scholarly journals Understanding the Impacts of Healing Agents on the Properties of Fresh and Hardened Self-Healing Concrete: A Review

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2206
Author(s):  
Harry Hermawan ◽  
Peter Minne ◽  
Pedro Serna ◽  
Elke Gruyaert
Keyword(s):  
Mix Design ◽  
Hardened Concrete ◽  
Self Healing ◽  
Conventional Concrete ◽  
Concrete Mix Design ◽  
Crack Sealing ◽  
Healing Efficiency ◽  
Concrete Mix ◽  
Healing Agent ◽  
The Impact

Self-healing concrete has emerged as one of the prospective materials to be used in future constructions, substituting conventional concrete with the view of extending the service life of the structures. As a proof of concept, over the last several years, many studies have been executed on the effectiveness of the addition of self-healing agents on crack sealing and healing in mortar, while studies on the concrete level are still rather limited. In most cases, mix designs were not optimized regarding the properties of the fresh concrete mixture, properties of the hardened concrete and self-healing efficiency, meaning that the healing agent was just added on top of the normal mix (no adaptations of the concrete mix design for the introduction of healing agents). A comprehensive review has been conducted on the concrete mix design and the impact of healing agents (e.g., crystalline admixtures, bacteria, polymers and minerals, of which some are encapsulated in microcapsules or macrocapsules) on the properties of fresh and hardened concrete. Eventually, the remaining research gaps in knowledge are identified.

scholarly journals Self-Healing Concrete Mix-Design Based on Engineered Cementitious Composites Principles

Proceedings ◽  
2020 ◽  
Vol 63 (1) ◽  
pp. 5
Author(s):  
Tudor Panfil Toader ◽  
Anamaria Cătălina Mircea
Keyword(s):  
Construction Industry ◽  
Raw Materials ◽  
Mix Design ◽  
Cementitious Composites ◽  
Self Healing ◽  
Engineered Cementitious Composites ◽  
Concrete Mix Design ◽  
External Agents ◽  
Concrete Mix ◽  
Healing Property

Concrete is the most used material in the construction industry, being prone to cracking. Following the action of aggressive external agents, through cracks, access routes to the embedded reinforcement are created. By enclosing in concrete various materials that can induce the self-healing property, by taking actions when the cracks appear, the access of the external aggressive agents to the reinforcement can be stopped, therefore creating more durable materials. The aim of the research is to design a micro concrete with self-healing properties, based on Engineered Cementitious Composites principles from the literature and using local raw materials.

scholarly journals Study of the Influence of an Air-Entraining Agent on the Rheology of Motars

2018 ◽  
Vol 149 ◽  
pp. 01054
Author(s):  
Nadia Tebbal ◽  
Zine El Abidine Rahmouni ◽  
Lamis Rabiaa Chadi
Keyword(s):  
Compressive Strength ◽  
Rheological Properties ◽  
Fresh Concrete ◽  
Experimental Studies ◽  
Air Entrainment ◽  
Mix Design ◽  
Hardened Concrete ◽  
Concrete Mix Design ◽  
Concrete Mix ◽  
Mixing Water

The objective of this study is to analyze the effect of the air entrainment on the fresh rheological properties as well as on the compressive mechanical resistances of the mortars. The hardened concrete contains a certain amount of randomly spread air, coming either from a drive during kneading or from the evaporation of the mixing water. The air quantity is in the order of 20 l / m3, ie 2% of the volume. However, the presence of a large volume of air bubbles causes the mechanical resistances to fall in compression. On the other hand, the use of air entrainment could improve the rheological properties of fresh concrete. Experimental studies have been carried out to study the effect of air entrainment on compressive strength, density and ingredients of fresh concrete mix. During all the study, water cement ratio (w/c) was maintained constant at 0.5. The results have shown substantial decreasing in water and mortar density followed with decreasing in compressive strength of mortar. The results of this study has given more promising to use it as a guide for mortar mix design to choose the most appropriate concrete mix design economically.

scholarly journals Effect of Alccofine on the Properties of Concrete Incorporating Steel Fibers

2020 ◽  
Vol 9 (5) ◽  
pp. 44-47
Keyword(s):  
Strength Properties ◽  
Steel Fibers ◽  
Mix Design ◽  
Morphological Properties ◽  
Conventional Concrete ◽  
Concrete Mix Design ◽  
Morphological Studies ◽  
Concrete Mix ◽  
Binder Ratio ◽  
Water Binder Ratio

