Cement Grout Research Articles

A study on carbon dioxide emissions of high-polymer road maintenance technology based on life cycle assessment evaluation

Road repair and maintenance is the foundation for maintaining the health of roads. High-polymer grouting technology is an advanced non-excavation road repair and reinforcement technique. However, there is limited existing research focusing on this material and technique's carbon dioxide emissions and influencing factors. This study aims to elucidate the carbon dioxide emissions in the life cycle assessment of high-polymer grouting repair technology, using the example of maintenance work on semi-rigid asphalt pavement. The solidification reaction of each kilogram of high-polymer grouting material will release approximately 11.82 g of carbon dioxide. Comparative analysis was conducted by juxtaposing the carbon dioxide emissions at various stages of high-polymer grouting technology with those of cement grouting techniques and traditional excavation-based repair methods, encompassing conventional assessment (CA) on fuel combustion of engineering equipment and comprehensive life cycle assessment (LCA) on the materials production, fuel production, traffic delay, and engineering equipment. The results indicate a substantial reduction in carbon dioxide emissions for highway maintenance projects employing high-polymer grouting repair technology. The carbon dioxide emissions were reduced by 76.1% and 87.3% respectively per kilometer. The primary contribution to carbon dioxide reduction is observed during the construction phase and in terms of alleviating traffic delays. An indirect relationship is established between the carbon dioxide emissions of high high-polymer grouting materials and their strength, providing a reference for dynamically selecting material density in maintenance projects. The analysis of potential strategies to reduce CO2 emission in the transport sector and other industrial sectors suggests that the LCA model has the capability to accurately pinpoint the main contributing factors and CO2 emission levels stemming from specific maintenance processes within the intricate transportation system. The emphasis on enhancing the production technology of high-polymer materials is pivotal for further reducing carbon dioxide emissions in the context of high-polymer grouting repair technology.

Bond performance between cementitious grout and normal concrete subjected to freeze–thaw damage

Owing to the increasing application of cementitious grout in strengthening projects in cold regions, the freeze–thaw durability of the bond between cementitious grout and concrete has attracted attention. This study investigates the bond performance of a cementitious grout–normal concrete interface after FTCs through splitting tensile and slant shear tests at different angles. The microstructure of the cementitious grout–concrete interface is observed via backscattered electron (BSE) microscopy. The results show that FTCs rapidly reduce the splitting bond strength and slant shear bond strength of the interface. After 240 FTCs, the splitting and slant shear bond strengths decrease by 40.7%–72.4% and 46.1%–57.3%, respectively. An increase in substrate strength significantly enhances the interfacial bond strength, particularly the slant shear bond strength. Freeze–thaw damage to the substrate reduces the interfacial bond strength and frost resistance. The slant shear strength increases significantly with the slant shear angle. The effects of FTCs on the interfacial shear strength parameters are reflected through a rapid decrease in cohesion, whereas the interface internal friction angle remains relatively unaffected. Empirical formulas for calculating the interface bond strength are obtained from experimental data and validated. The BSE images show that cracks begin to appear at the cementitious grout–normal concrete interface as the number of FTCs increases, thereby decreasing the interfacial bond strength.

Experimental Research on Application of Waste Concrete Powder-Waste Brick Powder-Cement Grout for Foundation Reinforcement in Mining Goaf.

Combined with a strategic policy for the recycling of construction waste, this paper puts forward a programme for treating a goaf foundation with waste concrete powder, waste brick powder, and cement grout (BCP cement grout). The BCP cement grout is prepared by replacing part of the waste concrete powder with waste brick powder, and the changeable rule of the setting time, water separation rate, stone rate, and viscosity of the grout with different rates for replacement are studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) are carried out. The mineral composition is analyzed and the microscopic mechanism is studied. The results show that the ratio of BCP cement grout developed by the experiment is reasonable; the unit cost is less than 160 yuan/t, which is 40% lower than that of pure cement grout; and both a good economic effect and good environmental effect are obtained. It has the advantages of low water separation rate, high stone rate, and low viscosity. When the ratio of cement powder: waste concrete powder: waste brick powder is 3:5:2 or 3:6:1, the 28 d compressive strength of the stone body is more than 2 MPa, meeting the filling requirements for a goaf foundation. It is not only technically feasible but also economically reasonable to apply construction waste powder to fill the goaf foundation. Recycling and utilizing construction waste can also achieve the ecological restoration of mined-out areas, highlighting the ecological benefits.

