Mortar Flow Research Articles

Formulation and characterization of one-part Ca-based alkali-activated slag-steel slag materials

This study aims to develop one-part Ca-based alkali-activated materials (OCAM) using steel slag (SS) and slag powder (SP) with a Ca-based activator. The effects of SS replacement rate on the flowability, setting time, and mechanical properties of paste were systematically investigated. Furthermore, methods such as Mercury intrusion porosimetry (MIP), heat of hydration, X-ray diffraction (XRD), and scanning electron microscope (SEM) were used to compare the effects of calcium oxide (CO) and calcium hydroxide (CH) on the microstructure of the OCAM. The results indicate that the addition of SS enhances mortar flowability and setting time, with optimal mechanical properties when the SS replacement rate is 20 %. However, strength gradually decreases as the replacement rate increases beyond this point. In addition, the incorporation of CO further enhances the mechanical properties of mortar. MIP test results show that the use of CO reduces the internal porosity and refines the micropore structure, although it also increases drying shrinkage. The hydration heat test results reveal that the use of CO increased the total heat release of the sample in the initial 72 h and accelerated the early hydration reaction. Moreover, XRD and SEM results indicate that CO improves carbonation resistance.

Feasibility of upcycling red mud for low-CO2 cement via calcination: A comparative study with FA and GGBFS based in China

This study examines the feasibility of developing low-CO2 cement using calcined red mud (RM) and explores positive scenarios that simultaneously attain technical, environmental, and economic benefits in reference to conventional fly ash (FA) and ground granulated blast furnace slag (GGBFS) cements. Based on the variables of RM's content and calcination temperature, we investigated the fresh properties (paste rheology and mortar flowability), strength development, microstructure, embodied CO2 emissions, and cost of the RM-blended cement. The results show that there was an optimal range of RM's calcination temperature (400–600 °C) that improved the cement paste viscosity while attaining a higher strength than that of FA cement. Considering the cradle-to-gate CO2 emissions and cost of cement production, the optimal cement composition is comprised of up to 30% RM calcined at 600 °C, where the cement cost is lowered by 19.3% compared to the FA reference having a comparable CO2 footprint. According to the geographical analysis, the calcined RM shows minimal advantages over GGBFS but could substitute FA as a cleaner, cheaper, and more reactive supplementary cementitious material in regions where electricity grid is dominated by clean energy. Therefore, RM offers a plausible solution to future low-CO2 cement in light of the increasing shortage of FA led by the declining use of coal-powered electricity.

Effect of alkaline rice straw fibers content and curing ages on static mechanical properties of cemented lithium mica tailings backfill

Alkaline rice straw fibers (ARSF), as a widely available and recyclable plant fiber source, can provide new insights for improving the mechanical properties of backfill and the treatment of agricultural waste resources research. Different amounts of ARSF were prepared to enhance the cemented lithium mica tailings backfill (CLMTB), and uniaxial compression strength (UCS) tests and Brazilian splitting tensile strength tests were conducted to study the influence of ARSF on the static mechanical properties of CLMTB samples. Firstly, the flowability of mortars with different ARSF content was tested, the results showed that the flowability decreased by a maximum of 5.4 %, which met the construction requirements of cement mortar in the construction process. The UCS showed an increasing trend and then reduced with the increased ARSF content, with 0.15 % being the optimal content, showing a maximum increase of 14.2 %. Under Brazilian splitting loading conditions, the tensile strength gradually increased with the increased ARSF content, with 0.60 % being the optimal content. The UCS of the CLMTB samples showed exponential growth with increased curing age. Additionally, there was a linear functional relationship between the curing age and the tensile strength of the CLMTB samples. The experimental results indicate that the ARSF improved the toughness and changed the failure mode of the CLMTB samples. In the meantime, it increased the residual bearing capacity and the peak tensile strain of the CLMTB samples.

