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New Findings in Cementitious Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Construction and Building Materials".

Deadline for manuscript submissions: closed (20 July 2023) | Viewed by 32171

Special Issue Editor

Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles, CA, USA
Interests: cement chemistry and mineralogy; thermodynamic modeling; chloride in cement; characterization techniques for cement-based materials; conservation of cultural heritage
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The discovery and exploitation of materials has greatly influenced our advancement as a civilization and enabled great improvements in our quality of life. This is especially true in the case of the materials of modern construction, viz. cement, concrete, and steel, which have led to the emplacement of buildings and infrastructure which fulfill functions ranging from human habitation structures, to sanitation and water conveyance systems and infrastructure. While, unarguably, cement, concrete (i.e., a mixture of cement, sand, stone, and water), and steel have found extensive use in the construction of building and infrastructure—e.g., in the construction of framed steel and reinforced concrete structures—the environmental impact of these materials poses foundational challenges. For example, at the current level of production—around 4.2 B tons in 2018—cement alone is responsible for nearly 9% of global CO2 emissions. This number is only expected to grow as development-related construction in Asia and Africa further expands the scale of cement production. This is an issue not only for the obvious impacts on climate change, but also because the imposition of CO2 penalties is expected to, in time, double the price of cement. The implications of this are straightforward, i.e., materials engineers working in the civil engineering field need to:

  • Identify alternate materials: Identify compositionally optimal, low-CO2 materials which can be used to replace and thereby reduce the use of cement as the binder in concrete or propose novel, functionally effective, and environmentally friendly construction materials;
  • Extend the service-life of infrastructure: Develop functional pathways to mitigate steel corrosion, which is unarguably the leading cause of premature structural decay of infrastructure.

Taking all of the above into consideration, this Special Issue aims to highlight recent findings and provide useful guidelines or problem solution options to consider for scientists and engineers dealing with sustainability and durability of the construction materials.

Assist. Adj. Prof. Magdalena Balonis
Guest Editor

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Keywords

  • corrosion
  • durability
  • sustainability
  • low CO2 cements
  • admixtures
  • cement alternatives

Published Papers (16 papers)

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Research

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24 pages, 17385 KiB  
Article
Strength and Microstructure Assessment of Partially Replaced Ordinary Portland Cement and Calcium Sulfoaluminate Cement with Pozzolans and Spent Coffee Grounds
by Soorya Pushpan, Javier Ziga-Carbarín, Loth I. Rodríguez-Barboza, K. C. Sanal, Jorge L. Acevedo-Dávila, Magdalena Balonis and Lauren Y. Gómez-Zamorano
Materials 2023, 16(14), 5006; https://doi.org/10.3390/ma16145006 - 14 Jul 2023
Viewed by 918
Abstract
Supplementary cementitious materials are considered a viable and affordable way to reduce CO2 emissions from the cement industry’s perspective since they can partially or nearly entirely replace ordinary Portland cement (OPC). This study compared the impact of adding spent coffee grounds (SCGs), [...] Read more.
Supplementary cementitious materials are considered a viable and affordable way to reduce CO2 emissions from the cement industry’s perspective since they can partially or nearly entirely replace ordinary Portland cement (OPC). This study compared the impact of adding spent coffee grounds (SCGs), fly ash (FA), and volcanic ash (VA) to two types of cement: OPC and calcium sulfoaluminate cement (CSA). Cement samples were characterized using compressive strength measurements (up to 210 days of curing), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), attenuated total reflection infrared spectroscopy, and hydration temperature measurements. In all the studied systems, the presence of SCGs reduced compressive strength and delayed the hydration process. CSA composite cement containing 3.5% SCGs, 30% FA, and 30% VA showed compressive strength values of 20.4 MPa and 20.3 MPa, respectively, meeting the minimum requirement for non-structural applications. Additionally, the results indicate a formation of cementitious gel, calcium silicate hydrate (C-S-H) in the OPC-based composite cements, and calcium alumino-silicate hydrate (C-A-S-H) as well as ettringite in the CSA-based composite cements. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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15 pages, 2852 KiB  
Article
Effect of Micro-Nano Bubble Water and Silica Fume on Properties of C60 Concrete
by Shuang He, Tingshu He, Zhenmin Wan and Qing Zhao
Materials 2023, 16(13), 4684; https://doi.org/10.3390/ma16134684 - 29 Jun 2023
Viewed by 774
Abstract
Micro-nano bubble water (WNBW) in concrete is relatively uncommon due to its newness as a technology. This paper presents the preparation of C60 concrete with 35% fly ash (FA) through WNBW and varying amounts of silica fume (0%, 4%, 7%, and 10% SF). [...] Read more.
