Mechanical Contribution of Silica Fume and Hydrated Lime Addition in Mortars Assessed by Ultrasonic Pulse Velocity Tests

Authors: Nacim Khelil, Amar Kahil, Said Boukais

Abstract:

The aim of the present study is to investigate the changes in the mechanical properties of mortars including additions of Condensed Silica Fume (CSF), Hydrated Lime (CH) or both at various amounts (5% to 15% of cement replacement) and high water ratios (w/b) (0.4 to 0.7). The physical and mechanical changes in the mixes were evaluated using non-destructive tests (Ultrasonic Pulse Velocity (UPV)) and destructive tests (crushing tests) on 28 day-long specimens consecutively, in order to assess CSF and CH replacement rate influence on the mechanical and physical properties of the mortars, as well as CSF-CH pre-mixing on the improvement of these properties. A significant improvement of the mechanical properties of the CSF, CSF-CH mortars, has been noted. CSF-CH mixes showed the best improvements exceeding 50% improvement, showing the sizable pozzolanic reaction contribution to the specimen strength development. UPV tests have shown increased velocities for CSF and CSH mixes, however no proportional evolution with compressive strengths could be noted. The results of the study show that CSF-CH addition could represent a suitable solution to significantly increase the mechanical properties of mortars.

Keywords: Compressive strength, condensed silica fume, hydrated lime, pozzolanic reaction, UPV testing.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.3566423

References:

[1] Goldman A., Bentur A. (1993). The influence of microfillers on enhancement of concrete strength. Cement and Concrete Research Vol.23, 962-972.
[2] Isaia G.C., Gastaldini A.L.G, Moraes R. (2003). Physical and pozzolanic action of mineral additions on the mechanical strength of high-performance concrete. Cement and Concrete Composites Vol. 25, 69-76.
[3] Ramezanianpour A. (2013). Cement Replacement Materials, Properties, Durability, Sustainability. Springer Geochemistry/Mineralogy: Heidelberg, Germany.
[4] Zhang M.H., Gjerv O. E. (1991), Effect of silica fume on pore structure and chloride diffusivity of low porosity cement paste, Cement and Concrete Research. Vol.21, 1006-1014.
[5] Mazloom M, Ramezanianpour A.A, J.J. Brooks (2004), Effect of silica fume on mechanical properties of high-strength concrete, Cement & Concrete Composites Vol.26, 347–357.
[6] Dembovska L., Bajare D., Pundiene I, Vitola L., (2017). Effect of Pozzolanic Additives on the Strength Development of High Performance Concrete, Procedia Engineering Vol. 172, 202-210.
[7] Ohtsu M., Shigeishi M., Sakata Y. (1998). Nondestructive evaluation of defects in concrete by quantitative acoustic emission and ultrasonics. Ultrasonics Vol. 36, 187–195.
[8] Mohammed T.U., Rahman M.D. (2016). Effect of types of aggregate and sand-to-aggregate volume ratio on UPV in concrete. Construction and Building Materials Vol. 125, 832–841.
[9] Lafhaj Z., Goueygou M., Djerbi A., Mariusz Kaczmarek (2006). Correlation between porosity, permeability and ultrasonic parameters of mortar with variable water/ cement ratio and water content. Cement and Concrete Research Vol. 36, 625 – 633.
[10] ASTM C597-2 (2002), Standard Test Method for Pulse Velocity Through Concrete, American Society for Testing Materials, Philadelphia, ASTM C597-2.
[11] BSI 196-1 (1995), Methods of testing cement-Part 1: Determination of strength, British standard institute.
[12] Prasanna Kumar Acharya, Sanjaya Kumar Patro, Narayana C. Moharana (2016), Effect of Lime on Mechanical and Durability Properties of Blended. Cement Based Concrete Vol. 97, 71–79.
[13] C. Ince, M. A. Carter, M. A. Wilson, N. C. Collier, A. El-Turki, R. J. Ball, G. C. Allen (2011). Factors affecting the water retaining characteristics of lime and cement mortars in the freshly-mixed state. Materials and Structures Vol.44, 509–516.