Cement Grout Research Articles

Behavior of Axially Loaded Concrete Columns Reinforced with Steel Tubes Infilled with Cementitious Grouting Material

The paper presents a novel method of reinforcing concrete columns using small-diameter steel tubes instead of traditional steel bars. The researchers conducted experimental investigations on twelve mid-scale circular concrete column specimens, which were divided into two groups consisting of six specimens each: short and long columns. Two of the specimens in each group were reinforced with steel bars, while the remaining four were reinforced with steel tubes filled with cementitious grouting material. The study proposed two concepts for cementitious grouted steel-tube reinforcement. The first concept utilized steel tubes with equivalent net areas to the steel bar areas used in the reference column, while the second concept used steel-tube reinforcement with the same diameter as the steel bars in the reference column. Nonlinear Finite Element (FE) analyses were conducted on experimental specimens using ABAQUS software. The results showed that using steel tubes with an area equivalent to that of steel bars instead of conventional columns increased the bearing capacity of reinforced concrete columns by 17%. Moreover, using steel tubes whose area matched 30% of the steel bar area achieved a bearing capacity of about 81% of the conventional concrete columns. The experimental and FE analysis findings indicate that this methodology can increase the bearing capacity of reinforced concrete columns when compared to traditional methods. The axial load-axial displacement curves, axial load-axial strain curves, and failure load of the FE model all demonstrated good convergence with the experimental data. Doi: 10.28991/CEJ-2024-010-02-017 Full Text: PDF

Analysis of the shear stress at the interface between steel and cement grout

The selection of materials for bridge construction is crucially based on cost-effectiveness and efficient on-site assembly. The integration of prefabricated slabs in mixed bridges expedites construction but presents challenges with conventional connections, often prolonging site work. Addressing this challenge, a novel adhesive connection has emerged as a structural innovation, aiming to establish a robust bond between steel and prefabricated concrete slabs, there by optimizing construction timelines.This study scrutinizes the performance of the cement-steel interface under shear forces. Through numerical analysis, our research investigates the distribution of shear stress and normal stress within the compact element of the assessed interface. Methodologically, our analysis initially utilized Catia software for conception, followed by transforming the model into Ansys software for simulation purposes. This process elucidates the behavior and durability of the adhesive connection.Our research specifically focuses on two geometric configurations: AR1, where the grooves of the steel plats are oriented perpendicular to the applied loads, and AR2, where the grooves run parallel to the applied loads, shedding light on the distinctive advantages of this innovative connection approach.

Numerical modeling for controlled compensation grouting

This article analyzes the numerical modeling of the stress-strain state of a gravity structure sand base during grouting works using the controlled compensation grouting technique. The modeling is performed using the finite element method and physical nonlinear soil models that take into account the Coulomb-Mohr strength condition. The modeling is done in the computational software JuliS as well as the universal software complex PC ZSoil. The goal of the research is to study the impacts of compensation grouting parameters on the elevation value of base slab. A model was created for the grout body as an expanding spheroid whose volume changes as cement grout is fed in the soil. The authors developed a grouting sequence for grouting solutions based on the location of grout body in the grouting pillar. It is more efficient to feed the grout starting from the lower grout body. The grouting solution feed mode is selected depending on the soil strength condition and accounting for the prevention of hydraulic fracture. As a result of the research, the initial subsidence of the soil on the daytime surface above the injection zone was obtained, which requires experimental confirmation and is a matter for discussion.

Strength and Deformation of Concrete-Encased Grouting-Filled Steel Tubes Columns Exposed to Monotonic Quasi-Static Loading Conditions

This study aimed to evaluate the effectiveness of a novel concrete-encased column (CE) using small circular steel tubes filled with cementitious grouting material (GFST) as the primary reinforcement instead of traditional steel bars. The research involved three different types of reinforcement: conventional steel bars, concrete-filled steel tubes with 30% of the reinforcement ratio of steel bars, and concrete-filled steel tubes with the same reinforcement ratio as steel bars. Twenty-four circular concrete columns were tested and categorized into six groups based on the type of reinforcement employed. Each group comprised four columns, with one subjected to concentric axial load, two subjected to eccentric axial load (with eccentricities of 25 mm and 50 mm, respectively), and one tested under lateral flexural loads. To validate the experimental results, finite element (FE) analysis was conducted using ABAQUS software version 6.14. The experimental findings for concentric load reveal that columns with the second type of reinforcement, concrete-filled steel tubes with 30% of the reinforcement ratio of steel bars exhibited a failure load 19% lower than those with steel bars, while columns with the third type of reinforcement, concrete-filled steel tubes with the same reinforcement ratio as steel bars achieved a failure load 17% greater than the traditional steel bars. The FE analysis demonstrates good agreement with the experimental outcomes in terms of ultimate strength, deformation, and failure modes.