Micro-nano bubble water (WNBW) in concrete is relatively uncommon due to its newness as a technology. This paper presents the preparation of C60 concrete with 35% fly ash (FA) through WNBW and varying amounts of silica fume (0%, 4%, 7%, and 10% SF). The study examines the impact of WNBW and SF on the working performance, compressive strength, and durability of concrete. The findings indicate that applying WNBW and SF independently or jointly deteriorates the working performance of fresh concrete. However, compared to regular mixing water, WNBW reduces the concrete passing time through the V-funnel, decreasing by 40%, 39.1%, 42.9%, and 50.5% for the four varying SF contents. Furthermore, using WNBW, SF, or both resulted in the increased compressive strength of concrete at 7 days and 28 days, with 7% SF content yielding a 12.2% and 6.6% increase, respectively. Using a combination of WNBW and SF has been shown to decrease the impermeability of concrete effectively. The addition of 4% SF results in the lowest electric flux when using regular mixing water, with a discernible decrease of 30.1% compared to the control group. Conversely, using WNBW as mixing water yields a decrease in electric flux at each SF content, with the maximum decrease being 39.7%. Furthermore, both the single and combined use of these materials can contribute to the reduction in the carbonation resistance of the concrete. C60 concrete mixed with 7% SF and 100% WNBW boasts enhanced frost resistance, as indicated by the mass loss and dynamic elastic modulus loss being the least following freeze–thaw under the same SF content. According to the findings of the tests, there is evidence that the incorporation of 7% SF and 100% WNBW into C60 concrete results in lowered viscosity, a highly advantageous attribute for actual construction. Additionally, this mixture displays impressive compressive strength and durability properties. These results provide technical support regarding the integration of WNBW and SF in C60 concrete. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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18 pages, 6879 KiB  
Article
Evaluation of Light Cementitious Matrix with Composite Textile Reinforcement from Garment Waste
by Kátia Jocasta Ortiz Grings, Francisco Roger Carneiro Ribeiro, Davi Vaz André Junior, Afonso Rangel Garcez de Azevedo and Marlova Piva Kulakowski
Materials 2023, 16(2), 733; https://doi.org/10.3390/ma16020733 - 11 Jan 2023
Cited by 1 | Viewed by 1599
Abstract
The use of recycled waste has been the focus of several studies due to its potential to allow a more sustainable use of construction materials and minimize improper waste disposal in landfills or incinerators. More specifically, garment textile waste has been examined as [...] Read more.
