Grout Mixtures Research Articles

Numerical Modelling of Backfill Grouting Approaches in EPB Tunneling

One of the main issues involved during tunnel construction with tunnel boring machines is the tail gap grouting. This gap is between the external diameter of tunnel lining and the excavation boundary that is filled with high-pressure grouting materials. In this work, three different approaches of gap grouting modeling in the FLAC3D software are investigated with a special attention to the influence of the grout material hardening process. In the first approach, the grout is modeled as a liquid during injection, and considering the TBM advancement and its hardening time, the grout characteristics are changed to the properties of the solid grouting. In the second approach, the grouting material from the beginning of injection is considered with the properties of solid grouting in the model, and the liquid phase is ignored. In the third approach, without considering the back-filled grouting area in the model geometry, only the injection pressure is applied to the end of the shield and behind the installed segments. The validity of the approaches is evaluated with respect to the maximum ground surface settlement. All the three approaches estimate different surface settlement but the result of the first approach is closer to the monitoring data. Also as a sensitivity analysis, in this work, we investigate the effect of the elastic modulus of liquid and solid grouting materials on the amount of surface settlement that can help to gain a more accurate insight into the effect of grout mixture.

Performance of hollow bar micropiles using green grout incorporating treated oil sand waste

Implementing waste materials in construction applications represents an effective solution for many waste management problems. This study presents an innovative solution for application of treated oil sands waste (TOSW) in grout mixtures used for micropiles construction. Effects of employing these grout mixtures on micropiles cross-section, surface interface properties and axial behaviour were investigated. The results showed an enhancement in the grout body diameter for micropiles installed using the developed grout, while maintaining the micropile surface properties. Micropiles installed using grout incorporating a high percentage of the TOSW (up to 30%) exhibited the same axial behaviour as that of micropile installed using conventional grout. Therefore, incorporating TOSW in micropile applications has high potential for producing cost efficient micropiles along with providing a green oil sands waste management solution.

The measurement of fresh properties of cement-based grout containing waste marble powder

This paper shows the results of an experimental study conducted to investigate the effect of waste marble powder (WMP) on the fluidity (marsh cone flow time (MCFT), mini-slump diameter and plate cohesion meter (PCM)) and the rheological properties (viscosity and yield stress) of cement based grout (CBG) mixtures. The experiments were done with the CBG mixture including 0.75, 1.00, 1.25, 1.50 water-binder (w/b) ratios and 5, 10, 15, 20 and 25% content of WMP. Test results illustrated that the rheological properties of the CBGs had been improved greatly by the addition of WMP to grout mix at various w/b ratios. It was observed that the CBG mixtures showed a strong shear thickening behavior all WMP content and all w/b ratios. Moreover, the increase in the w/b ratio decreases the MCFT at the constant WMP content. Additionally, the increase in the percentage of WMP amount up to %15 did not effect on mini slump flow diameter, however the mini - slump flow diameter decreased above %15 WMP.

Effect of high salinity in grout on the performance of cement-stabilized marine clay

Constructing a soilcrete column by injecting grout into the soil is a common method of stabilizing loose soil in coastal areas. Although tap water usually is used in the grout mixture for soil improvement projects, before the cement in grout mixture has completely set, tap water will mix with in situ saline seawater. Researchers have not previously considered the behavior of clay-cement under marine conditions, especially the effect of water salinity, on the performance of soilcrete. The goals of this study were to investigate the effect of the use of naturally saline seawater in grout preparation on the mechanical, physical and microstructural behavior of cement-stabilized marine clay. Marine clay and seawater samples were prepared along the northern shore of the Persian Gulf. Tap water as low salinity water, brackish water as medium salinity water (50% tap water and 50% seawater) and natural seawater as high salinity water were used. Specimens were prepared using the deep mixing method recommendations for laboratory soilcrete tests. Macroscopic evaluation was performed by unconfined compressive strength and indirect Brazilian tension test. The physical aspects of the plasticity of the soilcrete specimens with regard to the Atterberg limits and changes in the particle size distribution caused by cement bonding were evaluated by hydrometer testing. For the micromechanical study, SEM images were prepared from selected specimens. The results show that the use of natural seawater does not reduce the strength in comparison with tap water. Specimens containing brackish water (50% seawater and 50% tap water) showed maximum strength due to flocculation in the structure of the clayey cluster in comparison with tap water. The compressive strength ranged from 1.5 to 5 MPa for clay-cement specimens made of natural soil and seawater. The ratio of tensile strength to compressive strength of these specimens was 0.15–0.25. The results show that the unconfined compressive strength of soilcrete specimens constructed under field conditions was 30% that of specimens constructed under laboratory conditions.