Microbial cement grout anchoring steel reinforcement pull-out test

Microbial cement, known for its superior fluidity, stable crystal formation, and strong bond with concrete, is an effective solution in fixing defects such as voids that appear due to insufficient grouting in the joints of precast concrete components. To evaluate the mechanical properties of rebar anchored with microbial cement grout, three pull-out tests were designed, taking into account parameters such as calcium source concentration, the filler in borehole voids, and the shape of the rebar. The results indicate that specimens with a higher concentration of calcium source require fewer grouting cycles, but the pull-out bearing capacity of the anchored rebar is lower. However, the introduction of quartz sand as a filler in the borehole voids results in a significant increase in the pull-out bearing capacity of the rebar compared to specimens without filler. Among these, the specimens with a medium particle size of 0.5 ~ 1 mm (1/4δ ~ 1/2δ, the gap of δ = 2 mm between the steel bars and hole wall) have the highest pull-out bearing capacity. In comparing rebar shapes, ribbed rebar slightly outperforms smooth round rebar in terms of pull-out bearing capacity. Based on the experimental results analysis, the anchoring mechanism of microbial cement grouting on reinforcement has been elucidated.

Multi-objective optimization for composition design of civil materials based on data-driven method

The performance of civil materials depends on their compositions. The material design is an important, challenging, and time-consuming work during the construction due to the complex relationship among different compositions and the conflict between properties and economic cost. This study developed a data-driven multi-objective optimization design framework to determine the reasonable material compositions based on laboratory experiment, reduced order model (ROM), and multi-objective optimization (MOO). The ROM was used to capture the complex relationship between the material compositions and the corresponding material performance. The MOO was utilized to determine the pareto optimal solution of compositions in the global space. Taking examples of cement grouts and modified asphalt binders, the develop framework was demonstrated and verified. The developed framework provides an excellent tool for composition design of civil materials.

Bond behaviour of smooth surface GFRP pultruded profiles with cement grout

The advantages of glass fibre reinforced polymer (GFRP) pultruded composite profiles, such as their high strength-to-weight ratio, corrosion resistance, and low maintenance costs, have attracted the attention of researchers and end users in structural applications. In spite of this, one of the challenges associated with using GFRP pultruded profiles is their smooth surfaces when bonded with concrete. To address this challenge, this study investigated four different approaches that can be used to improve the bond performance between GFRP pultruded profiles and concrete surfaces. These approaches are the incorporation of glass sand into cement grout, the variation in the size of the sand particles in the grout, the surface preparation of GFRP profiles, and the use of various cement characteristics. The experimental results show that the surface preparation of the GFRP profiles is the most effective method of improving the bond strength between the GFRP profiles and the concrete surface. Additionally, a theoretical model is developed to predict the bond behaviour, and it is observed that the linear elastic theory with the inclusion of the bond surface roughness coefficient is capable of predicting bond behaviour. The overall outcome of the study will assist design engineers and end users in the application of smooth surface GFRP profiles in concrete structures.

Study on Vertical Bearing Capacity of Pile Foundation with Distributed Geopolymer Post-Grouting on Pile Side.

To study the applicability of the new geopolymer grouting material for super-long and large-diameter post-grouting bored piles in silty fine sand geology, this paper compares the bearing capacity of two grouting materials, geopolymer and normal Portland cement, and different grouting volume pile side-distributed grouting piles in silty fine sand based on field model tests are analyzed through the diffusion forms of the two materials in silty fine sand through the morphology of the grouted body after excavation. The results show that the ultimate bearing capacities of P0 (ungrouted pile), P1 (8 kg cement grouted pile), P2 (6 kg geopolymer-grouted pile), P3 (8 kg geopolymer-grouted pile) and P4 (10 kg geopolymer-grouted pile) are 5400 N, 8820 N, 9450 N, 11,700 N and 12,600 N, respectively, and that the ultimate bearing capacity of the grouted pile is improved compared with that of the ungrouted pile since, under the same grouting amount, the maximum bearing capacity of the pile using geopolymer grouting is increased by 133% compared with that of the pile with cement grouting. This further verifies the applicability of the geopolymer grouting material for the post-grouting of the pile foundation in silty fine sand. Under the action of the ultimate load, the pile side friction resistance of P1, P2, P3 and P4 is increased by 200%, 218%, 284% and 319% compared with that of P0. In addition, the excavation results show that the geopolymer post-grouting pile forms the ellipsoidal consolidation body at the pile side grouting location, which mainly comprises extrusion diffusion with a small amount of infiltration diffusion, and the cement grouting pile forms a sheet-like consolidation body at the lower grouting location, which primarily comprises split diffusion. This study can provide a reference basis for the theoretical and engineering application of post-grouting piles using geopolymers.