The use of recycled waste has been the focus of several studies due to its potential to allow a more sustainable use of construction materials and minimize improper waste disposal in landfills or incinerators. More specifically, garment textile waste has been examined as internal reinforcement of cementitious matrices to increase the deformability and control fissure formation. In this study, polyester textiles are analyzed and incorporated in cementitious composites in order to evaluate their mechanical properties. Results show that significant improvements in mechanical properties of composites are obtained depending on the impregnation treatment applied to the textile waste. In the direct tensile stress test, the waste impregnation with styrene butadiene polymer plus silica fume improved 35.95% in the weft direction and 9.33% in the warp direction. Maximum stress increased 53.57% and 64.48% for composites with styrene–butadiene rubber impregnation and styrene–butadiene rubber plus silica fume impregnation, respectively, when compared to the unreinforced composite. The flexural tensile strength of composites impregnated reinforcements with styrene–butadiene rubber and styrene–butadiene rubber plus silica fume presented increases in strength by 92.10% and 94.73%, respectively, when compared to the unreinforced sample. The impact test confirmed that styrene–butadiene rubber plus silica fume impregnation produced greater tenacity of the composite. In the microstructure, it is confirmed that the impregnated textile reinforcement resulted in composites with greater adhesion between the fabric and the cementitious matrix. Thus, light textile waste is concluded to be a viable construction material for non-structural elements. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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19 pages, 4889 KiB  
Article
Evaluation of Applicability of Minimum Required Compressive Strength for Cold Weather Concreting Based on Winter Meteorological Factors
by Jiahui Cui, Nguyen Duc Van, Feng Zhang and Yukio Hama
Materials 2022, 15(23), 8490; https://doi.org/10.3390/ma15238490 - 28 Nov 2022
Cited by 5 | Viewed by 988
Abstract
In this paper, we evaluated the applicability of the minimum required compressive strength for cold weather concreting based on winter meteorological factors. In this study, a compressive strength test, dynamic elastic modulus test, hydration degree test, underwater weighing test, and freeze–thaw test were [...] Read more.
In this paper, we evaluated the applicability of the minimum required compressive strength for cold weather concreting based on winter meteorological factors. In this study, a compressive strength test, dynamic elastic modulus test, hydration degree test, underwater weighing test, and freeze–thaw test were performed to investigate the effect of compressive strength development at early ages on frost resistance of concrete. In particular, the ASTM equivalent number of cycles (CyASTMsp) of various locations was estimated based on winter meteorological factors. The results of experiments showed that the frost resistance of concrete at early ages increases with increased compressive strength. The relative dynamic modulus of elasticity of concrete of 5.0 MPa showed that it can be maintained above 90% within 18 freeze–thaw cycles. In addition, the CyASTMsp results showed that a compressive strength of 5.0 MPa can protect concrete from early age frost damage in all investigated locations, indicating that a compressive strength of 5.0 MPa is the minimum required for safe and reliable cold weather concreting. However, for concrete structures subjected to repeated freeze–thaw cycles, it is necessary to select a higher compressive strength value according to the construction condition. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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17 pages, 2809 KiB  
Article
Quantifying the Workability of Calcium Sulfoaluminate Cement Paste Using Time-Dependent Rheology
by Sukanta K. Mondal, Adam Welz, Carrie Clinton, Kamal Khayat, Aditya Kumar and Monday U. Okoronkwo
Materials 2022, 15(16), 5775; https://doi.org/10.3390/ma15165775 - 21 Aug 2022
Cited by 5 | Viewed by 1464
Abstract
Poor workability is a common feature of calcium sulfoaluminate (CSA) cement paste. Multiple chemical admixtures, such as set retarders and dispersants, are frequently employed to improve the workability and delay the setting of CSA cement paste. A quantitative assessment of the compatibility, efficiency, [...] Read more.