This paper deals with the investigation of concrete containing varying replacement percentages of Alccofine and conjointly Alccofine and different proportions of steel fibers with aspect ratio 50 to investigate mechanical and morphological properties. The replacement levels of Alccofine was chosen as 5% to 15% with 5% increment and steel fibers of 0.5% to1.5% with an increment of 0.5% by volume of concrete. Mix design was done by using British D.O.E method, fixing water binder ratio as 0.45. Results indicated that concrete replaced with Alccofine in addition of steel fibers increased the compressive and flexural strength of concrete. The maximum strength was obtained for the concrete mix containing 15% Alccofine and 1.5% circular crimped steel fibers. Morphological studies indicated the excess C-S-H gel for concrete mixes containing Alccofine as compared to conventional concrete. Hence, it can be culminated that Alccofine and addition of steel fibers increases the strength properties and crack resistant strength of concrete.

scholarly journals Conventional Concrete Mix Design for Producing the Low and High Volume of Fly Ash Based Fiber Reinforced Concrete

2019 ◽  
Vol 8 (6) ◽  
pp. 1157-1162 ◽  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Activity Index ◽  
Research Work ◽  
Binder Content ◽  
Fiber Reinforced Concrete ◽  
Mix Design ◽  
Conventional Concrete ◽  
Concrete Mix Design ◽  
Concrete Mix

The present research work analysis the conceptual concrete mix design regarding the packing unit density concept for multi initial trial and error perfect shaped methodologies. In initial, a high strength based concrete with desired target compressive strength of M40 Graded concrete was shaped for various mixing proportion and Also, a stabilized standard chart has been developed for the various packing constituents (percentage) in various parameters, where the aggregates (F/c) ratio 0.5 to 0.8, Binder-Total aggregate (B/Ta) ratio 0.27 to 0.24 and water-binder content (w/b) ratio 0.30. The laboratory experimental research work results contain fly ash percentage replacement level at 25 and 50% in Portland cement and inclusion of both ends hooked type of steel fibers along with 1.50% of superplasticizers by weight of binder content for the various mix produced for the good tracking of the UPV values by using fabricating Plexiglas moulds, Pozzolanic Activity Index (PAI), if the compressive strength increases automatically less volumetric shrinkage takes place.

scholarly journals Application of Supplementary Cementitious Materials in Precast Concrete Industry

2021 ◽  
Author(s):  
Amin Akhnoukh
Keyword(s):  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Hardened Concrete ◽  
Initial Strength ◽  
Multi Wall Carbon Nanotubes ◽  
Concrete Mix Design ◽  
Concrete Properties ◽  
Concrete Mix ◽  
Project Sustainability ◽  
The Impact

Supplementary cementitious materials (SCMs) are increasingly incorporated into the concrete mix design. Silica fume, fly ash, and multi-wall carbon nanotubes are used to improve concrete mix properties. The objective of this chapter is to decipher the impact of different SCMs on the fresh and hardened concrete properties, including concrete flowing ability, initial strength, final strength, modulus of elasticity, and modulus of rupture. In addition, the impact of SCMs on mitigating the alkali-silica reactivity of concrete and increasing the hardened concrete long-term performance is investigated. Developed concrete mixes, incorporating SCMs, are used in fabricating different precast/prestressed bridge girders. The impact of improved concrete properties on precast girder performance in increased flexure, shear, and span-to-depth ratio significantly improves project sustainability and reduces the overall project life cycle cost.

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.

Mechanical responses of microencapsulated self-healing cementitious composites under compressive loading based on a micromechanical damage-healing model

2021 ◽  
pp. 105678952110112
Author(s):  
Kaihang Han ◽  
Jiann-Wen Woody Ju ◽  
Yinghui Zhu ◽  
Hao Zhang ◽  
Tien-Shu Chang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Micromechanical Model ◽  
Cementitious Composites ◽  
Self Healing ◽  
Damage Degree ◽  
Healing Efficiency ◽  
The Matrix ◽  
Healing Agent ◽  
Damage Healing

The cementitious composites with microencapsulated healing agents have become a class of hotspots in the field of construction materials, and they have very broad application prospects and research values. The in-depth study on multi-scale mechanical behaviors of microencapsulated self-healing cementitious composites is critical to quantitatively account for the mechanical response during the damage-healing process. This paper proposes a three-dimensional evolutionary micromechanical model to quantitatively explain the self-healing effects of microencapsulated healing agents on the damage induced by microcracks. By virtue of the proposed 3 D micromechanical model, the evolutionary domains of microcrack growth (DMG) and corresponding compliances of the initial, extended and repaired phases are obtained. Moreover, the elaborate studies are conducted to inspect the effects of various system parameters involving the healing efficiency, fracture toughness and preloading-induced damage degrees on the compliances and stress-strain relations. The results indicate that relatively significant healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will lead to a higher compressive strength and stiffness. However, the specimen will break owing to the nucleated microcracks rather than the repaired kinked microcracks. Further, excessive higher values of healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will not affect the compressive strength of the cementitious composites. Therefore, a stronger matrix is required. To achieve the desired healing effects, the specific parameters of both the matrix and microcapsules should be selected prudently.

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