Capillary Flow Characteristics of an Autogenic and Autonomic Healing Agent for Self-Healing Concrete

Abstract

Gardn er, D ec 15, 2016 C apillary flow characteris tics of an au togen ic an d au ton om ic healin g agen t for s elf-healin g 3 4 agen ts . B oth techn iqu es prim arily rely on the tran s port of flu id ( w ater or healin g agen t) in a dis crete 3 5 crack to m icrocracked z on es of dam age.3 6 3 7The s election of a healin g agen t is driven m ain ly by cos t an d availability, althou gh it is im portan t that 3 8 its phys ical properties s u ch as vis cos ity, s u rface ten s ion , bon din g characteris tics an d its com patibility 3 9 w ith the cem en titiou s m atrix over tim e, are con s idered du rin g the s election proces s . In gen eral, 4 0 healin g agen ts w ith low vis cos ity an d s ign ifican t capillary poten tial are u s u ally preferred. 4 1 4 2 C om pared to au ton om ic healin g agen ts , au togen ic healin g agen ts s u ch as thos e bas ed on 4 3 s u pplem en tary cem en titiou s m aterials ( Sahm aran et al. 2013) , m in eral adm ixtu res ( hn an d K is hi 4 4 2010) an d geom aterials ( K is hi 2013) afford im proved com patibility w ith the hos t m atrix du e to the 4 5 n atu re of the chem ical com pos ition of the healin g produ cts . M oreover, throu gh the u s e of a 4 6 poz z olan ic m aterial, bon d s tren gths com parable w ith thos e of u n dam aged cem en titiou s m aterials 4 7 m ay be achieved. V aryin g m ethods have been propos ed to em bed au togen ic healin g agen ts in to 4 8 cem en titiou s m aterials . Thes e ran ge from com bin in g them in their n atu ral form w ith other m ix 4 9 1 9 5 order of w eeks / m on ths , w hich are greatly in exces s of the du ration of the tes ts reported herein . 1 9 6 1 9 7The s es s ile drops w ere obs erved for on e hou r follow in g the in itial m eas u rem en t. N egligible chan ge in 1 9 8 the con tact an gle w as obs erved for P C 20 after this on e hou r period, w hils t the w ater an d GGB S( S) 1 9 9 s es s ile drops evaporated after 15 m in u tes of expos u re to the laboratory en viron m en t. 2 0 0 2 0 1 T im e-V is cos ity relation s hip 2 0 2The developm en t of a bes poke vis com eter, as s how n in Figu re 5, des ign ed to exam in e the chan ge in 2 0 3 vis cos ity of the healin g agen t w hen in con tact w ith a cem en titiou s m atrix has previou s ly been 2 0 4 4 3 7

A specialised finite element for simulating self-healing quasi-brittle materials

“…The transport of the healing agent through the crack was calculated using the modified Lucas-Washburn equation of Gardner et al [72][73][74] (see also Selvarajoo et al [75]), that reads:…”

Research Progress on Numerical Models for Self‐Healing Cementitious Materials

“…The specific issue of simulating the flow of healing agents in natural cracks has been considered in detail by Gardner et al Their investigations have explored the flow properties of a range of healing agents in artificial and natural cracks over a range of crack openings. The model developed by the authors is based on modified Lucas–Washburn equation and allows for stick‐slip, meniscus and wall friction effects.…”

Numerical Simulation of the Response of Concrete Structural Elements Containing a Self-Healing Agent

“…The proposed finite element formulation accounts for the self-healing by adding a term to account for the healed material. The approach accounts for the healing agent circulation in the material continuum by a modified Lucas–Washburn model [ 54 , 55 , 56 , 57 ]. The capillary pressure is evaluated by the Young–Laplace equation, defining the dynamic contact angle according to [ 58 ].…”