Rheology modification of flowable mortar with CO2

The rheological properties of mortar samples with different additions of CO2 during mixing were determined. Flowable cement-based mortars at three different w/c (0.55, 0.45 and 0.35) were produced and the effects of CO2 gas were examined on the fresh properties of slump flow, yield stress and plastic viscosity. According to the experimental results, the mortar yield stress and plastic viscosity increased faster over time than in a reference system with the increasing addition of CO2 and greater effects were seen at the lowest w/c of 0.35 than at the others. The impact of the CO2 on the yield stress was more pronounced than on the viscosity. In the w/c 0.35 system the properties showed no effect at dosages of 0.06% and 0.13% CO2 by weight of cement. Increasing dosages to 0.19 and 0.25% resulted in an increasing reduction in slump flow, immediate increases in yield stress of 62 and 298%, increases in structural buildup by a factor of 5 and 10, respectively, and increased the initial plastic viscosity by 33 and 148%, respectively. The effects are attributable to the growth of reaction products decreasing the interparticle spacing and increasing the surface area as associated with the CaCO3 and gel phase. CO2 was demonstrated to be a potential yield stress control agent; an appropriate dose can increase rheological properties as measured immediately after and increase their rate of change with time. This aligns with specialized applications that hinge upon changing rheology such as form pressure control or 3D concrete printing.

3D concrete printing using computational fluid dynamics: Modeling of material extrusion with slip boundaries

This paper investigates the role of slip boundary conditions in computational fluid dynamics modeling of material extrusion and layer deposition during 3D concrete printing. The mortar flow governed by the Navier-Stokes equations was simulated for two different slip boundary conditions at the extrusion nozzle wall: no-slip and free-slip. The simulations were conducted with two constitutive models: a generalized Newtonian fluid model and an elasto-viscoplastic fluid model. The cross-sectional shapes of up to three printed layers were compared to the experimental results from literature for different geometrical- and speed-ratios. The results reveal that employing free-slip boundary conditions at the extrusion nozzle wall improves layer-mimicking quality for both constitutive models, indicating the presence and importance of a lubricating layer of fine particles at the concrete-solid wall interface. This enhanced performance is primarily due to the observed decrease in extrusion pressure that minimizes layer height- and width-deviations compared to the experimental prints. Furthermore, the free-slip boundary conditions play an important role in predicting the multilayer prints, its deformation and groove shapes.

On the Flow of a Cement Suspension: The Effects of Nano-Silica and Fly Ash Particles.

Additives such as nano-silica and fly ash are widely used in cement and concrete materials to improve the rheology of fresh cement and concrete and the performance of hardened materials and increase the sustainability of the cement and concrete industry by reducing the usage of Portland cement. Therefore, it is important to study the effect of these additives on the rheological behavior of fresh cement. In this paper, we study the pulsating Poiseuille flow of fresh cement in a horizontal pipe by considering two different additives and when they are combined (nano-silica, fly ash, combined nano-silica, and fly ash). To model the fresh cement suspension, we used a modified form of the power-law model to demonstrate the dependency of the cement viscosity on the shear rate and volume fraction of cement and the additive particles. The convection-diffusion equation was used to solve for the volume fraction. After solving the equations in the dimensionless forms, we conducted a parametric study to analyze the effects of nano-silica, fly ash, and combined nano-silica and fly ash additives on the velocity and volume fraction profiles of the cement suspension. According to the parametric study presented here, larger nano-silica content results in lower centerline velocity of the cement suspension and larger non-uniformity of the volume fraction. Compared to nano-silica, fly ash exhibits an opposite effect on the velocity. Larger fly ash content results in higher centerline velocity, while the effect of the fly ash on the volume fraction is not obvious. For cement suspension containing combined nano-silica and fly ash additives, nano-silica plays a dominant role in the flow behavior of the suspension. The findings of the study can help the design and operation of the pulsating flow of fresh cement mortars and concrete in the 3D printing industry.

Symbiotic impact of carbon quantum dots on microstructural development and mechanical behaviour of cement mortars

Carbon Quantum Dots (CQDs) are a new environmentally pleasant material of the carbon family that has gained great interest in construction engineering due to their unique and valuable properties, such as high stability, minimizing toxic activity, and good water solubility. Therefore, this study aims to synthesize the CQDs using glucose as a precursor and apply it as nano-reinforcements in cement mortar. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and transmission electron microscopy (TEM) technologies were used to characterize the generated CQDs. The mechanical properties of the created CQDs-cement mortar were investigated by assessing the compressive and flexural strengths as well as the workability of the mortar samples. Experimentally, four different percentages of the developed CQDs— ranging from 0.005% to 0.030%—were added to the cement mortar. The acquired results showed that, at the age of 56 days utilizing 0.025% CQDs, the compressive and flexural strengths of the CQDs-cement mortar had grown by 72% and 59%, respectively. The workability study's findings revealed no evidence of a significant impact of CQDs on the mortar's flow characteristics. In conclusion, the findings of this study may suggest that CQDs can be used to enhance the mechanical properties of materials based on cement.

