Cementitious Building Materials Research Articles

Multidisciplinary approach for the prediction of cement paste rheological properties: physical analysis, experimental rheology and microstructural modelling

AbstractIn this contribution, an interdisciplinary approach was employed to investigate and describe the fresh rheology of cementitious pastes, using analytical techniques, microstructural modelling, and experimental rheometry. The pastes, based on Ordinary Portland Cement and Limestone Calcined Clay Cement at a solid volume fraction of Φ = 0.45, were subjected to various analyses. Physical and chemical analyses were conducted including laser granulometry and isothermal heat flow calorimetry. Dynamic rotational rheometry and static oscillatory rheometry, along with viscoplastic and viscoelastic rheological modelling were used to support the characterization of the pastes. A physics‐based Monte‐Carlo algorithm was developed to numerically describe rheological properties such as structural buildup and yield stress. The results showed that as the physical properties of the pastes became more complex, the correlation of several analysis methods went more challenging. However, the combination of analytical, experimental, and phenomenological rheology allowed for a more distinct characterization of the cement paste. These findings can serve as a basis for further multidisciplinary rheological characterization of cementitious building materials.

Manufacture of eco-friendly cementitious building materials of high performance from Egyptian industrial solid wastes

One of the goals of modern societal development is to achieve environmental sustainability by expanding the number of smart cities with eco-friendly buildings. A research was carried out to investigate the possibility of utilizing Egyptian industrial solid wastes from factories to create sustainable construction materials in order to accomplish this goal. Along with various waste products including cement kiln dust (CKD) and silica fume (SF), which were chemically categorized, the investigation identified metakaolin (MK) and dealuminated kaolin (DK). Various dry mixes were used to determine the hydration characteristics of the binders, including MK-CKD, DK-CKD, OPC-DK, DK-CKD-SF, MK-CKD-SF, and OPC-DK-SF.The physico-chemical and mechanical properties of the cement pastes were analyzed using compressive strength (CS), chemically combined water (Wn, %), and free lime (CaO, %) content over time. The hydration products were identified using differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Scanning electron microscopy (SEM) analyses. The findings revealed that DK had a larger surface area (95 m2/g) than MK and displayed greater pozzolanic activity, particularly during early hydration. Moreover, the inclusion of SF provided further densification of the microstructure of the hardened DK-CKD-SF and/or OPC–DK–SF pastes.According to the findings, the OPC-DK pozzolanic cement pastes had a denser structure than the neat OPC paste. Moreover, the inclusion of SF resulted in additional densification of the microstructure of the hardened OPC-DK-SF pastes, which was evident in the observed increase in compressive strength values at all ages of hydration. The use of industrial solid waste as a sustainable building material has the potential to assist Egypt in meeting its goals for sustainable development and climate protection.

Utilization of nanoparticles and waste materials in cement mortars

Abstract Cement has shaped the modern built environment, but its production generates substantial carbon dioxide emissions. Consequently, there is an urgent need to identify alternative cementitious building materials for sustainable construction. In this study, cement mortars (CMs) were produced by partially replacing cement with nanoclay (NC) and granite dust (GD). The replacement proportions (% by weight of cement) of these materials were 1.5, 3, and 4.5% for NC and 10, 20, and 30% for GD. For mortars containing NC but not GD, the strength was maximized when the NC replacement proportion was 3%. To evaluate the combined effect of partially replacing cement with both NC and GD on the fresh and hardening properties of cement-blended mortars, ternary binder mixtures containing 3% NC together with 10, 20, or 30% GD were prepared, and their workability, bulk density, compressive strength (at 7, 28, and 90 days), and flexural strength were measured. Increasing the content of NC and/or GD reduced the flowability of these mortars relative to that of the reference mortar mix because it increased the content of fine materials. CM containing 3% NC and 10% GD had the highest compressive strength at 7, 28, and 90 days while also having the greatest flexural strength when compared to the control mix. This is most likely due to the high silica and alumina content of NC and GD, as well as their high specific surface area, which would improve the maturity and density of the matrix when compared to cement alone.