Mechanical behaviour of fiber-reinforced grout in rock bolt reinforcement

Grouted rock bolts subject to axial loading in the field exhibit various failure modes, among which the most predominant one is the bolt-grout interface failure. Thus, mechanical characterization of the grout is essential for understanding its performance in ground support. To date, few studies have been conducted to characterize the mechanical behaviour of fiber-reinforced grout (FRG) in rock bolt reinforcement. Here we experimentally studied the mechanical behaviour of FRG under uniaxial compression, indirect tension, and direct shear loading conditions. We also conducted a series of pullout tests of rebar bolt encapsulated with different grouts including conventional cementitious grout and FRG. FRG was developed using 15% silica fume (SF) replacement of cement (by weight) and steel fiber to achieve high-strength and crack-resistance to overcome drawbacks of the conventional grout. Two types of steel fibers including straight and wavy steel fibers were further added to enhance the grout quality. The effect of fiber shape and fiber volume proportion on the grout mechanical properties were examined. Our experimental results showed that the addition of SF and steel fiber by 1.5% fiber volume proportion could lead to the highest compressive, tensile, and shear strengths of the grout. The minimum volume of fiber that could improve the mechanical properties of grout was found at 0.5%. The scanning electron microscopy (SEM) analysis demonstrated that steel fibers act as an excellent bridge to prevent the cracks from propagating at the interfacial region and hence to aid in maintaining the integrity of the cementitious grout. Our laboratory pullout tests further confirmed that FRG could prevent the cylindrical grout annulus from radial crack and hence improve the rebar's load carrying capacity. Therefore, FRG has a potential to be utilized in civil and mining applications where high-strength and crack-resistance support is required.

Recent failures of external prestressing grouted tendons: when the ducts take on water…

AbstractThe article describes recent cases of tendon ruptures by corrosion and investigations carried out on some bridges in France. Several causes related to HDPE ducts have been identified such as damages during handling, threading and tensioning of strands, defective connection of the duct to the anchorage, damage during construction or operation, low quality of HDPE material, etc. These cases of tendon rupture exclusively concern ducts injected with cement grout. To our knowledge, no structure built after the application of the 2001 circular [1] (prohibiting cement grout for the injection of external prestressing) is currently exhibiting major disorders.A warning note on existing structures with external prestressing has been updated by Cerema in November 2018 [2]. It describes the diagnosis methodology based on analysis of documentation, thorough visual inspection, destructive and nondestructive investigations. New non‐destructive techniques such as guided‐wave ultrasonic technique and magnetic leakage field test using permanent magnets and induction coils are presented. Innovative methods of local repair of the ducts are also described. Finally, different protective devices are analysed in terms of worker safety in the event of a sudden failure of tendon.

Geological and geotechnical characterization of Ziragn Dam sitting, northwestern Ethiopia

The goal of this study was to look at the geological and geotechnical conditions of the Ziragn dam, which would be built across the Ziragn river for irrigation purposes. The objectives of the study were to investigate and characterize the geological, hydrogeological, and seismicity condition, reservoir area, construction materials, and geotechnical situations of the dam site. During the physical investigation, geotechnical interpretations were done using the drilling logged data, laboratory tests as well as drilling core samples. Results of the study revealed that the area is characterized by slightly fractured massive basaltic rocks which are found at the dam axis and spillway area. The reservoir area is also covered by silty clay soils basaltic rocks and silty clay soil. The stream bed and the banks are made up of the same geological materials of basaltic rock. The basaltic rocks at the reservoir area are characterized by low permeability while the abutment areas were moderately fractured and weathered and the silty clay soil is characterized by medium to high plastic impervious soil. Based on the findings, the following recommendations are forwarded: (a) Design a masonry/concrete cut-off wall at the central portion of the dam. (b) On the left bank at the upstream, vertically jointed rocks permitted seepage problems, it needs cement grouting. (c)Rocks at the abutment sides show fractured and weathered which needs the removal of the surface and treatment by cement injection. (d) Even though the dam was micro it needs serious monitoring and follow-up during and after construction.

