Hydraulic Grouts Research Articles

Diffusion-hydraulic properties of grouting geological rough fractures with power-law slurry

Different from the conventional planar fracture and simplified Newton model, for power-law slurries with a lower water-cement ratio commonly used in grouting engineering, flow model in geological rough fractures is built based on ten standard profiles from Barton (1977) in this study. The numerical algorithm is validated by experimental results. The flow mechanism, grout superiority, and water plugging of pseudo plastic slurry are revealed. The representations of hydraulic grouting properties for JRCs are obtained. The results show that effective plugging is based on the mechanical mechanisms of the fluctuant structural surface and higher viscosity at the middle of the fissure. The formulas of grouting parameters are always variable with the roughness and shear movement, which play a key role in grouting. The roughness can only be neglected after reaching a threshold. Grouting pressure increases with increasing roughness and has variable responses for different apertures within standard profiles. The whole process can be divided into three stationary zones and three transition zones, and there is a mutation region (10 10.8) on the permeability of surfaces cannot be underestimated. The determination of grouting parameters depends on the slurry groutability in terms of its weakest link with discontinuous streamlines. For grouting water plugging, the water-cement ratio, grouting pressure and grouting additives should be determined by combining the flow conditions and the apparent widths of the main fracture and rough surface. This study provides a calculation method of grouting parameters for variable cement-based slurries. And the findings can help for better understanding of fluid flow and diffusion in geological fractures.

Effects of Polypropylene Fibers and Measurement Methods on the Yield Stress of Grouts for the Consolidation of Heritage Masonry Walls

The injection of grouts is a consolidation technique suitable for overcoming the structural deterioration of old stone masonry walls. Grouting operations involve introducing a suspension (grout) into a masonry core with the aim of improving the load capacity of the wall, as well as reducing its brittle mechanisms. The yield stress of injection grouts will affect the injection pressure and their flow inside the masonry. However, the determination of some rheological properties such as yield stress in hydraulic grout is challenging, due to the combined effects of hydration reactions and interactions between the particles present in the suspension. In this study, the determination of the yield stress of natural hydraulic lime-based grouts with polypropylene fibers was carried out. The changes in yield stress with time, fibers content and hydration were evaluated by two measurement methods using a rotational rheometer. Additionally, the static and dynamic yield stress as well as the critical shear–strain rate were determined, which provided useful information on the grout design in order to achieve successful grouting operations.

Effectiveness analysis of external heating system of gauge tank of pumping unit using exhaust piping of the IC engine

Introduction. The heating efficiency or regulation of the operating temperature of the fluid located in the gauge tank of a mobile pumping unit (PU) using the exhaust system of the internal combustion engine (ICE) is studied. The paper objective is to improve the design process and to reduce costs of field experiments. Materials and Methods . To solve this problem, numerical analysis methods were used when calculating the heating systems of the gauge tank with the external location of the pipeline from the ICE exhaust system by the example of the widely used installations (TsA-320, UNB, AChF, etc.). Siemens STAR-CCM+, a non-stationary non-linear solver of gas-dynamic processes, was used, which evaluates the correctness of the problem statement and reduces significantly the costs of full-scale field tests. Research Results. The study was conducted for the operating conditions of the cementing unit on the Kamaz-43118 chassis with the SIN-32 pump and a drive from the power take-off attachment on the gearbox of the chassis engine. In the calculation model, a convection-type heat transfer was applied between the body of the gauge tank and the surrounding air; between the body of the gauge tank and the liquid; between the chassis exhaust system duct and ambient air; between the exhaust system duct and exhaust gases. The following study results were obtained: characteristic curves of the temperature variation of the gauge tank liquid at the watch points; the distribution of the temperature field of the liquid in the gauge tank; the distribution of the ambient air temperature field; lines of flows and ambient air speed field and of the ICE exhaust gases. Discussion and Conclusions . The study has revealed poor effectiveness of the considered structure. The data analysis allows us to offer an improved design of the gauge tank heating. The results obtained in the work can be used in the calculations of such devices used in the hydraulic fracturing units and grout machines.

