scholarly journals Preparation and Characterization of Self-Healing Mortar Based on “Build-In” Carbonation

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 644
Author(s):  
Xin Wang ◽  
Wenting Li ◽  
Zhengwu Jiang
Keyword(s):  
Healing Rate ◽  
Cement Mortar ◽  
Setting Time ◽  
Heat Of Hydration ◽  
Self Healing ◽  
Pore Filling ◽  
Healing Efficiency ◽  
Negative Effect ◽  
New Type

In this study, a new type of cement-based healing pellets (CHPs) were proposed to accelerate the healing efficiency of concrete, which was mainly based on the introduced Na2CO3 on promoting the formation of calcium carbonate (CaCO3) in cracks. The effects of Na2CO3 on the characteristics of CHPs were firstly investigated, and then the properties of cement mortar mixed with CHPs were studied quantitatively, including the workability, mechanical properties and healing ability. The results showed that higher dosages of Na2CO3 in CHPs decreased the size range of pellets and reduced the setting time, fluidity and heat of hydration of mortar. Still more, CHPs reduced the early strength of mortar but kept the intensity growth rate stable such that it had nearly no negative effect on the later strength. With the content of CHPs increasing, the strength of mortar showed a decreasing trend, while the pore-filling efficiency and strength healing rate of mortar were further improved. In addition, as a new type of self-healing pellets for concrete based on the “build-in” carbonation, CHPs improved the strength and healing effectiveness of cement mortar. When the dosage of Na2CO3 in CHPs and the content of CHPs in mortar were at 10% and 25%, respectively, mortar obtained highest strength in the later stage and the best healing effect.

Effect of furfuryl alcohol on the properties of hydrated cement mortar

2003 ◽  
Vol 18 (5) ◽  
pp. 1131-1140 ◽  
Author(s):  
V. K. Singh ◽  
R. K. Singh ◽  
S. D. Khatri
Keyword(s):  
Corrosion Resistance ◽  
Water Absorption ◽  
Open Porosity ◽  
Furfuryl Alcohol ◽  
Bending Strength ◽  
Cement Mortar ◽  
Setting Time ◽  
Heat Of Hydration ◽  
Indentation Method ◽  
Three Point Bending

The effect of furfuryl alcohol addition to ordinary cement on its properties, such as heat of hydration, setting time, compressive strength, and tensile strength was studied by adding 0.5–3.0% by weight of cement. Hardness was tested using the Vickers indentation method. Fracture toughness of cementitious bond and bending strength were determined using the three-point bending system. Corrosion resistance of resulting products was tested against 0.1 and 1.0 N HCI and H2SO4 and seawater, respectively. Water absorption/open porosity and microstructure were also determined. It was observed that strength, hardness, toughness, and corrosion resistance increase up to 3.0% addition of furfuryl alcohol in ordinary Portland cement. Polymeric phase was interspersed in cement, causing a decrease in water absorption/open porosity, and its interaction with hydrating cement caused additional bond formation, leading to the increase in strength.

Characterization of Self-Healing Processes Induced by Calcium Nitrate Microcapsules in Cement Mortar

2017 ◽  
Vol 29 (1) ◽  
pp. 04016189 ◽  
Author(s):  
Gabriel A. Arce ◽  
Marwa M. Hassan ◽  
Louay N. Mohammad ◽  
Tyson Rupnow
Keyword(s):  
Cement Mortar ◽  
Calcium Nitrate ◽  
Self Healing ◽  
Healing Processes

scholarly journals Preparation and Performance of a New-Type Alkali-Free Liquid Accelerator for Shotcrete

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Yanping Sheng ◽  
Bin Xue ◽  
Haibin Li ◽  
Yunyan Qiao ◽  
Huaxin Chen ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Cement Mortar ◽  
Retention Rate ◽  
Setting Time ◽  
Test Results ◽  
Initial Setting Time ◽  
Initial Setting ◽  
New Type ◽  
And Performance