Eco-friendly 3D Printing Mortar with Low Cement Content: Investigation on Printability and Mechanical Properties

The conventional approach to achieving optimal printability and buildability in 3D printing mortar relies heavily on cement, which is both costly and environmentally detrimental due to substantial carbon emissions from its production. This study aims to mitigate these issues by investigating the viability of slag as a partial substitute for cement, with the goal of developing an eco-friendly alternative. The newly formulated mortar, featuring a 30% reduction in cement content (from 830 to 581 kg/m3) and the inclusion of 0.10% micro-fibers, exhibits properties comparable to conventional 3D printing mortar. The research is structured into two parts: Part 1 focuses on determining the optimal fiber content, while Part 2 delves into the investigation of fiber-reinforced mortar with reduced cement content for 3D printing. Criteria were established to ensure mortar flow at 115%, initial printable time below 60 minutes, and 7-day compressive strength exceeding 28 MPa. Part 1 results indicate that a fiber content of 0.1% by volume meets the specified requirements. In Part 2, it was observed that increasing the slag replacement percentage extended the initial printable time and time gap. However, even at a 30% replacement rate, the initial printable time remained within the acceptable range, partially attributed to the presence of fibers in the mix. Additionally, higher slag content led to increased flow and reduced filament height in the mixes. Notably, all formulations surpassed the 7-day compressive strength threshold. These findings underscore the potential of slag as a sustainable alternative to cement in 3D printing fiber-reinforced mortar, offering promising prospects for environmentally friendly construction practices. Doi: 10.28991/CEJ-2024-010-03-010 Full Text: PDF

Analysis of the Influence of PET and Glass Packaging Waste Materials on the Physical and Mechanical Properties of Cementitious Composites

The limited availability of natural resources, such as sand, and the need to reduce CO2 emissions, which are produced in large quantities in the production of binding materials, indicate the need to look for alternative raw materials used in construction materials. At the same time, there is a strong need to utilise waste packaging materials, the global production of which is constantly increasing. This work aims to investigate the possibility of using recycled polyethylene terephthalate (PET), utilised as a partial substitute for fine aggregate, and waste glass, implemented as powder, serving as a partial substitute for cement in the manufacturing of the cementitious composites. An experimental study was carried out to evaluate the physical and mechanical properties of the resultant cementitious composites. The incorporated PET aggregate comprised 0%, 5%, and 10% by volume of silica sand and 0%, 10%, and 20% glass powder by weight of cement. The addition of waste raw materials augmented the flow of fresh mortars, predominantly subsequent to the introduction of PET recyclate. The deployment of artificial aggregate in mortars induces a decrease in the volumetric density. Concurrently, the mechanical properties of mortars enriched with waste materials exhibited a reduction, in terms of both compressive and flexural strength, with the detriment escalating in conjunction with the content of waste raw materials. An analysis of statistical significance of effects, grounded in an analysis of variance, is delineated within this document, pinpointing the quantities of waste raw materials that can be assimilated in mortars without inducing a substantial deterioration of strength properties. Through studies on phase composition, it has been demonstrated that the utilised glass waste, possessing a grain size analogous to cement, exhibited poor pozzolanic properties. The test results indicate that it is possible to partially replace cement with glass powder, up to 10%, and fine aggregate with PET waste, up to 5%, without a significant reduction in the mechanical properties of the material.

Investigating mechanism for mortar-porous aggregate interfacial bond improvement based on coupled XCT-DVC analysis

Interfacial property enhancement through increased mortar flowability could be a feasible method to improve overall behavior of lightweight aggregate concrete (LWAC). However, the underlying mechanism improved LWAC mechanical properties through altering mortar-aggregate interaction was yet fully understood. To fill this gap, the underlying mechanism was investigated in the present study through quantifying ITZ bond behavior. The interfacial bond performance was characterized by an XCT-DVC-based analysis method on samples cast with varying superplasticizer dosages. The XCT test results showed that the mortar with a high flowability had a higher penetration depth inside the porous aggregate. Analysis of the DVC results showed that a better mortar penetration could improve the synergistic deformation capacity between matrix and aggregates, which in turn enhanced the overall mechanical strength. But not all penetrated areas could fully contribute to the bond strength. The penetration area of mortar can be further classified into well-bonded and poorly-bonded zones according to the matrix-aggregate interaction condition and the contribution of ITZ in load transfer.

