Durability Of Cement Composites Research Articles

Durability analysis of sustainable mortars with biomass fly ash as high-volume replacement of Portland cement

Utilization of various supplementary cementitious materials was in the last decades considered beneficial for the replacement of the energy-intensive Portland cement to meet sustainable targets. However, structural changes in energy production and heavy industry in Europe significantly limit the availability of coal fly ash and blast furnace slag for blended cement production. On the other hand, the increasing production of biomass ash (BA) presents not only challenges for its disposal but also new opportunities for the concrete industry. In this paper, the durability of cement composites containing up to 70 wt% of BA as Portland cement (PC) replacement was analyzed, taking into consideration also microstructure and mechanical properties. The experimental results showed a preservation of good mechanical performance up to the 30 wt% limit. The freeze-thaw resistance was not affected significantly up to the 40 wt% BA dosage during the first 300 cycles. The analyzed composites also exhibited a good overall resistance to alkali silica reaction- and sulfate-induced expansion up to the 50 wt% PC replacement. BA can thus be considered as a prospective future alternative to coal fly ash and blast furnace slag to meet the sustainable development goals in the building industry.

Building a Greener Future: Advancing Concrete Production Sustainability and the Thermal Properties of 3D-Printed Mortars

The integration of waste materials in extrudable cement mixtures has the potential to make the construction industry more sustainable by reducing carbon footprints and developing eco-friendly materials. This along with advancements in 3D concrete printing (3DCP) provides engineering and architectural benefits by reducing material waste and costs. In this paper, the impact of waste incorporation on properties of mortar and concrete is examined. The use of waste materials, such as pumice, coal slag, agricultural lignocellulosic residues, and recycled rubber tyres, to improve thermal insulation and durability of cementitious composites is discussed. In addition, the incorporation of air-entraining admixtures with surfactant activity is explored for their indirect effect on thermal behaviour, pore size reduction, and enhancement in concrete properties. This review includes important topics such as a strength resistance to freezing and thawing, fire resistance, plasticising effect, and delay in cement hydration. These findings highlight the benefits of using diverse waste materials in construction, providing a multidimensional approach to waste management, cost optimization, and enhanced construction materials in the context of 3DCP.

Experimental Study of a Superabsorbent Polymer Hydrogel in an Alkali Environment and Its Effects on the Mechanical and Shrinkage Properties of Cement Mortars.

As internal curing self-healing agents in concrete repair, the basic properties of superabsorbent polymers (SAPs), such as water absorption and release properties, are generally affected by several factors, including temperature and humidity solution properties and SAP particle size, which regulate the curing effect and the durability of cementitious composites. This study aimed to investigate the water retention capacities of SAPs in an alkaline environment over extended periods by incorporating liquid sodium silicate (SS) into SAP-water mixtures and examining the influence of temperature. The influence of SAP particle size on mortar's water absorption capacity and mechanical behavior was investigated. Two mixing techniques for SAPs (dry and pre-wetting) were employed to assess the influence of SAP on cement mortars' slump, mechanical properties, and cracking resistance. Four types of SAPs (SAP-a, SAP-b, SAP-c, and SAP-d), based on the molecular chains and particle size, were mixed with SS to study their water absorption over 30 days. The results showed that SAPs exhibit rapid water absorption within the first 30 min, exceeding 85% before reaching a saturation point, and the chemical and temperature variations in the water significantly affected water absorption and desorption. The filtration results revealed that SAP-d exhibited the slowest water release rate, retaining water for considerably longer than the other three types of SAPs. The mechanical properties of SAP mortar were reduced due to the addition of an SAP and the improved cracking resistance of the cement mortars.

Influence of Graphene Oxide on Mechanical Properties and Durability of Cement Mortar.

