Use Of Cementitious Materials Research Articles

Cleaner Production of Cementitious Materials Containing Bioaggregates Based on Mussel Shells: A Review

This text provides a bibliographic review on bioaggregates obtained from mussel shells and similar materials, evaluating the main properties altered with the use of this type of recycled aggregate in cementitious materials. The bibliographic analysis highlights the main problems and challenges of using bioaggregates related to the presence of organic impurities and chlorides and due to the lamellar and flat shape of the grains, which impair adhesion in the transition zone. The advantages of mussel shell bioaggregates include their limestone-based chemical composition, properties that are inert and compatible with the application, and a specific mass close to conventional aggregates. Regarding their use in cementitious materials, in general, there is a reduction in workability and an increase in incorporated air, porosity, and water absorption, resulting in a reduction in compressive strength. However, it is observed that lower replacement levels make it possible to use bioaggregates, especially fine aggregates, in cementitious materials for different applications, such as structural concrete, coating mortar, and sealing systems. The positive points are related to the promotion of thermal insulation and the reduction in density, which allow for various uses for cementitious materials with bioaggregates, such as lightweight concrete, permeable concrete, and thermal and acoustic insulation mortars. It is concluded that the use of bioaggregates in concrete and mortars is viable, but the need for more experimental work to solve the main problems encountered, such as high water absorption and low compressive strength, is highlighted.

Cementitious composites for structural strengthening of reinforced concrete members: A review

Abstract Existing concrete buildings are always in need of repair or renovation as they are getting older, carrying more weight, or needing to be redesigned. The most common materials used to strengthen concrete structures are ferrocement, fiber-reinforced polymer, engineered cementitious composite, and ultra-high-performance concrete. However, there are some other methods and materials that can be used as well. There are pros and cons to every composite material that is unique to it. Each material works very well in certain situations and is known around the world for being able to be used in a wide range of situations. This paper gives a brief overview of several cement-based strengthening materials that have shown very promising results when used to repair older structures. This review looks at certain factors, such as how to retrofit a structure for bending, shear, and confinement. In conclusion, more studies should be done to come up with flexible industry standards for the use of cementitious materials to strengthen structures made of reinforced concrete.

Reviewing experimental studies on sensible thermal energy storage in cementitious composites: report of the RILEM TC 299-TES

Thermal energy storage (TES) systems have been a subject of growing interest due to their potential to address the challenges of intermittent renewable energy sources. In this context, cementitious materials are emerging as a promising TES media because of their relative low cost, good thermal properties and ease of handling. This article presents a comprehensive review of studies exploring the use of cementitious materials, particularly concrete, as sensible heat storage media at varying scales, ranging from laboratory investigations to prototype evaluations. Starting from the different kinds of energy storage systems and applications where concrete has been used as a storage media, this article reviews the important properties which makes them a suitable material for the purpose. Reported observations are discussed and summarised based on concrete mix composition/design, aggregate/addition type, size gradation, etc., and performance of these materials. Finally, different cement-based prototypes are examined highlighting their strengths and weaknesses, and general conclusions are drawn.

Understanding the multiple actions of phosphoric acid-modified steel slag powder on early-age hydration of cement

The retardation of the early-age hydration of cement by steel slag powder severely restricts its use in cementitious materials. This paper reports on the modification of steel slag powder with phosphoric acid, which is found to alleviate its inhibition of cement hydration. Comprehensive investigations of solid phase assemblage and elements dissolving behavior in cement pastes reveal that multiple actions combine to determine the effect of phosphoric acid-modified steel slag powder on cement hydration. By using an appropriate amount of phosphoric acid for modification, a noteworthy reduction in C12A7 content and a significant increase in the specific surface area of steel slag powder can be achieved. This consequently diminishes the negative inhibitory effect of steel slag powder on hydration. However, excessive use of phosphoric acid exacerbates the delayed effect of calcium phosphate on mineral dissolution, so that the inhibitory effect of steel slag powder on cement hydration cannot be alleviated.