Incorporation of High Loss-on-ignition Fly Ash in Producing High-strength Flowable Mortar

A large amount of fly ash with a high loss on ignition (over the maximum allowance value stipulated by ASTM C618) is being released and increasing daily in Vietnam. The recycling of this fly ash is still limited, while a big remaining part is disposed of in storage yards, causing environmental pollution. On the other hand, the demand for high-strength mortar as a repair material is increasing for high-rise buildings and important projects, gradually depleting natural resources. However, the application of this fly ash in the production of mortar is restricted in the literature. In this study, local fly ash with a high loss on ignition is used to replace 0%, 15%, 30%, 45%, and 60% cement content in producing high-flowability and high-strength mortar. Changes in the fresh and hardened mortar properties were systematically investigated using samples produced with various fly ash contents. Test results indicate that the effect of impurities in fly ash on the mortar’s workability can be neglected due to the spherical shape of fly ash. The unit weight, thermal conductivity, and drying shrinkage of mortars decreased with increasing fly ash content. Although some other properties of mortar are reduced due to the use of high loss-on-ignition fly ash, all mortars produced in this study still showed good quality with the presence of silica fume. In addition, the relationships between compressive strength and flexural strength with ultrasonic pulse velocity were established to predict the strength of mortar in a non-destructive method.

Mechanical Performance of Mortars with Partial Replacement of Cement by Aluminum Dross: Inactivation and Particle Size

Although the use of primary aluminum dross as cement replacement has shown promising results in mortars and concretes, there is a knowledge gap between the effect of the secondary dross inactivation process and particle sizes on the mechanical properties and consistency. So, by using X-ray diffraction, laser granulometry, and scanning electron microscopy, this article describes first the inactivation process applied to a secondary aluminum dross. Second, this manuscript presents the fresh and hardened properties of mortar mixes containing 5, 10, and 20% inactivated secondary aluminum dross with three different particle sizes (i.e., fine, intermediate, and coarse). Mortar flow test results indicate that compressive and flexural strengths of mixes containing up to 20% fine and intermediate aluminum dross as cement replacement were satisfactory, respectively. These results have the potential to reduce the environmental and health impacts caused by cement production and secondary aluminum dross disposal, respectively. Moreover, the durability aspects of the mortar mixes, as well as the effectivity of the investigated inactivation process, are identified as future research topics.

Relationships between Mortar Spread and the Fresh Properties of SCC Containing Local Metakaolin

Self-compacting concrete (SCC) production is a complex operation that requires finding a good combination and suitable dosages for its constituents. Several formulation methods have been developed to meet the workability requirements of SCC. Mortar spread is used to estimate SCC’s rheological properties, but the use of supplementary cementitious materials, such as metakaolin, could affect the accuracy of the estimation. In this paper, the relationships between the fresh properties of local-metakaolin (MK)-based SCC and the spreading of its mortar portion were investigated. The results showed the existence of good correlations between the spreading of mortar portion of SCC and its fresh state properties. The partial substitution of cement with MK did not affect these correlations. The mortar flow should be chosen according to the required rheological properties of the SCC. This can be achieved by using an appropriate viscosity-enhancing agent (VEA).

Effects of binder proportion and curing condition on the mechanical characteristics of volcanic ash- and slag-based geopolymer mortars; machine learning integrated experimental study

