Water seepage flow in concrete

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.

► The starting pressure gradient (λ) was proved exist in non-cracked concrete.
► Water would penetrate in the concrete, only when the external water pressure difference higher than the value of λ.
► External tensile stress will decrease the value of λ of the concrete.
► The modified Navier–Stokes Equation could describe the seepage law in real concrete cracks well.