Swedish grouting design: hydraulic testing and grout selection

To ensure successful sealing of rock and soil, an adequate description of the system to be grouted is required as a basis for the grouting design and the selection of the grouting material. In rock, the individual fractures and the hydraulic apertures of these fractures form the basis of the Swedish grouting design concept. The hydraulic aperture is a key parameter when describing grouting behaviour and it is used to determine the extent to which the grout can enter fractures – that is, the penetrability. The hydraulic aperture also determines the penetration length, and therefore the grout parameters (e.g. yield stress and viscosity) as well as the grouting pressure and time needed to be adopted to the hydraulic aperture. Once these parameters are chosen, a suitable grouting technique can be adopted. Simple, practical rock and grout tests are important inputs to ensure correct design and performance. The aim of this paper is to present a testing procedure and provide examples from laboratory and field experience to demonstrate that the approach also works in practice.

Stability of hydraulic grouts for masonry strengthening

Stability of hydraulic grouts for masonry strengthening

Penetrability of hydraulic grouts

Design of hydraulic grouts for strengthening of masonry historical buildings seems to follow rather empirical procedures, with all the related uncertainties, both in terms of economy and efficiency. This paper is part of a broader attempt to establish a rational methodology for the design of such grouts, based on their discrete injectability characteristics, i.e. (i) Penetrability, (ii) Fluidity and (iii) Stability. This paper deals with penetrability and constitutes the first part of this holistic methodology. The second part regarding the fluidity and the third regarding the stability are separately published. Grouting is intended to fill voids, fissures and open joints of the masonry as a system, producing a “dendrite” (a three-dimensional skeleton), directly contributing to the strength of the masonry as a whole. However, to do so, the grout should be able to pass through the “narrowest” possible width of such discontinuities, in order to reach the maximum possible internal volume of masonry and open joints, avoiding most of possible blockages. In the specific case of three-leaf masonries, the most decisive result of the grouting is expected to be the strengthening of the bond along the interfaces between the external layers and the infill; the rather small voids, as well as pre-existing fissures along these interfaces have to be penetrated. In this paper the penetrability of hydraulic grouts is discussed, and relationships between two characteristic diameters of the grains of the solid phase of the grout and the nominal minimum width of fissures and voids of the structure to be injected are proposed. Furthermore the beneficial role of replacing part of the cement or hydraulic lime with ultrafine materials in order to improve penetrability is presented, and related criteria are proposed.

Fluidity of hydraulic grouts for masonry strengthening

Design of hydraulic grouts for strengthening of masonry historical buildings seems to follow a rather empirical procedure, with all the related uncertainties, both in economical and efficiency terms. This paper is part of a broader attempt to establish a rational methodology for the design of such grouts, based on their discrete injectability characteristics, i.e. (i) penetrability, (ii) fluidity and (iii) stability. The first part of this holistic methodology proposing a procedure to be followed in order to make a first selection of suitable grain size distribution of solid materials of the grout to fulfill penetrability requirements was published elsewhere. The second part regarding the fluidity of the grouts is the subject of this paper. A new practical fluidity measurement is proposed (the fluidity factor test [FFT]); and a “fluidity factor” is defined. It is proved that the follow-up of this factor as a function of the water-to-solids ratio may reveal fundamental characteristics of the grout-composition under design. The influence of the mixing method and superplasticizer on grout’s fluidity is also examined. The paper concludes with a case study to highlight the practical use of the proposed test. Furthermore, stability of the suspension against segregation or excessive bleeding should also be ensured since, otherwise, blockage may soon appear and the quality of the intervention could be severely affected. This matter is examined by the authors in a separate paper, where specific semi empirical formulae permitting a first selection of water content and percentage of ultrafine materials, useful for the design of a grout composition are proposed.

