scholarly journals Superabsorbent polymers to seal and heal cracks in cementitious materials

2018 ◽  
Vol 3 ◽  
pp. 32-38 ◽  
Author(s):  
Didier Snoeck
Keyword(s):  
Crack Width ◽  
Autogenous Shrinkage ◽  
Building Blocks ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Current Status ◽  
Self Healing ◽  
Superabsorbent Polymers ◽  
Concrete Cracking ◽  
Freeze Thaw

Superabsorbent polymers (SAPs) are promising admixtures to improve properties in cementitious materials. Not only useful to mitigate autogenous shrinkage and to increase the freeze-thaw resistance, SAP particles may enhance self-sealing and self-healing in cementitious materials. The self-sealing leads to a regain in water tightness and promoted autogenous healing may prove to be useful to limit repair works caused by concrete cracking. By providing sufficient building blocks for healing, limiting the crack width by means of synthetic microfibers and inducing water by means of SAPs, a smart cementitious material is obtained. This material can be an excellent material to use in future building applications such as tunnel works and ground-retaining structures. This paper gives an overview of the current status of the research on SAPs in cementitious materials to obtain sealing and healing.

scholarly journals Crack-healing in cementitious material to improve the durability of structures: Review

2018 ◽  
Vol 250 ◽  
pp. 03005 ◽  
Author(s):  
Hassan Amer Ali Algaifi ◽  
Suhaimi Abu Bakar ◽  
Abdul Rahman Mohd Sam ◽  
Ahmad Razin Zainal Abidin
Keyword(s):  
Crack Width ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Self Healing ◽  
Crack Healing ◽  
Harmful Substances ◽  
Crack Faces ◽  
Crack Widths ◽  
Long Term Studies

One of the most commonly used materials in the field of construction is concrete. Nevertheless, there are strong inclinations for concrete to form cracks, which would then allow the penetration of both aggressive and harmful substances into the concrete. Subsequently, this will decrease the durability of the affected structures. Thus, the ability for cracks to heal themselves in the affected cementitious materials is in demand to prolong the life of any structure. Autogenous self-healing is one approach to overcome smaller crack widths (macrocracks). Nowadays, crack width-healing is of great importance. Having said that, both polymers and bacteria are the most common approach to enhance autogenous self-healing and bond crack faces. Crack width-healing of up to 0.97 mm was achieved via bacteria-based self-healing. In this paper, the mechanisms of these approaches and their efficiency to heal crack were highlighted. Both bacteria-and polymers-based self-healing are promising techniques for the future. However, long term studies are still required before real applications can be made.

scholarly journals Evaluation of the Self-Healing Ability of Mortar Mixtures Containing Superabsorbent Polymers and Nanosilica

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 380 ◽  
Author(s):  
Gerlinde Lefever ◽  
Didier Snoeck ◽  
Dimitrios G. Aggelis ◽  
Nele De Belie ◽  
Sandra Van Vlierberghe ◽  
...  
Keyword(s):  
Crack Width ◽  
Mechanical Performance ◽  
Cementitious Material ◽  
The Self ◽  
Optical Measurements ◽  
Self Healing ◽  
Superabsorbent Polymers ◽  
Healing Efficiency ◽  
Good Healing ◽  
External Conditions

Addition of superabsorbent polymers (SAPs) to cementitious mixtures promotes the self-healing ability of the material. When cracking occurs; SAPs present inside the crack will swell upon contact with water and subsequently release this water to stimulate the further hydration of unhydrated cement particles and the calcium carbonate crystallization. However; the inclusion of SAPs affects the mechanical performance of the cementitious material by the creation of macro-pores as water is retracted from the swollen SAP. To counteract the reduction in strength, part of the cement is replaced by nanosilica. In this research, different mixtures containing either SAPs or nanosilica and a combination of both were made. The samples were subjected to wet–dry cycles simulating external conditions, and the self-healing efficiency was evaluated by means of the evolution in crack width, by optical measurements, and a water permeability test. In samples containing SAPs, an immediate sealing effect was observed and visual crack closure was noticed. The smaller influence on the mechanical properties and the good healing characteristics in mixtures containing both nanosilica and SAPs are promising as a future material for use in building applications.

scholarly journals The Contribution of Elastic Wave NDT to the Characterization of Modern Cementitious Media