A Critical Review on Properties of PCM-Incorporated Cementitious Building Materials

Abstract Addressing the current global warming issues and carbon dioxide emission, the prime objective of the construction industry sector today is to develop energy-efficient environmentally friendly techniques to reduce thermal fluctuation inside buildings. Because phase change material (PCM) has good energy storage and release capacity, many researchers have shown interest in implementing PCM to increase thermal inertia of various building materials such as concrete, mortar, and gypsum board. PCM-incorporated building material is reported to reduce building energy consumption, shift peak energy demand, and reduce thermal swing, leading to improved thermal comfort inside the building. In addition to the aforementioned benefits, there are several other economic benefits and environmental benefits, as discussed in various sections in this paper. Although the use of PCM in buildings has a lot of advantages, it has some negative impacts on fresh state properties, mechanical behavior, and durability-related properties of building materials. However, it is to be noted that the extent of negative impact is dependent on the type of PCM, incorporation technique, dosage of PCM, and encapsulation material, which are also critically reviewed in this paper. To summarize, this paper provides a systematic classification of the literature on PCM in building materials in terms of properties of different types of PCM; PCM incorporation methods; effect of PCM on fresh state, mechanical, durability, and thermal properties of concrete; and various benefits of PCM. This paper also provides structured insight into various issues that hamper PCM’s robustness and commercial viability in buildings. Furthermore, challenges and recommendations are provided by summarizing the significant research gaps from the literature.

Optimization of biochar and fly ash to improve mechanical properties and CO2 sequestration in cement mortar

The novelty of this study is to find out the optimum amount of biochar and high calcium fly ash to improve mechanical performance and promote CO2 uptake in cement mortar. The potential of biochar-fly ash mixes was optimized using response surface methodology (RSM) considering the influence of different amounts of fly ash (FA), biochar (B), and their interactions to achieve the optimal mix design with improved performance and carbonate mineralization. Additionally, the effect on the mineralization of different polymorphs of calcium carbonate was also investigated. The experimental results indicate that the accelerated carbonation of high calcium fly ash mortar enriched with biochar enables the effective utilization of biochar up to 5% for enhancing both the mechanical properties and CO2 sequestration. However, under normal curing conditions, it was observed that the optimal amount of biochar that can be used is <1%. This is a promising approach in terms of utilizing waste material and reducing cement content in the mix design together with the additional benefit of storing 50% of ambient CO2 permanently in the cementitious matrix. Carbonation of biochar-fly ash cement composite substantially improves fracture strength, and modulus of elasticity compared to uncarbonated cement mortar at 7 and 28 days. The present study demonstrates the advantages of synergistically combining biochar and fly ash in the development of low-carbon, sustainable cementitious building materials that have the potential to transform building structures into carbon sinks in the future.

Internal hydrophobization of cement-based materials by means of silanes

The paper shows the opportunity of application of an organosilicon compound such as triethoxyoctylsilane (OTES) containing long, hydrophobic alkyl sidechains (octyl groups – C8H17) attached to the silicon atoms, as the admixtures for internal hydrophobization of cementitious building materials characterized by a porous internal structure. The study included the cement paste, mortar and concrete with three different hydrophobic admixtures based on triethoxyoctylsilane, but with miscellaneous concentration of the triethoxyoctylsilane in the admixture and different dosage in the fresh mix. The impact of organosilicon hydrophobic admixtures on the mechanical properties such as compressive strength, capillary water absorption of the cement mortar and concrete and the microstructure of cement paste was investigated. The hydrophobic, silicon-based admixtures decrease the capillary water absorption coefficient significantly. Even by 81.1% in case of cement mortar. The mechanical strength of cement mortar is also decreased, by 23.6%. The noticeable changes in the internal structure of pores of cement paste only for one admixture is observed.

Research needs for cementitious building materials with focus on Europe

The needs for research on cementitious materials are reviewed with a focus on Europe. These are considered under 8 topics: clinker production, alternatives to Portland cement, composite cements based on Portland clinker, concrete, admixtures, durability, recycling, digitisation in concrete construction, and, carbon capture and use or storage; finally, the key research questions and their potential for CO2 reduction are summarised in a “Watermelon” diagram with a list of 30 key questions to be addressed (see Appendix).

