1. College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310014, China 2. Key Laboratory of Civil Engineering Structure & Disaster Prevention and Mitigation Technology of Zhejiang Province, Hangzhou 310014, China
Permeability is a major indicator of concrete durability, and depends primarily on the microstructure characteristics of concrete, including its porosity and pore size distribution. In this study, a variety of concrete samples were prepared to investigate their microstructure characteristics via nuclear magnetic resonance (NMR), mercury intrusion porosimetry (MIP), and X-ray computed tomography (X-CT). Furthermore, the chloride diffusion coefficient of concrete was measured to explore its correlation with the microstructure of the concrete samples. Results show that the proportion of pores with diameters<1000 nm obtained by NMR exceeds that obtained by MIP, although the difference in the total porosity determined by both methods is minimal. X-CT measurements obtained a relatively small porosity; however, this likely reflects the distribution of large pores more accurately. A strong correlation is observed between the chloride diffusion coefficient and the porosity or contributive porosity of pores with sizes<1000 nm. Moreover, microstructure parameters measured via NMR reveal a lower correlation coefficient R2 versus the chloride diffusion coefficient relative to the parameters determined via MIP, as NMR can measure non-connected as well as connected pores. In addition, when analyzing pores with sizes>50 µm, X-CT obtains the maximal contributive porosity, followed by MIP and NMR.
M G Alexander, B J Magee. Durability performance of concrete containing condensed silica fume. Cement and Concrete Research, 1999, 29(6): 917–922 https://doi.org/10.1016/S0008-8846(99)00064-2
2
L F Yang, R Cai, B Yu. Investigation of computational model for surface chloride concentration of concrete in marine atmosphere zone. Ocean Engineering, 2017, 138: 105–111 https://doi.org/10.1016/j.oceaneng.2017.04.024
L J Wu, W Li, X N Yu. Time-dependent chloride penetration in concrete in marine environments. Construction & Building Materials, 2017, 152: 406–413 https://doi.org/10.1016/j.conbuildmat.2017.07.016
Y N Yu, J S Yu, Y Ge. Water and chloride permeability research on ordinary cement mortar and concrete with compound admixture and fly ash. Construction & Building Materials, 2016, 127: 556–564 https://doi.org/10.1016/j.conbuildmat.2016.09.103
L' Bágel' , V Živica. Relationship between pore structure and permeability of hardened cement mortars: On the choice of effective pore structure parameter. Cement and Concrete Research, 1997, 27(8): 1225–1235 https://doi.org/10.1016/S0008-8846(97)00111-7
9
B B Das, B Kondraivendhan. Implication of pore size distribution parameters on compressive strength, permeability and hydraulic diffusivity of concrete. Construction & Building Materials, 2012, 28(1): 382–386 https://doi.org/10.1016/j.conbuildmat.2011.08.055
10
Z Q Zhang, B Zhang, P Y Yan. Hydration and microstructures of concrete containing raw or densified silica fume at different curing temperatures. Construction & Building Materials, 2016, 121: 483–490 https://doi.org/10.1016/j.conbuildmat.2016.06.014
11
K J Mun, S Y So, Y S Soh. The effect of slaked lime, anhydrous gypsum and limestone powder on properties of blast furnace slag cement mortar and concrete. Construction & Building Materials, 2007, 21(7): 1576–1582 https://doi.org/10.1016/j.conbuildmat.2005.09.010
P K Mehta, J M Paulo. Concrete: Microstructure, Properties, Materials. 4th ed. New York: McGraw-Hill Press, 2006
14
