Mortar Structure Research Articles

Fly ash admixture originating from lignite combustion in construction mortars – Time evolution of technical parameters and heavy metals leachability

The production of cement, the predominant construction binder, is associated with high energy consumption, enormous raw material depletion, and a large volume of CO2 emissions, making cement one of the most polluting materials. This study aims to contribute to the sustainability of the construction industry by significantly reducing the proportion of Portland cement (PC) in the composition of mortars. The binder content reduction was achieved by the addition of large amounts of fly ash admixture (FA) from lignite combustion while studying the effectiveness of the immobilization of heavy metals (HMs), which are present in FA, in the PC/FA matrix. Along with the analysis of the FA admixture amount on the properties of the prepared mortars, emphasis was put on the study of the influence of prolonged curing on the development of the physical parameters of the mortars and the immobilization efficiency of the HMs. It was revealed that FA can be added to PC by up to 20 wt%, enabling the production of construction mortars with high strength and low porosity, while confining hazardous substances such as HMs in the matrix. Prolonged curing at elevated relative humidity led to the continuous evolution and solidification of the mortar structure, improving its engineering properties and HMs immobilization efficiency.

Inhibiting efflorescence of alkali-activated slag mortar by improving its hydrophobicity with methyl-terminated polydimethylsiloxane (PDMS): Evidences showing the remained PDMS

This paper proposes to prepare hydrophobic alkali-activated slag (AAS) mortars with methyl-terminated polydimethylsiloxane (PDMS), a hydrophobic polymer with low surface energy, to minimize its water sorptivity and efflorescence. To depict the efflorescence process of PDMS-modified AAS mortars, visual inspections of efflorescence features, the leaching behavior of sodium ions, water absorption characteristics of mortars and contact angle tests were conducted. Additionally, the hydration process, microscopic morphology, and chemical structure of PDMS-modified AAS mortars and pastes were examined by compressive strength, isothermal calorimetry, TEM, SEM, FT-IR, 29Si NMR, enabling the explanation of PDMS working mechanisms. The results demonstrated that the addition of PDMS successfully mitigated esthetic issues and the spalling of mortars caused by efflorescence. Furthermore, PDMS reduced the risk of long-term durability issues of AAS mortars by restricting the loss of sodium ions after efflorescence. At the same time, the introduction of PDMS with dosage below 5 % did not significant retarder the hydration reaction process or the development of strength of AAS. However, it did alter the micromorphology and chemical structure of the hydration product. PDMS linked to the hydration products through covalent bonds and acted as a bridging role to alter the micromorphology of the hydration products. The resulting multi-structured material exhibited micropapillary and nano-coating layers with hydrophobic methyl functional groups, imparting hydrophobicity to the PDMS-AAS hydration product.

Effects of binder component and curing regime on compressive strength, capillary water absorption, shrinkage and pore structure of geopolymer mortars

Effects of binder component and curing regime on compressive strength, capillary water absorption, shrinkage and pore structure of geopolymer mortars

A Study on the Mechanical and Wear-Resistance Properties of Hybrid Fiber Mortar Composites with Low Water-Cement Ratios.

Based on mortar composites with a low water-cement ratio, the effects of hybrid aramid fiber (AF), calcium sulfate whisker (CSW), and basalt fiber (BF) on their mechanical properties and wear resistance were studied, and the correlation between wear resistance and compressive strength are discussed. A microstructure analysis was conducted through scanning electron microscopy (SEM) and the nitrogen-adsorption method (BET). The research results show that compared with the control group, the compressive strength, flexural strength, and wear resistance of the hybrid AF, CSW, and BF mortar composites with a low water-cement ratio increased by up to 33.6%, 32%, and 40.8%, respectively; there is a certain linear trend between wear resistance and compressive strength, but the discreteness is large. The microstructure analysis shows that CSW, AF, and BF mainly dissipate energy through bonding, friction, mechanical interlocking with the mortar matrix, and their own pull out and fracture, thereby enhancing and toughening the mortar. A single doping of CSW and co-doping of CSW and AF can refine the pore structure of the mortar, making the mortar structure more compact.

