scholarly journals Calcium hydroxide influence in autogenous self-healing of cement-based materials in various environmental conditions

2021 ◽  
Vol 21 (2) ◽  
pp. 209-224
Author(s):  
Deividi Maurente Gomes da Silva ◽  
Vanessa Giaretton Cappellesso ◽  
Maurício Germano Lopes Garcia ◽  
Angela Borges Masuero ◽  
Denise Carpena Coitinho Dal Molin
Keyword(s):  
Portland Cement ◽  
Calcium Hydroxide ◽  
Environmental Conditions ◽  
Water Source ◽  
The Self ◽  
Self Healing ◽  
Cement Type ◽  
Initial Strength ◽  
Cement Based Materials ◽  
Type V

Abstract Several factors, such as chemical shrinkage or environmental attack can produce concrete cracks. Calcium hydroxide content from the environment or cement hydration can promote the self-healing phenomenon (SHP). This study evaluates the calcium hydroxide concentration influence on the self-healing phenomenon of cement-based materials. Cracked mortars with different types of cement, such as a filler, pozzolanic, and high initial strength, were exposed to four environmental conditions. Titration was the method proposed to determine the amount of calcium hydroxide content leached in the water, and the cracks closure were analyzed by optical microscopy. CPII F (Portland Cement, type II, compound with limestone) samples showed no trend to Ca(OH)2 leached, and to superficial cracking closure. Regarding CPV (Portland cement, type V, high initial strength cement) samples, their behavior showed the highest Ca(OH)2 content to all environmental exposure, and cracking closure to samples in submerged condition. Thus, a significant influence in the cracks´ closure regarding the presence of Ca2+ leached to the exposure environments, and a water source related to this behavior seems to be a primary factor to improve the SHP.

An FTIR, SEM and EDS investigation of solidification/ stabilization of chromium using portland cement Type V and Type IP

1992 ◽  
Vol 30 (3) ◽  
pp. 273-283 ◽  
Author(s):  
M.Yousuf A. Mollah ◽  
Yung-Nien Tsai ◽  
Thomas R. Hess ◽  
David L. Cocke
Keyword(s):  
Portland Cement ◽  
Cement Type ◽  
Type V

scholarly journals Experimental Characterization of the Self-Healing Capacity of Cement Based Materials: An Overview

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 454 ◽  
Author(s):  
Liberato Ferrara ◽  
Estefania Cuenca Asensio ◽  
Francesco Lo Monte ◽  
Marta Roig Flores ◽  
Mercedes Sanchez Moreno ◽  
...  
Keyword(s):  
The Self ◽  
Self Healing ◽  
Experimental Characterization ◽  
Cement Based Materials

scholarly journals Self-Healing Properties of Bioinspired Amorphous CaCO3/Polyphosphate-Supplemented Cement

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2360 ◽  
Author(s):  
Emad Tolba ◽  
Shunfeng Wang ◽  
Xiaohong Wang ◽  
Meik Neufurth ◽  
Maximilian Ackermann ◽  
...  
Keyword(s):  
Portland Cement ◽  
The Self ◽  
Progressive Damage ◽  
Hydrated Cement ◽  
Self Healing ◽  
Natural Polymer ◽  
Cement Concrete ◽  
Amorphous Calcium Carbonate ◽  
Inorganic Polyphosphate ◽  
Repair Capacity

There is a strong interest in cement additives that are able to prevent or mitigate the adverse effects of cracks in concrete that cause corrosion of the reinforcement. Inorganic polyphosphate (polyP), a natural polymer that is synthesized by bacteria, even those on cement/concrete, can increase the resistance of concrete to progressive damage from micro-cracking. Here we use a novel bioinspired strategy based on polyP-stabilized amorphous calcium carbonate (ACC) to give this material self-healing properties. Portland cement was supplemented with ACC nanoparticles which were stabilized with 10% (w/w) Na–polyP. Embedding these particles in the hydrated cement resulted in the formation of calcite crystals after a hardening time of 10 days, which were not seen in controls, indicating that the particles dissolve and then transform into calcite. While there was no significant repair in the controls without ACC, almost complete closure of the cracks was observed after a 10 days healing period in the ACC-supplemented samples. Nanoindentation measurements on the self-healed crack surfaces showed a similar or slightly higher elasticity at a lower hardness compared to non-cracked surfaces. Our results demonstrate that bioinspired approaches, like the use of polyP-stabilized ACC shown here, can significantly improve the repair capacity of Portland cement.