The effect of graphene oxide (GO) on the mechanical strengths and durability of cement composites was researched by preparing GO-modified cement mortars. Thermogravimetric analysis (TGA) and nuclear magnetic resonance (29Si MAS-NMR) were performed on the cement paste to evaluate the influence of GO on the hydration process and chain structure of calcium-silicate-hydrate (C-S-H) gels. TGA revealed that the high GO dosage increased the content of C-S-H by 5.46% compared with the control at 28 days. Similarly, 29Si-NMR improved the hydration degree and main chain length (MCL) in GO-modified samples at 28 days. The GO led to increases of 2.54% and 7.01% in the hydration degree and MCL, respectively, compared with the control at 28 days. These findings underscore the multifaceted role of GO in improving the mechanical properties and durability of cement composites. Mechanical strength tests, such as compressive and flexural tests, were conducted on cement mortars. The optimal dosage of GO increased the compressive strength by 9.02% after 28 days. Furthermore, the flexural strength of cement mortars with the combination of GO and superplasticizer (SP) after 28 days increased by 21.86%, compared with reference mortar. The impact of GO proved to be more pronounced and beneficial in the durability tests, suggesting that GO can enhance the microstructure through hydration products to create a dense and interconnected microstructure.

Influence of PVA fibers on the durability of cementitious composites under the wet–heat–salt coupling environment

Abstract To investigate the effects of wet–heat–salt coupling environment (WHSCE) and the content of polyvinyl alcohol (PVA) fibers on the durability of cementitious composites (CC), a series of durability tests were carried out. In this study, the salt concentration in the WHSCE was set to 5%, the temperature at 50°C, and the relative humidity at 100%. Six different contents of PVA fibers were set up in the test for exploring their effects on the durability (impermeability, chloride ion penetration resistance, freeze–thaw resistance, and chloride salt erosion resistance under dry and wet cycle conditions) of CC. The results showed that durability of CC under the WHSCE was enhanced regardless of the content of PVA fibers added. At the PVA fiber amount of 1.2%, the impermeability pressure, electric flux, mass loss rate, compressive strength loss rate, and compressive strength corrosion resistance coefficient under the WHSCE reached the optimal values. This indicated that the durability of CC was most favorable when the amount of PVA fibers was 1.2% since many engineering structures are subject to erosion by various factors in the ocean, which can inevitably affect the service life of the purchase. In this study, the effect of PVA fiber content on the durability of CC in complex environment is studied, which provides experimental data and analytical ideas for improving engineering located in the ocean, hoping to provide a theoretical basis for their subsequent application in practical engineering.

Nucleation effect of graphene in mechanical and microstructure properties of mortar with copper slag and quarry dust

In recent days, research on graphene-based cement has gained prominence owing to its distinct characteristics, such as ultimate ductile behavior, enhanced specific surface area, and activation effect. Previous research suggests that Graphene Nanoplatelets (GNP) have the potential to enhance the micro- and macro-properties of cement-based composites. This study analyzes the performance of graphene nanoplatelets (GNP) with industrial by-products, such as copper slag (CS) and quarry dust (QD) admixed as partial replacement fine aggregates in mortar mixes. The mix proportions were optimized by improving the packing intensity through particle packing theory (Andersen and Modified Andreasen model) to reduce the number of trial mixes. According to the particle packing theory, the experimental analysis revealed that copper slag and quarry dust exhibited maximum strength at 40% replacement. A maximum compressive strength of 63.23 MPa was achieved in the mortar mixed with 0.25% GNP and 40% copper slag (25G2CS). In addition to the experimental analysis, the functional groups and changes in the elemental characteristics of the different cement composites were studied using microstructure analysis. The significance of this research is to optimize the materials used in the construction industry as well as to enhance the strength and durability of cement composites.

