Self-healing properties of reactive powder concrete with nanofillers

Abstract

The study presented in this paper aims to investigate the self-healing properties of reactive powder concrete (RPC) modified with nanofillers, which has the self-healing ability of compressive and flexural strength. The inner damage of RPC with nanofillers during loading is analyzed by using an acoustic emission system. Three types of nanofillers (nano-SiO2, nano-TiO2 and nano-ZrO2) and two curing methods (water curing and air curing) are selected for identifying the influencing factors. Experimental results indicate that all incorporated nanofillers have the ability to enhance the self-healing ability of RPC. However, we noted that the enhancement is more evident when the RPC is cured in water. Composite with nano-SiO2 has the largest self-healing coefficients of compressive (Cs) and flexural strength (Fs) with water curing of 1.31 and 1.19, which increases by 39.4% and 33.7% compared to RPC without nanofillers, respectively. The incorporation of nanofillers weakens and even eliminates the Kaiser effect of RPC under secondary loadings, indicating that to a certain extent, crack healing has taken place. The effect of the nanofiller modification mechanisms on the RPC self-healing properties is thought to be attributed to three main features: (1) the provision of nanofillers provides the hydration environment for unhydrated cement particles and nucleation sites for the hydration products; (2) nanofillers improve the 3D network structure of concrete matrix, produce more fine cracks and disperse the propagation direction of the cracks; (3) the pozzolanic reaction of nanofillers (including nano-SiO2 and nano-TiO2), especially for nano-SiO2, produces additional calcium silicate hydration, and increases the compactness of RPC.

Toward Self-Healing Concrete Infrastructure: Review of Experiments and Simulations across Scales

“…Second, the nanofillers can help form a dense cement matrix. Third, some nanofillers, such as nano-SiO 2 , have pozzolanic reactivity, 147 which promotes the formation of dense calcium− silicate−hydrates. Siad et al 142 reported that adding 0.25−0.5% carbon nanotubes can lead to accelerated recovery of flexural strength.…”

“…In the meantime, more fractures were generated but with smaller crack widths. Wang et al 147 reported that the addition of inorganic nanomaterials (e.g., SiO 2 , TiO 2 , or ZrO 2 ) could enhance the cement's self-healing properties. Among those materials, nano-SiO 2 works best for the healing process.…”

Use of Methylcellulose-Based Pellet to Enhance the Bacterial Self-Healing of Cement Composite

“…Such propagation can be inhibited by self-healing processes of cementitious materials, specifically the autogenous healing mechanism [2], which is an intrinsic repair property of cementitious material. Autogenous healing can be accelerated by applying mineral admixture [3], fiber [4,5], nanofiller [6], and curing agent [7,8]. Another self-healing concrete process is the autonomous healing, which involves the incorporation of capsules containing healing agents or bacteria spores to the composites including electrodeposition [9,10], epoxy injection [11][12][13], polymers [13][14][15], and shape-memory alloys [16].…”

Effect of Clinker Binder and Aggregates on Autogenous Healing in Post-Crack Flexural Behavior of Concrete Members

“…The restless search for durability and resilience of concrete structures has led some researchers to focus on self-healing concrete composites with the built-in ability of repairing narrow cracks without human or external intervention [ 2 , 3 , 4 , 5 ]. Two major types of self-healing concretes have emerged: the autogenous type [ 4 ], which is achieved by autogenous healing materials such as mineral admixtures like ground-granulated blast-furnace slag (GGBFS), silica fume or fly ash, fibers and nanofillers [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ]; and, the autonomous type [ 3 ], which is realized by unconventional engineered additions such as shape memory alloys, capsules, polymers or bacteria to seal the cracks [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Autogenous healing is an old and well-known phenomenon that originates naturally from the cementitious material like the hydration of clinker minerals or the carbonation of calcium hydroxide while autonomous healing requires a trigger to activate the process.…”