile and compression strength behaviour of them. There are many different testing set-ups and tests have been conducted considering the physical properties of them. In this study, two different TSL products supplied by two TSL manufacturers are tested comparatively. During laboratory studies, samples that are prepared in the laboratory conditions with different curing times (1, 7, 14, 21 and 28 days) are tested based on ASTM standards. In addition, distinct element numerical modelling of the test results are carried out using PFC2D in an attempt to simulate the tests numerically, since the constitutive behaviour of the TSLs are yet to be determined. It is concluded that the increase in the curing time improves the tensile and compressive strength of the TSLs (2 to 9 times). Moreover, as an extra conclusion from the testing procedure, the difference between the common malpractices of measuring the sample displacement from the grips of the loading machine versus from the sample’s gauge length is observed to be significant (1 to 13 times). In addition, PFC numerical models with the tests enabled the derivation of two important parameters of TSLs; such as, bond strength and bond elastic modulus values of TSLs which can be used for numerical modelling of TSLs` support mechanisms in PFC by the researchers.