Design and application of hydraulic grouts of high injectability for the structural restoration of the column drums of the Parthenon Opisthodomos

The column drums of the Opisthodomos of the Parthenon featured a multitude of very fine cracks, due to the great fire of the 3rd century A.D. and the explosion of the building in 1687. Instead of dismantling the columns, the in situ structural restoration by hydraulic grouts injections was decided, as this would involve the least intervention to the monument. The objective of this intervention was to fill in the best possible way the very fine cracks, while maintaining the structural independence of the column drums, thus preserving the existing structural system of the columns. In this paper, the methodology of the design, the most important results of the comparative parametric studies for the selection of the optimum compositions, the basic principles of in situ production and application, the quality control of the injections and the extent of crack filling, will be presented and commented upon.

New autogenous lime-based grouts used in the conservation of lime-based wall paintings

The best material to be used in the restoration of a work of art is that most similar to the original. When grouting of lime-based wall paintings is necessary, lime-based grouts are the obvious choice. Compatibility is particularly important for grouting, as this is an irreversible operation. To set, lime-based grouts need air, specifically carbon dioxide, CO2. However, in the narrow space between two delaminating layers where the grout is injected, CO2 is not usually available in large enough quantities for this process to occur satisfactorily. To overcome this problem, extensive use has been made of hydraulic grouts, which set with water, and grouts containing synthetic or natural organic binders. A search was conducted for additives that would facilitate the setting of lime-based grouts, even at low CO2 concentrations. In this study, a group of substances that produce CO2 by reacting with water in an alkaline environment, esters of carbonic acid, were identified and tested to understand the kinetics of the setting process. Additives that would increase the fluidity of the grouting mixture, thus improving its injectability, were also investigated. The practical application of these grouting mixtures is illustrated by the recent restoration of Masaccio and Masolino's frescoes in the Brancacci Chapel in Florence.

Site conservation during excavation: stabilization and consolidation of Roman funerary monuments in Carthage

Foreign archaeological excavations in North Africa and the Middle East are beginning to include architectural or site conservators. The site conservation activities during the Yasmina cemetery excavations in the summers of 1994-95 illustrate how the presence of an architectural conservator, carrying out timely consolidation treatments using lime-based hydraulic grouts and mortar repairs on masonry, wall plaster and stucco decoration, insured the safe excavation and future preservation of several Roman funerary monuments, two of which had been severely damaged in antiquity by an earthquake. Some of the monuments had been partially uncovered in the early 1980s, and were ‘temporarily’ protected with gauze facings and plaster edging repairs before reburial. These emergency treatments, in particular the facings, were revealed to be neither necessary nor easily reversible. Site protection between excavation seasons is discussed. In this case, the archaeologist chose to construct temporary brick structures around the monuments, rather than backfill with soil, due to cost and time constraints. This option was not very successful, especially in preventing crystallization of salts on the wall plaster surfaces. Although recourse was then made to poulticing as an alternative preventive measure against salt damage, backfilling with soil remains the best technique for site protection between seasons unless methods that are less labor-intensive can be found.

Design and evaluation of hydraulic lime grouts for the reattachment of lime plasters on earthen walls

A laboratory and field testing programme for the formulation and evaluation of hydraulic grouts was developed for the reattachment of lime plasters on earthen (adobe) walls. Formulations utilizing kaolin, hydraulic lime, ceramic microspheres, and fine silica sand, with and without the addition of an acrylic emulsion, were prepared and evaluated in a three-stage testing programme. Standard tests were employed to measure injectability, viscosity, set time, shrinkage, weight, splitting/tensile strength, water vapour transmission rate, and adhesive bond strength. Grout microstructure was comparatively examined using scanning electron microscopy. Of the 18 grout formulations tested, only one mixture composed of (parts by weight) 1 part microspheres, 1 part sand, 2 parts hydraulic lime, 10% part acrylic emulsion was found to meet all the essential performance criteria established.