Mechanical properties of preplaced lightweight aggregates concrete

Abstract Preplaced casting scheme is applicable for manufacturing the minimum unit weight lightweight aggregate concrete with a higher content of lightweight aggregates. High-volume of aggregate can be achieved by fully packing aggregates in the empty formwork and filling the interstitial voids with grout mixtures. This unique manufacturing process of preplaced lightweight aggregate concrete forms extensively interconnected aggregate network with the grout-coated aggregate grains, influencing the mechanical characteristics of concrete. Thus, these complex homogeneities are considered in a micromechanical four-phase model, from which we predict the elastic properties of preplaced lightweight aggregate concrete. The inverse homogenization is used for the identification of equivalent homogeneous parameters of concrete composites referring the microstructural images of intermediate zone. The compressive strength and drying shrinkage of preplaced lightweight aggregate concrete are also investigated by proposing the corresponding micromechanics-based models using the elastic moduli of grout and equivalent aggregate network. Finally, the predicted strength and drying shrinkage well agree with the measurements on preplaced lightweight aggregates concrete.

Effect of Waste Marble Powder and Fly Ash on the Rheological Characteristics of Cement Based Grout

This paper shows the results of an experimental study conducted to research the impact of waste marble powder (WMP) and fly ash (FA) on the fluidity (marsh cone flow time (MCFT), mini-slump diameter and plate cohesion meter (PCM)) and the rheological properties (viscosity and yield stress) of cement based grout (CBG) mixtures. The experiments were applied with the CBG mix including 1.00 water-binder (w/b) ratios and combined use of WMP (5-25%), FA (5-25%) and WMP+FA (10-30% + constant 25%). Test results illustrated that the rheological properties of the CBGs importantly have been improved by the addition of WMP, FA and WMP+FA to grout mix at w/b=1 ratio. Strongly shear thickening behaviour was got from the CBG mixtures the all WMP, FA and WMP+FA content. The increase in the percentage of WMP (5-25%) amount reduced the mini-slump flow diameter. Moreover, the increment in the percentage of FA (5-25%) amount increments the mini slum flow. According to the control sample, the increment in the percentage of WMP (10-25%) amount increased the mini-slump flow diameter for constant FA (25%) content. Also, the increase in WMP amount in the CBG mix, there is no effect on MCFT. Also, MCFT decreased with the increase of FA amount. Especially, FA increased the fluidity of CBG, when the WMP showed negative effect in increase the MCFT in WMP+FA content.

Study of the Suitability of Different Types of Slag and Its Influence on the Quality of Green Grouts Obtained by Partial Replacement of Cement.

This paper is part of a research line focused on the reduction of the use of cement in the industry. In this work, the study of work methodologies for the manufacture of green cementitious grout mixtures is studied. Grout is widely used in construction and it requires an important use of raw materials. On the other hand, the steel industry faces the problem of the growing generation of slag wastes due to the increase in steel manufacturing. The green grout aims to achieve the dual objective of reducing the demand for cement and improve the slag waste valorization. Slag is not introduced as an aggregate but through the direct replacement of cement and no additives. The research seeks a product where we can use steel slag intensively, guaranteeing minimum resistance and workability. Results with substitutions between a 25% to 50% and water/cement ratio of 1 are presented. In particular, the suitability of different slags (two Ladle Furnace Slag (LFS) and one Blast Furnace Slag (GGBS)) in the quality of the final product are analyzed. The feasibility of replacing cement with slag and the importance of the origin and pretreatment are highlighted.

Application of Bentonite Grout in AKARPILES

AKARPILES is an innovative solution for slope stabilization with less environmental footprint. Grout is one of the key components in AKARPILES. This study focused on stabilizing surficial slope failure, which commonly occurred in Malaysia. There are many methods help to improve slope stability of slopes. The idea of AKARPILES was innovated from the function of the tree root system in slope stabilization. Grout was pumped in and discharged through the outlets on the piles, after the piles are installed on the slope and intercepting the slip plane. The grout had then filled the voids within the soil with random pattern. SKW mixture was used to simulate the soil slope. Trial mix of the grout was carried out to obtain the optimum mixing ratio of bentonite: cement: water. Cone penetration test (CPT) and vane shear test (VST) were conducted on the grout mixture in a different mix ratio to obtain the strength gained. Grout dispersion area by two different designs of AKARPILES were recorded and compared. The results were affected by the design of piles.