Contradicting natures of volcanic ash (VA)- and ground granulated blast furnace slag (GGBFS)- based geopolymers with regard to their need for being exposed to a heating source for conducting alkali-reactions make meaningful differences in the strength and flowability of mortars. To address the impacts of types of the geoploymerizing agent, their proportions, and different curing regimes on their strength and shrinkage behavior, three different curing scenarios including curing at room temperature, RT curing; resting under room temperature for various curing periods, and then hydrothermally curing at an elevated temperature for one day, RO curing; and curing in the oven for one day and then resting at the room temperature, for various curing periods, OR curing, are considered. Based on the flowability, setting time, unconfined compressive strength (UCS), and drying shrinkage tests on eight different mixtures, the effects of binder proportion and curing conditions are evaluated. It was observed that with the substitution of 30% VA with GGBFS, specimens cured at RT condition outperformed OR specimens. This threshold was 45% while comparing RT and RO specimens and with higher slag content, RT specimens gain higher UCS. Also, for GGBFS proportion less than 45%, specimens cured at RO conditions showed higher long-term UCS compared to the OR specimens, and this behavior was reversed for higher GGBFS content. Scanning electron microscopy test results indicated that N-A-S-(H) type gel is the dominant geopolymeric gel in VA-based specimens, and as the amount of slag increases, the gels formed change to N-(C)-A-S-H and with further addition of GGBFS, C-A-S-H type gel is the dominant gel which results in strength development in GGBFS-based specimens. Based on the results of 80 UCS and 140 drying shrinkage tests, different machine learning (ML) algorithms and an evolutionary model were employed to present accurate and cost-effective predictive models as useful and capable methods for practitioners and researchers for the preliminary design stages of projects. A comparative study revealed the superior prediction efficiency of the gradient boosting (GB) model with the R2 score of 95% among 8 different ML algorithms and advanced ensemble models. In addition, evolutionary models with the coefficients of determination of 92% and 95% are, respectively, proposed for the drying shrinkage and the UCS. This study advances the field by assessing VA-GGBFS blend and curing effects on geopolymer mortars and developing ML-based models for compressive strength and drying shrinkage, facilitating efficient optimization in practical applications.

Mortar and concrete with lime-rich calcined clay pozzolana: A sustainable approach to enhancing performances and reducing carbon footprint

Low environmental impact sustainable building materials have become a crucial requirement and challenges to the contemporary construction industry. This study is an extensive effort for the development of a green cementitious composite to limit extensive extraction and consumption of nonrenewable mineral resources and CO2 emission generation by the reduction of clinker cement production. In this route, 10%, 25%, 35%, and 50% of CaO-based calcined clay were adopted as a partial replacement for ordinary Portland cement (OPC) in mortar mix. The raw clay was extracted from Nizwa city (NZS) and ground into particles with size less than 75 µm. As per its chemical composition, the clay was classified as cementitious and pozzolanic material as per ASTM C618 standard specifications. The mill was then calcined at different temperatures of 950 °C, 850 °C, and 750 °C. The blend mortar mixes were assessed in terms of their mechanical, microstructural, durability, and thermal performances using various experimental tests. The results indicated that replacement levels of lime-rich calcined clay varying from 10% to 35% of OPC could generally offer similar to better strengths, durability, and thermal performances to a plain mortar. The mortar flow was reduced when incorporating calcined clay, while density was unaffected. Meanwhile, CaO-based calcined clay generally exhibited better performance with regard to permeable voids, combined sulphate + chloride, sulfuric acid attacks, and chloride ions permeability. The outcome of the present work sheds light on the massive potential of calcined clay pozzolana to develop sustainable, affordable, and locally produced blend cement for a variety of infrastructure applications, including energy-efficient and sustainable development, to reduce the carbon footprint.

Research on the particle characteristics of manufactured sands affecting the flow ability of fresh mortar

This paper combined digital image processing (DIP) and discrete element method (DEM) to investigate the relationship between the particle characteristics of manufactured sand and the flow ability of mortar, and clarified the key characteristics parameters of particle shape influencing the flow ability of mortar. A method for batch calculation of shape characteristic parameters (elongation ne, angularity index na and fullness ratio nf) of aggregates based on DIP was proposed. The fluidity tests and corresponding simulations of mortar at different water-cement ratios were carried out respectively, and the results showed that the errors of simulated fluidity (fm) were around 7%. The simulation results demonstrated that the fm decreased with increasing content of large-size aggregates in the mortar. The augment of both ne and na reduced the flowability of mortar. The magnitude of rolling/sliding friction coefficients of aggregates are the important parameters that determine the flowability of mortar.