Experimental study on bio-treatment effect of the dredged Yellow River silt based on soybean urease induced calcium carbonate precipitation

As the river with highest silt content in the world, the Yellow River is dredged annually to relieve the pressure of flood control. Prior studies indicated that the dredged Yellow River silt cannot be directly utilized as construction filling material because of the deficiency in strength and stability. In this study, soybean urease induced calcium carbonate precipitation (SICP) method was proposed to solidify the Yellow River silt for the purpose of promoting its mechanical properties. The influences of soybean powder concentration and pH value on the soybean urease activity were investigated. By estimating the urease activity of per unit mass, the soybean powder concentration with highest extraction efficiency were determined. The optimum bio-treatment recipe including cement solution concentration and grouting time of the biological solidification agent suitable for the Yellow River silt was characterized through unconfined compressive strength (UCS) test and CaCO3 content test. Meanwhile, scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis of the bio-treated Yellow River silt sample verified the effectiveness of solidification from microscopic viewpoint. The findings of this study suggest that soybean urease induced calcium carbonate precipitation (SICP) method can effectively improve the geotechnical engineering properties of Yellow River silt and provide a technical approach for the resource utilization of the Yellow River silt.

Efficient use of ceramic waste powder in Cementitious Grout for the Development of Sustainable Semi-Flexible Pavement Surfaces

Cement-based grouts are described as a liquid mixture with higher flowability that contains cement, additives, water, and a superplasticizer. Cement-based grouts can be utilized to fill minor voids and gaps in addition to repairing cracks in earthen structures to restore structural continuity. In most cases, structural grouting is used in conjunction with other strengthening methods like adding tie-rods or reinforcing meshes. Grout is usually used with semi-flexible pavement (SFP). SFP is a new pavement technology comprised of open-graded asphalt concrete with a high air void content that is filled by injecting special grouting materials. The goal of this research is to figure out what happens to the mechanical properties of grout when a proposed by-product is used as a supplement to cementitious materials. The specified grouts were made from cement, water, ceramic waste powder (CWP), and superplasticizer (SP). Scanning electron microscopy (SEM) and energy-dispersive x-ray (EDX) analysis were used to characterize the physical and chemical properties of the waste material after it had been crushed and finely ground. The pozzolanic behaviour of the material was evaluated by substituting ceramic waste for Portland cement at varying percentages (from 15% to 50%), and the modified grout was characterized through a variety of tests that included flow cone testing, as well as compression and flexural strength tests Based on the results of these tests, the best amount of CWP to use as a replacement for cement in terms of its mechanical properties is 20%.

Detection of wire breaks and corrosion in external prestressed tendons using a magnetic rope testing device

AbstractExternal prestressing tendons are a major structural element for the durability of concrete bridges. In France several cases of sudden breaks in external pre‐stressing tendon made of HDPE duct injected by cement grout directly in contact with strands have been recorded in the past decade [2].In order to prevent this sudden breaks Cerema has experimented the magnetic rope testing technology from ropeways to develop a non‐destructive inspection technic of the free length and junction of prestressing. The method is based on magnetic leakage field detection and allows to detect defaults of the strands inside the tendon such as corrosion and wire breaks.The article first focuses on the magnetic rope testing technic. Then tests previously performed on laboratory tendons with reference wire breaks will be analyzed for defaults characterization. Finally, the particular methodology adapted to the nondestructive magnetic inspection of prestressing tendons on site will be detailed. A general feedback including handling issues and analysis of non‐destructive magnetic controls completed with visual controls by removing the high‐density polyethylene (HDPE) sheath will be given.