Development and testing of grouts based on perlite by-products and lime

Abstract Grouting is a widely used intervention technique for the consolidation and strengthening of historic masonries. During the recent decades, lime-based grouts have been developed, tested and applied, taking into account parameters, such as their compatibility with the historic structures and their performance both in terms of fresh and hardened state properties. The exploitation of perlite by-products on the other hand (named as ‘waste perlite’), is a field that should be further envisaged, due to the gradually increasing demand of expanded perlite production, as well as the need of minimizing the environmental burden from its industrial process. To this direction, a series of grout mixtures based on two types of perlite by-products (D1S and D1C) and lime (air and hydraulic) were manufactured and tested. According to the experimental results, waste perlite-based grouts presented effaceable fresh and hardened state properties, while their performance was enhanced when superplasticizer and a short proportion of white cement or metakaolin was added in the air lime mixtures. In the hydraulic lime mixtures, the addition of waste perlite enhanced their properties and significantly increased their strength. Therefore, it was concluded that according to specific requirements, both perlite by-products studied could be used in combination with lime, for the manufacture of light-weight, low cost and environmental friendly grouts. Future oriented research should be therefore made in order to further investigate the parameters influencing the performance of grouts based on other waste perlite types.

Superplasticizer and Shrinkage Reducing Admixture Dosages for Microfine Cement in Grout Systems

Grouts have numerous applications including crack repair as maintenance in construction industries. Microfine cements are intensively used for high strength mortar and grout products. They are ideal for injection grouting in structural repair. Such grouts should have suitable rheological properties to be injectable, especially those used in repair and rehabilitation. The use of superplasticizers (SP) in these products is thus becoming increasingly crucial to achieve favorable workability and viscosity properties. A difficulty in such grouts is the plastic shrinkage due to finer particles used. It is thus necessary to determine optimum SP and shrinkage reducing admixture (SRA) dosages for a microfine cement based grout. In this study, a saturation dosage was decided from two Polycarboxylate ether (PCE) based SPs in relation to neat cement using slump flow and rheological parameters. A range of grout mixtures was formulated containing micro silica (MS) and fly ash (FA), and tested for suitable rheological and mechanical parameters. Based on the results, a grout mixture with MS and FA was selected to determine optimum SRA content. According to the results, a SP dosage of 3% by weight of neat cement is sufficient to achieve saturation. The grout material including MS and FA can produce comparable properties to neat cement grout. MS is found to improve compressive strength within the range considered, whereas a higher FA content provides favourable rheological properties. Finally, a SRA dosage of 4%, which could reduce the shrinkage by about 43% after 28d days, is determined for the grout system.

Physiochemical Characteristics and its Applicable Potential of Blast Furnace Slag Grout Mixtures of Sodium Silicate and Calcium Hydroxide

Physiochemical Characteristics and its Applicable Potential of Blast Furnace Slag Grout Mixtures of Sodium Silicate and Calcium Hydroxide

Field Investigation on Limestone Treatment using Fissure Grouting Method

This paper documents a field study on fissure grouting for limestone with a specific aim to investigate grout injection into the rock in order to reduce its permeability. The study focused on grouting in advance of excavation and it is applicable to grouting carried out to seal exposed rock surfaces. Investigation concentrated on the need to carry out fissure grouting to seal off excessive water entering the excavation through fractured rocks. In this case, the grout mixtures involved a combination of Ordinary Portland cement (OPC) and bentonite with appropriate amount of water. The grouting was performed at each stage until the grout flow rate and pressure reached a constant level for the last five minutes. If the stage of grouting in a borehole required more grout, this implies that there exist more fissure and cracks in the rock. The ultimate outcome of the rock fissure grouting was to obtain a good feed into limestone rock fissures, and thus, the process involved high injection pressure. The minimum grouting pressure was indicated as the hydrostatic pressure plus line loss pressure. To ensure that the outcome was achieved, it was recommended for an additional two bar pressure to be maintained as hydrostatic pressure.