A review of microscopic characterization and related properties of fiber-incorporated cement-based materials

Abstract Fiber-reinforced concrete (FRC) has apparent benefits over traditional cementitious composites and possesses a great prospect in civil engineering projects. Previous studies reported that fiber admixtures could effectively enhance the mechanical properties, impermeability, and durability of cementitious composites. Nevertheless, the trade-off of the reinforcing efficiency, cost, and properties of the cementitious composites in different aspects has been a challenge in the application of FRC to practical engineering. This article summarizes a review concerning the recent development of FRC enhanced by different fibers and mainly focused on the fiber-reinforcing effects on the microstructure and the corresponding properties of cementitious composites. The addition of a small amount of fiber material has a significant change in the microstructure and related properties of cement-based materials, but the presence of fibers also causes structural damage and other problems. The direction of future development of some cutting-edge technologies such as coating and hybridization methods on fiber modification was concluded to assist further research in FRC. This review will further enhance the understanding of fiber for reinforcing cementitious composites.

Influence of (1D/2D) hybrid nanomaterials on the mechanical and durability properties of pozzolana portland cementitious mortar

This paper investigates the mechanical, microstructural, and durability properties (acid/sulfate attack, water absorption, electrical resistivity, and drying shrinkage) of carbon nanomaterial cementitious mortars (CCMs). With the help of sika superplasticizers, mortars with a water-to-binder ratio (w/b) of 0.42 were fabricated. The functionalities, morphology, and microstructural behavior of the specimens were characterized by powdered X-ray Diffraction (PXRD), Fourier Transform-Infrared Spectroscopy (FT-IR), Field Emission-Scanning Electron Microscope (FE-SEM), and Transmission Electron Microscopy (TEM). The capillary suction test and acid/sulfate resistance were significantly improved in the presence of carbon nanomaterials (CNMs) in mortars. The incorporation of CNMs revealed a significant role in the process of pore refinement. The research results provide a potential new pathway to improve the toughness and durability of cement composites.

Influence of synthesized nanomaterials in the strength and durability of cementitious composites

The development of high-performance materials has been prompted by a constantly expanding infrastructure with complex technical constraints. Performance modification of cement composites using nanoparticles has been thoroughly researched to address demands in the construction industry. This cutting-edge review examines the various parameters of cement composites, such as fresh properties, mechanical properties, and durability characteristics that can be improved using synthesized nanomaterials such as nano-SiO2, nano-Al2O3, graphene oxide, and carbon nanotubes, as well as their inherent limitations. Based on the detailed review, the ideal replacement levels of nano-SiO2 (1–4 wt%), nano-Al2O3 (1–3 wt%), graphene oxide (0.05–0.1 wt%), and carbon nanotubes (0.1–0.5 wt%) can be recommended for the practical applications. It has been noted that the addition of synthesized nanomaterials tends to lower the workability of cement composites. However, nanoalumina, graphene oxide, nano-silica, and carbon nanotubes improve mechanical qualities such as compressive strength, flexural strength, and resistance to abrasion of the blended cementitious system at an optimum replacement level. Similarly, resistance against chemical attacks was imporved with the addition nano-silica, while the addition of graphene oxide in cement is more effective against chloride migration and fire exposure. The overall effect of synthesized nanomaterials is also compared in the study.

Effect of Municipal Solid Waste Slag on the Durability of Cementitious Composites in Terms of Resistance to Freeze-Thaw Cycling.

The article presents durability results for cement mortars made with the addition of slag from municipal waste incineration plants as a replacement for natural aggregate. The undertaken durability tests included frost resistance tests and evaluation of strength, microstructure, water absorption and abrasiveness before and after 150 freeze-thaw cycles. The work reveals that MSWI slag in amounts up to 50 vol. % caused deterioration in the workability and water absorption of cement mortars, regardless of the type of cement used. This, in turn, resulted in a reduction in the compressive and flexural strengths of the composites compared to mortars made with sand alone. Nevertheless, the use of a higher grade of cement, CEM I 52.5 R, resulted in an increase in compressive strength and thus increased the mortars' frost and abrasion resistance. In addition, after the induced freeze-thaw cycles, mortars made with MSWI slag showed comparable or higher frost and abrasion resistance than those made using natural aggregate.