Up to 100% Replacement of Natural Materials from Residues: Recycling Blast Furnace Slag and Fly Ash as Self-Leveling Cementitious Building Materials.

The objective of this research is to study the use in the construction industry of recycled slag (SL) and fly ash (FA) using from 0.1 to 5% calcium sulfate (wCS¯). These wastes have been used to make ternary mixture systems and evaluated in terms of technological properties as cementitious materials for building applications. Studying their micro-structure as hydration products, setting times and mechanical properties shows a way to develop new mixtures from high proportion of waste, which are alternatives to the traditional nature ternary systems: Portland cement (PC), calcium aluminate cement (CAC) and calcium sulphate (CS¯). Based on previous work with natural products, the selected SL/FA ratios were 9 and 2.3 and the sulphate contents were 0, 1 and 5%. The water/binder ratio used for these cementitious mixes was 0.4. The specimens prepared for strength determination were prisms of 10 × 10 × 60 mm. The pastes were prepared and cured at 20 °C and 98% relative humidity for 1 day and then either stored at 20 °C at 98% humidity (dry) or immersed in distilled water (wet) for 14 and 28 days. The results showed that both FA and SL mixed with CS¯ produce ettringite after 28 days of setting, and this phase was the main crystalline hydrated product in all mixes. Calcium sulphate stimulates the hydration reactions of the mixes and the strength increases when the CS¯ content is higher due to ettringite formation, while the setting time decreases, as happened in the systems prepared with natural materials.

The Effect of Milled Municipal Solid Waste Incineration Bottom Ash on Cement Hydration and Mortar Properties

Large amounts of municipal solid waste incineration bottom ash (MSWI BA) are formed worldwide, and this quantity is growing because of the establishment of new waste-to-energy plants. This waste is generally kept in landfills but can be used for the manufacturing of cementitious building materials. This article analyzes the use of MSWI BA as a microfiller in cement mortars. The effects of MSWI BA on the properties of cement binder and mortar were analyzed by using them separately or in combination with other microfillers: milled quartz sand, metakaolin, milled glass, and microsilica. This article investigates the flowability of cement-based mixtures, the volume change as a result of the evolution of hydrogen gas, cement hydration, XRD, TG, the physical and mechanical properties of the mortar samples, and leaching. The addition of milled MSWI BA in cement mortars was found to significantly increase slump flow; therefore, MSWI BA can be used as a microfiller. The addition of metakaolin changed the kinetics of H2, which evolved due to the reaction between Al and alkali, and had a positive effect on the mechanical properties of cement mortar.

Treatments of nanofiber cellulose biomass for cementitious building materials

Treatments of nanofiber cellulose biomass for cementitious building materials

Study of the Interaction of Cement-Based Materials for 3D Printing with Fly Ash and Superabsorbent Polymers

The use of superabsorbent polymers (SAP) in construction is a relatively new trend, and not a completely explored area. However, SAP itself has been on the market for over 80 years. SAPs have a cross-linked three-dimensional structure, thanks to which they have the unique ability to absorb extreme amounts of water, up to a hundred times their weight. By using this property, it is possible to prevent water losses, which is important at the time of maturation in cementitious building materials. When there is a lack of water needed for hydration processes, the physical and mechanical properties deteriorate. The subject of this article is to determine the possible positive effect of the presence of SAP in the cement matrix in order to optimize the parameters of silicate composites for 3D printing. For this purpose, a special methodology was compiled consisting of tests through which it is possible to assess the suitability of the tested mixtures for 3D printing. This methodology consists of determining consistency, volumetric weight, ultrasonic analysis, buildability, X-ray diffraction, flexural tensile and compressive strength. For determining of buildability and ultrasonic analysis new methodologies were created in this research in order to be suitable for the 3D printing materials. Last but not least, efforts are also being made to increase the incorporation of secondary raw material (fly ash) in order to reduce the environmental impact of industrial production and, conversely, to increase its sustainability while maintaining or improving the mechanical–physical parameters of building materials. From the results presented in this paper it is apparent, that created methodology is efficient for determining properties of 3D printable mixtures. SAPs also significantly influenced properties of these mixtures. Mainly buildability and flexural tensile strength (by up to 30%) were increased and volumetric weight was decreased (by up to 5%).