Mechanics and microstructure analysis of geopolymer utilizing ilmenite tailing and metakaolin powder as alkali-activated materials

Geopolymers derived from bulk solid waste are considered ideal substitutes for cement-based materials in developing environmentally friendly construction materials. The utilization of solid waste tailings powder as a precursor for alkali activation of geopolymer can enhance the mechanical characteristics of geopolymer. This study conducted extensive experimental studies on the compressive strength, flexural strength, SEM microstructure, thermogravimetric curve, and variable influence of alkali-activated ilmenite tailings (IT) geopolymer mortar, using the liquid-solid ratio and the number of tailings as variables. An analysis was conducted on the mortar's mechanical characteristics, microstructure, and machine-learning properties. Furthermore, the impact of different atomic ratios on the structure and characteristics of geopolymer mortars was also examined. The test results revealed that the metakaolin-iron titanium tailings geopolymer, when doped with 10% ilmenite tailings, exhibited a compressive strength of 72.30MPa at 14 days. Similarly, the flexural strength of the geopolymer reached 4.76MPa at 14 days when doped with 30% ilmenite tailings. XRD analysis showed that Magnesiohornblende particles Mg-F-A-S-H and C-A-S-H gel had positive and negative correlations, respectively, with the tailings doping level. TG results indicated that the specimens exhibit enhanced thermal stability following treatment with tailings. SEM analysis revealed that combining ilmenite tailings with metakaolin formed Me-(F)-A-S-H gels. The examination of surface porosity, pore shape, and unreacted material determined that adding ilmenite tailings increased the Si/Al and Fe/Si ratios, enhancing the transformation of the lamellar structure to the three-dimensional disordered gel mesh structure. Additionally, the tailings contributed a significant amount of Ca, elevating the Ca/Na ratio (0.1−0.6) and triggering calcium precipitation within a Ca/Si range of 0.03−0.2. This increase in calcium led to a decrease in the sample's strength as the curing time was extended. Based on prior research and the application of the Gray Wolf optimization algorithm in extreme learning, a clear negative correlation was identified between the liquid-solid ratio and strength. Furthermore, increasing the Si/Al ratio enhanced the geopolymer's strength, while an extended curing time negatively correlated with strength. The impact of tailings mixing was deemed insignificant when the tailings amount did not exceed 20%. Geopolymers may derive significant environmental and industrial benefits from the improvement of their mechanical properties, thermal stability, and optimization using machine learning.

Effect of curing condition on mechanical properties and durability of alkali-activated slag mortar

While alkali-activated slag (AAS) has emerged as a promising alternative binder in construction engineering, a consensus on the optimal curing condition for this material has not been reached yet. It is well known that AAS can harden at ambient temperatures, but the influence of humidity on its properties remains poorly understood. Herein, we considered five curing conditions with different relative humidities (RH), including ambient/dry condition (RH=55 %), sealed condition (RH=80–95 %), fog condition (RH>95 %), water immersion condition (RH=100 %), and saturated limewater immersion condition (RH=100 %). Various properties have been examined, including flexural and compressive strengths, elastic modulus, shrinkage, pore structure, carbonation resistance, and freeze-thaw resistance of AAS mortars (AASM). Two types of activators, sodium hydroxide and sodium silicate (modulus at 1) solutions were used. The experimental results indicate that drying at early ages is detrimental to almost all the properties investigated. Sealed curing can deliver desirable mechanical properties and durability, but considerable shrinkage. Fog and water curings are highly effective at mitigating early shrinkage in AASM, but the problem of leaching adversely affects its long-term properties. Generally, limewater curing offers limited benefits compared to other high-humidity curing methods.