Utilization of Cement and Concrete for Deep Sea Infrastructure

AbstractThe use of cementitious materials in deep sea environments, focusing on the durability challenges of low‐temperature seawater and hydraulic pressure, are presented in this paper. The authors conducted laboratory and deep‐sea field experiments, thermodynamic calculation, and evaluated the performance of different types of binders in deep sea conditions. Durability of rebar in cementitious materials was investigated. In situ construction methods using cementitious materials was demonstrated on the deep‐sea field. Testing results revealed that deep sea conditions, especially low‐temperature seawater, can accelerate the disintegration of cement hydrates, and the use of pozzolanic admixture and calcium aluminate cement can improve its resistance. Our study provides valuable insights and applicability of cementitious materials to deep sea infrastructure construction.

Preparation of coatings for moisture migration control of cementitious materials under low-vacuum environment

Moisture dispersion restricts the long-term use of cementitious materials in vacuum pipeline beams. This study designs a fire-new coating merging organic (silica sol-modified polyacrylate) with inorganic surface modifiers (water glass). The coating on the mortar surface can mitigate its mass loss, with the coating composed of polyacrylate, silica sol, and water glass (in a mass ratio of 72:18:10) being the most promising improvement. This interpenetrating organic–inorganic network structure penetrates into mortar and reacts with hydration products to produce new substances and more dense structure. These findings provide valuable insights into enhancing the durability of cementitious materials under low-vacuum conditions.

Analysis of the Microstructure and Porosity of Cement Pastes with Functionalized Nanosilica with Different Contents of Aminosilane.

This research aims to analyze the effect of functionalized nanosilica (NSF) with different levels of amine groups in the formation of hydration products. Four cement pastes were investigated, one reference with Portland cement and three replacing 1% of Portland cement by nanosilica (NS), NSF with a low content of amine groups, and NSF with a high content of amine groups. The heat of hydration of the pastes was evaluated up to 7 days of hydration, the amount of calcium hydroxide (CH) and hydrated phases by means of the thermogravimetric analysis (TGA) test and compressive strength at 2, 7, and 28 days, and porosity through tests of mercury intrusion porosimetry and computed tomography at 28 days of hydration. It was possible to observe that the NSF directly influenced the hydration kinetics of the pastes, delaying the hydration of the Portland cement; however, it demonstrated a similar mechanical performance to the paste with NS at 2 days of hydration and an increase of 10% at 28 days of hydration due to the improvement in the hydration process. Thus, it is possible to conclude that the functionalization of NSF with a low 3-aminopropyltriethoxysilane (APTES) content is promising for use in cementitious materials and may improve hydration and mechanical performance at more advanced ages compared to NS.

First study of Micromonospora echinospora isolation from a rocky site of Eastern Algeria and first report of its potential use in cementitious materials biohealing

In recent years, bio-healing based on microbial induced carbonate precipitation in cracks has been widely exploited to improve concrete properties and thus increase its durability. In this context, the present study aims to explore the possibility of using nine bacterial isolates as biohealing agent of cementitious materials; these bacteria (coded B1 to B8) were obtained from the three different rocky sites, i.e., 795 L1 (limestone rock site), 795 L2 (ordinary soil site), and 812 (clayey site); situated in Oulad Rahmoun (Constantine-Algeria). The primary identification showed that eight isolates belonged to a Bacillus genus, and one isolate B8 developed particularly morphological characterized by branched and septate hyphae. The isolates B4 and B8 were selected for their ability to produce calcium carbonate in precipitate calcium (PC) liquid and solid media after five days of incubation. The addition of urea in PC liquid media accelerated the formation of calcite which appeared after 3 days of incubation. The growth curve of both selected isolates on LB liquid medium showed that B8 was characterized by a long exponential growth phase (up to 72 hours) compared to B4 which had an exponential phase up to 48 hours, which could explain the largest amount of calcite precipitate observed in the case of B8 cultivated in PC liquid medium. Results of the bio-healing experiment carried on cementitious batches showed that a beginning of a slight repair of the cracks from the 11th day was only observed in the case of the bacterium B8 but the bio-healing capacity was absent in the control. This bio-healing agent was identified as Micromonospora echinospora (NCBI-NO139612), according to N-Blast of 16S-DNA sequence. In conclusion, the present study is the first to isolate M. echinospora species from rocky sites; and to describe it as an efficient bacterial agent in concrete bio-healing applications.