Evaluation of long-term strength and durability performance of cementitious composites with low polypropylene fiber content and local river sand

This study aims to investigate the long-term mechanical properties and durability of cementitious composites (CC) with low polypropylene (PP) fiber content and local river sand. The CC samples were prepared with different water-to-binder (w/b) ratios (0.20, 0.25, and 0.3), low PP fiber content (0.6% by mass of binder), locally available river sand, and fly ash (FA) sourced in the Mekong Delta region, corresponding to the mixture name WB20, WB25, and WB30, respectively. Then, the mechanical properties were investigated through compressive and flexural strengths and ultrasonic pulse velocity tests, while durability was assessed via chloride ion penetration and sulfate resistance. The results revealed that the mixture with the w/b of 0.25 achieved the best performance in terms of both mechanical and durability performance due to the optimal conditions of compaction, mixing water content, and also the latent pozzolanic reaction of FA in the hydrated cementitious composites. Besides, the CC samples with 0.6% PP fiber exhibited ductility behavior under compression and flexure, characterizing that CC samples do not completely separate from each other when damaged due to the fiber bridging effect. Moreover, the CC samples obtained excellent long-term durability (up to 120 days old) in terms of sulfate attack and chloride resistance in the following order WB25 > WB20 > WB30. The results of this study confirm the applicability of the local materials for producing good quality and low-cost cementitious composites.

Strength, Carbonation Resistance, and Chloride-Ion Penetrability of Cement Mortars Containing Catechol-Functionalized Chitosan Polymer.

There have been numerous recent studies on improving the mechanical properties and durability of cement composites by mixing them with functional polymers. However, research into applying modified biopolymer such as catechol-functionalized chitosan to cement mortar or concrete is rare to the best of our knowledge. In this study, catechol-functionalized chitosan (Cat-Chit), a well-known bioinspired polymer that imitates the basic structures and functions of living organisms and biological materials in nature, was synthesized and combined with cement mortar in various proportions. The compressive strength, tensile strength, drying shrinkage, accelerated carbonation depth, and chloride-ion penetrability of these mixes were then evaluated. In the ultraviolet–visible spectra, a maximum absorption peak appeared at 280 nm, corresponding to catechol conjugation. The sample containing 7.5% Cat-Chit polymer in water (CPW) exhibited the highest compressive strength, and its 28-day compressive strength was ~20.2% higher than that of a control sample with no added polymer. The tensile strength of the samples containing 5% or more CPW was ~2.3–11.5% higher than that of the control sample. Additionally, all the Cat-Chit polymer mixtures exhibited lower carbonation depths than compared to the control sample. The total charge passing through the samples decreased as the amount of CPW increased. Thus, incorporating this polymer effectively improved the mechanical properties, carbonation resistance, and chloride-ion penetration resistance of cement mortar.

The effect of using polypropylene fibers on the durability and fire resistance of concrete

In order to study the effect of polypropylene fibers on the durability of cementitious composites, several experimental tests have been carried out in the laboratory. The composite was tested with different volume fractions of polypropylene fibers (0.05%, 0.10%, 0.30% and 0.50%). All the results relating to the indicators (porosity accessible to water εb, to the oxygen permeability Kapp.gas and diffusivity Dns) indicate that the addition of polypropylene fibers in a cement matrix represents only a small effect on durability. This panel of general sustainability indicators can be supplemented by indicators more specific to each degradation process identified or envisaged depending on the environmental conditions of the structure. However, the addition of the volume fraction of polypropylene fibers (0.50%) in a cementitious composite, increases fire resistance. Such behavior gives fiber composites interesting properties which favor their use in structures exposed to fire risks.

Effect of Crystallization Additives on Durability of Cement Composites in Aggressive Environments

This article analyses the effect of crystallization additives on the long-term durability of self-compacting concretes (SCCs) in relation to specific types of chemically aggressive environments. The effect of both an inorganic acid solution and the aggressive solutions produced during plant ensilage were tested, while the effect of diesel on these modified concretes was also investigated. Attention was given to the effect of crystallization additives on the characteristically capillary porous structures of self-compacting concrete, specifically in terms of the long-term durability of SCCs in relation to the above-stated chemically aggressive solutions. The effect of aggressive environments was evaluated through a set of physical-mechanical trials and physical-chemical analyses.

