scholarly journals Meta-Analysis and Machine Learning Models to Optimize the Efficiency of Self-Healing Capacity of Cementitious Material

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4437
Author(s):  
Shashank Gupta ◽  
Salam Al-Obaidi ◽  
Liberato Ferrara
Keyword(s):  
Meta Analysis ◽  
Cementitious Materials ◽  
Initial Crack ◽  
Supplementary Cementitious Materials ◽  
Structural Performance ◽  
Self Healing ◽  
Design Strategies ◽  
Healing Efficiency ◽  
Cement Based Materials ◽  
Artificial Neural Network Ann

Concrete and cement-based materials inherently possess an autogenous self-healing capacity. Despite the huge amount of literature on the topic, self-healing concepts still fail to consistently enter design strategies able to effectively quantify their benefits on structural performance. This study aims to develop quantitative relationships through statistical models and artificial neural network (ANN) by establishing a correlation between the mix proportions, exposure type and time, and width of the initial crack against suitably defined self-healing indices (SHI), quantifying the recovery of material performance. Furthermore, it is intended to pave the way towards consistent incorporation of self-healing concepts into durability-based design approaches for reinforced concrete structures, aimed at quantifying, with reliable confidence, the benefits in terms of slower degradation of the structural performance and extension of the service lifespan. It has been observed that the exposure type, crack width and presence of healing stimulators such as crystalline admixtures has the most significant effect on enhancing SHI and hence self-healing efficiency. However, other parameters, such as the amount of fibers and Supplementary Cementitious Materials have less impact on the autogenous self-healing. The study proposes, through suitably built design charts and ANN analysis, a straightforward input–output model to quickly predict and evaluate, and hence “design”, the self-healing efficiency of cement-based materials.

scholarly journals Effects of Curing Conditions and Supplementary Cementitious Materials on Autogenous Self-Healing of Early Age Cracks in Cement Mortar

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 752
Author(s):  
Mian Luo ◽  
Kang Jing ◽  
Jingquan Bai ◽  
Ziqi Ding ◽  
Dingyi Yang ◽  
...  
Keyword(s):  
Cement Mortar ◽  
Cementitious Materials ◽  
Visual Observation ◽  
Healing Time ◽  
Supplementary Cementitious Materials ◽  
Early Age ◽  
Self Healing ◽  
Replacement Ratio ◽  
Curing Conditions ◽  
Healing Efficiency

The autogenous healing potential of cement-based materials is affected by multiple factors, such as mix composition, crack width, pre-cracking age and external environmental conditions. In this study, the effects of curing conditions and supplementary cementitious materials (SCMs) on autogenous self-healing of early age cracks in cement mortar were investigated. Three curing conditions, i.e., standard curing, wet–dry cycles and incubated in water, and two SCMs, i.e., fly ash (FA) and blast furnace slag (BFS) with various contents (cement replacement ratio at 0%, 20%, and 40%) were examined. A single early age crack (pre-cracking age of 3 days) with a width of 200~300 μm was generated in cylindrical mortar specimens. Autogenous crack self-healing efficiency of mortar specimens was evaluated by performing a visual observation and a water permeability test. Moreover, microstructure analysis (XRD, SEM and TG/DTG) was utilized to characterize the healing products. The results indicated that the presence of water was essential for the autogenous self-healing of early age cracks in cement mortar. The efficiency of self-healing cracks was highest in specimens incubated in water. However, no significant self-healing occurred in specimens exposed to standard curing. For wet–dry cycles, a longer healing time was needed to obtain good self-healing compared to samples incubated in water. SCMs type and content significantly affected the autogenous self-healing ability of early age cracks. The self-healing efficiency of early age cracks decreased with increases in FA and BFS content. BFS mortars exhibited greater recovery in relation to water penetration resistance compared to the reference and FA mortars. Almost the same regain of water tightness and a lower crack-healing ratio after healing of 28 days in FA mortars were observed compared to the reference. The major healing product in the surface cracks of specimens with and without SCMs was micron-sized calcite crystals with a typical rhombohedral morphology.

scholarly journals Numerical Studies of the Effects of Water Capsules on Self-Healing Efficiency and Mechanical Properties in Cementitious Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Haoliang Huang ◽  
Guang Ye
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Cementitious Materials ◽  
Self Healing ◽  
Negative Effects ◽  
Numerical Studies ◽  
Healing Efficiency ◽  
The Impact ◽  
Positive Effect

In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases.

scholarly journals Encapsulation Techniques and Test Methods of Evaluating the Bacteria-Based Self-Healing Efficiency of Concrete: A Literature Review

2020 ◽  
Vol 62 (1) ◽  
pp. 63-85
Author(s):  
Rahul Roy ◽  
Emanuele Rossi ◽  
Johan Silfwerbrand ◽  
Henk Jonkers
Keyword(s):  
Service Life ◽  
Polymeric Materials ◽  
Cementitious Materials ◽  
Test Methods ◽  
Self Healing ◽  
Load Factors ◽  
Healing Efficiency ◽  
Healing Agent ◽  
Maximum Crack ◽  
Encapsulated Bacteria