Crack morphology tailoring and permeability prediction of polyvinyl alcohol -steel hybrid fiber engineered cementitious composites

The intrinsic tensile strain-hardening properties of engineered cementitious composites (ECC) determines its multiple cracking and crack control characteristics. The relatively low permeability of cracked ECC is of special significance for more efficient use of cementitious materials, which contributes to the mitigation of carbon emissions. The crack morphology of ECC plays an important role in tailoring the permeability of cracked ECC, as well as the durability of structures made or strengthened by ECC. In the present study, the characterization of crack morphology is conducted by digital image processing (DIP) method, which mainly involves the grey processing, background elimination, binarization and pixel column labeling of digital image. Crack morphologies of ECC are modified by blending PVA fibers with a volume content of 2.0% and steel fibers with volume contents of 0.0%, 0.3%, and 0.6%. A permeability model for cracked hybrid fiber ECC (HyECC) has been proposed based on the Weibull distribution of crack width and crack number. The results indicate that the addition of steel fibers in ECC optimizes the crack morphology, yielding more tortuous and finer cracks. The average crack width decreases from 67.3-115.8 μm in mono fiber system to 46.0-67.6 μm in hybrid system with steel fiber content of 0.6%. The average crack width and crack number increase with the tensile strain, while the average crack spacing behaves in an opposite manner. The evolution of crack morphology could be described by Weibull distribution as a function of tensile strain. The permeability model derived from the crack morphology and the modified Hagen-Poiseuille law well predicts the permeability of cracked HyECC. It reveals that the addition of steel fiber enhances the impermeability of cracked HyECC, especially at large strains. The flow rate at tensile strain of 1.5% is reduced from 7.75 × 10−7 m3/s to 4.82 × 10−9 m3/s as the steel fiber content increases from 0.0% to 0.6%. The findings are expected to support the material-efficient design, crack control and durability improvement of ECC in structural applications.

Bond Behavior of a Bio-Aggregate Embedded in Cement-Based Matrix.

This paper investigates the bond behavior between a bio-aggregate and a cement-based matrix. The experimental evaluation comprised physical, chemical, image, and mechanical characterization of the bio-aggregate. The image analyses about the bio-aggregate’s outer structure provided first insights to understand the particularities of this newly proposed bio-aggregate for use in cementitious materials. A mineral aggregate (granitic rock), largely used as coarse aggregate in the Brazilian civil construction industry, was used as reference. The bond behavior of both aggregates was evaluated via pull-out tests. The results indicated that both aggregates presented a similar linear elastic branch up to each respective peak loads. The peak load magnitude of the mineral aggregate indicated a better chemical adhesion when compared to the bio-aggregate’s. The post-peak behavior, however, indicated a smoother softening branch for the bio-aggregate, corroborated by the microscopy image analyses. Although further investigation is required, the macaúba crushed endocarp was found to be a thriving bio-material to be used as bio-aggregate.

Solubility of niobium(V) in cementitious systems relevant for nuclear waste disposal: Characterization of the solubility-controlling solid phases

Neutron activation of 93Nb in structural materials of nuclear reactors generates the radioactive, β‒‒γ emitting 94Nb isotope (t1/2= 2.04·104 a). Waste streams containing 94Nb are disposed in repositories for low- and intermediate-level waste, which are characterized by the extensive use of cementitious materials. The chemical behavior of niobium in these systems remains ill-defined, especially with respect to the solid phases controlling its solubility. Oversaturation solubility experiments in synthetic solutions representative of cementitious pore water (10 ≤ pH ≤ 12.5) show the precipitation of Nb, with [Nb] < 10–7 M at equilibrium. The increase in solubility observed at pH > 12.5 is attributed to negatively charged hydrolysis species stabilized by Ca. Solids controlling Nb solubility were characterized by a multi-method approach. XRD, Raman and quantitative chemical analysis support the predominance of cubic pyrochlore Ca2Nb2O7(cr) at pH ≈ 13.5, as well as in systems at pH ≈ 12 and high [Ca]. The incorporation of K in the pyrochlore structure was observed in pore water systems containing potassium, whereas CaNb2O6(cr) plays a predominant role at pH ≈ 10–11. This work provides an improved scientific basis to assess solid phase formation and solubility behavior of Nb(V) in cementitious systems relevant for nuclear waste disposal.

