Durability of UHPFRC functionalised with nanoadditives due to synergies in the action of sulphate and chloride in cracked and uncracked states

Abstract

This paper studies the durability of Ultra High Performance Fibre Reinforced Concrete (UHPFRC) with high Blast Furnace Slag content (BFS) and nanoadditives such as crystalline admixture (CA), alumina nanofibres (ANF) and cellulose nanocrystals (CNC), exposed to different aggressive environmental conditions: 1) three aggressive media: a) deionized water (dw), b) sulphate rich solution (ss) and c) simulated geothermal water (sgw) containing sulphate and chloride; 2) two water interaction conditions: a) static and b) dynamic (water impact); and 3) with and without the presence of cracks. Durability was analysed over 24 months, measuring several physical and chemical parameters of the system, recording changes in both the aggressive media and the concrete. All UHPFRC types demonstrate good durability, showing high resistance to expansion and deformation in the sulphate-rich media. A leaching process occurs in all water interaction systems, the dynamic interaction in sgw being the most aggressive. The interaction of sgw inside the crack favours the formation of solid phases such as calcium carbonates and ettringite, while the presence of nanoadditives affects the response of both the matrix and the formation of precipitates within the crack.

A review of the efficiency of self-healing concrete technologies for durable and sustainable concrete under realistic conditions

“…Blast furnace slag [213,236] . Fly ash [235] Organic chelation agents [237][238][239][240][241][242][243] Crystalline admixture [59,106,203,221,[244][245][246] Granules of Ca(OH) 2 and Na 2 SO 4 [236] Cellulose nanocrystals [59,203,244,247] Fibres…”

“…While the self-healing performance of UHPC made with CEM III was generally better than with CEM I, the differences tended to fade upon multiple re-cracking and longer exposure times. Effects of nanoparticles were evident in enhancing the crack-width control capacity of the material, guaranteeing single cracks not wider than a few tens of microns for the same level of deformation, and hence guaranteeing a better healing performance [247]. For the same UHPCs and aggressive scenario, Giménez et al [247] have developed a tailored test set-up to simulate interaction with continuously flowing water as it occurs, e.g.…”

“…Effects of nanoparticles were evident in enhancing the crack-width control capacity of the material, guaranteeing single cracks not wider than a few tens of microns for the same level of deformation, and hence guaranteeing a better healing performance [247]. For the same UHPCs and aggressive scenario, Giménez et al [247] have developed a tailored test set-up to simulate interaction with continuously flowing water as it occurs, e.g. in cooling towers in geothermal power plants.…”

“…HPFRC [59,203,244,247] . Alumina nanofibers [59,203,244,247] . Cellulose nano-fibrils [59,203,244] Sporosarcina halophila bacteria [248,249] Freeze-thaw attack with deicing salts…”

Structural validation of geothermal water basins constructed with durability enhanced ultra high performance fiber reinforced concrete (Ultra High Durability Concrete)

“…3, which shows an appreciable ductility performance particularly in the tensile behavior. The durability parameters have also been evaluated and reported in several publications and are summarized in Table 3 [23][24][25][26][27][28][29][30][31][32].…”