A new type of alkali-free liquid accelerator for shotcrete was prepared. Specifically, the setting time and strength and shrinkage performance of two kinds of Portland cement with the accelerator were fully investigated. Moreover, the accelerating mechanism of alkali-free liquid accelerator and the hydration process of the shotcrete with accelerator were explored. Results show that alkali-free liquid accelerator significantly shortened the setting time of cement paste, where the initial setting time of cement paste with 8 wt% of the accelerator was about 3 min and the final setting time was about 7 min. Compressive strength at 1 day of cement mortar with the accelerator could reach 23.4 MPa, which increased by 36.2% compared to the strength of cement mortar without the accelerator, and the retention rate of 28-day compressive strength reached 110%. In addition, the accelerator still shows a good accelerating effect under low temperature conditions. However, the shrinkage rate of the concrete increased with the amount of the accelerator. 5~8% content of accelerator is recommended for shotcrete in practice. XRD and SEM test results showed that the alkali-free liquid accelerator promoted the formation of ettringite crystals due to the increase of Al3+ and SO42- concentration.

scholarly journals AN INVESTIGATION ON THE USE OF BACILLUS SUBTILIS HU58 IN CEMENT MORTAR

2017 ◽  
Vol 7 (2) ◽  
pp. 1-8
Author(s):  
Nguyen Ngoc Tri Huynh ◽  
Nguyen Khanh Son
Keyword(s):  
Bacillus Subtilis ◽  
Calcium Carbonate ◽  
Portland Cement ◽  
Cement Mortar ◽  
Cement Matrix ◽  
Self Healing ◽  
Curing Time ◽  
Mortar Sample ◽  
New Type ◽  
Compressive And Flexural Strengths

Literature studies reveal the fact that incorporating bacteria into cement matrix could generate the formation of precipitated product of calcium carbonate. In this work, a new type of microorganism Bacillus subtilis HU58 was used as mixing component in formulating mortar sample of Portland cement and the effectiveness of self-healing character after 1 year of curing time was observed. Results showed the consequence in the enhancement of both compressive and flexural strengths of bacteria-modified mortar while comparing to a controlled mortar: 60MPa>56MPa (in compression) and 11MPa >9MPa (in flexion). Furthermore, those pre-existing artificial cracks 1mm in width of the prismatic mortar 40x40x160mm filled up partially (self-healing) by mineral glue.

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 Use of Methylcellulose-Based Pellet to Enhance the Bacterial Self-Healing of Cement Composite

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6113
Author(s):  
Indong Jang ◽  
Dasom Son ◽  
Yongjun Son ◽  
Jihyeon Min ◽  
Chongku Yi
Keyword(s):  
Cement Composite ◽  
Bacterial Spores ◽  
Early Age ◽  
Self Healing ◽  
Healing Efficiency ◽  
Alkaline Environments ◽  
New Type ◽  
Main Component ◽  
Early Age Concrete ◽  
Number Of Bacteria

In this study, a new type of bacterial carrier using methylcellulose was presented, and its applicability to self-healing concrete has been explored. Methylcellulose, the main component of a 2 mm pellet-shaped carrier, can remain stable in alkaline environments and expand in neutral or acidic environments. These properties allow bacteria to survive in the high-alkaline and high-pressure environments of early age concrete, and the number of bacteria increases rapidly in the event of cracks, accelerating crack closure. The results show that the survival rate of bacterial spores inside the mortar was increased, and the pellet provides an enhanced biological anchor suitable for bacterial activity, bacterial growth, and mineral precipitation. Further, the results indicate an improved self-healing efficiency compared with mixing bacteria directly into the cement composite.

An Innovative Admixture to Enhance the Fresh Properties of Slag Pastes

2013 ◽  
Vol 477-478 ◽  
pp. 915-919
Author(s):  
Qun Pan ◽  
Shuang Zhao ◽  
Han Ying Zheng ◽  
Bin Zhu
Keyword(s):  
Setting Time ◽  
Heat Of Hydration ◽  
Fresh Properties ◽  
Slag Cement ◽  
Setting Times ◽  
Initial Setting ◽  
New Type ◽  
Activated Slag ◽  
Alkali Activated ◽  
Initial Peak

This study reports a new type compound admixture YP developed for slag cement activated by water glass. The effect of the compound admixture on properties of slag pastes, including mini slump, setting time and heat of hydration was examined. It is found that the slump of slag paste was increased from 60 mm to 120 mm by using the admixture. Furthermore, the initial and final setting times of paste with the admixture were 96 min and 132 min, while it only took 18 min and 23 min to achieve initial setting and final setting for the paste without using the admixture. In addition, the results also indicate that the initial peak was delayed for nearly 7 hours and the heat flow of hydration was reduced from 5864 μw/g to 461μw/g, when the admixture was added. It can be concluded that the new admixture is capable of imparting a significant improvement of workability of alkali-activated slag cement with a suitable setting behavior.