Utilization of Thermally Treated SiC Nanowhiskers and Superplasticizer for Cementitious Composite Production.

Nanomaterials are potential candidates to improve the mechanical properties and durability of cementitious composites. SiC nanowhiskers (NWs) present exceptional mechanical properties and have already been successfully incorporated into different matrices. In this study, cementitious composites were produced with a superplasticizer (SP) and 0–1.0 wt % SiC NWs. Two different NWs were used: untreated (NT-NW) and thermally treated at 500 °C (500-NW). The rheological properties, cement hydration, mechanical properties, and microstructure were evaluated. The results showed that NWs incorporation statistically increased the yield stress of cement paste (by up to 10%) while it led to marginal effects in viscosity. NWs enhanced the early cement hydration, increasing the main heat flow peak. NWs incorporation increased the compressive strength, tensile strength, and thermal conductivity of composites by up to 56%, 66%, and 80%, respectively, while it did not statistically affect the water absorption. Scanning electron microscopy showed a good bond between NWs and cement matrix in addition to the bridging of cracks. Overall, the thermal treatment increased the specific surface area of NWs enhancing their effects on cement properties, while SP improved the NWs dispersion, increasing their beneficial effects on the hardened properties.

Surface Treatment of Cement based Composites: Nano Coating Technique

Geometry, size, and shape of the surface pores, as well as, capillarity, and exposure environment are directly influence strength and durability of cementitious composites. The current research aimed to improve the resistance to abrasion and decrease the surface porosity of cement-based composites by nano surface coating technique. All samples were coated with a mixture of methanol alcohol, ordinary Portland cement and nano powder of (TiO2, MgO, ZnO and ZrO2) separately in percentages of (1, 1.5, and 2 %) by weight of cement. The hardness, abrasion, water absorption, density, porosity, and microstructural analysis: Scanning Electron Microscopy and X-Ray Diffraction (SEM & XRD) were studied for all coated and control specimens. Results showed an improvement in mechanical properties for all coated specimens as compared to control. The highest Vickers micro hardness value had reached 29%, while the largest value of abrasion resistance had increased by 39% for coated samples with 2% ZrO2. Also, the results showed a reduction in the porosity and water absorption of all coated samples, having highest scores obtained from the coated samples with 2% MgO. While the total water absorption rate decreased by 45% and the density had increased by 1% and the porosity had decreased by 46%. Additionally, the results of microstructural tests revealed pattern and images for each of SEM and XRD. Also, results indicated that the nano coating leads to significant consumption of Portlandite (CH) associated with production of a stable structure of CSH and reduction of voids, and this is evident from the enhancement in the physical properties.

The non-uniform spatial dispersion of graphene oxide: A step forward to understand the inconsistent properties of cement composites

Graphene oxide (GO) has been extensively employed to improve the mechanical strength, hydration and durability of cement composites. Recently, an interesting phenomenon can be found that the variation of cement performances is inconsistent with identical GO dosage. However, the related mechanisms remain unclear. Herein, we elucidate the relationship between the spatial dispersion of GO and inconsistent properties of cement composites. Firstly, X-ray computed tomography is developed to observe the distribution of GO. Moreover, the morphology and pore structure of hardened cement paste are studied. Finally, the scattered degree of mechanical strength is evaluated. Obtained results show GO forms many agglomerations with irregular flat shape. Polycarboxylate-ether could reduce the amount of GO aggregations, but not completely eliminate the agglomerations. Aggregated GO induces uncertain pores and sequentially increases the total porosity. The spatial distribution of GO aggregations is non-uniform. These factors lead to the larger scattered strength of specimens with GO. The discrepancies in dispersion degree of GO are mainly responsible for the inconsistent properties of cement composites. This study could provide a deeper understanding of the conflicting properties of GO reinforced cement-based materials.