Mechanical and durability properties of self-compacting concrete with recycled concrete aggregate, silica fume and nanosilica

The current study addresses the effect of substitution of silica fume and nanosilica on the mechanical and durability properties of self-compacting concrete containing recycled coarse aggregate (RCAs). A self-compacting concrete (SCC) was prepared by the incorporation of silica fume and nanosilica as a replacement of cement. Two series of concrete mixtures were prepared in the laboratory. In these series, RCAs with the replacement of 25%, 50%, 75%, and 100 % respectively were used with and without supplementary cementitious materials (SCMs). J-ring and Slump flow tests were conducted to investigate the fresh properties SCC. The incorporation of supplementary cementitious materials enhanced the properties of SCC and the result showed that the use of these cementitious materials can reduce water absorption and chloride diffusion up to a great extent. The mechanical and durability properties of SCC were determined by different tests like compressive strength test, water absorption test, and rapid chloride migration test. The use of cementitious materials showed a better result after 90 days of compressive strength. The test results indicate that silica fume and nano-silica were very effective and have great resistance against chloride diffusion.

Life cycle assessment (LCA) and environmental sustainability of cementitious materials for 3D concrete printing: A systematic literature review

This article presents a literature review on the use of cementitious materials for 3D printing applications in the context of environmental sustainability and the construction sector. In this study are presented materials currently used for 3D concrete printing. Structural and non-structural applications are considered. New research regarding more durable and sustainable materials is discussed. Furthermore, recent contributions on the use of Life Cycle Assessment (LCA) to evaluate the potential environmental impacts of the concrete 3D printing technology are summarized. A discussion on the current studies is conducted, and recommendations for the environmental performance improvement of printed concrete are produced. The review showed that there are few studies on the LCA of concrete for 3D printing and that the concrete employed for this purpose generally uses large volume fractions of Portland cement in order to achieve proper rheology. New studies, however, demonstrate that supplementary cementitious materials, recycled wastes, and alternative matrices can be applied to reduce life cycle environmental impacts. Studies also show that the environmental performance of the printed structures can be improved through functional hybridization, structural optimization, and increasing the energy efficiency of the printing systems.

Study of engineering properties of low-pH self-compacting concrete for concrete plug

Engineered Barrier Systems (EBS) is the primary concept in the design of the Geological Disposal Facility (GDF). In the design of EBS, bentonite is usually used as a buffer/backfill material. Due to its unique design, the concrete plug, used to close the junction between the transport tunnel and the disposal tunnel, is made of self-compacting concrete. Because the high pH solution in normal concrete reduces the performance of bentonite, low-pH self-compacting concrete with pH value less than 11 must be used to manufacture concrete plug. The silica fume (SF) and fly ash (FA) were used as mineral admixtures to discuss the effect of the mineral admixture addition level, Increased use of cementitious materials, and w/p on the engineering properties of Low-pH Self-Compacting Concrete (LPSCC). The test result shows that adding SF and FA could effectively prolong the setting time. Using only SF, the initial setting time of the mix increased up to 4.2 h with the addition of 40 wt% SF, while the combination of 40 wt% SF + 10 wt% FA could also increase the initial setting time to 3.92 h, which was much longer than 2 h working time requirement. Furthermore, at 90 days of curing, the pH value of each mixture was lower than 11, while the compressive strength enhanced to 118–132% compared to the control group. This addition could increase compactness, which leads to relatively strong sulfate resistance. The compressive strength could be enhanced by increasing the cementitious materials, which in turn, increases the pH and dry shrinkage. The LPSCC would lose strength when the w/p was reduced. The SF reacted with Ca(OH)2 in the LPSCC to generate a C-S-H gel. It was the primary factor in the drop of pH. The existence of SF and FA improved the pore structure in the matrix, compacting the structure of LPSCC. All that has been stated above are the dominant mechanism for improving the engineering properties. The pH value of mixture B300W29 was only 10.6 at 90 d, and the compressive strength could reach 61.66 MPa. Moreover, its drying shrinkage was about 0.047% at 90 d, and 0.055% at 150 d. Therefore, it should be considered as a potential material for concrete plug. The swelling property of bentonite was tested to validate the LPSCC material. No evident influence on the swelling property of bentonite was found. Replacing the conventional concrete with the designed material in disposal facilities can effectively enhance safety.