Self-healing evaluation of bacteria grouted light weight aggregate concrete containing rice husk ash and steel fibers

Utilization of microbiologically induced calcite precipitation along with fiber composite have great influence on improving strength and durable properties of concrete. The concept of mechanical properties of grouted concrete added with bacteria, steel fibers (SF), rice husk ash (RHA) and light weight aggregate (LWA) has been focused on this work. In the fabrication of concrete specimens, concentration of bacteria, combination of steel fibers and LWA was placed in the formwork, and to fill the voids flowable grout was injected. The variables studied in this work are two different sizes of LWA viz., 10 mm and 12.5 mm with constant dosage of 2% hooked end steel fibers by volume of concrete, 10% RHA was used as cement replacement for preparation of grout and bacteria was incorporated in cement grout by direct application. The properties such as compressive strength (CS), compressive strength regain (CSR), crack width healing, impact strength for first crack and final failure, rate of healing was studied for pre-cracked specimens using visual and microscopic observation. In addition, microstructure was studied for grouted concrete without bacteria and with bacteria under immersed curing conditions. From the experimental results, performance of bacteria added grouted concrete properties such as CS, CSR, cracking healing capacity, and impact strength has improved with the addition of fibers.Utilization of microbiologically induced calcite precipitation along with fiber composite have great influence on improving strength and durable properties of concrete. The concept of mechanical properties of grouted concrete added with bacteria, steel fibers (SF), rice husk ash (RHA) and light weight aggregate (LWA) has been focused on this work. In the fabrication of concrete specimens, concentration of bacteria, combination of steel fibers and LWA was placed in the formwork, and to fill the voids flowable grout was injected. The variables studied in this work are two different sizes of LWA viz., 10 mm and 12.5 mm with constant dosage of 2% hooked end steel fibers by volume of concrete, 10% RHA was used as cement replacement for preparation of grout and bacteria was incorporated in cement grout by direct application. The properties such as compressive strength (CS), compressive strength regain (CSR), crack width healing, impact strength for first crack and final failure, rate of healing was studied for pre-cracked specimens using visual and microscopic observation. In addition, microstructure was studied for grouted concrete without bacteria and with bacteria under immersed curing conditions. From the experimental results, performance of bacteria added grouted concrete properties such as CS, CSR, cracking healing capacity, and impact strength has improved with the addition of fibers.

Comparative study on the properties of cement grout modified with PAM and PANA at elevated temperatures

A comparative investigation of cement grout doped with anionic polyacrylamide (PAM) and sodium polyacrylate (PANA) at elevated temperatures was conducted. The results revealed that both the PAM and PANA significantly decreased the bleeding rate and improved the apparent viscosity. After adding 1% content of PAM or PANA, the bleeding rate decreased from 16.484% to 5.311% and 7.146% at 20 °C, while 17.528% to 11.911% and 9.739% at 80 °C. The cement grout doped with PAM exhibited higher viscosity and stronger washout resistance. PAM and PANA reduced compressive strength at high temperatures but eliminated the difference between the upper and lower parts, as it decreased from 131.77% to 29.94% and 48.74% respectively. The quantity and morphology of C-S-H gels were changed, related to the hydrogen bonds, the crosslink of admixtures, and the formation of micro-gels. The differences between the PAM and PANA are in conjunction with the molecular structures and the resulting behaviors.

Optimization on overall performance of Modified Ultrafine Cementitious Grout Materials (MUCG) and hydration mechanism analysis.