Fiber Reinforced Concrete with Natural Plant Fibers—Investigations on the Application of Bamboo Fibers in Ultra-High Performance Concrete

Natural plant fibers represent a sustainable alternative to conventional fiber reinforcement materials in cementitious materials due to their suitable mechanical properties, cost-effective availability and principle carbon neutrality. Due to its high tensile strength and stiffness as well as its worldwide distribution along with rapid growth, bamboo offers itself in particular as a plant fiber source. In experimental studies on concrete beams reinforced with plant fibers, a positive influence of the fibers on the flexural behavior was observed. However, the load-bearing effect of the fibers was limited by the poor bond, which can be attributed, among other things, to the swelling behavior of the fibers. In addition, the plant fibers degrade in the alkaline environment of many cementitious building materials. In order to improve the bond and to limit the alkalinity and to increase the durability, the use of ultra-high performance concrete (UHPC) offers itself. Since no tests have been carried out, investigations on the flexural behavior of UHPC with bamboo fibers were carried out at the Institute of Concrete Construction of Leibniz University Hannover. The test results show a significantly improved load-bearing behavior of the fibers and the enormous potential of the combination of UHPC and bamboo fibers.

Nanomodified Concrete with Enhanced Characteristics Based on River Snail Shell Powder

The utilization of aquaculture waste, such as snail shells, is a severe issue. These shells are common in water-sources and are a by-product of sifting sand for masonry and concrete work. Calcium-rich river shells are of great interest for cement building materials. In this regard, the purpose of this article was to develop a nanomodified concrete with improved characteristics based on the powder of snail shells. Experimental studies have confirmed the effectiveness of the use of river shells in concrete without a decrease in strength characteristics and deterioration of other properties. It has been found that the optimal replacement by the snail shell powder that replaced cement is in the amount of 6%. By the nanomodification of concrete with the powdered shells of river snails, it was possible to achieve an increase in compressive strength up to 12%, axial compressive strength—up to 8%, tensile strength in bending—up to 9%, axial tensile strength—up to 11%, elastic modulus—up to 8%. Concrete nanomodification with snail shell powder in the amount of 6% contributed to a reduction of deformations of up to 7%. The study of the microstructure of concrete samples nanomodified with snail shell powder confirmed the obtained dependences of the cement’s properties on the nanomodifier dosage, as well as the most effective dosage of snail shell powder.

Viscoelastoplastic classification of cementitious suspensions: transient and non-linear flow analysis in rotational and oscillatory shear flows

Rheological modeling of special concretes such as ultra-high performance concretes (UHPCs), self-compacting concretes (SCCs), or environmentally friendly concretes with low clinker contents but containing many fine particles increases model complexity because high amounts of colloidal and fine particles and complex chemistry result in strongly non-Newtonian rheological behavior. Straight-forward viscoplastic rheological models such as the well-known Bingham- or Herschel-Bulkley approach do not fit the flow behavior on a large scale at and lead to boundary value problems in numerical flow simulations. Increased viscoelastic properties due to chemical admixtures are not described by pure viscoplasticity analysis methods. To fill this gap, our research presents viscoplastic and viscoelastic linear and non-linear rheological characterization methods for common and strongly non-Newtonian cement pastes and combines the methods for a comprehensive viscoelastoplastic modeling of cementitious building materials. We illustrate and discuss the benefits and boundaries of each measurement technique in dependence of cementitious paste complexity. Three solid volume fractions from phi = 0.45 to 0.55 and three different flowability ranges, adjusted through varying superplasticizer amounts, were investigated in respect of steady-state and transient yield stress, viscosity, and non-linear viscoelastic material properties. Our results reveal that with increasing solid volume fraction and polymer amount, viscoelastoplastic modeling describes rheological flow on a large flow scale more appropriately than common viscoplastic methods. The results show a new approach for a full quantitative and qualitative rheological classification of cementitious building materials and thus improve the understanding of densely packed colloidal cementitious suspensions. The findings serve as prospective guideline to model complex cementitious building materials both at low and high shear rates, and to find an appropriate rheological description at the boundaries of flow.Graphical abstract