On the rheology of using geopolymer for grouting: A comparative study with cement-based grout included fly ash and cold bonded fly ash

A friendly novel material called geopolymer has recently presented some promising uses for enhancement of weak ground through grouting alternative to Portland cement especially for avoiding from large CO2 emissions during cement production. However, research using the geopolymer technology is still insufficient for grouting specifically concerning with rheology. This paper investigates the rheological properties (shear stress, apparent viscosity, shear rate, yield stress, plastic viscosity) of geopolymer grout in comparison with the cement-based grouts included fly ash and cold bonded fly ash (i.e., geopolymer aggregate) at various dosage rates (0%–100%) and water/binder ratios (0.75–1.5). Some alkaline activator solutions (sodium hydroxide, sodium silicate) and some precursor of aluminosilicate sources (fly ash, silica fume) are used for obtaining the geopolymer grout. Rheometer tests are performed for the grout rheology. It is found from the experimental work that most of the grout mixtures lead to dilatant behavior similar to the one of native cement, while some geopolymer grouts result in the pseudoplastic and Bingham behaviors. All rheological responses of grouts decrease with increased water/binder ratios. While the inclusions of fly ash and geopolymer aggregate bring about minor changes in the rheological properties, the geopolymer grouts mostly result in the magnitudes more pronounced. The grout rheology becomes more close to the ones of native cement by the proportions 30%–40% of fly ash and geopolymer aggregate, and using the geopolymer grout in the combinations with 30%–60% silica fume. The plastic viscosity versus yield stress produces moderate correlations for the grouts with fly ash, but strong correlations for the geopolymer grouts and the grouts with geopolymer aggregate. The study indicates that the geopolymer comparatively attempted with fly ash and geopolymer aggregate could offer many choices for experimenters in practice for feasible grouting compared to native cement.

Granular Soil Improvement by Using Polyester Grouts

For decades, grouting has been the most popular soil stabilization method. Some additives (especially waste materials) as well as cement and polymeric materials are also widely used as grout mixtures in order to lower costs and achieve the best engineering properties with early strength gain. In this study, unconfined compression and dynamic tests of grouted granular soils were conducted with different mixtures to evaluate the feasibility of using polyester, red mud and micronized clay as grouting materials. The samples were cured for 1, 3 and 7 days in order to determine early strength gain. Unconfined compressive strength of all grouted samples has increased with increasing additive percentages and curing time. The damping ratio of all grouted samples has increased with increasing curing time. The overall evaluation of results has revealed that polyester with red mud and micronized clay promising and confer potential as a candidate for grouting applications.

Effect of grout strength on the stress distribution (tensile) of fully-grouted rockbolts

The paper deals with and axial stress distribution (ASD) obtained from pull-out tests of strain gauged rockbolts in high strength rock media. For this purpose, an experimental research was conducted considering the only axial forces acting on fully grouted rockbolts (FGR). Strain gauges were used to observe the behavior of rockbolts and to determine the load transfer mechanism of the bolts to rock mass. In the test, five grout mixture having different properties was prepared and stress–strain mechanism of the bolt-grout interface was investigated for these conditions. ASD was demonstrated elastic load transfer behavior from the rockbolt to the outlying rock under the applied load (for each grout type) and stress concentration was rather a high level at 70 mm distance from rock surface. Axial stress curves drawing with the aid of strain readings were showed the regular distribution with increasing of grout stiffness. The test results of strain gauged rockbolts show that the shear stress distribution (SSD) is uniform and, the style of the distributions along the rockbolt was similar under various loading levels for all grout types. Shear stress was rather a small amount at the pulling end of rockbolt but it reached the peak after a short distance away from the pulling end of rockbolt and subsequent to peak value decayed rapidly with the load increase. The results were showed that strength properties of grout played an important role in SSD and ASD along the rockbolt. The increase in grout strength and rigidity made the stress distributions regular along the rockbolt.

Examination of the mechanical properties and failure pattern of soilcrete mixtures modified with rice husk ash

This paper evaluates the unconfined compressive strength (UCS), stability (bleeding), modulus of elasticity and failure patterns of cement-based grout mixtures that were prepared by placing of rice husk ash (RHA) with cement at various water to binder (w/b) ratios. In order to investigate these parameters, UCS and bleeding tests were conducted on the soilcrete samples that prepared at 5, 10, 20 and 30% replacement level of RHA with cement for .75, 1.00 and 1.25 w/b ratios. Test results showed that the UCS values of the samples for 28 day curing are higher than 1 MPa and E/qu ratios obtained from soilcrete mixtures were less than the corresponding value from slurry clay–cement mixes given in the literature. In addition, all bleeding test results are lower than the level of .5%. Finally, most of the mixtures prepared for this study failed along foliations.