Preface

On November 4, 2021, the symposium "Vision and Strategies for Reinforcing Additively Manufactured (AM) Concrete Structures" scientific network "Adaptive Reinforcement of Geometrically Complex Cementitious Shaped Structures" was hosted at the Technical University of Dresden to conclude the funding period. The aim of this network, which is funded by the German Research Foundation (DFG), was to increase the design freedom in the use of cementitious materials through the use of end-to-end digital processes. The complexity of this task was reflected in the group of participants, which included architects and civil engineers as well as computer scientists and materials scientists. In addition to its many positive properties, the cement material, which is important for architecture, has clear weaknesses, particularly in the transmission of tensile forces. Without the addition of reinforcement, the potential of the material is significantly limited. Processing in an automated process such as so-called 3D printing does not initially change this. Regardless of the design, economic and ecological advantages associated with AM processes, the mechanical properties may even deteriorate without the integration of reinforcement. The known reinforcement methods, i.e. the use of rods and mats, usually cannot be integrated into the automated processes. In order to be able to use the mentioned potentials nevertheless, new reinforcement methods have to be developed for this purpose. During the symposium, various approaches, methods and materials were presented, as well as solutions for the complete elimination of reinforcement.

Partial replacement of cement with alternative cementitious material in the production of concrete: A review

Cement is the main and costliest material in the making of concrete. Also, the cement production is the second largest industrial CO2 source on earth. So, there is need for cement alternative in concrete production to reduce the cement production. This review paper focuses on the use of cementitious materials as a limited substitute for cement in the production of concrete. The use of cementitious material as a partial alternative helps in the making of cost efficient-concrete. The paper summarizes the previous research paper that used cementitious materials like fly ash (FA), metakaolin (MK), silica fume (SF), rice husk ash (RHA), ground granulated blast-furnace slag (GGBS), alccofine, etc. A certain amount of replacement with these cementitious materials with cement have showed good results in terms of strength. The concrete made with these materials showed less mechanical strength compared with conventional concrete but have achieved the required target strength at different time interval. The concrete made with alccofine as a partial replacement had a chloride diffusion because of its natural fine pore structure and its resistance against chemicals showed reduced penetration of chlorides elements into the concrete. Some materials showed, that amount of water required to attain the normal workability as conventional concrete has increased and vice-versa. Finally, it is concluded that the cementitious materials may be used as an alternative to cement for the production of cost and environmentally friendly concrete.

Interactions between Reduced Graphene Oxide with Monomers of (Calcium) Silicate Hydrates: A First-Principles Study.