Formulations of hydraulic grouts for the injection of fine cracks and cavities in damaged concrete and masonry structures (In French) : Paillere, A M; Serrano, J J; Miltiadou, A E Bull Liaison Lab Ponts ChausseesN186, July–Aug 1993, P61–78

Formulations of hydraulic grouts for the injection of fine cracks and cavities in damaged concrete and masonry structures (In French) : Paillere, A M; Serrano, J J; Miltiadou, A E Bull Liaison Lab Ponts ChausseesN186, July–Aug 1993, P61–78

New sorbing grouts for radioactive and toxic heavy metals

According to European regulations, toxic industrial wastes (classified as class 1) should be stored in an impervious medium. Technically, the impervious medium could be either a natural clay layer, 5 m thick, with a hydraulic conductivity lower than 10 −9 m s −1, or an artificial watertight barrier around and/or under the disposal site. The purpose of these barriers is to prevent the seepage of polluted water from the waste into the environment. The hydraulic grouts named “Petrisol” (used in the case of radioactive wastes) and “Ecosol” (for toxic industrial wastes) presented here are intended to be used as a physicochemical barrier to reduce the pollution of the groundwater around neglected waste deposits. These grouts are made of standard bentonite and cement with the addition of complementary agents as follows: siliceous materials (silica fumes or fly ash), special clays or zeolites, and chemical additives. Their specific characteristic is their capacity to retain the ions of polluting substances found in solution in groundwater. The aim of our research has been to quantify the efficiency of the grouts and to compare their retention properties with grouts conventionally used in public works: mixes of bentonite—cement in defined proportions. We chose out of the most dangerous and frequently occurring elements: lead (Pb 2+), cadmium (Cd 2+), and mercury (Hg 2+). For the radioactive wastes, we chose two elements well known for their great mobility: caesium (Cs +) and strontium (Sr 2+). In the first instance, we were interested in the retention of the different cations by raw materials (clays=Ca montmorillonite, Na bentonite, vermiculite, palygorskite, illite; and zeolithes=chabazite and an artificial zeolite) in determining the maximum capacity of the fixing of the cation by a material using the method of differences or an adsorption test. The values we have obtained vary with a large number of parameters: the contact time with solid solution, the temperature of fixing, the concentration of cations in the initial solution, the nature of the cations, the nature of the absorbing materials, the pH, and so on. From this experimental study of the fixation of the polluting cations passing through hydraulic grouts, after a curing time of 7 to 90 days, we are able to class the cations in the conditions of the previous experiment in order of decreasing affinity with respect to materials and grouts studied: Cd 2+ >Cd 2+ >Pb 2+ >Sr 2+ >Cs + >Hg 2+. Regarding the materials, we established a similar classification in order of decreasing fixing capacity: artificial zeolite>Na bentonite>montmorillonite>vermiculite>illite>chabazite>palygorskite. In the second instance, we considered the hardened grouts and we compared normal percolation of cationic solutions and distilled water, under perfectly defined experimental conditions (notably pressure). Thus, we are able to calculate the quantity of fixed cations by a grout of

Methods of heating the concrete for grouting the joints of the dam at the Zeya hydroelectric station

1. The electrical heating system of a joint with embedded electrodes, being technologically efficient in assembly and reliable in heating the zone of the joint being grouted, proved to be unconditionally preferable to the system of heating by tubular electric heaters through boreholes. All tests of systems of embedded electrodes were favorable and all sections were grouted successfully. 2. The experience of heating concrete by steam through a coil specially installed in a section showed the effectiveness of this method (with simpler installation of its components in comparison with the electrical heating system). It is necessary to continue work on the use of this method. Steam heating of concrete through boreholes is ineffective and requires large labor expenditures. 3. The method of heating concrete by injection of hot calcium chloride brine can be used only if the grouting system and joint are open and the section airtight. It should be carried out as an auxiliary measure during hydraulic testing and grouting after heating the concrete by either of the two other methods named above. 4. It is not advisable to use a system of regrouting with valve-type outlets if the concrete is frozen: First, grouting of frozen concrete is carried out at the maximum openings of the joint, which precludes additional opening during the operational period; second, the multiple-acting valves themselves can become clogged with salt during passage of hot brine through them.