Poor workability is a common feature of calcium sulfoaluminate (CSA) cement paste. Multiple chemical admixtures, such as set retarders and dispersants, are frequently employed to improve the workability and delay the setting of CSA cement paste. A quantitative assessment of the compatibility, efficiency, and the effects of the admixtures on cement paste workability is critical for the design of an appropriate paste formulation and admixture proportioning. Very limited studies are available on the quantitative rheology-based method for evaluating the workability of calcium sulfoaluminate cement pastes. This study presents a novel and robust time-dependent rheological method for quantifying the workability of CSA cement pastes modified with the incorporation of citric acid as a set retarder and a polycarboxylate ether (PCE)-based superplasticizer as a dispersant. The yield stress is measured as a function of time, and the resulting curve is applied to quantify three specific workability parameters: (i) the rate at which the paste loses flowability, (ii) the time limit for paste placement or pumping, marking the onset of acceleration to initial setting, and (iii) the rate at which the paste accelerates to final setting. The results of the tested CSA systems show that the rate of the loss of flowability and the rate of hardening decrease monotonously, while the time limit for casting decreases linearly with the increase in citric acid concentration. The dosage rate of PCE has a relatively small effect on the quantified workability parameters, partly due to the competitive adsorption of citrate ions. The method demonstrated here can characterize the interaction or co-influence of multiple admixtures on early-age properties of the cement paste, thus providing a quantitative rheological protocol for determining the workability and a novel approach to material selection and mixture design. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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18 pages, 4704 KiB  
Article
Reinforced Concrete Structure Performance in Marine Structures: Analyzing Durability Indexes to Obtain More Accurate Corrosion Initiation Time Predictions
by Mauricio Arreola-Sanchez, Elia M. Alonso-Guzman, Wilfrido Martinez-Molina, Andres A. Torres-Acosta, Hugo L. Chavez-Garcia and Jose M. Ponce-Ortega
Materials 2021, 14(24), 7662; https://doi.org/10.3390/ma14247662 - 12 Dec 2021
Cited by 3 | Viewed by 2314
Abstract
This paper presents a comparison of six index properties collected during durability inspections of five Mexican seaports. Typical durability indicators such as compressive strength, saturated electrical resistivity, ultrasonic pulse velocity, percent total void content, capillary porosity, and chloride concentration profiles were analyzed to [...] Read more.
This paper presents a comparison of six index properties collected during durability inspections of five Mexican seaports. Typical durability indicators such as compressive strength, saturated electrical resistivity, ultrasonic pulse velocity, percent total void content, capillary porosity, and chloride concentration profiles were analyzed to obtain empirical correlations with the non-steady-state chloride diffusion coefficient. These indices were compared to determine correlation coefficients that are the most important for obtaining better corrosion initiation forecasting. Two models of corrosion initiation time (ti) were used: Fick’s second law of diffusion and the reported UNE-83994-2 (Spanish Association for Standardization, UNE) in which electrical resistivity was used to calculate concrete service life. The data from both models were cleaned using correlated variables, and the initial variables were compared with ti. The main result achieved was the verification of the feasibility of using correlations of variables to clean unnecessary data in order to calculate ti. Additionally, electrical resistivity was identified as one of the main durability indexes for in-service concrete structures exposed to marine environments. This is important because electrical resistivity is a non-destructive and reliable test that can be measured both in the laboratory and in the field very easily. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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15 pages, 6372 KiB  
Article
Durability Performance Indices for Cement-Based Mortars
by Rebeca Visairo-Méndez, Andrés A. Torres-Acosta and Roberto Alvarado-Cárdenas
Materials 2021, 14(11), 2758; https://doi.org/10.3390/ma14112758 - 23 May 2021
Cited by 1 | Viewed by 1546
Abstract
Corrosion-induced damaged structures are generally repaired using locally available materials. Nevertheless, determining the durability of the repair materials to be used is necessary to forecast its service life after being placed on the damaged structure. In previous investigations, the most commonly used durability [...] Read more.
Corrosion-induced damaged structures are generally repaired using locally available materials. Nevertheless, determining the durability of the repair materials to be used is necessary to forecast its service life after being placed on the damaged structure. In previous investigations, the most commonly used durability indices are saturated electrical resistivity (ρS), ultrasonic pulse velocity (UPV), total void content (TVC), water capillary absorption (WCA), rapid chloride permeability (RCP), and compressive strength (fc). Four repair mortar types were evaluated. For each mortar type, 5 × 5 cm2 cubes, 5 × 10 cm2 (small) cylinders, and 10 × 20 cm2 (large) cylinders were made from each mortar evaluated. On the basis of the present results, the durability design of mortars should consider not only the mechanical strength, but also the durability index values to define its durability performance. According to the empirical correlations obtained between all durability indices, ρS vs. RCP, TVC vs. WCA, and RCP vs. WCA were the ones with higher correlation coefficient. These correlations could be used for mortar mixture durability forecasting. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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14 pages, 4744 KiB  
Article
Composite Binder Containing Industrial By-Products (FCCCw and PSw) and Nano SiO2
by Vilma Banevičienė, Jurgita Malaiškienė, Jiri Zach and Karel Dvorak
Materials 2021, 14(7), 1604; https://doi.org/10.3390/ma14071604 - 25 Mar 2021
Cited by 5 | Viewed by 1833
Abstract
This article analyzes the integrated effect of industrial by-products (spent fluidized bed catalytic cracking catalyst waste (FCCCw) and paper sludge waste (PSw) generated in paper manufacturing) combined with nano-SiO2 (NS) on the properties of cement binder, when a certain part of the [...] Read more.