Microstructural modifications of lime-based mortars induced by ceramics and nanoparticle additives

Lime-based mortars are one of the principal choices for building and restoration projects, owing to their unique qualities and material compatibility. Admixtures have long been incorporated to enhance the performance and durability of mortars, with ceramics being a traditional choice. More recently, the addition of nanoparticles has been explored as a means to further improve these properties. However, the effective optimization of the complex interplay between additives in lime-based mortars, which is crucial for enhancing their sustainability, remains an ongoing area of research. This study investigated the effects of red-clay ceramic aggregates (RCC) and nanoparticle-based solutions of Ca(OH)2 and SiO2 on the mineralogy, hydraulicity, surface properties, pore structure, and mechanical properties of lime-based mortars. The addition of nanoparticle-based solutions increased the carbonation reactivity, whereas the ceramic aggregates caused a more extensive conversion of portlandite to calcite on the external faces, indicating reduced porosity during the carbonation process. Pozzolanic reactions and the formation of new calcium silicate compounds were observed, along with improved compaction, smoother surfaces, and microcrack formation. The porosity increased with the addition of the ceramic aggregates, whereas the addition of nanoparticles significantly increased the number of pores in the mesoporous range. The specific surface area of the mortars increased with the inclusion of ceramic aggregates and nanoparticles, whereas the open porosity increased and the density and compressive strength decreased with the addition of nanoparticles and associated pozzolanic reactions that occurred with the inclusion of ceramic aggregates. These findings lay the groundwork for future improvements in the formulation of lime-based mortars to balance hydraulicity, surface characteristics, and mechanical performance while preserving porosity.

Impact of Physico-Chemical Characteristics on the Mechanical Strength and Pore Structure of Air Lime Mortars with Isparta Tuff and Banahmeta Additives

The physical and chemical interactions between the lime and pozzolans in conservation mortars are fundamental to sustainable building practices. Here, we report experimental investigations on pure air lime mortar, air lime-isparta tuff mortar, and air lime-banahmeta mortar. Isparta Tuff is formed from volcanic rocks found in the Southwest between Isparta and Burdur city centres in Anatolia, belonging to the Gölcük volcanism. The microstructural and physiochemical interactions of these mixed designs were investigated. Importantly, this study quantifies critical performance parameters of air lime mortars incorporating Isparta tuff as a pozzolan. It supports using local and natural volcanic tuffs in developing sustainable mortars for the conservation of historical assets in Turkey.

Particle packing optimization and pore structure assessment of ternary cementitious system based on X-ray computed tomography and mercury intrusion porosimetry

The introduction of high-volume steel slag into ordinary Portland cement (OPC) has a negative effect on the pore structure due to its poor hydraulic reactivity. Synergistic effects between steel slag and ground granulated blast furnace slag (GGBFS) in cementitious system have drawn increasing attention. In this study, the modified Andreasen and Andersen (MAA) model was adopted for the mixture design of ternary cementitious system incorporating high-volume ultrafine steel slag (USS) and GGBFS without a compromise in strength. X-ray computed tomography (X-CT) and mercury intrusion porosimetry (MIP) were applied to characterize the pore structure of various cementitious mortars in terms of porosity, pore size, pore number, pore morphology and homogeneity. Results manifested that the adverse impact of USS addition on the pore structure of binary cement was effectively mitigated in the ternary cement USS-GGBFS-OPC after mixture optimization, whereby the pore size was shifted toward a finer distribution and simultaneously with a higher uniformity and consequently promoting the compressive strength development. An increase of cumulative pore volume as captured by X-CT was associated with an exponential decrease of the number of pores while together with larger pore sizes. The increase in the number of small pores led to an increase in the pore tortuosity and degree of sphericity. The fractal dimension of pores was negatively correlated with pore inhomogeneity and compressive strength. These findings provide new insights into homogeneity-oriented mixture design of composite cementitious binders based on gap-graded particle packing, together with their synergistic effects on hydration progress.