Utilization of titanium slag in cement grout for gamma radiation shielding: hydration, microstructure, mechanical properties and gamma-ray attenuation performance

The utilization of industrial waste materials for civil engineering structures has received massive attention in recent decades. In this work, the feasibility of using titanium slag to enhance the radiation attenuation properties of cementitious grout at the ages of 3 days and 2 years was studied. Titanium slag (TS) was incorporated as cement grout replacement at 0%, 10% 20% and 30%. Hardened blocks in dimension of 146×146×30mm were fabricated. The porosity of titanium slag was characterized while the phases in the raw materials as well as the fabricated grout were identified. The influence of the titanium slag addition on the grout hydration kinetics, density, compressive strength and porosity of hardened grouts was evaluated. The results show a decrease in density with the increase of titanium slag content as well as a decrease in compressive strength at curing ages of 3, 7 and 28 days. The slag also refined the microstructure, leading to a reduction in average pore diameter. Furthermore, the hardened blocks were subject to gamma-ray sources such as 137Cs (0.662 MeV) and 60Co (1.173 and 1.332 MeV) and the Linear Attenuation Coefficient (LAC) and Half Value Layer (HVL) were evaluated. The results show that increasing curing age improves the shielding performance of the composite. At 30% replacement, the LAC improvement of the samples exposed to Co sources (1.173 and 1.332 MeV) at 3 days was 11.7% and 12.8% respectively while at 2 years, 9.9% and 9.8% improvement was obtained. Reduced HVL is obtained for an increase in replacement percentage and increased curing age. Therefore, this gives an indication of the possibility of developing low-density radiation shielding cement-based materials.

Specific heat and excess heat capacity of grout with phase change materials using heat conduction microcalorimetry

Microencapsulated phase-change-materials (PCMs) incorporated in cementitious grout can be used as a source of energy in an underground thermal energy storage system. Differential scanning calorimetry (DSC) is a widely used technique to measure the latent heat or specific heat of PCM-embedded cementitious materials. However, using milligram sample sizes (as required by DSC) of a cementitious material fails to represent the actual scale of cementitious components. This is the reason why, in the present paper, non-isothermal heat conduction microcalorimetry (MC) was evaluated as a tool for determining the thermal properties of PCM-embedded grout as well as pure PCM (three PCMs were used). An MC experimental protocol (using both single and 5–6 temperature cycles) was developed and used to measure latent heat and melting and crystallization temperatures, which were in good agreement with those reported for pure PCMs by the producers. In addition, the specific heats of the PCM-containing grout also agreed with measurements using the hot disk technique. Overall, the results show that the MC technique can be used as a potential standard method in determining thermal processes in complex systems, such as in PCM-embedded cementitious systems, where a large sample size is needed to represent the material.

Bond stress distribution and suggestions for anchoring length of deformed steel bars in different types of cementitious grout

Eight sets of pull–out specimens were tested by considering four types of cementitious grout (CGM-380, CGM-340, CGM-300, and CGM-270) and two anchoring lengths (3d and 10d) in this study. Discussions were had on the failure modes, bond load–slip curves, stress distribution of steel bars, and bond stress distribution. Results indicated that the relationship between the magnitude of peak bond load of 3d–group specimens composed of different types of cementitious grout was shown as CGM-270>CGM-300>CGM-340>CGM-380. Simultaneously, the stress of the steel bars in specimens gradually increased with the increase in external load, and the steel bars were in the elastic stage. For the 10–group specimens, the peak bond load of each specimen was basically the same, and the steel bars had yielded when the specimen was damaged. In addition, the stress distribution of the steel bars was similar to that of 3d–group specimens before the steel bars yielding. After the load reached the yield load, however, the yield position gradually shifted toward the free end with the load further increased, and the yield section length of the steel bars gradually increased. Besides, in contrast to the unimodal bond stress distribution curves of the 3d–group specimens, the bond stress distribution curves of the 10d–group specimens were all in the shape of a multimodal distribution. The peak bond stress of 10d–group specimens were located near the loading end before the steel bars yielding. However, as the load was raised continuously after the steel bars yielded, the bond stress in the yield section dramatically dropped, the yield penetration depth progressively grew, and the peak bond stress gradually shifted towards the free end. Additionally, design suggestions for the critical anchoring length of steel bars in cementitious grout and the anchoring length of steel bars after yielding were provided.