Evaluating Material Properties of Grout for PSC Bridge According to Admixture Type

This experimental study investigates material properties of prestressed concrete (PSC) grout depend on the combination of fly ash (FA), silica fume (SF) and zirconia silica fume (Zr). Based on the test results, when FA and Zr were included in grout mixtures, the fluidity, bleeding and volume change increased with less superplasticizer. The compressive strength of all grout mixtures was quite high at the age of 7 and 28 days, and the ternary mixtures had the excellent development of strength than binary mixtures. Furthermore, autogenous shrinkage properties of ternary grout combining shrinkage reducing agent (SRA) and expansive additive (EA) was evaluated. The 47~80% autogenous shrinkage was reduced by using SRA and EA. In addition, the effectiveness of using SRA and EA was higher for the grout mixture with SF than that with Zr. Keywords: PSC Grout, Bleeding, Autogenous Shrinkage, Silica Fume, Zirconia Silica Fume

Two-Stage Concrete as a Sustainable Production

Two-stage concrete (TSC) is a sustainable concrete which is produced by forcing a flowable cement grout mixture through the voids of a skeletal mass made of compacted preplaced aggregates. From the technical and economic aspects, TSC is particularly useful for construction and repair of concrete structures especially foundations, underwater construction, nuclear reactors, concrete dams, heritage structures and in constructions with closely spaced reinforcement. TSC differs from ordinary concrete in that it contains a higher proportion of stone aggregate and the aggregate stays in point-to-point contact as placed. Thus, the mechanical characteristics of the TSC in failure conditions are distinctly different from ordinary concrete. This paper presents the results of experimental investigations conducted to evaluate the compressive, tensile strength and modulus of elasticity of TSC using grouts with different water-to-cement ratios and admixture contents. It was found that the modulus of elasticity and splitting tensile strength of TSC are equivalent or higher than that of conventional concrete at the same compressive strength. In this method of construction, the splitting tensile strength can be conservatively estimated using the American concrete institute (ACI) equation for conventional concrete.

Two-Stage Concrete as a Sustainable Production

Two-stage concrete (TSC) is a sustainable concrete which is produced by forcing a flowable cement grout mixture through the voids of a skeletal mass made of compacted preplaced aggregates. From the technical and economic aspects, TSC is particularly useful for construction and repair of concrete structures especially foundations, underwater construction, nuclear reactors, concrete dams, heritage structures and in constructions with closely spaced reinforcement. TSC differs from ordinary concrete in that it contains a higher proportion of stone aggregate and the aggregate stays in point-to-point contact as placed. Thus, the mechanical characteristics of the TSC in failure conditions are distinctly different from ordinary concrete. This paper presents the results of experimental investigations conducted to evaluate the compressive, tensile strength and modulus of elasticity of TSC using grouts with different water-to-cement ratios and admixture contents. It was found that the modulus of elasticity and splitting tensile strength of TSC are equivalent or higher than that of conventional concrete at the same compressive strength. In this method of construction, the splitting tensile strength can be conservatively estimated using the American concrete institute (ACI) equation for conventional concrete.

Effects of supplementary cementitious materials on mechanical and durability properties of high-performance non-shrinking grout (HPNSG)

High-performance non-shrinking grout (HPNSG) is a high strength material designed for precision grouting and general construction applications. The main purpose of this research study is to develop HPNSG using fly ash, slag, and silica fume. These supplementary cementitious materials were tested in different replacement percentages by examining mechanical and durability properties. Both fresh and hardened properties of grouts were assessed. The compressive strength, shrinkage, dynamic modulus of elasticity, electrical resistance, shrinkage, and abrasion of the grouts were tested. The compressive strength increased with increasing slag and silica fume content, which is attributed to the higher pozzolanic reactivity of these materials than that of fly ash and pumice. However, the effect of incorporating materials into grout mixtures was very slight at early ages. By passing the time, C–S–H gel grew outward from the cement particles and resulted in less porosity.