Effect of mechanical activation on hydration properties of natural volcanic rock towards partially replacing cement in composite cementitious materials

With the rapid increase in the consumption of various mineral admixtures, using regional distinctive raw materials to prepare cement mineral admixtures is an effective approach to achieve green and sustainable development. In this paper, the natural volcanic rocks (NVR) in Western Sichuan are mechanically activated at different times, subsequently, the ion dissolution characteristics of NVR powder at different activation times and the hydration mechanism of NVR powder composite cementitious material are studied. In a simulated alkaline environment of cementitious liquid phase, based on the dissolution behavior of Si4+, Al3+, and Ca2+ ions in NVR powder and the morphological analysis of NVR powder before and after dissolution, it is indicated that SiO2 and Al2O3 are the primary sources of reactivity in NVR powder and the reduction in particle size promotes the breakage of Si–O and Al–O bonds in NVR powder. Analysis of the hydration process, mineral composition of hydration products, and their microscopic morphology reveals that an appropriate amount (15 %) of NVR powder, after 45 min of mechanical activation, can promote the generation of hydration products and denser mortar structure, enhancing the strength of the composite cementitious material. Mainly attributed to the increased volcanic ash activity of NVR powder through mechanical activation, as well as the nucleation induction and filling effects of NVR powder. This study provides theoretical and technical supports for the efficient use of raw materials with regional characteristics to prepare mineral admixtures.

The use of air entraining/plasticizing admixtures in cement-lime masonry mortars: Effects on fresh and hardened mortar properties

Modern day masonry mortars rely on more than just standard constituents, which by definition include binder, aggregates and water. Due to different requirements imposed onto various types of masonry construction, ready mix mortar manufacturers and even masons and labourers on construction sites add certain additives to their mortar formulations. In this study, one standardized admixture is studied – an air entrainer/plasticizer (EN 934-3), coming in two forms – liquid and powder. It is applied to increase the air content and plasticity of cement-lime masonry mortar, formulated in volumetric proportions of 1:1:6 for cement, lime and aggregates. The dosage of admixtures is gradually increased starting with the manufacturer’s recommendations until the excessive air entrainment is achieved in order to determine the optimal dosage. Fresh mortar properties, including consistency, air content and bulk density are used to assess the enhancement of mortar influenced by the addition of the admixture, whereas compressive and flexural testing is performed at 7 and 28 days to monitor the disadvantages brought by reducing density. The results of this study reveal that the efficacy of a liquid admixture is better than that of a powdered air entrainer/plasticizer, albeit it being more difficult to use accurately. In both cases, higher dosage than manufacturer’s recommendations was required to reach satisfactory improvement of the fresh mortar structure, which resulted in a mixing water reduction, increased air content and reduced bulk density. That subsequently influenced the decreased strength, although optimally formulated mortars adhered to their strength class requirements.

A comprehensive evaluation of the photo-catalytic performance of recycled glass aggregate incorporated permeable cement-based mortar with TiO2 as a photo-catalyst

This study aims to investigate the effectiveness of incorporating recycled glass aggregate (RGA) in TiO2-containing cement-based permeable mortars in terms of their photo-catalytic performance. To do this, standard and permeable mortars were produced with the RGA utilization rates of 15% and 30% (by weight of total aggregate content). Photo-catalytic activity of the mortars was evaluated through the determination of NOx and NO degradation capacities, NO2 transformation ratio and the selectivity, and their photo-catalytic activity performances were compared with each other and with reference specimens without any RGA to assess the efficiency of RGA utilization in terms of photo-catalytic degradation. Microstructural and mechanical properties of the mortars were also evaluated by performing scanning electron microscope (SEM) analysis and compressive strength test, respectively. According to the experimental results, regardless of curing age, utilization of RGA as aggregate caused decrements in the strength results because of the lower adherence capability with matrix. NOx degradation results indicated that permeable structure of the photo-catalytic mortars allows NOx species to diffuse to the inner part of the hardened specimen in favor of stimulation of photo-catalytic degradation reactions in deep along with the surface. RGA utilization was also allowed to penetration of UV lights throughout the matrix providing improved the photo-catalytic activity for the TiO2-containing specimens. The correlation between the selectivity results and the degradation rates of NOx demonstrates the reliability of selectivity as a parameter for evaluating the photo-catalytic performance.

