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 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 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.

Characterization of Mechanical Properties in Multifunctional Structural-Energy Storage Nanocomposites for Lightweight Micro Autonomous Systems

2011 ◽  
Author(s):  
Daniel P. Cole ◽  
Monica Rivera ◽  
Mark Bundy
Keyword(s):  
Energy Storage ◽  
Electrode Materials ◽  
Mechanical Performance ◽  
Autonomous Systems ◽  
Deposition Process ◽  
Mechanical Tests ◽  
Energy Storage Materials ◽  
Structural Components ◽  
Storage Materials

A major concern in the design of micro-robotic systems is an on-board energy supply capable of providing the necessary power requirements, while limiting the volume/mass burden to the vehicle. The conventional solution to this design problem is to maximize the energy density of the on-board power supply. An alternative approach is to replace single-function structural components with multifunctional structural-energy storage materials. The mass and volume savings associated with the material substitution could potentially result in improved endurance and/or increased payload (e.g. video camera, microphone, chemical/biological sensors). In this study, carbon nanotube (CNT) based composites were used to fabricate structural-energy storage materials. Specifically, supercapacitor electrodes were constructed from paper covered with CNT ink and from polymer matrices infused with aligned CNT forests. The composites were subject to bulk mechanical tests in order to characterize their suitability as structural components in micro-autonomous systems. Tensile tests on the paper composites show directional and strain rate dependencies. The CNT-ink deposition process was found to degrade the elastic modulus of the paper by approximately 50%, although the tensile strength of the materials was largely unaffected. Preliminary electrical characterization of the CNT-coated electrode materials indicate that the nanomaterials potentially reach a percolation threshold after multiple depositions, resulting in a conductive surface network. Initial results indicate that improvements in the electrical properties of the CNT paper electrodes are met with reductions in the mechanical performance of the composites.

Sign in / Sign up

Export Citation Format

Share Document