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2959 ◽  
Author(s):  
Gerlinde Lefever ◽  
Didier Snoeck ◽  
Nele De Belie ◽  
Sandra Van Vlierberghe ◽  
Danny Van Hemelrijck ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Autogenous Shrinkage ◽  
Measuring Method ◽  
Cementitious Materials ◽  
Mechanical Tests ◽  
Self Healing ◽  
Destructive Testing ◽  
Superabsorbent Polymers ◽  
Non Destructive

To mitigate autogenous shrinkage in cementitious materials and simultaneously preserve the material’s mechanical performance, superabsorbent polymers and nanosilica are included in the mixture design. The use of the specific additives influences both the hydration process and the hardened microstructure, while autogenous healing of cracks can be stimulated. These three stages are monitored by means of non-destructive testing, showing the sensitivity of elastic waves to the occurring phenomena. Whereas the action of the superabsorbent polymers was evidenced by acoustic emission, the use of ultrasound revealed the differences in the developed microstructure and the self-healing of cracks by a comparison with more commonly performed mechanical tests. The ability of NDT to determine these various features renders it a promising measuring method for future characterization of innovative cementitious materials.

scholarly journals The Influence of Superabsorbent Polymers and Nanosilica on the Hydration Process and Microstructure of Cementitious Mixtures

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5194
Author(s):  
Gerlinde Lefever ◽  
Dimitrios G. Aggelis ◽  
Nele De Belie ◽  
Marc Raes ◽  
Tom Hauffman ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Isothermal Calorimetry ◽  
Autogenous Shrinkage ◽  
Hydration Process ◽  
Microstructural Development ◽  
Self Healing ◽  
Hydration Kinetics ◽  
Superabsorbent Polymers ◽  
Water To Cement Ratio ◽  
Supplementary Material

Superabsorbent polymers (SAPs) are known to mitigate the development of autogenous shrinkage in cementitious mixtures with a low water-to-cement ratio. Moreover, the addition of SAPs promotes the self-healing ability of cracks. A drawback of using SAPs lies in the formation of macropores when the polymers release their absorbed water, leading to a reduction of the mechanical properties. Therefore, a supplementary material was introduced together with SAPs, being nanosilica, in order to obtain an identical compressive strength with respect to the reference material without additives. The exact cause of the similar compressive behaviour lies in the modification of the hydration process and subsequent microstructural development by both SAPs and nanosilica. Within the present study, the effect of SAPs and nanosilica on the hydration progress and the hardened properties is assessed. By means of isothermal calorimetry, the hydration kinetics were monitored. Subsequently, the quantity of hydration products formed was determined by thermogravimetric analysis and scanning electron microscopy, revealing an increased amount of hydrates for both SAP and nanosilica blends. An assessment of the pore size distribution was made using mercury intrusion porosimetry and demonstrated the increased porosity for SAP mixtures. A correlation between microstructure and the compressive strength displayed its influence on the mechanical behaviour.

scholarly journals Development of an improved cracking method to reduce the variability in testing the healing efficiency of self-healing mortar containing encapsulated polymers

2018 ◽  
Vol 199 ◽  
pp. 02017 ◽  
Author(s):  
Tim Van Mullem ◽  
Kim Van Tittelboom ◽  
Elke Gruyaert ◽  
Robby Caspeele ◽  
Nele De Belie
Keyword(s):  
Crack Width ◽  
Control Technique ◽  
Self Healing ◽  
Concrete Cracking ◽  
Crack Control ◽  
Control Techniques ◽  
Healing Efficiency ◽  
Flow Test ◽  
Equivalent Reduction ◽  
External Intervention

Concrete cracking can result in a significant reduction of the durability and the service life due to the ingress of aggressive agents Self-healing concrete is able to heal cracks without external intervention, thereby mitigating the need for manual repair. In the assessment of the healing efficiency of self-healing concrete the to-be-healed crack width is an important parameter and different researchers have emphasised that the variability of the crack width significantly hampers an accurate assessment of the healing efficiency. With two new crack control techniques the variability of the crack width was reduced in order to decrease the variability on the calculated healing efficiency. This paper reports on the application of these techniques for the assessment of self-healing mortar containing encapsulated polyurethane. The healing potential was investigated by looking at the degree of sealing using a water flow test setup. It was observed that by using a crack control technique the variability on the crack width can indeed be reduced. Nonetheless, this does not translate in an equivalent reduction on the variability of the healing efficiency. This indicates that other factors contribute to the variability of the healing efficiency.