Enhancement effect of multiwalled carbon nanotubes on mortars prepared with different grades of recycled fine aggregates

Recycling construction waste while reducing natural sand mining has proven to be a sustainable option for environmental protection. Multiwalled Carbon nanotubes (MWCNTs) have the potential to enhance the mechanical characteristics of recycled fine aggregates (RFA) mortars. This research aims to explore the feasibility of applying MWCNTs in the RFA mortars. Various concentrations of MWCNTs were added to different grades of RFA-prepared mortar to obtain an optimal concentration. Besides, the scanning electron microscopy (SEM) analysis was conducted to observe the microstructure inside the RFA-prepared mortar. The nuclear magnetic resonance (NMR) test was used to test the pore structure of mortars. The results show that the RFA quality is relevant to the initial compressive strength of the RFA resource. The optimal concentration and the enhancement effect of MWCNTs on the three different RFA-prepared mortars are obtained with mechanical properties proven. The SEM images show that more cracks exist in the RFA-prepared mortars, and the NMR test shows that the number of pores inside the RFA-prepared mortars is significantly larger than that in the natural sand mortar. Nevertheless, an appropriate amount of MWCNTs can create a dense network and great bond inside the mortar, improving its mechanical properties.

Impact of bacterial admixtures on the compressive and tensile strengths, permeability, and pore structure of ternary mortars: Comparative study of ureolytic and phototrophic bacteria.

The addition of bacterial biomass to cementitious materials can improve strength and permeability properties by altering the pore structure. Photoautotrophic bacteria are understudied mortar bio-additives that do not produce unwanted by-products compared to commonly studied ureolytic species. This study directly compares the impact of the addition of heterotrophic Bacillus subtilis to photoautotrophic Synechocystis sp. PCC6803 on mortar properties and microstructure. Cellulose fibers were used as a bacteria carrier. A commercial concrete healing agent composed of dormant bacterial spores was also tested. Strength, water absorption tests, mercury intrusion porosimetry, differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscopy were applied to experimental mortar properties. The photoautotrophic modifications had a stronger positive impact on mortar strength and permeability properties than sporulated heterotrophic modifications due to differences in surface properties and production of exopolysaccharides. The findings provide support for photoautotrophic species as additives for mortars to move away from ammonia-generating species.

Effects of copper mining wastewater on the performance of waste-based low-clinker cement mortars

The presence of copper mining wastewater (CMw) in wet copper tailings (CTs) significant impediment to the reutilization of wet CTs in cementing material. This paper investigates the influence of CMw on the performance of waste-based low-clinker cement (Lcc) mortars, aiming to address the fundamental issues related to the application of wet CTs. In this regard, four Lcc mortars were prepared by using CMw to replace 0, 25 %, 50 % and 100 % of tap water. The influence of CMw on the setting time, hydration kinetics, hydration products, pore structure, compressive strength and microstructure of Lcc mortars were analyzed. Experimental results show that the addition of CMw prolonged the setting times and retarded the hydration process of Lcc paste due to the presence of acids and organic substances in CMw. Nevertheless, the presence of Ca2+, Na+, and Mg2+ in CMw can accelerate the dissolution of Lcc, contributing to the formation of expansive ettringite and hydrotalcite. As a result, Lcc mortars with CMw possessed denser pore structures. By using 50 % CMw, the compressive strengths of mortars can be increased by 3.5 % at 3d, 5.21 % at 7d, and 8.75 % 28d. The feasibility of adding CMw in Lcc mortars was verified, which would serve as the foundation for the preparing of Lcc-based materials with wet CTs.