Given the challenges encountered in injecting grout into micro-cracked rock masses, a modified ultrafine cementitious grout material (MUCG) was developed using ultrafine cement, polyvinyl alcohol (PVA) fibers, and a high-efficiency superplasticizer. To identify the optimal ratio of constituents for grouting these rock masses, extreme difference and multiple linear regression analyses were conducted based on test results of flowability and mechanical properties. A mix comprising 9% silica fume, 0.2% bentonite, 0.3% PVA fibers, 0.15% superplasticizer, and 2% setting accelerator was identified as the optimal mix. The microstructure characteristics of the optimal MUCG (MUCGop) grout cemented body were analyzed using XRD, FTIR, BET, and SEM. XRD and FTIR analyses indicated that a substantial amount of C-(A)S-H gel, CH, and AFt were formed within the first 3 days, highlighting the early strength characteristics of MUCGop. Over time, the content of C-A-H stabilized at 22%, the amount of CH decreased from 19% to 14%, whereas the amount of AFt increased to 15.9% by Day 28. Unexpectedly, CaCO3 content increased due to carbonation, reaching 37.3% by Day 28. BET and SEM analyses demonstrated that the specific surface area and porosity (most probable pore size) gradually decreased over time. At various ages, mesopores (cumulative pore diameter, median pore diameter) initially increased and then decreased. Micro-cracks appeared in the cemented body by Day 7, resulting in a slight decrease in strength (3.92%) from Day 3 to Day 7. The formation of well-developed needle-like AFt, C-(A)S-H gel, and small-volume plate-like CH contributed to uniform cementation and a denser structure. From Day 7 to Day 28, there was a slight increase in strength, by an amount of 10.66%. These findings have significant scientific implications for understanding the mechanisms of grouting reinforcement in micro-cracked rock masses.

Review on Application of Cementitious Grouting Materials

Review on Application of Cementitious Grouting Materials

A polymer latex modified superfine cement grouting material for cement-stabilized macadam – Experimental and simulation study

Cement-stabilized macadam (CSM) has been prevalently employed in transportation infrastructure owing to its superior bearing capacity and stability. However, with inherent dry shrinkage, temperature shrinkage, and inadequate tensile capacity, cracks will inevitably occur. These cracks can reflect on the asphalt layer and cause diseases such as transverse cracks, dynamic water scouring, voids, etc. A predominant remediation method involves utilizing grouting material for trenchless repair. In this research, a vinyl acetate-ethylene (VAE) latex modified superfine cement (VMSC) for grouting material is proposed to improve the flexibility of the grouting material and enhance crack repair dimensions. The interaction mechanism was investigated through mechanical experiments, microscopic tests, and molecular simulation. The results show that VMSC30 exhibits the highest fluidity. VAE latex addition extends the initial and final setting times of the grouting material, alongside an escalation in yield stress and plastic viscosity. VAE latex reduces the compressive strength of the grouting material, while 10% can increase the flexural strength, and the overall toughness can be improved. Characteristic spectral peaks of VAE latex are identified at 1740 cm−1 and 1240 cm−1, respectively, and it can form a film to cover the surface of cement, inhibit hydration diminish the CH peak value. VAE can form the 2.95 Å ionic bond and the 3.05 Å hydrogen bond on the Ca atom and water molecules, respectively. The peak value of the ionic bond is higher. The ionic bond and hydrogen bond formed by bridging can improve the strength of VAE and cement interfaces.

Effects of cementing matrix characteristics and particle size on the adhesion rule and mechanical properties of cemented granular materials

The process of filling self-compacting cement grout (SCCG) into granular packing without disturbing the granular skeleton culminates in the formation of a well-defined cemented granular materials (CGMs). The inherent attributes of both the cementing matrix and granular packing critically dictate the adhesion behavior and mechanical performance of CGMs. A succession of cement grout flow tests was conducted to elucidate the influence of particle size and the SCCG flowability on SCCG adhesion mechanism within granular packing. Furthermore, the influence of particle size and the cementing matrix volume on the mechanical characteristics of CGMs was scrutinized via uniaxial compressive testing. The results illuminate that the adhesion behavior of SCCG within granular packing is predominantly dependent on the yield stress of SCCG and the average particle size. Additionally, it is established that the peak strength of CGMs is intimately intertwined with the cementing matrix volume and the average particle size, as corroborated by a substantial aggregate of 135 uniaxial compression tests.

A Multi-Depth Deflectometer/Global Navigation Satellite System Method for Measuring Concrete Slab Track Deformation

This study introduces a Multi-Depth Deflectometer (MDD) combined with a Global Navigation Satellite System (GNSS) which was developed for measuring the deformation of railway slab track layers. We newly designed the MDD with the addition of laser sensor modules for increasing precision in which the MDD head is fixed at the top of the track slab. The MDD/GNSS system can measure the relative deflection between each track layer as well as the total deflection at the top of the track slab, which makes it possible to evade the fixed condition problem of classical MDD. The new MDD/GNSS system was installed at the transition zone between a tunnel entrance and its embankment, which experienced high settlement levels prior to repair. The system was used to monitor whether the repaired concrete track foundation with pressurized cement grouting was stabilized effectively and what track layer position was most unstable so that it had the most influence. The GNSS system was designed and built for computing net settlement at each track layer even when the MDD could not be fixed firmly at the end point, which is a major drawback of classical MDD. The results obtained from MDD and GNSS measurements indicated significant potential in aiding railway track settlement measurements.

