Investigation of In-Situ Compressive Strength of Fiber-Reinforced Mortar and the Effect of Fibers on the Adhesion of Mortar/Steel
الموضوعات :Ali Saberi Varzaneh 1 , Mahmood Naderi 2
1 - Ph.D. Candidate, Department of Civil Engineering, Imam Khomeini International University, Qazvin, Iran
2 - Professor, Department of Civil Engineering, Imam Khomeini International University, Qazvin, Iran
الکلمات المفتاحية: Fibre, Finite Element Method, Bond, Steel, Mortar,
ملخص المقالة :
The proper connection between mortar and steel is one of the crucial issues in civil engineering. This paper has investigated the effect of polypropylene fibbers on the bond between cement mortar and steel, using “Twist-off” and “pull-off” tests. Moreover, in order to assess the in-situ mechanical properties of fibre-reinforced mortars, the correlation of records obtained from semi-destructive methods of “Twist-off” and “pull-off” with those of laboratory tests was determined, and calibration curves were provided, using the regression analyses. The mentioned tests were modelled with the ABAQUS software to evaluate the distribution of stresses and cracks developed during the semi-destructive tests. The results show that the addition of polypropylene fibbers reduces the shrinkage of mortars by about 13% and this has a direct effect on the bond between the mortar and steel. So that the shear and tensile bond of fibre-reinforced mortars at 90 days is 75% and 94% higher than conventional mortars, respectively. The reason for this is the effect of fibbers on the process of hydration of mortars and also to prevent excessive opening of cracks, which is shown by SEM. According to the results, instead of using an expensive and imported pull-off device, a cheap and internal twist-off device can be used to measure adhesion. Also, to evaluate the compressive strength of mortars, twist-off and pull-off tests can be used by placing the readings obtained in the equations y = 0.156x + 0.329 and y = 0.055x-0.001 instead of x, respectively, to evaluate the compressive strength of mortars.
[1] Neville, A. M., Properties of Concrete, Fifth ed., Harlow, United Kingdom, 2012, pp. 141-142, ISBN 9780273755807.
[2] Naderi, M., Adhesion of Different Concrete Repair Systems Exposed to Different Environments, J. Adhesion., Vol. 84, 2008, pp. 78-104, https://doi.org/10.1080/00218460801888433.
[3] Lifang, L., Peiming, W., and Xiaojie, Y. Effect of Polypropylene Fiber on Dryshrinkage Ratio of Cement Mortar, J. Build. Mater., Vol. 8, 2005, pp. 373-377.
[4] Mohamed, R. A. S., Effect of Polypropylene Fibers On the Mechanical Properties of Normal Concrete, J. Eng. Sci., Vol. 34, 2006, pp. 1049-1059.
[5] Dharan, D. S., Lal, A., Study the Effect of Polypropylene Fiber in Concrete, Int. Res. J. Eng. Tech., Vol. 3, 2016, pp. 616-619.
[6] Vikrant, S., Kavita, V., Kene, S., and Deshpande, N. V., Investigation on Compressive and Tensile Behavior of Fibrillated Polypropylene Fibers Reinforced Concrete, Int. J. Eng. Res. Appl., Vol. 2, 2012, pp. 1111-1115.
[7] Tilly, G. P., Jacobs, J., Concrete Repairs: Observations On Performance in Service and Current Practice, Watford, UK, 2007.
[8] Beushausen, H., Alexander, M., Localised Strain and Stress in Bonded Concrete Overlays Subjected to Differential Shrinkage, Mater. Struct., Vol. 40, 2007, pp. 189–199.
[9] Wu, D., Gao, W., Feng, J., and Luo, K. Structural Behaviour Evolution of Composite Steel-Concrete Curved Structure with Uncertain Creep and Shrinkage Effects, Compos. B. Eng., 2016, pp261-272.
[10] Martinola, G., Sadouki, H., and Wittmann, F., Numerical Model for Minimizing the Risk of Damage in A Repair System, J. Mater. Civ. Eng., Vol. 13, 2001, pp. 121–129.
[11] Neville, A. M., Brooks, J. J., Tecnologia Do Concreto, Porto Alegre: Bookman, 2013.
[12] Araujo, D. A., Danin, A. R., Melo, M. B., and Rodrigues, P. F., Influence of Steel Fibers On the Reinforcement Bond of Straight Steel, Revista IBRACON de Estruturas e Materriais - RIEM, Vol. 6, No. 2, 2013.
[13] Naderi, M., Friction-Transfer Test for the Assessment of In-Situ Strength & Adhesion of Cementitious Materials, Constr. Build. Mater., Vol. 19, 2005, pp. 454-459.
[14] Naderi, M., Ghodousian, O., Adhesion of Self-Compacting Overlays Applied to Different Concrete Substrates and Its Prediction by Fuzzy Logic, J. Adhesion, Vol. 88, 2012, pp. 848-865.
[15] Naderi, M., Effects of Cyclic Loading, Freeze-Thaw and Temperature Changes on Shear Bond Strengths of Different Concrete Repair Systems, J. Adhesion, Vol. 84, 2008, pp. 743-763.
[16] Naderi, M., New Twist-Off Method for the Evaluation of In-Situ Strength of Concrete, J. Test. Eval., Vol. 35, 2007, pp. 602-608.
[17] ASTM C1583, Standard Test Method for Tensile Strength of Concrete Surfaces and The Bond Strength or Tensile Strength of Concrete Repair and Overlay Materials by Direct Tension (Pull-Off Method), West Conshohocken PA, American Society for Testing and Materials, 2004.
[18] ASTM C900 – 01, Standard Test Method for Pullout Strength of Hardened Concrete. West Conshohocken PA, American Society for Testing and Materials, 2001.
[19] Naderi, M., Shibani, R., New Method for Nondestructive Evaluation of Concrete Strength, Aust. J. Basic Appl. Sci., Vol. 7, 2013, pp. 438-447.
[20] Naderi, M., Evaluating in Situ Shear Strength of Bituminous Pavments, In Proceedings of the Institution of Civil Engineering, 2006, pp. 61-65.
[21] Naderi, M., An Alternative Method for in Situ Determination of Rock Strength, Can. Geotech. J., Vol. 48, 2001, pp. 1901-1905.
[22] Naderi, M., New Method for Nondestructive Evaluation of Concrete Strength, Aust. J. Basic Appl. Sci., Vol. 7, No. 2, 2013, pp. 438-447.
[23] ASTM C127, Standard Test Method for Density, Relative Density (Specific Gravity), And Absorption of Fine Aggregate, West Conshohocken PA, American Society for Testing and Materials, 2012.
[24] ASTM C157, Test Method for Length Change of Hardened Hydraulic Cement Mortar and Concrete, West Conshohocken PA, American Society for Testing and Materials, 2008.
[25] ASTM C490, Standard Practice for Use of Apparatus for The Determination of Length Change of Hardened Cement Paste, Mortar, And Concrete, West Conshohocken PA, American Society for Testing and Materials, 2011.
[26] ASTM C109, Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in or [50-mm] Cube Specimens), American Society for Testing and Materials, 2013.
[27] Alnkaa, A., Yaprak, H., MEMİŞ, S., and Kaplan, G., Effect of Different Cure Conditions on the Shrinkage of Geopolymer Mortar, Int. J. Eng. Res. Develop., Vol. 14, 2018, pp. 51-55.