M H Zhang, H Li. Pore structure and chloride permeability of concrete containing nano-particles for pavement. Construction & Building Materials, 2011, 25(2): 608–616 https://doi.org/10.1016/j.conbuildmat.2010.07.032
15
P Pipilikaki, M Beazi-Katsioti. The assessment of porosity and pore size distribution of limestone Portland cement pastes. Construction & Building Materials, 2009, 23(5): 1966–1970 https://doi.org/10.1016/j.conbuildmat.2008.08.028
16
J Zhou, G Ye, K van Breugel. Cement hydration and microstructure in concrete repairs with cementitious repair materials. Construction & Building Materials, 2016, 112: 765–772 https://doi.org/10.1016/j.conbuildmat.2016.02.203
17
K Tanaka, K Kurumisawa. Development of technique for observing pores in hardened cement paste. Cement and Concrete Research, 2002, 32(9): 1435–1441 https://doi.org/10.1016/S0008-8846(02)00806-2
18
J Liu, G F Ou, Q W Qiu, X C Chen, J Hong, F Xing. Chloride transport and microstructure of concrete with/without fly ash under atmospheric chloride condition. Construction & Building Materials, 2017, 146: 493–501 https://doi.org/10.1016/j.conbuildmat.2017.04.018
F Brue, C A Davy, F Skoczylas, N Burlion, X Bourbon. Effect of temperature on the water retention properties of two high performance concretes. Cement and Concrete Research, 2012, 42(2): 384–396 https://doi.org/10.1016/j.cemconres.2011.11.005
21
J Liu, F Xing, B Q Dong, H Y Ma, D Pan. Study on water sorptivity of the surface layer of concrete. Materials and Structures, 2014, 47(11): 1941–1951 https://doi.org/10.1617/s11527-013-0162-x
22
D L Y Kong, J G Sanjayan, K Sagoe-Crentsil. Comparative performance of geopolymers made with metakaolin and fly ash after exposure to elevated temperatures. Cement and Concrete Research, 2007, 37(12): 1583–1589 https://doi.org/10.1016/j.cemconres.2007.08.021
23
H H Tian, C F Wei, H Z Wei, R T Yan, P Chen. An NMR-based analysis of soil-water characteristics. Applied Magnetic Resonance, 2014, 45(1): 49–61 https://doi.org/10.1007/s00723-013-0496-0
24
H H Tian, C F Wei, H Z Wei, J Z Zhou. Freezing and thawing characteristics of frozen soils: Bound water content and hysteresis phenomenon. Cold Regions Science and Technology, 2014, 103: 74–81 https://doi.org/10.1016/j.coldregions.2014.03.007
25
X X Wang, X D Shen, H L Wang, H X Zhao. Nuclear magnetic resonance analysis of air entraining natural pumice concrete freeze-thaw damage. Advanced Materials Research, 2014, 919–921: 1939–1943 https://doi.org/10.4028/www.scientific.net/AMR.919-921.1939
26
Y B Yao, D M Liu. Comparison of low-field NMR and mercury intrusion porosimetry in characterizing pore size distributions of coals. Fuel, 2012, 95: 152–158 https://doi.org/10.1016/j.fuel.2011.12.039
27
A du Plessis, B J Olawuyi, W P Boshoff, S G le Roux. Simple and fast porosity analysis of concrete using X-ray computed tomography. Materials and Structures, 2016, 49(1-2): 553–562 https://doi.org/10.1617/s11527-014-0519-9
28
Y J Huang, Z J Yang, W Y Ren, G H Liu, C Zhang. 3D meso-scale fracture modelling and validation of concrete based on in-situ X-ray computed tomography images using damage plasticity model. International Journal of Solids and Structures, 2015, 67–68: 340–352 https://doi.org/10.1016/j.ijsolstr.2015.05.002
29
X Qin, Q Xu. Statistical analysis of initial defects between concrete layers of dam using X-ray computed tomography. Construction & Building Materials, 2016, 125: 1101–1113 https://doi.org/10.1016/j.conbuildmat.2016.08.149
30
J Z Zhang, J Guo, D H Li, Y R Zhang, F Bian, Z F Fang. The influence of admixture on chloride time-varying diffusivity and microstructure of concrete by low-field NMR. Ocean Engineering, 2017, 142: 94–101 https://doi.org/10.1016/j.oceaneng.2017.06.065
31