Exploring waste marble dust as an additive in cementitious grouts for semi-flexible pavement applications: Analysis and optimization using RSM

This research aims to explore the potential utilization of waste marble dust (MD) within cementitious grouts for applications in semi-flexible pavements, a hybrid pavement type combining the benefits of both flexible and rigid pavements. MD was used to replace cement (ranging from 0 to 25%), combined with w/c ratios of 0.35 to 0.50, in the formulation of cementitious grouts. The assessment of grout characteristics encompassed evaluations of flowability and compressive strength (7d and 28d curing). Moreover, the microstructural characteristics of cement grouts incorporating MD were scrutinized through Scanning electron microscope-SEM and Energy dispersive X-Ray spectroscopy-EDS analyses. Additionally, response surface methodology (RSM) was used for experimental design, analysis, and the optimization of the factors (MD and w/c ratio). The significance of the model was examined through various statistical indicators. The optimal composition of cementitious grouts was determined using optimization technique within the RSM framework. Furthermore, optimal grout combinations were employed in fabricating semi-flexible mixtures and evaluated for Marshall stability, moisture susceptibility, indirect tensile stiffness modulus, dynamic modulus, compressive strength, and resistance to fuel spillage. The results indicated that an optimal combination of 15% waste marble dust and a 0.40 w/c ratio was identified through optimization techniques within the RSM methodology. Furthermore, Analysis of variance formula-ANOVA outcomes exhibiting a higher R² value (>0.80) and higher adequate precision (>4.0) underscore the significance of the proposed models, revealing a robust correlation between experimental and predicted data. The semi-flexible mixtures also showcase superior performance in terms of Marshall stability, stiffness, dynamic modulus, moisture resistance, and resistance to fuel spillage. Moreover, the integration of waste marble dust in cementitious grouts for constructing semi-flexible pavements not only addresses disposal concerns but also contributes to environmental sustainability.

Modified pull-off test evaluation of bond properties in preplaced aggregate concrete incorporating silica fume

In this study, an experimental investigation was conducted to examine the bond strength of preplaced aggregate concrete (PAC) using a modified pull-off test that avoids the necessity for coring. The PAC was produced using 10 mm and 20 mm coarse aggregates and cement grout with and without the addition of silica fume (SF). Further, the bond strength of conventional concrete was examined to draw a comparison to PAC. The results demonstrate that although the compressive strength of PAC improved by around 20 % with the reduction in coarse aggregate size, the bond strength of PAC decreased by around 49 %. However, with the incorporation of SF, the bond strength improved by nearly 57 %, irrespective of the size of the coarse aggregate used. For the conventional concrete and PAC samples exhibiting similar compressive strength, the bond strength of the PAC was significantly lower than that of conventional concrete.

Modifying the Strength of Soft Soils via Heating and Cement Grouting Method

Modifying the Strength of Soft Soils via Heating and Cement Grouting Method

Optimization of the fresh and hardened properties of cement grouting material for semiflexible pavement using polypropylene fiber

To enhance the cracking resistance of semiflexible pavement, short polypropylene fibers with lengths of 3 mm and 6 mm were incorporated into cement grouting material, and their effect on fluidity, mechanical properties, drying shrinkage, and pore structures was systematically investigated. When polypropylene fiber dosage is less than 0.9 vol%, the reduction in fluidity is relatively minor. Polypropylene fiber can not only improve toughness, but also inhibit water loss and reduce drying shrinkage, which is related to the distribution of polypropylene fiber and the bonding performance between fiber and matrix. However, excessive polypropylene fiber can lead to uneven distribution of the porosity along vertical direction. With a 0.9 vol% of 3 mm polypropylene fiber, the 28d flexural strength of the grouting material increased by 38%, and the drying shrinkage decreased by 22%. This article provides some guidance for enhancing the overall performance of cement grouting material using polypropylene fiber.

Experimental Study on the Mechanical Properties of Loess-Based Grout Materials

In order to develop a controllable low-strength loess-based grout material, loess is used as the primary material with cement and additives as supplements. By employing the controlled variable method and orthogonal experimental design, various samples were prepared with cement content and curing age as variables. The study investigates their impact on the unconfined compressive strength, shear strength, and compression coefficient of loess-based grout materials. Experimental results indicate that within the 4% to 12% cement content range, the relationship between cement content and curing age, and the unconfined compressive strength of loess-based cement grout materials, follows linear and quadratic parabolic patterns, respectively. The research findings have reference significance for the application of loess-based grout materials in embankment slope engineering.