Proposed mechanism for the enhanced microstructure of graphene oxide–Portland cement composites

Graphene oxide (GO) nanosheets can enhance the nanostructure of calcium silicate hydrate (C–S–H), the binder phase of Portland cement, and thereby increase the strength and durability of building materials. However, the mechanism underlying the observed enhancements remains to be elucidated, impeding the full realization of GO in the cementitious composites. Based on a comprehensive microscopy analysis of the effect of GO on C–S–H gel formed in tricalcium silicate cement, Portland cement, and synthetic systems, here we present a growth model that can explain the GO-induced improvements in the C–S–H nanostructure. It is proposed that GO nanosheets function as two-dimensional platforms to promote the growth of C–S–H gel via the Stranski–Krastanov (island-on-wetting-layer) growth mode. This growth mode can account for the formation of C–S–H with compact nanostructure leading to the cement matrix densification that has been widely reported in the literature. Through reconciliation with well-established descriptions of C–S–H gel, the proposed model can rationalize the superior mechanical and durability properties of cement building materials containing GO and other 2D nanomaterials.

A Bibliometric-Statistical Review of Organic Residues as Cementitious Building Materials

Climate deterioration and environmental pollution has been widely studied by a wide scientific community. The effects of the ecosystem deterioration impacts directly to human activities. In this scenario, the building industry has increased the pressure on proposing new materials to replace the cementicious component and natural resources (water, sand, gravel, and limestone) on mortar and concrete to reverse this trend. To this end, organic residues can offer opportunities as an available alternative for construction applications. Therefore, this paper aims to broaden the scope of research in this field by investigating the potential use of organic residues as cementicious building material based on bibliometric-statistical analysis using scientific information. A preliminary bibliometric analysis using VOSviewer was carried out to define the keywords co-ocurrence from Scopus database. Type of organic material, constructive use, and its properties (physicochemical, mechanical, and thermal) were extracted from scientific publications. Then, a systematic analysis criteria was defined to limit the scope of the study. Finally, statistical variance analysis and multiple correlation for identifying constructive application were applied. From the co-ocurrence analysis of keywords, we determined that 54% of the selected scientific publications were closely related to the scope of this study. State-of-the-art study established that related researches grew exponentially at a rate of about 30%/year. Moreover, scientific publications reported the use of a wide variety of organic residues, such as wheat, paper, hemp, rice, wood, molluscs, olive, coconut, among others. Mainly, agricultural residues (82%) with building applications related to structural concrete, mortar, bricks, and blocks, had been evaluated. Physicochemical properties from organic residues (extractives content, lignin content, and density) were correlated to mechanical (compressive, flexural and tensile strength) and thermal properties (thermal conductivity). The identification of the physicochemical properties of the organic residues allow us to predict the mechanical and thermal behavior of the material with residues. In summary, agricultural residues are the most promising organic building material due to their abundance and lignin content, exhibiting better mechanic and thermal properties than any other organic residues.

An Experimental Study on the Strength and Crack Healing Performance of E. coli Bacteria-Induced Microbial Concrete

The most commonly used building material in the construction industry is concrete. However, the weak features of concrete are its low ductility and limited tension capacity and hence crack development with the increase in load. These cracks get more worsened by the intrusion of water and salt present in the composition and hence causing deterioration and reducing the longevity of the material. This study focuses on an innovative approach to mitigate concrete’s fractures and flaws by utilizing microbiologically induced calcite (CaCO3) precipitation (MICP) excited by Escherichia coli (E. coli) bacteria to improve the performance of cementitious building materials. The study investigated the development of microbiological concrete in plain water using only one culture density (OD600 0.5 ± 0.1). In this study, two water-to-bacterial mix ratios (75 : 25 and 50 : 50) were used and compared to the conventional concrete (100 : 0). 100-mm cube-sized specimens cured for a period of 7, 28, 90, and 365 days were tested for compressive strength, water absorption capacity, ultrasonic pulse velocity (UPV), and SEM analysis, which were performed on the samples at regular intervals. According to the results of these experiments, microbial concrete with the 50 : 50 ratio exhibited the highest strength for all curing times. From the water absorption test of samples, it is found that the absorption of the materials got reduced due to the infusion of microorganisms in concrete. On the other hand, the UPV test showed high velocity than the control samples for specimens with an OD600 0.5 ± 0.1. Scanning electron microscope (SEM) analysis performed on distinct concrete groups at the age of 28 days showed fewer voids in the concrete lumps due to the increase in water substitution rate caused by microbial culture.