AbstractCrack formation in concrete structures due to various load and non-load factors leading to degradation of service life is very common. Repair and maintenance operations are, therefore, necessary to prevent cracks propagating and reducing the service life of the structures. Accessibility to affected areas can, however, be difficult as the reconstruction and maintenance of concrete buildings are expensive in labour and capital. Autonomous healing by encapsulated bacteria-based self-healing agents is a possible solution. During this process, the bacteria are released from a broken capsule or triggered by water and oxygen access. However, its performance and reliability depend on continuous water supply, protection against the harsh environment, and densification of the cementitious matrix for the bacteria to act. There are vast methods of encapsulating bacteria and the most common carriers used are: encapsulation in polymeric materials, lightweight aggregates, cementitious materials, special minerals, nanomaterials, and waste-derived biomass. Self-healing efficiency of these encapsulated technologies can be assessed through many experimental methodologies according to the literature. These experimental evaluations are performed in terms of quantification of crackhealing, recovery of durability and mechanical properties (macro-level test) and characterization of precipitated crystals by healing agent (micro-level test). Until now, quantification of crack-healing by light microscopy revealed maximum crack width of 1.80mm healed. All research methods available for assesing self-healing efficiency of bacteria-based healing agents are worth reviewing in order to include a coherent, if not standardized framework testing system and a comparative evaluation for a novel incorporated bacteria-based healing agent.

Effect of Polyurethane Viscosity on Self-Healing Efficiency of Cementitious Materials Exposed to High Temperatures from Sun Radiation

2018 ◽  
Vol 30 (7) ◽  
pp. 04018145 ◽  
Author(s):  
B. Van Belleghem ◽  
E. Gruyaert ◽  
K. Van Tittelboom ◽  
W. Moerman ◽  
B. Dekeyser ◽  
...  
Keyword(s):  
High Temperatures ◽  
Cementitious Materials ◽  
Self Healing ◽  
Healing Efficiency

Self-healing efficiency of cementitious materials containing tubular capsules filled with healing agent

2011 ◽  
Vol 33 (4) ◽  
pp. 497-505 ◽  
Author(s):  
Kim Van Tittelboom ◽  
Nele De Belie ◽  
Denis Van Loo ◽  
Patric Jacobs
Keyword(s):  
Cementitious Materials ◽  
Self Healing ◽  
Healing Efficiency ◽  
Healing Agent

Evaluation of Self-Healing Efficiency of Reinforced Concrete Beams with Calcium Nitrate Microcapsules

2017 ◽  
Vol 2629 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Luis Bonilla ◽  
Marwa Hassan ◽  
Hassan Noorvand ◽  
Tyson Rupnow ◽  
Ayman Okeil
Keyword(s):  
Concrete Beams ◽  
Calcium Nitrate ◽  
Cementitious Materials ◽  
The Self ◽  
Reinforced Concrete Beams ◽  
Self Healing ◽  
Initial Stiffness ◽  
Air Content ◽  
Healing Efficiency ◽  
Control Samples

The self-healing efficiency of cementitious materials was improved by developing several strategies to provide and deliver the products (healing agents) needed for cracks to self-repair. This study evaluated the self-healing efficiency of microcapsules filled with calcium nitrate in reinforced and unreinforced concrete beams. The structural behavior and healing efficiency were evaluated by measuring and then comparing the initial stiffness, peak strength, and deformation with posthealing measurements. Furthermore, as part of this study, crack monitoring was conducted to evaluate crack healing over time. Then characterization analysis was carried out with energy dispersive X-ray spectroscopy to quantify the healing components in the cracked areas. Results showed that the air content in samples containing microcapsules was two times higher than that in the control samples. Furthermore, addition of microcapsules lowered the flexural strength of concrete beams compared with that of the control samples. A positive stiffness recovery was recorded for all groups, with and without microcapsules or steel. Control samples showed the lowest stiffness recovery; however, the use of steel with microcapsules presented a superior healing efficiency and improved stiffness recovery significantly by 38%. Results from image analysis showed that crack widths did not completely heal for the control samples, while using microcapsules allowed the cracked widths to heal more efficiently. The best observed performance was for the microcapsules–steel group, which yielded 100% healing of the cracks.

scholarly journals Impact of Bio-Carrier Immobilized with Marine Bacteria on Self-Healing Performance of Cement-Based Materials

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4164 ◽  
Author(s):  
Hayeon Kim ◽  
Hyeongmin Son ◽  
Joonho Seo ◽  
H. K. Lee
Keyword(s):  
Mechanical Properties ◽  
Mercury Intrusion Porosimetry ◽  
Tap Water ◽  
Bottom Ash ◽  
Self Healing ◽  
Mixing Process ◽  
Mercury Intrusion ◽  
Healing Efficiency ◽  
Cement Based Materials ◽  
Healing Agent

The present study evaluated the self-healing efficiency and mechanical properties of mortar specimens incorporating a bio-carrier as a self-healing agent. The bio-carrier was produced by immobilizing ureolytic bacteria isolated from seawater in bottom ash, followed by surface coating with cement powder to prevent loss of nutrients during the mixing process. Five types of specimens were prepared with two methods of incorporating bacteria, and were water cured for 28 days. To investigate the healing ratio, the specimens with predefined cracks were treated by applying a wet–dry cycle in three different conditions, i.e., seawater, tap water, and air for 28 days. In addition, a compression test and a mercury intrusion porosimetry analysis of the specimens were performed to evaluate their physico-mechanical properties. The obtained results showed that the specimen incorporating the bio-carrier had higher compressive strength than the specimen incorporating vegetative cells. Furthermore, the highest healing ratio was observed in specimens incorporating the bio-carrier. This phenomenon could be ascribed by the enhanced bacterial viability by the bio-carrier.

Sign in / Sign up

Export Citation Format

Share Document