This article analyzes the integrated effect of industrial by-products (spent fluidized bed catalytic cracking catalyst waste (FCCCw) and paper sludge waste (PSw) generated in paper manufacturing) combined with nano-SiO2 (NS) on the properties of cement binder, when a certain part of the binder is replaced with the said by-products in the cement mix. Standard testing methods were used to analyze the physical and mechanical properties of cement-based materials. For structure analysis, we used X-ray diffraction (XRD), derivative thermogravimetry (DTG), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). It was found that the replacement of cement by a combined additive of FCCCw, PSw and NS is important not only for ecological reasons (abatement of CO2 emissions and recovery of waste through secondary raw materials), but also in order to enhance the properties of cement-based binders. Presumably, higher amounts of calcium silicate hydrate (CSH) and calcium alumina silicate hydrate (CASH) in the compound binder are the result of the low content of portlandite and alite in the test specimens. The specimens modified with all three additives had the highest density (~2100 kg/m3), ultrasonic pulse velocity (UPV) (~4160 m/s) and compressive strength (~105 MPa), which was ~40% higher than in the control specimens. The average pore diameter of the complex binder decreased by 21%, whereas the median pore diameter decreased by 47%. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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9 pages, 1196 KiB  
Article
Alkaline Activity of Portland Cement with Additives of Waste Glass
by Wiktor Szewczenko and Galyna Kotsay
Materials 2021, 14(6), 1346; https://doi.org/10.3390/ma14061346 - 10 Mar 2021
Cited by 6 | Viewed by 1383
Abstract
The concept of the alkaline activity of powdered materials introduced into cement compositions has been proposed, along with methods for its determination. The possibility of using waste glass as an active additive to Portland cement was evaluated from the standpoint of alkaline activity. [...] Read more.
The concept of the alkaline activity of powdered materials introduced into cement compositions has been proposed, along with methods for its determination. The possibility of using waste glass as an active additive to Portland cement was evaluated from the standpoint of alkaline activity. Replacing the Portland cement component with glass waste in the form of glass powder at amounts from 1 to 35% made it possible to maintain the cement composition’s alkaline activity at a level that met the standard requirements. The previously unknown effects of mixed alkali in Portland cement in the presence of glass waste are described. Portland cement has a high potassium alkaline activity; however, container glass has a high sodium alkaline activity and a fairly low potassium alkaline activity. When glass waste is introduced into the structure of cement compositions, potassium alkaline activity is reduced. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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14 pages, 4209 KiB  
Article
Opuntia Ficus-Indica (OFI) Mucilage as Corrosion Inhibitor of Steel in CO2-Contaminated Mortar
by Andrés A. Torres-Acosta and Paola Y. González-Calderón
Materials 2021, 14(5), 1316; https://doi.org/10.3390/ma14051316 - 09 Mar 2021
Cited by 9 | Viewed by 1973
Abstract
The present investigation is directed to determine if a natural/botanical addition, from Opuntia ficus-indica (OFI) cactus, increases durability for cement-based materials exposed to CO2-laden environments (urban and industrial). The use of this botanical addition in cement-based material applications has shown good [...] Read more.