Prediction of compressive strength of cementitious grouts for semi-flexible pavement application using machine learning approach

This study involves the preparation of cement grout samples by varying proportions of superplasticizer (SP) and water-cement (w/c) ratio (0.25–0.45) which were tested for computing flow value and 1-day, 7-day, and 28-day compressive strength. With 75 data points a neural network model was developed to predict the 28-day compressive strength based on w/c ratio, superplasticizer percentage, flow value, and compressive strengths of 1-day and 7-day as input variables. Due to the better performance of Artificial Neural Networks (ANN) over other applied models, this study predicts a confident pattern of relationship between w/c ratio (indirect), superplasticizer (direct up to 3%), and the corresponding strength characteristics of the study samples. The prediction power of the developed model has been improved from R2 = 0.959 to R2 = 0.984 by optimizing the number of neurons, activation function, and optimizer. The best performance was observed in the case of Model45-R_A. The same model was used for assessing the effect of the percentage of superplasticizer and water cement ratio on 28 days compressive strength where the compressive strength of 73.941 MPa was recorded in the case of 3% superplasticizer and w/c of 0.25.

Investigating the qualities of grouting material used modifiers in the semi-flexible pavement

Semi-flexible pavement has a more notable advantage over asphalt concrete pavement in terms of rutting performance. Cement grouting and open-graded asphalt concrete are components of the semi-flexible pavement. In cement grouting, two commercial modifiers from Sika Vietnam were used, Sika Latex and Sika TH Latex, with different contents from 4.5% to 7.5% for Sika Latex and 7.5% to 9.5% for Sika TH Latex. 72 samples of cement mortar were fabricated in laboratory conditions from PCB40. All cement grouts were cured at the age of 7 days. The paper results focus on the flexural strength and the compressive strength of both mortars, the suggestion of Sika content to produce the stable strength of cement grout, and the viscosity of cement mortar based on the Sika contents.

Compressive strength and impact strength of preplaced aggregate fibre reinforced concrete

A new form of concrete composites known as prepacked aggregates fiber reinforced concrete (PAFRC) has recently attracted the research community's attention. Preparing PAFRC involves inserting and packing coarse aggregate fibers in a mold. Afterward, a cement grout that has a high flowability is injected into the gaps between the particles to complete the construction. This study aimed to examine PAFRC's resistance to impact using a drop weight impact test. Four mixtures were prepared with three different dosages (1, 3 and 5%) of steel fibres. All of the specimens were put through an impact test as per the recommendations of the ACI Committee 544. The impact resistance of PAFRC specimens dosed with 1, 3, and 5% steel fibres was increased by 7.86, 20.64, and 30.57 times, respectively, compared to those without fibres. The information that was gleaned from this analysis serves as a baseline for more extensive scientific research into PAFRC when it is being affected by an impact.

Uniaxial compressive behaviour of a FRP standing support made of mine wastes

Twenty-seven specimens were tested to investigate the uniaxial compression behaviour of an innovative standing support for underground space applications. The innovative standing support consisted of an external fibre reinforced polymer (FRP) jacket and the infill column made of cementitious grout, tailings and coal wash rejects. Effects of the FRP layers number and water to the cementitious grout (w/g) ratio were evaluated. Test results indicated that lower w/g ratios produced stronger infill columns. With FRP confinement, the standing support demonstrated strain-hardening loading characteristics with a significant improvement in both strength and ductility. The highest strength and strain of the specimens achieved was 58.4 MPa and 11.8% respectively. Compared with the unconfined specimens, the confinement with four FRP layers increased the specimen strength and associated strain up to 3.6 and 27.0 times respectively. A correlation between the compressive strength of the infill material and the ultrasonic pulse velocity was also investigated. Furthermore, a simple design-oriented model was proposed to predict the peak strength and the corresponding strain of the innovative standing support.

Sewing Concrete Device-Combining In-Line Rheology Control and Reinforcement System for 3D Concrete Printing.

