Effect of Chelating Additive on Pore Structure and Mechanical Property of Mortar under Different Curing Conditions

Abstract:

Effect of chelating additive on microstructure, hydration products and mechanical property of mortar under different curing conditions was investigated. The microstructure was tested by nuclear magnetic resonance and scanning electron microscope. And the chemical composition of hydration products was analyzed by X-ray diffraction. The compressive strength was measured under different curing conditions at different curing age, including standard curing, water immersion, seawater immersion and salt mist curing. After curing for 28 days in water, compared to control mortar, the reduction ratio of harmful pores whose size larger than 0.1μm in mortar with chelating additive (CA mortar) was 14.6%, followed by 8.9%, 9.2% and 2.9% which was under standard curing, seawater immersion and salt mist curing, respectively. From the scanning electron microscope image, there were more needle-like and bar-like crystals in CA mortar making it more compact, which was mainly calcium silicate hydrate through component analysis. Besides, the raising percentage of compressive strength of CA mortar under water immersion is 28.6% compared to control mortar at the age of 28 days, followed by 26.8%, 21.8% and 16.3% which was under standard curing, seawater immersion and salt mist curing, respectively. The results indicate that chelating additive can enhance compactness and compressive strength of cement-based materials especially under water immersion by promoting the formation of calcium silicate hydrate.

• Periodical: Materials Science Forum (Volume 944)
• Pages: 1172-1178
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.944.1172
• Online since: January 2019
• Authors: Peng He, Rui Yang Wang, Ya Gang Zha, Jian Ying Yu*
• Keywords: Chelating Additive, Curing Condition, Mechanical Properties, Mortar, Pore Structure

References

[1] Zhang P, Dai Y Q, Ding X Y, et al. Self-healing behaviour of multiple microcracks of strain hardening cementitious composites (SHCC)[J]. Cement & Concrete Research. 169 (2018) 705-715.

DOI: 10.1016/j.conbuildmat.2018.03.032

[2] Wang K, Jansen D C, Shah S P, et al. Permeability study of cracked concrete[J]. Cement & Concrete Research, 27(3) (1997) 381-393.

DOI: 10.1016/s0008-8846(97)00031-8

[3] Zhang P, Wittmann F H, Zhao T, et al. Neutron imaging of water penetration into cracked steel reinforced concrete[J]. Physica B Physics of Condensed Matter, 405(7) (2010) 1866-1871.

DOI: 10.1016/j.physb.2010.01.065

[4] Li W, Dong B, Yang Z, et al. Recent Advances in Intrinsic Self-Healing Cementitious Materials [J]. Advanced Materials, 30(17) (2018) 1705679.

DOI: 10.1002/adma.201705679

[5] Ma H, Qian S, Zhang Z. Effect of self-healing on water permeability and mechanical property of Medium-Early-Strength Engineered Cementitious Composites[J]. Construction & Building Materials, 68(3) (2014) 92-101.

DOI: 10.1016/j.conbuildmat.2014.05.065

[6] Shi H S, Huang X Y, Study on heat of hydration of Portland cement and its current progression[J]. Cement, (12) (2009) 4-10.

[7] Scrivener K L, Juilland P, Monteiro P J M. Advances in understanding hydration of Portland cement [J]. Cement & Concrete Research, 78 (2015) 38-56.

DOI: 10.1016/j.cemconres.2015.05.025

[8] Zhang M, Xing F, Shi K Y, et al. Study on Organic Microcapsule Based Self-Healing Cementitious Composite[J]. Advanced Materials Research, 239-242 (2011) 764-767.

DOI: 10.4028/www.scientific.net/amr.239-242.764

[9] Roig-Flores M, Moscato S, Serna P, et al. Self-healing capability of concrete with crystalline admixtures in different environments[J]. Construction & Building Materials, 86(6) (2015) 1-11.

DOI: 10.1016/j.conbuildmat.2015.03.091

[10] Roig-Flores M, Pirritano F, Serna P, et al. Effect of crystalline admixtures on the self-healing capability of early-age concrete studied by means of permeability and crack closing tests[J]. Construction & Building Materials, 114 (2016) 447-457.

DOI: 10.1016/j.conbuildmat.2016.03.196

[11] Liu X, Li J, et al. Experimental study for the effect of capillary crystalline admixtures on the mechanical properties of concrete [C]// Industrial construction 2016 supplement II. 46 (2016) 599-602.

[12] Zha Y, Yu J, Wang R, et al. Improvement on Freeze-Thaw Resistance of Cement-Based Materials by Functional Admixtures[C]// Chinese Materials Conference. Springer, Singapore, 2017, pp.617-626.

DOI: 10.1007/978-981-13-0158-2_63

[13] Wu Z W. Discussion on the development direction of concrete science and technology in the near future [J]. China Ceramic Society, (3) (1979) 82-90.