SYNTHESIS AND CHARACTERIZATION OF SELF-HEALING MORTAR WITH MODIFIED STRENGTH

2015 ◽  
Vol 76 (1) ◽  
Author(s):  
Gassan Fahim Huseien ◽  
Jahangir Mirza ◽  
Nur Farhayu Ariffin ◽  
Mohd Warid Hussin
Keyword(s):  
Early Stage ◽  
Polymeric Materials ◽  
Building Blocks ◽  
Ultrasonic Pulse Velocity ◽  
Cementitious Materials ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Diglycidyl Ether ◽  
Self Healing ◽  
Research Initiative

Cementitious materials being the most prospective building blocks achieving their absolute strength to avoid the deterioration in the early stage of service life is ever-demanding. Minimizing the labor and capital-intensive maintenance and repair cost is a critical challenge. Thus, self-healing mortars with modified strength are proposed. Lately, self-healing of micro-cracks by introducing bacteria during the formation of mortar or concrete became attractive. Self-healing with polymeric admixtures is considered to be relatively more durable and faster process. Certainly, the self-healing of synthetic polymeric materials is inspired by biological systems, where the damage triggers an autonomic healing response. This emerging and fascinating research initiative may significantly improve the durability and the safety limit of the polymeric components potential for assorted applications. In this work, using epoxy resin (diglycidyl ether of bisphenol A) without any hardener as admixture polymeric-cementitious materials is prepared. These epoxy-modified mortars are synthesized with various polymer-cement ratios subjected to initial wet/dry curing (WDC) together with long term dry curing (DC). Their self-healing function and hardening effects are evaluated via preloading and drying of the specimens, chemical analysis, and ultrasonic pulse velocity testing. It is demonstrated that 10% of polymer is the best proportion for polymer-cement ratio. Furthermore, the wet/dry curing is established to be superior process for healing hairline cracks present in the mortar. The excellent features of the results suggest that our novel method may constitute a basis for improving the compressive strength and self-healing features of mortars.    

scholarly journals Mechanical and self-healing properties of cementitious materials with pH-responsive semi-synthetic superabsorbent polymers

2017 ◽  
Vol 50 (6) ◽  
Author(s):  
Arn Mignon ◽  
Jolien Vermeulen ◽  
Didier Snoeck ◽  
Peter Dubruel ◽  
Sandra Van Vlierberghe ◽  
...  
Keyword(s):  
Cementitious Materials ◽  
Self Healing ◽  
Ph Responsive ◽  
Superabsorbent Polymers

scholarly journals Key Factors Determining the Self-Healing Ability of Cement-Based Composites with Mineral Additives

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4211
Author(s):  
Kamil Tomczak ◽  
Jacek Jakubowski ◽  
Łukasz Kotwica
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Crack Width ◽  
Defect Formation ◽  
Cementitious Materials ◽  
The Self ◽  
Supplementary Cementitious Materials ◽  
Self Healing ◽  
Key Factors ◽  
Important Indicator

This paper reveals the relationships between key factors that determine the ability of cementitious composites to self-heal autogenously and specific measures for quantifying the effects of this process. The following material factors: water-to-binder ratio (w/b), uniaxial compressive strength and age of the composite at the time of defect formation were considered, as well as the method and degree of damage to the tested material. The subjects of this study were mortars and concretes in which Portland cement was partially replaced, to varying degrees, with mechanically activated fluidized bed combustion fly ash (MAFBC fly ash) and siliceous fly ash. The samples were subjected to three-point bending or cyclic compression tests after 14 or 28 days of aging, in order to induce defects and then cured in water for 122 days. Microscopic (MO) and high-resolution scanning (HRS) observations along with computer image processing techniques were used to visualize and quantify the changes occurring in the macro-crack region near the outer surface of the material during the self-sealing process. Techniques based on the measurement of the ultrasonic pulse velocity (UPV) allowed the quantification of the changes occurring inside the damaged materials. Mechanical testing of the composites allowed quantification of the effects of the activity of the binder-supplementary cementitious materials (SCMs) systems. The analysis of the results indicates a significant influence of the initial crack width on the ability to completely close the cracks; however, there are repeated deviations from this rule and local variability of the self-sealing process. It has been shown that the compressive strength of a material is an important indicator of binder activity concerning crack width reduction due to self-sealing. Regardless of the crack induction method, the internal material changes caused by self-sealing are dependent on the degree of material damage.

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