Jiangsu Key Laboratory on Civil Engineering Materials

Nanjing, China

Jiangsu Key Laboratory on Civil Engineering Materials

Nanjing, China

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Huang B.,Nanjing Southeast University | Huang B.,Jiangsu Key Laboratory on Civil Engineering Materials | Qian C.,Nanjing Southeast University
Construction and Building Materials | Year: 2011

This paper deal-with concrete behavior under chemical and mechanical degradation. Experimental investigations were described where the effects of the calcium leaching process of concrete on its mechanical properties were highlight. The compressive strength and the stress-strain relationship of leached concrete with different leaching degradations were investigated experimental. As leaching grew, a loss of stiffness and strength were observed and an obvious decrease of peak strain was noted. The leaching degradation was measured by nondestructive or local-damage methods such as phenolphthalein solution, ultrasonic wave and pH value in pores, which showed the better linear relationship of the compressive strength of the leached concrete. The uniaxial compression failure mode of leached concrete was a shear mode under the experimental condition. Then the analytical regression for the stress-strain relationship of leached concrete were given, which could be directly used in theoretical and numerical analysis as well as practical engineering design of leached structures. To quantify the leaching evolution, the leached concrete was analyzed by MIP and TGA. The results showed that the dissolution happened both in portlandite and C-S-H gel during the leaching duration and at the early stages of leaching CH dissolution is the main cause of mass loss. The number of harmful pores with size above 200 nm increased which was associated with the leaching of portlandite, was considered to significantly affect the durability of leached concrete. © 2010 Elsevier Ltd. All rights reserved.


Qian C.,Nanjing Southeast University | Qian C.,Jiangsu Key Laboratory on Civil Engineering Materials | Gao G.,Nanjing Southeast University | Gao G.,Jiangsu Key Laboratory on Civil Engineering Materials
Construction and Building Materials | Year: 2012

In order to evaluate the effect of suspension of phase change material (SPCM) on interior temperature rise and temperature gradient in concrete, a semi-adiabatic device was designed to measure the temperature changing in concrete specimens. Both SPCM and water were used as cooling fluid to evaluate its cooling effect. The temperature difference (TD) and temperature gradient (TG) at different locations were tested and analyzed. The consumption of cooling fluid and corresponding temperature difference between concrete and cooling fluid was also calculated. The results showed that when water was replaced by SPCM as cooling fluid, the temperature reducing extent can be increased 27-28%, and the temperature difference can be decrease 7.6-8.4%. SPCM has a great significance on the cooling of interior temperature rise caused by cement hydration. © 2011 Elsevier Ltd. All rights reserved.


Nie Y.,Nanjing Southeast University | Qian C.,Nanjing Southeast University | Qian C.,Jiangsu Key Laboratory on Civil Engineering Materials
Journal of Testing and Evaluation | Year: 2012

The disturbed state concept (DSC) provides a general way for constitutive modeling of deforming materials. This paper presents the experimental and analytical results for the development of methodology for predicting the stress-strain response of concrete attacked by sulfate. Ultrasonic pulse velocity (UPV) is used to identify a function for disturbance (D). The elastoplastic model and simplified hydrostatic stress model are adopted for the definition of the relative intact state (RI) and fully adjusted state (FA), respectively. Thus, the stress-strain curve can be predicted using the DSC model based on nondestructive method. The comparison results show that the proposed constitutive model is satisfied with application in similar condition. Copyright © 2012 by ASTM International.


Qian C.,Nanjing Southeast University | Qian C.,Jiangsu Key Laboratory on Civil Engineering Materials | Huang B.,Nanjing Southeast University | Huang B.,Jiangsu Key Laboratory on Civil Engineering Materials | He Z.,Shaoxing University
Key Engineering Materials | Year: 2015

This paper deal with concrete behavior under chemical and mechanical degradation. Experimental investigations were described where the effects of the calcium leaching process of concrete on its mechanical properties were highlight. The compressive strength and the stress-strain relationship of leached concrete with different leaching degradations were investigated experimental. As leaching grew, a loss of stiffness and of strength were observed and an obviously decrease of peak strain was noted. Then the micromechanical damage constitutive model of the leached concrete was proposed. The proposed model was applied to simulate typical laboratory tests. And it was shown that the proposed model was able to describe the main features of mechanical behavior of concrete in sound and leaching degraded states. And the parameters in the proposed model can be got by testing the pH value of pore solution, which it is easier to measure from the existing concrete. © (2015) Trans Tech Publications, Switzerland.


Qian C.,Nanjing Southeast University | Qian C.,Jiangsu Key Laboratory on Civil Engineering Materials | Huang B.,Nanjing Southeast University | Huang B.,Jiangsu Key Laboratory on Civil Engineering Materials | And 4 more authors.
Construction and Building Materials | Year: 2012

The waterproofing durability of concrete is an attentive focus in underground engineering and hydraulic structures. Water seepage law in non-cracked concrete, concrete under tension, straight smooth surface cracks and real cracks in concrete were mainly studied in this paper. And the waterproofing capacity of concrete was analyzed based on the research results. The experimental results indicated that Non-Darcy model was followed in non-cracked concrete weather it bears tensile stress or not. There existed a balance depth in the process of the water permeation. Tensile stress could change the starting pressure gradient (λ) of concrete. With the increase of tension, the λ decreased. When the concrete was cracked, water infiltrated into the concrete through cracks, the linear Darcy Law was followed in this case. To characterize the water seepage law in the real concrete cracks, two parameters τ (tortuosity of cracks) and m (toughness of cracks) were introduced into the Navier-Stokes Equation. And the result indicated the modified Navier-Stokes Equation could describe the seepage law in real concrete cracks well and the value of m in the real concrete cracks was less than 1.15 according to the experimental results. © 2012 Elsevier Ltd. All rights reserved.

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