ASSESSMENT OF THE AGGREGATES IMPACT ON THE PROPERTIES OF RECOVERY POLYMER MORTARS

The peculiarities of polymer mortar application for renovation and restoration are determined on the basis of priority data integration about the destruction mode of valuable historical buildings. The possibilities of controlling technological, physical-mechanical, and operational properties of recovery polymer mortar due to the aggregates of different nature are shown. For the analysis and optimisation, the quantitative relations between the structure and property factors of recovery polymer mortars and the factors of recipes and technology determining them were obtained in the form of experimental and statistical models calculated using the COMPEX system. The optimisation methods of recipe and technological solutions based on the use of experimental and statistical models are proposed. The optimisation of polymer mortar composition according to the package of quality indexes and property stability at high temperature has been carried out. The package of "mixture-technology-properties" models has been obtained, with the help of which the change mechanisms of direct and summarizing indexes of mixture technological properties and mechanical properties of recovery polymer mortars have been established when changing the type of aggregates (ceramics, quartz, carbonates, their binary and triple mixtures). The influence of aggregates on the durability change of polymer mortar under the influence of various temperature-climatic and operational factors (UV-irradiation, alternate action of temperature and aggressive aqueous solutions) has been studied. It is recommended to use quantity and type optimal aggregates to provide the complex of technological and operational properties of polymer mortar and to reduce the consumption of imported polymer. The rational compositions of polymer mortar with increased stability of properties under changing temperature and climatic conditions are proposed for different restoration technologies. The series of nomograms have been developed for the initial selection of the "area" of rational polymer mortar compositions, providing for further correction in relation to a specific repairable object. Technological and marketing analysis according to the research results are carried out.

Study on the microscale structure and sulfate attack resistance of cement mortars containing graphene oxide nanoplatelets

This study investigates the corrosion resistance of cement-based materials modified with GO (graphene oxide) against sulfate, employing a series of experiments. The results demonstrate that the inclusion of GO enhances the corrosion resistance of cement in terms of mechanical properties, sulfate ion diffusion, and microstructural characteristics. The internal pore network structural parameters of the composite were analyzed using X-ray microcomputed tomography processing techniques at a microscopic scale. The permeability of the composites was numerically simulated using hydrodynamic equations, such as the Hagen-Poiseuille and Kozeny-Carman equations. The additional amount of GO in the composite cement was varied as follows: 0%, 0.01%, 0.03%, 0.05%, and 0.1%, with 0% serving as the reference specimen. In the flexural and compressive strength tests, the strength of the GO-modified specimens exhibited varied improvements after 180 days of exposure to a sodium sulfate solution. The flexural and compressive corrosion resistance coefficients were optimized by 12.34% and 11.07%, respectively, with the addition of 0.03% GO. The diffusion coefficients of sulfate ions were consistently observed at a level of 10-6 mm2/s and decreased over time. Furthermore, the presence of GO hindered the transport of sulfate ions. The gas permeability test results indicated that the GO-modified cement mortar exhibited lower porosity and permeability compared to the reference mortar. The pore network structure model revealed that the reference specimen possessed a connected porosity of 8%, an average porosity of 10%, and a wide distribution of pore and throat radii. In contrast, the 0.03% GO composite cement specimens exhibited a connected porosity of 5.3% and an average porosity of 8%. Through simulations using the Kozeny-Carman equation, it was determined that the reference specimen had higher permeability and faster internal flow rates.

Electrically insulating PBO/MXene film with superior thermal conductivity, mechanical properties, thermal stability, and flame retardancy

Constructing flexible and robust thermally conductive but electrically insulating composite films for efficient and safe thermal management has always been a sought-after research topic. Herein, a nacre-inspired high-performance poly(p-phenylene-2,6-benzobisoxazole) (PBO)/MXene nanocomposite film was prepared by a sol-gel-film conversion method with a homogeneous gelation process. Because of the as-formed optimized brick and mortar structure, and the strong bridging and caging effects of the fine PBO nanofibre network on the MXene nanosheets, the resulting nanocomposite film is electrically insulating (2.5 × 109 Ω cm), and exhibits excellent mechanical properties (tensile strength of 416.7 MPa, Young’s modulus of 9.1 GPa and toughness of 97.3 MJ m−3). More importantly, the synergistic orientation of PBO nanofibres and MXene nanosheets endows the film with an in-plane thermal conductivity of 42.2 W m−1 K−1. The film also exhibits excellent thermal stability and flame retardancy. This work broadens the ideas for preparing high-performance thermally conductive but electrically insulating composites.