scholarly journals The Effect of Exposure on the Autogenous Self-Healing of Ordinary Portland Cement Mortars

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3926 ◽  
Author(s):  
Magdalena Rajczakowska ◽  
Karin Habermehl-Cwirzen ◽  
Hans Hedlund ◽  
Andrzej Cwirzen
Keyword(s):  
Calcium Carbonate ◽  
Portland Cement ◽  
Crack Closure ◽  
Water Immersion ◽  
Pure Water ◽  
Healing Process ◽  
Silica Particles ◽  
The Self ◽  
Phase Identification ◽  
Self Healing

Exposure conditions are critical for the autogenous self-healing process of Portland cement based binder matrixes. However, there is still a significant lack of fundamental knowledge related to this factor. The aim of this paper was to investigate and understand the effects of various potentially applicable curing solutions on the efficiency of the crack closure occurring both superficially and internally. Four groups of exposures were tested, including exposure with different water immersion regimes, variable temperatures, application of chemical admixtures, and use of solutions containing micro particles. The self-healing process was evaluated externally, at the surface of the crack, and internally, at different crack depths with the use of optical and scanning electron microscopes (SEM). The phase identification was done with an energy dispersive spectrometer combined with the SEM. The results showed very limited self-healing in all pure water-based exposures, despite the application of different cycles, temperatures, and water volumes. The addition of a phosphate-based retarding admixture demonstrated the highest crack closure, both internally and externally. The highest strength recovery and a very good crack closure ratio was achieved in water exposure containing micro silica particles. The main phase observed on the surface was calcium carbonate, and internally, calcium silicate hydrate, calcium carbonate, and calcium phosphate compounds. Phosphate ions were found to contribute to the filling of the crack, most likely by preventing the formation of a dense shell composed of hydration phases on the exposed areas by crack unhydrated cement grains as well as by the additional precipitation of calcium and phosphate-based compounds. The micro sized silica particles presumably served as nucleation sites for the self-healing products growth. Changes in the chemical composition of the self-healing material were observed with a distance from the surface of the specimen.

scholarly journals Research on the Improvement of Concrete Autogenous Self-healing Based on the Regulation of Cement Particle Size Distribution (PSD)

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2818 ◽  
Author(s):  
Lianwang Yuan ◽  
Shuaishuai Chen ◽  
Shoude Wang ◽  
Yongbo Huang ◽  
Qingkuan Yang ◽  
...  
Keyword(s):  
Particle Size ◽  
Portland Cement ◽  
Ultrasonic Test ◽  
The Self ◽  
Internal Crack ◽  
Cement Particle ◽  
Hydrated Cement ◽  
Self Healing ◽  
Optical Micrograph ◽  
Suitable Amount

Overgrinding of Portland cement brings excessive shrinkage and poor self-healing ability to concrete. In this paper, through the ultrasonic test and optical micrograph observation, the self-healing properties of concrete prepared by cement with different particle size distributions were studied. Besides, the effect of carbonation and continued hydration on self-healing of concrete was analyzed. Results show that, for the Portland cement containing more particles with the size 30~60 μm, the concrete could achieve a better self-healing ability of concrete at 28 days. For the two methods to characterize the self-healing properties of concrete, the ultrasonic test is more accurate in characterizing the self-healing of internal crack than optical micrograph observation. The autogenous self-healing of concrete is jointly affected by the continued hydration and carbonation. At 7 days and 30 days, the autogenous self-healing of concrete is mainly controlled by the continued hydration and carbonation, respectively. The cement particle size could affect the continued hydration by affecting un-hydrated cement content and the carbonation by affecting the Ca(OH)2 content. Therefore, a proper distribution of cement particle size, which brings a suitable amount of Ca(OH)2 and un-hydrated cement, could improve the self-healing ability of concrete.

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