Modification of cementitious composites with graphene oxide and carbon nanotubes

Both graphene oxide (GO) and carbon nanotubes (CNTs) are carbon-based nanomaterials. Due to their favorable dispersibility in water and excellent mechanical properties, they are potential additives for use as reinforcements in cementitious composites. In this laboratory study, GO and CNTs were simultaneously used as additives to improve the mechanical properties (e.g., compressive strength) and durability (e.g., frost resistance, water impermeability) of cementitious composites. To maintain and optimize the mortar fluidity, fly ash (20% by the mass of the cementitious materials) was also added into the cementitious composite. Based on the laboratory test results, the compressive strength of the cementitious composite was maximized to 43.50 MPa with an optimal dosage of 0.08% GO, by weight of the total mixture. Addition of 0.04% GO (by total mixture weight) and higher dosages of up to 0.08% exhibited a strengthening effect on the cement composites due to the simultaneous bridging effect of 0.15% CNTs and the nucleation effect of GO. Furthermore, the addition of GO and CNTs contributed to improving the freeze–thawing resistance and impermeability of the cementitious composites. Overall, the study results indicated that the addition of GO and CNTs could potentially improve the mechanical properties and durability of cementitious composites, which could be very beneficial for various industrial applications such as concrete roads or building constructions.

Evaluation of CNT/GNP’s synergic effects on the Mechanical, Microstructural, and durability properties of a cementitious composite by the novel dispersion method

In this paper, the synergic effects of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) on the mechanics, microstructure, and durability of cementitious composites were investigated. Furthermore, due to the high potential of CNTs and GNPs to agglomerate, a novel technique was proposed by utilizing the combined effect of Pluronic F-127 and Tributyl phosphate (TBP) while optimizing the effective factors such as surfactant concentration, sonication time, and temperature to achieve an affordable and compatible industrial scale-up method for a high-quality dispersion of CNT + GNP (50/50). The UV–Vis spectroscopy, optical microscopy image analysis, zeta potential, and bundle size measurements indicated that a high-quality CNT + GNP dispersion with a low agglomeration area and bundle size (<1.2% and 219 nm) was achieved with 10% Pluronic (wt% of nanoparticles) over 3 h of sonication at 40 °C with the presence of TBP (50 wt% of surfactant). Flexural and compressive tests of the reinforced cementitious composites using different CNT + GNP concentrations showed a significant improvement in mechanical behavior during different periods of hydration. The measured bulk density, none destructive ultrasonic, and capillarity tests also indicated a denser and improved composite microstructure for the CNT + GNP reinforced specimens. The formation of an adsorption layer due to the presence of phosphate and hydroxyl functional groups (proven by FTIR analysis) had positive effects on regulating the microstructures of the hydration crystals. The SEM, TGA, XRD, and EDX analysis results showed that CNTs + GNPs increased the hydration rate. Moreover, CNT + GNP reinforcement led to a significant reduction in carbonation depth. Ultimately, the results obtained demonstrate that an optimum concentration of CNT + GNP is around 0.5%.

Evaluation of Cracking Patterns in Cement Composites-From Basics to Advances: A Review.

The structure and the development degree of a cracking pattern has a key impact on the durability of cement composites. This literature review focuses on the four most important aspects related to the evaluation of the surface cracking patterns, i.e., the process of formation, propagation and evolution of cracks into a branched system of cracks from the point of view of the fracture mechanics; the detection techniques of the cracking patterns on the surface of cement composites, where the tools of computer image analysis are the most used; parameters which can quantify the development degree and morphology of the cracks system; and also the influence of a cracking pattern on the functional features of cement composites. The studies described so far indicate the necessity of continuous development of this research area, because the knowledge of key relationships between the cracking patterns and functional properties of a cement composite is necessary to estimate the degree of material degradation. Researchers agree that the works carried out in the field of evaluation of the cracking patterns, to a large extent, contributes to the development of non-destructive testing methods in the field of cement composites technology.