Improvement of microporous structure and impermeability of cement mortars using fly ash and blast furnace slag under low curing pressures

Low air pressures in high plateau will degrade the impermeability and air void structure of cement mortars. In this study, the feasibility and mechanism of fly ash (FA) and ground granulated blast furnace slag (GGBFS) improving the microporous structure and impermeability of cement mortars under low curing pressure were investigated. Results showed that the slag significantly improved the impermeability and air voids distribution of cement mortars, while the fly ash did not benefit the impermeability, as well as the air void in mixed mortars. The heat releasing rate and hydration product composition of the slag mixed paste were superior to that of the FA. The reduction of Ca(OH)2, gentler hydration rate, and filling effect of fine slag particles are believed to contribute to the improvement of impermeability. The water vapor isotherm sorption test demonstrated that low curing pressure changed the surface characteristics of hydrates, and inhibited the adsorption and desorption process (including the capillary condensation process and ink-bottle effect) with the range of relative humidity (RH) > 40%. Meanwhile, the titting parameters variation certified according to Guggenheim-Anderson-deBoer (GAB) model certified that the addition of slag achieved the same result as increasing curing pressure. Moreover, futher analysis showed that if partial OPC was replaced by slag, it could befinit energy consumption, CO2 emission, and materials cost compared with pure OPC. This study provides an initial evidence for applications of slag in low air pressure conditions.

Development of Ultra-High-Performance Silica Fume-Based Mortar Incorporating Graphene Nanoplatelets for 3-Dimensional Concrete Printing Application

Although the use of 3D printing in civil engineering has grown in popularity, one of the primary challenges associated with it is the absence of steel bars inside the printed mortar. As a result, developing 3D printing mortar with ultra-high compressive, flexural, and tensile strengths is critical. In the present study, an ultra-high-performance mortar incorporating silica fume (SF) and graphene nanoplatelets (GNPs) was developed for 3D printing application. The concrete mixture added SF to the concrete mixture in the range between 0% and 20%, while GNPs were added as a partial replacement by cement weight from 0.5% to 2%. The flowability and the machinal properties of the proposed mortar, including compressive (CS), tensile (TS), and flexural strength (FS), were investigated and assessed. Microstructure analysis involving FESEM and EDX was also investigated and evaluated, while response surface methodology (RSM) was considered to predict and optimize the optimum value of GNPs and SF. Workability results show that the flowability is reduced when the amount of graphene increases. Based on the predicted and experimental results, ultra-high-strength mortar can be developed by including 1.5% of GNPs and 20% of SF, in which the CS jumped from 70.7 MPa to 133.3 MPa at the age of 28 days. The FS and TS were 20.66 MPa and 14.67 MPa compared to the control mix (9.75 MPa and 6.36 MPa), respectively. This favorable outcome was credited to the pozzolanic activity of SF and the effectiveness of GNPs in compacting the pores and bridging the cracks at the nanoscale level, which were verified by FE-SEM and EDX. In addition, the developed quadratic equations proved their accuracy in predicting and optimizing the mechanical properties with low error (less than 0.09) and high correlation (R2 > 0.97). It can be concluded that the current work is an important step forward in developing a 3D printing mortar. The lack of reinforcement in the printed mortar structure has been a considerable difficulty, and the SF and GNPs have increased the compressive, flexural, and tensile strengths of the mortar. Thus, these improvements will encourage the industry to utilize sustainable materials to produce more affordable housing.