Reducing clinker factor in limestone calcined clay-slag cement using C-S-H seeding – A way towards sustainable binder

C-S-H seeding was used in limestone calcined clay cement (LC3) to reduce the ordinary Portland cement (OPC, equivalent to clinker factor) while maintaining strength similar to that of neat OPC. The combination of calcined clay with other supplementary cementitious materials (LC3+), including microsilica, slag (GGBFS), and fly ash, was investigated. The impact of anhydrite content and Na2SO4 was studied. The results showed that C-S-H seeding dramatically enhanced strength from hours to 1 year. The OPC content can be <50 wt% in LC3 and LC3+ cement with C-S-H seeding to achieve comparable strength. The combination of calcined clay, GGBFS and portlandite with C-S-H seeding significantly reduced the OPC content to 20 wt%. Replacing part of the calcined clay by fly ash, GGBFS or limestone improved the mortar flow. Correlations of heat release and pore size with strength showed that C-S-H seeding increased strength by not only acceleration but also through microstructural changes.

Performance of Composite Portland Cements with Calcined Illite Clay and Limestone Filler Produced by Industrial Intergrinding

The performance of five composite Portland cements (CPCs) with limestone filler (LF = 10%–25% by mass) and calcined illite clay (CIC = 10%–25% by mass) elaborated by intergrinding was analyzed in paste, mortar, and concrete. Hydration was studied by isothermal calorimetry, bound water, and XRD. Flow and compressive strength (2 to 90 days) were determined in standard mortar. Concretes (w/b = 0.45; binder content = 350 kg/m3; slump = 15 ± 3 cm) were elaborated to determine compressive and flexural strength, water penetration, and chloride migration. Intergrinding CPCs have a large specific surface area when LF + CIC increases, with a similar size range of clinker particles. Supplementary cementing material replacements decreased the heat rate, prolonged the dormant period, and decreased the acceleration rate at early ages. According to the Fratini test, all CPCs had positive pozzolanicity after 28 days, but XRD analysis showed Ca(OH)2 associated with monocarboaluminate phases. Mortar flow was slightly reduced when the proportion of CIC was increased. Mortar strength decreased when the sum of LF + CIC increased. CPC strength class was limited by compressive strength after 28 days. Concretes were workable, and the compressive strength after 28 days depended on the LF + CIC, and CIC contributed after 90 days. After 28 days, the water penetration depended mainly on the LF + CIC content. The chloride migration coefficient was also reduced when CPC contained more CIC and less LF.

Underlying mechanisms of the influence of fine aggregates' content and properties on mortar's plastic viscosity

It is well known that the fine aggregate's content and properties have a significant influence on the plastic viscosity of mortar made with them. However, the underlying mechanisms of this influence remain unclear. The aim of this paper is to clarify these mechanisms by analysing the basic mechanical interactions working during mortar's flow. Twelve types of fine aggregates with different grading and morphology were employed in the analysis. The experimental work confirmed previously documented results reporting that the different content, grading, and morphology of the fine aggregates cause, indeed, significant differences in the plastic viscosity of mortar made with them. Based on the basic mechanical behaviour of mortar flow, the authors deduced that the plastic viscosity is determined by the viscous stress generated during the process as a result of the hydrodynamic interaction between fine aggregate particles and cement paste, as well as the contact interaction between the various fine aggregate particles. Then, a semi-quantitative model of the relative plastic viscosity of mortar was developed, combining the contribution of hydrodynamic and contact interactions. This model can explain the experimental results and provide a good prediction of the plastic viscosity of mortar.

EFFECTS OF CHEMICAL ADMIXTURES FOR CEMENT CONCRETE ON MORTAR FLOW AND COMPRESSIVE STRENGTH OF GEOPOLYMER

Huge amounts of Portland cement which is a main constituent material of concrete is manufactured and carbon dioxide (CO2) emitted by the manufacturing process of cement can cause global warming. Geopolymer (GP) contains no cement as a binder and several industrial by-products such as fly ash and blast furnace slag, so the spread of GP contributes to the reduction of global warming and the environmental load. GP has low CO2 emissions, high durability due to chemical attack and fire resistance, however, viscosity of GP is higher than that of cement concrete. Although chemical admixtures can be effective to the improvement of workability, most commercial products of them are for cement concrete. In this study, mortar flow and compressive strength of GP were experimentally evaluated in order to investigate effects of several chemical admixtures for cement concrete. Water glass and caustic soda solution were used as an alkaline-activating solution, and water glass causes high viscosity of GP mortar, so mortar flow test and compression test were conducted by using GP mortar with and without water glass. Test results indicate that the GP mortar without water glass had lower viscosity and lower compressive strength than that with water glass. The chemical admixture whose base component is naphthalenesulfonic acid was most effective to fluidity and compressive strength of GP mortar without water glass.