Multivariate statistical assessment of natural radioactivity and radiological hazards data of cement building materials mainly used in Cameroon

Multivariate statistical assessment of natural radioactivity and radiological hazards data of cement building materials mainly used in Cameroon

Carbon sequestration in cementitious matrix containing pyrogenic carbon from waste biomass: A comparison of external and internal carbonation approach

Cement manufacturing and concrete constructions are associated with high carbon dioxide (CO2) emission. This can be potentially reduced by sequestering CO2 through calcium carbonate mineralization using the technique of accelerated carbonation curing (ACC). This research investigates and compares the role of biochar – as-produced (BC) and CO2-saturated (SatBC), and silica fume (SF) respectively on carbon sequestration, strength and hydration of cement composites. In case of SatBC, the CO2 is pre-adsorbed in biochar pores a priori before deployment in cement matrix. The study found that addition of BC can densify the cement matrix through accelerating hydration and improving the total hydration. This leads to reduction in carbon dioxide diffusion and carbonate mineralization initially (7-day age) than control. However, the net carbonate mineralization in biochar-cement paste is similar to control and silica fume-paste after 28 days of carbonation. Accounting for the carbonate mineralization and carbon sequestered in the biochar structure, ACC of BC-CP and internal carbonation in SatBC-CP can lead to 5–6% reduction in carbon dioxide-equivalent (CO2-eq) than control. Addition of biochar yields higher carbonate mineralization from carbonation of calcium hydroxide compared to silica fume-cement (SF-CP), where more carbonate mineralization is contributed by carbonation of binder gel. This leads to 8–10% higher compressive strength and lower loss in strength (4–5% loss) in BC-CP compared to SF-CP (15% loss) at 28-day age. Application of SatBC as admixture substantially improves compressive strength compared to uncarbonated control and SF-CP at 7-day age and demonstrates similar strength as carbonated SF-CP after 28 days. The results suggest that spent biochar, previously used as industrial CO2 adsorbent, can be valorized as “green admixture” in cement-based materials. In summary, this research illustrates the potential of biochar to manufacture low carbon cementitious building materials, that can turn future cities into “carbon sinks”.

Carbonaceous admixtures in cementitious building materials: Effect of particle size blending on rheology, packing, early age properties and processing energy demand

Application of biochar, produced from locally generated wastes, as admixture in cement is a strategy to upcycle biomass waste and produce durable building materials. This research explores the influence of particle size and porosity of biochar, prepared from coconut shell and wood waste, added at 2 wt% of cement, on rheology, setting time, hydration and early age strength of cement mortar. For each biochar type, three particle size gradations are explored – coarser biochar (d50 = 45–50 μm) (obtained by sieving), finer biochar (d50 = 10–18 μm) (obtained by ball milling) and combination of coarser and finer biochar (d50 = 15–25 μm). Experimental findings suggest that combination of coarser and finer biochar improves workability and rheological properties of binder pastes compared to that with (only) coarser biochar. Depending on biochar type, hydration and rate of setting are accelerated compared to control. Inclusion of finer biochar and combination of finer and coarser biochar improve packing density and degree of hydration of pastes compared to coarser biochar and control, leading to 12–19% enhancement in compressive strength at 7-day age. Micro-structural investigations show that the macro-pores of coarser biochar can be filled with dense hydration products, although some macro-pores may remain unfilled. This offsets improvement in strength that can be achieved through enhancement in packing density. The approach of blending coarser and finer biochar reduces the energy demand and cost associated with ball-milling by 23–37% and SGD 2.30–4.80 per ton respectively compared to only finer (ball-milled) biochar per cubic meter of concrete. Overall, the findings from this research demonstrate that blending of biochar of different particle size distributions can enhance physical properties of cement-based materials, while reducing associated energy consumption.