scholarly journals Technological aspects of usage of calcareous fly ash as a main constituent of cements

2021 ◽  
Author(s):  
Jacek Gołaszewski ◽  
Tomasz Ponikiewski ◽  
Aleksandra Kostrzanowska-Siedlarz ◽  
Patrycja Miera
Keyword(s):  
Fly Ash ◽  
Setting Time ◽  
Volume Density ◽  
Economic Benefits ◽  
Heat Of Hydration ◽  
Cement Production ◽  
Air Content ◽  
Plastic Shrinkage ◽  
Negative Effect ◽  
Mineral Additives

The use of mineral additives allows you to modify the properties of concrete and result in substantial economic benefits. The research the influence cement type with calcareous fly ash (W) content in cement, method of cement production, activation by grinding calcium fly ash and batch of fly ash on the rheology, plastic shrinkage, air content, the setting time and heat of hydration of mortar are presented in this paper. The results show that cements produced by intergrinding of the constituents or blending with fly ash pre-processed by milling, are characterized by acceptable technological properties, not differing significantly from other currently used cements. It is not recommended to use cements obtained by blending with raw calcareous fly ash W. Calcareous fly ash used for the production of cement should be selected because of its properties. According to conducted tests, this criterion can be the volume density of the ash, which should be at least 900 kg/m3. The negative effect of calcareous fly ash used as an additive for cement on workability is considerably smaller than when it is used as an additive type II.

scholarly journals Preparation and characterization of a high strength self-repairing galactomannan hydrogel

BioResources ◽  
2019 ◽  
Vol 14 (4) ◽  
pp. 9853-9866
Author(s):  
Jiufang Duan ◽  
Yuxue Gao ◽  
Yirong Huang ◽  
Lin Li ◽  
Jianxin Jiang
Keyword(s):  
Methylene Blue ◽  
Water Absorption ◽  
Removal Rate ◽  
High Strength ◽  
Maximum Adsorption Capacity ◽  
Self Healing ◽  
Healing Efficiency ◽  
Maximum Water ◽  
Water Absorption Property

Autonomous self-repairing properties can prolong the service life of materials. In this paper, galactomannan hydrogel with high mechanical strength was prepared by graft copolymerization of galactomannan with acrylamide and octadecyl methacrylate in aqueous solution. The microstructure, water absorption property, self-healing behavior, and mechanical properties of the hydrogels were investigated using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM), etc. The galactomannan hydrogel had the highest tensile strength of 49 KPa and strain of 3000%. The water absorption reached 2340%, and the removal rate of methylene blue was more than 80%. Galactomannan hydrogels demonstrated significant self-healing properties. The cut hydrogel was quite effective in self-repairing in a few minutes, and the self-repairing strength increased with increasing contact time of hydrogel cut surfaces. The healing efficiency of fracture strain could reach 92.7% of the original sample in 10 h. The maximum water absorption of hydrogel reached 2340%. The maximum removal rate of methylene blue by hydrogel reached 80.5%, and the maximum adsorption capacity was 19.3 mg/g. The novelty of the work lies in octadecyl methacrylate being used for galactomannan cross-linking with the ability to self-repair after fracture. The galactomannan self-healing hydrogel has potential in water treatment and sealing technology.

ON THE USE OF SLAG CEMENT COMPOSITIONS IN THE CONSTRUCTION OF WELLS

2017 ◽  
pp. 80-85
Author(s):  
V. P. Ovchinnikov ◽  
O. V. Rozhkova ◽  
N. A. Aksenova ◽  
P. V. Ovchinnikov
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Elevated Temperatures ◽  
Cement Mortar ◽  
Setting Time ◽  
Rheological Parameters ◽  
Slag Cement ◽  
Furnace Slag

In the article studies of oil-filled compositions with the addition of blast-furnace slag for strength at elevated temperatures are presented. The rheological parameters of the slag cement slag cement mortar, as well as the setting time, were studied. Conclusions are drawn about the prospects of further study of slag cementcontaining compositions.

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