The present investigation is directed to determine if a natural/botanical addition, from Opuntia ficus-indica (OFI) cactus, increases durability for cement-based materials exposed to CO2-laden environments (urban and industrial). The use of this botanical addition in cement-based material applications has shown good performance when these materials are exposed to chloride-laden environments, but no investigations to date have shown the performance of this addition in urban/industrial environments. Therefore, the aim of this investigation is to complement OFI mucilage performance in the most hazardous environments where most of these construction materials are naturally exposed: marine, urban, and industrial. Steel-reinforced mortar prisms, containing OFI mucilage at different addition levels (0%, 1.5%, 4%, 8%, 42%, and 95%, by water mass replacement concentration), were exposed for 14 years (5110 days) in a natural CO2-laden environment. Linear polarization resistance measurements were performed in a wet–dry cycle (between 5020 and 5110 days of age, after mortar fabrication) to determine the possible corrosion-inhibiting effect of OFI mucilage additions. Little corrosion-induced cracking was observed in carbonated mortars with OFI mucilage additions, compared with the carbonated control mortar that showed high corrosion-induced cracking. The electrochemical results showed corrosion-inhibiting efficiencies for steel in carbonated mortar with OFI mucilage additions of 40–70% for low OFI mucilage concentrations (1.5% and 4%), and 70–90% for medium and high OFI mucilage concentrations (8%, 42%, and 95%). Experimental findings suggest that adding OFI mucilage might be useful as a corrosion inhibitor for steel in carbonated cement-based materials (i.e., mortar) because corrosion rates and cracking initiation/propagation were decreased. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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32 pages, 15209 KiB  
Article
Concrete Examination of 100-Year-Old Bridge Structure above the Kłodnica River Flowing through the Agglomeration of Upper Silesia in Gliwice: A Case Study
by Barbara Słomka-Słupik, Jacek Podwórny, Beata Grynkiewicz-Bylina, Marek Salamak, Bibianna Bartoszek, Wiktoria Drzyzga and Marcel Maksara
Materials 2021, 14(4), 981; https://doi.org/10.3390/ma14040981 - 19 Feb 2021
Cited by 5 | Viewed by 2701
Abstract
The article analyzes the composition of concrete taken from various elements from a 100-year-old bridge in South Poland, so as to analyze its technical condition. The main methods applied during experimental work were: Designation of pH, free chloride content, salinity, XRD and SEM [...] Read more.
The article analyzes the composition of concrete taken from various elements from a 100-year-old bridge in South Poland, so as to analyze its technical condition. The main methods applied during experimental work were: Designation of pH, free chloride content, salinity, XRD and SEM examinations, as well as metals determination using inductively coupled plasma mass spectrometry (ICP­MS), high-performance liquid chromatography (HPLC)-ICP-MS, and cold-vapor atomic absorption spectroscopy (CV-AAS). The concrete of the bridge was strongly carbonated and decalcified with an extremely high content of chlorides. The pH of the concrete was in a range from 10.5 to 12.0. Acid soluble components were between 9.9% and 17.6%. Typical sulfate corrosion phases of concrete were not detected. Friedels’ salt was found only at the extremity of an arch. The crown block was corroded to the greatest extent. Various heavy metals were absorbed into the concrete, likely from previous centuries, when environmental protection policy was poor. The applied research methodology can be used on bridges exposed to specific external influences. The acquired knowledge can be useful in the management processes of the bridge infrastructure. It can help in making decisions about decommissioning or extending the life cycle of the bridge. This work should also sensitize researchers and decision-makers to the context of “bridge safety”. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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21 pages, 3310 KiB  
Article
Properties and Performance of Novel Mg(OH)2-Based Coatings for Corrosion Mitigation in Concrete Sewer Pipes
by Domna Merachtsaki, Georgios Fytianos, Efthimios Papastergiadis, Petros Samaras, Haris Yiannoulakis and Anastasios Zouboulis
Materials 2020, 13(22), 5291; https://doi.org/10.3390/ma13225291 - 23 Nov 2020
Cited by 18 | Viewed by 2567
Abstract
The biological activity occurring in urban sewerage systems usually leads to the (biogenic) corrosion of pipe infrastructure. Anti-corrosion coating technology was developed in an effort to protect sewer pipes from degradation. This study evaluates a new class of relatively low-cost magnesium hydroxide-based coatings, [...] Read more.