Graphene is a two-dimensional material, with exceptional mechanical, electrical, and thermal properties. Graphene-based materials are, therefore, excellent candidates for use in nanocomposites. We investigated reduced graphene oxide (rGO), which is produced easily by oxidizing and exfoliating graphite in calcium silicate hydrate (CSHs) composites, for use in cementitious materials. The density functional theory was used to study the binding of moieties, on the rGO surface (e.g., hydroxyl-OH/rGO and epoxide/rGO groups), to CSH units, such as silicate tetrahedra, calcium ions, and OH groups. The simulations indicate complex interactions between OH/rGO and silicate tetrahedra, involving condensation reactions and selective repairing of the rGO lattice to reform pristine graphene. The condensation reactions even occurred in the presence of calcium ions and hydroxyl groups. In contrast, rGO/CSH interactions remained close to the initial structural models of the epoxy rGO surface. The simulations indicate that specific CSHs, containing rGO with different interfacial topologies, can be manufactured using coatings of either epoxide or hydroxyl groups. The results fill a knowledge gap, by establishing a connection between the chemical compositions of CSH units and rGO, and confirm that a wet chemical method can be used to produce pristine graphene by removing hydroxyl defects from rGO.

Utilization of polymer chemical admixtures for surface treatment and modification of cellulose fibres in cement-based composites: a review

Present day construction activities have led to the reduction of huge quantities of non-renewable resources. The effects are found in millions of toxic mineral wastes generated accompanied by unprecedented high levels of greenhouse gas emissions. It is therefore imperative that studies on renewable materials such as cellulose fibres be examined to explore their potentials as building materials. However, two of the major challenges bedevilling its adoption on a large scale are the durability and interfacial adhesion issues which can be solved through fibre surface treatment and polymer modification. This present review is an attempt to summarize relevant selected studies on the various surface treatment methods and polymer modification used in cellulose fibre reinforced cementitious application. The review covers (1) Properties of cellulose fibres and interaction with cement (2)Types of cellulose fibers and polymers used (3) Limitations of its use in cementitious materials (4) Physical and chemical methods of surface modification (5) Factors and mechanisms responsible for improved performance of the composites and (6) Models explaining the mechanisms involved in the enhanced properties.

Alkali-silica reaction: understanding the phenomenon

The alkali-silica reaction in cementitious composites occurs through the chemical association of the solution contained in the matrix pores, which is strongly basic and rich in alkalis, and the reactive phases of some aggregates. For the process to begin, high relative humidity and a high concentration of total alkalis are required. The degradations resulting from this reaction involve expansion, cracking, exudation and decreased mechanical performance of the structure, which can cause it to break depending on the magnitude of the phenomenon. Understanding the reaction development process is necessary to propose measures that can effectively extinguish or mitigate the occurrence. One of the measures widely studied is the incorporation of supplementary cementitious materials in concrete. In Brazil, technical regulations already exist that recommend the use of these cementitious materials. The Northeast region of the country is a major producer of fly ash and granulated blast furnace slag, but not all of this material is destined for other industries. The article in question is a compendium of technical information from relevant research developed about alkali-silica reaction. His contribution is in the didactic approach that allows the understanding of students in the engineering area and professionals who do not have the expertise in the subject in order to stimulate future research on the use of supplementary cementitious materials in Northeast Brazil, mainly.

Micro-structural analysis of recycled concretes made with recycled coarse concrete aggregates

This paper investigates the microstructure of 100% recycled concrete (RC) containing recycled coarse concrete aggregates (RCA) using scanning electron microscopy (SEM). In this study, the effect of 100% replacement of RCA along with the use of cementitious materials (CM's) including micro-silica (SF), fly ash (FA) and natural zeolite (Z) was investigated. For a more accurate understanding of the changes in concrete microstructure, we performed compressive strength (CS), ultrasonic pulse velocity (UPV) and water absorption by immersion (WAI) tests. After 180 days of hydration, the results of SEM as well as the high qualitative loss of RC from the UPV test showed that, there was still a large amount of pores and discontinuties at the mortar surface and the interfacial transition zone (ITZ) of RC without pozzolan. In contrast, the use of 10% of SF in RC, significantly reduced the pores and compressed ITZ and by bridging the hydration products; the ITZ of this concrete was very close to that of conventional concrete (CC). The slow pozzolanic reactions in the FA as well as the low reactive capacity of the Z made the RC containing these two pozzolans have relatively porous and uncompressed microstructures. Consequently, beside the poor results of mechanical properties, excessive discontinuities were also observed in the ITZ of this type of concretes.