Of the digital concrete-additive-manufacturing techniques, extrusion-based systems are probably the most widespread and studied. Despite the significant potential offered by 3D printing, several challenges must still be overcome. For instance, although several solutions have already been explored, the automated reinforcement of the layer-wise printed structures represents a challenge. The inline quality control of the fresh-state properties of 3D-printed materials is also an open question that needs to be addressed to find an efficient shared practice. This study proposes a new device designed to simultaneously reinforce 3D-printed structures along and through the layers and to be used as an inline quality-control device. This device consists in a sewing system, which is composed of a rotating system, and a hollow needle, which drives a reinforcing cable or yarn and can be used to inject cement grout to fill holes and improve bonding with reinforcement. The rotation is induced by a stepper motor, which measures the torque that is required to make the needle penetrate. This measurement can be used as a quality-control index to ensure material homogeneity. This paper aims to present an original reinforcement system that can be fully automated and simultaneously create reinforcement patterns in different directions of the printed structure while controlling the material's fresh properties.

The experimental determination of shear stress distribution along fully grouted rock bolts with different bond lengths subjected to pull testing

In this study, laboratory pull tests of rock bolts were conducted to verify and update existing stress transfer models. The rock bolt samples in the study had different bond lengths that were fully encapsulated in cementitious grout with different water-cement ratios. The test results show that the existing models do not correctly describe the shear stress distribution on the bond length in some loading stages. Three new models were proposed for the distribution of shear stress along the bond length. The first model describes cases where the bolt sample has a bond length that is much longer than the critical bond length, the second model describes cases where the bolt sample has a bond length slightly shorter than the critical bond length, and the third model describes cases where the bolt sample has a bond length that is much shorter than the critical bond length. In these models, the bolt is fully debonded along the section between the borehole collar and a depth of approximately one bolt diameter (db). The bolt is then partially debonded and the residual shear stress on the bolt increases with depth. In the first model, the shear stress reaches the maximum at a depth of approximately 3db. The shear stress then attenuates to zero at a depth of 25db. In the second and third models, the entire bond length is mobilized to carry load.

GIN method applied to the consolidation of cracked rocks: case study of the Memve’ele hydroelectric dam (southern Cameroon)

The empirical GIN (grouting intensity number) method is one of the most popular methods for structural stabilization and is increasingly used in many projects. The concept of this method is to limit the combination of pressure and volume injected to a specific grouting intensity number in order to control the energy induced in the rock fractures and to avoid heaving. In order to ensure the water tightness of the foundation of the Memve’ele hydroelectric dam, the treatment by the GIN method was implemented. The protocol implemented consisted to carry out a veil of injection drilling, consolidation, and control of effective treatment on each geotechnical hazard zone. Thus, 1240 injection boreholes were opened over a total length of 1600 m, i.e.: 613 pre-treatment boreholes and 627 consolidation boreholes. The results of the monitoring tests show that the 0.7 cement grouting treatment contributed to a reduction in crack permeability to less than 5 Lu (Lugeon units), a reduction of over 94%. This confinement of the rock was confirmed by geophysical imagery whose signature at the fractured interval varied after treatment. Geophysical and geohydrological characterization through permeability testing and electrical tomography revealed the existence of highly permeable discontinuity zones (over 90 Lu) below the bedrock surface, up to 15 m wide. Notwithstanding the volume of drilling carried out, the results obtained support the use of the GIN method in the stabilization of foundations of structures in the granite-gneissic basement zone.

Analysis and effect of lateral forces on Micropiles

Micro piles are small diameter pile (less than 300mm). Micro piles are generally used when there are difficult ground conditions, such as natural or man-made obstructions, sensitive ground with adjacent structures, limited access/low headroom. Micro piles are small diameter drilled and grouted friction piles. Each pile includes steel elements that are bonded into the bearing soil or rock – usually with cement grout. The bearing stratum is logged during installation drilling to assure that bearing capacity is adequate. This chapter presents a summary of various parameters defining the computational models. The bearing capacity and spring constant values for different pile diameter and different length is studied in this paper. Also, lateral pressure is also checked on the pile. The software SAFE 2016 used for the analysis of model.