The biological activity occurring in urban sewerage systems usually leads to the (biogenic) corrosion of pipe infrastructure. Anti-corrosion coating technology was developed in an effort to protect sewer pipes from degradation. This study evaluates a new class of relatively low-cost magnesium hydroxide-based coatings, regarding their ability to adhere efficiently onto the concrete surface, and offer efficient corrosion protection. Six magnesium hydroxide-based coatings were prepared with the addition of two different types of cellulose, used as adhesion additives, and these were applied on concrete specimens. Pull-off measurements showed that the addition of higher amounts of cellulose could improve the coating adhesion onto the concrete surface. An accelerated sulfuric acid spraying test was used to evaluate the consumption time of the applied coatings and their efficiency in maintaining over time slightly alkaline pH values (above 8) on the coated/protected surfaces. At the end of spraying test, a mineralogical analysis of surface samples was performed, indicating that the formation of corrosion by-products (mainly gypsum) was increased when the added amount of cellulose was lower. Hardness and roughness measurements were also conducted on the concrete surfaces, revealing that the coatings helped the concrete surface to preserve its initial surface properties, in comparison to the uncoated specimens. A SEM/microstructure analysis showed that aggregates were formed (possibly consisting of Mg(OH)2), affecting the reactivity of the protected surface against sulfuric acid attack. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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21 pages, 22928 KiB  
Article
The Examination of Hydrated Cement Paste Made of CEM III/A 42,5 N-LH/HSR/NA under the Influence of Urea Solution
by Barbara Słomka-Słupik
Materials 2020, 13(21), 4984; https://doi.org/10.3390/ma13214984 - 05 Nov 2020
Cited by 4 | Viewed by 1520
Abstract
The production of urea, used inter alia in agriculture, is increasing. Therefore, urea hydrolysis products are expected in groundwater. Due to lack of new research on the influence of urea on the technical condition of concrete structures, the changes that this compound may [...] Read more.
The production of urea, used inter alia in agriculture, is increasing. Therefore, urea hydrolysis products are expected in groundwater. Due to lack of new research on the influence of urea on the technical condition of concrete structures, the changes that this compound may cause to hardened cement paste were initially check. After 11 months of immersion of hardened cement paste in 20% CO(NH2)2 solution, tests were conducted at different depths of penetration. A pH of 11.97 was recorded in the first layer with a thickness of 0.5 mm, and the pH of the innermost layer was 12.48. The decalcification process and the formation of predominantly secondary calcite in the edge layers were confirmed using XRD, SEM, and analytical methods. No nitrogen phase was formed, but the deeper was the layer, more wollastonite was present. Moreover, up to a depth of about 20 mm, the sample was mechanically weak-breakable by the force of the hands. The examination of the filtrate’s conductivity, leachable calcium content, and pH along the way of urea diffusion confirmed changes in the examined material. When analyzing the technical condition of concrete treated with urea, pH could be an indicator due to the possibility of buffer reactions. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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14 pages, 3848 KiB  
Article
Heat-Induced Acceleration of Pozzolanic Reaction Under Restrained Conditions and Consequent Structural Modification
by Nankyoung Lee, Yeonung Jeong, Hyunuk Kang and Juhyuk Moon
Materials 2020, 13(13), 2950; https://doi.org/10.3390/ma13132950 - 01 Jul 2020
Cited by 13 | Viewed by 3070
Abstract
This study investigated the heat-induced acceleration of cement hydration and pozzolanic reaction focusing on mechanical performance and structural modification at the meso- and micro-scale. The pozzolanic reaction was implemented by substituting 20 wt.% of cement with silica fume, considered the typical dosage of [...] Read more.