J Z Zhang, F Bian, Y R Zhang, Z F Fang, C Q Fu, J Guo. Effect of pore structures on gas permeability and chloride diffusivity of concrete. Construction & Building Materials, 2018, 163: 402–413 https://doi.org/10.1016/j.conbuildmat.2017.12.111
32
N Q Feng, F Xing. High performance concrete technology. Beijing: Atomic Energy Press, 2000
33
N Q Feng, X X Feng, T Y Hao, F Xing. Effect of ultrafine mineral powder on the charge passed of the concrete. Cement and Concrete Research, 2002, 32(4): 623–627 https://doi.org/10.1016/S0008-8846(01)00731-1
R Kumar, B Bhattacharjee. Study on some factors affecting the results in the use of MIP method in concrete research. Cement and Concrete Research, 2003, 33(3): 417–424 https://doi.org/10.1016/S0008-8846(02)00974-2
36
S Diamond. Mercury porosimetry: An inappropriate method for the measurement of pore size distributions in cement-based materials. Cement and Concrete Research, 2000, 30(10): 1517–1525 https://doi.org/10.1016/S0008-8846(00)00370-7
37
B Li, J Z Mao, T Nawa, T Y Han. Mesoscopic damage model of concrete subjected to freeze-thaw cycles using mercury intrusion porosimetry and differential scanning calorimetry (MIP-DSC). Construction & Building Materials, 2017, 147: 79–90 https://doi.org/10.1016/j.conbuildmat.2017.04.136
38
Y Zhang, W Verwaal, M F C van de Ven, A A A Molenaar, S P Wu. Using high-resolution industrial CT scan to detect the distribution of rejuvenation products in porous asphalt concrete. Construction & Building Materials, 2015, 100: 1–10 https://doi.org/10.1016/j.conbuildmat.2015.09.064
39
Y J Huang, D M Yan, Z J Yang, G H Liu. 2D and 3D homogenization and fracture analysis of concrete based on in-situ X-ray computed tomography images and monte carlo simulations. Engineering Fracture Mechanics, 2016, 163: 37–54 https://doi.org/10.1016/j.engfracmech.2016.06.018
40
J Zhou, G Ye, K van Breugel. Characterization of pore structure in cement-based materials using pressurization-depressurization cycling mercury intrusion porosimetry (PDC-MIP). Cement and Concrete Research, 2010, 40(7): 1120–1128 https://doi.org/10.1016/j.cemconres.2010.02.011
41
Y Wang, Q Yuan, D H Deng, T Ye, L Fang. Measuring the pore structure of cement asphalt mortar by nuclear magnetic resonance. Construction & Building Materials, 2017, 137: 450–458 https://doi.org/10.1016/j.conbuildmat.2017.01.109
42
Y Zhou, D S Hou, J Y Jiang, P G Wang. Chloride ions transport and adsorption in the nano-pores of silicate calcium hydrate: Experimental and molecular dynamics studies. Construction & Building Materials, 2016, 126: 991–1001 https://doi.org/10.1016/j.conbuildmat.2016.09.110
43
C Sun, B Bai. Diffusion of gas molecules on multilayer graphene surfaces: Dependence on the number of graphene layers. Applied Thermal Engineering, 2017, 116: 724–730 https://doi.org/10.1016/j.applthermaleng.2017.02.002
44
W G Sun, W Sun, C H Wang. Relationship between the transport behavior of modern concrete and its microstructures: Research methods and progress. Materials Review, 2018, 32: 3010–3022 https://doi.org/10.11896/j.issn.1005-023X.2018.17.014
45
P Zhang, F H Wittmann, T J Zhao, E H Lehmann, P Vontobel. Neutron radiography, a powerful method to determine time-dependent moisture distributions in concrete. Nuclear Engineering and Design, 2011, 241(12): 4758–4766 https://doi.org/10.1016/j.nucengdes.2011.02.031
46
L Korat, V Ducman, A Legat, B Mirtiĉ. Characterisation of the pore-forming process in lightweight aggregate based on silica sludge by means of X-ray micro-tomography (micro-CT) and mercury intrusion porosimetry (MIP). Ceramics International, 2013, 39(6): 6997–7005 https://doi.org/10.1016/j.ceramint.2013.02.037