This study investigated the heat-induced acceleration of cement hydration and pozzolanic reaction focusing on mechanical performance and structural modification at the meso- and micro-scale. The pozzolanic reaction was implemented by substituting 20 wt.% of cement with silica fume, considered the typical dosage of silica fume in ultra-high performance concrete. By actively consuming a limited amount of water and outer-formed portlandite on the unreacted cement grains, it was confirmed that high-temperature curing greatly enhances the pozzolanic reaction when compared with cement hydration under the same environment. The rate of strength development from the dual reactions of cement hydration and pozzolanic reaction was increased. After the high-temperature curing, further strength development was negligible because of the limited space availability and preconsumption of water under a low water-to-cement environment. Since the pozzolanic reaction does not directly require the anhydrous cement, the reaction can be more easily accelerated under restrained conditions because it does not heavily rely on the diffusion of the limited amount of water. Therefore, it significantly increases the mean chain length of the C–S–H, the size of C–S–H globules with a higher surface fractal dimension. This finding will be helpful in understanding the complicated hydration mechanism of high-strength concrete or ultra-high performance concrete, which has a very low water-to-cement ratio. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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14 pages, 4451 KiB  
Article
Effects of Calcination Conditions on the Formation and Hydration Performance of High-Alite White Portland Cement Clinker
by Lei Huang, Geling Cheng and Shaowen Huang
Materials 2020, 13(3), 494; https://doi.org/10.3390/ma13030494 - 21 Jan 2020
Cited by 11 | Viewed by 2554
Abstract
The purpose of this study was to evaluate the effects of sintering temperature and sintering time on mineral composition of high-alite white Portland cement clinker and hydration activity of the clinker. Effects of sintering temperature and sintering time on clinker mineral composition, C [...] Read more.
The purpose of this study was to evaluate the effects of sintering temperature and sintering time on mineral composition of high-alite white Portland cement clinker and hydration activity of the clinker. Effects of sintering temperature and sintering time on clinker mineral composition, C3S polymorph and size and hydration heat release rate were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), differential scanning calorimetry&Thermogravimetric Analysis (DSC-TG) and isothermal heat-conduction calorimetry. Results shown that, with the increase of sintering temperature (1450–1525 °C) and sintering time (60–240 min), free lime (f-CaO) in clinker decreased, C3S grain size increased, and C3S crystal type changed from T3 to M type and R type, which exhibits higher symmetry. The hydration activity of different C3S crystals ranged from high to low as follows: T3→M1→M3→R@. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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Review

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27 pages, 74594 KiB  
Review
Microorganism, Carriers, and Immobilization Methods of the Microbial Self-Healing Cement-Based Composites: A Review
by Li’an Shen, Wenlu Yu, Lin Li, Tong Zhang, Ismail Yusuf Abshir, Pingping Luo and Zhuangzhuang Liu
Materials 2021, 14(17), 5116; https://doi.org/10.3390/ma14175116 - 06 Sep 2021
Cited by 15 | Viewed by 3336
Abstract
Low tensile strength, poor elastic modulus, and complex concrete cracking work condition are almost unavoidable due to the intrinsic brittleness. To deal with concrete maintenance and durability, microbial self-healing concretes have been rapidly developed and widely applied recently. The microbial self-healing can specifically [...] Read more.
Low tensile strength, poor elastic modulus, and complex concrete cracking work condition are almost unavoidable due to the intrinsic brittleness. To deal with concrete maintenance and durability, microbial self-healing concretes have been rapidly developed and widely applied recently. The microbial self-healing can specifically patch fractures as well as boost the concrete structure’s capacity, durability, and permeability. This paper presents the state-of-the-art in the microbe induced self-healing in cement-based composites. The microorganism and carriers were classified according to the working theory and repair effects. Additionally, the precise efficiency and effect of various technologies are also evaluated for microbial immobilization. Based on the literature review and summary from the perspective of microorganism, carriers, and immobilization methods, challenges and further works are discussed. Full article
(This article belongs to the Special Issue New Findings in Cementitious Materials)
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