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Journal ArticleDOI

Development of an injectable grout for concrete repair and strengthening

TL;DR: In this paper, the coupled effect of temperature and silica fume addition on rheological, mechanical behaviour and porosity of grouts based on CEMI 42.5R, proportioned with a polycarboxylate-based high range water reducer was investigated.
Abstract: This paper deals with the coupled effect of temperature and silica fume addition on rheological, mechanical behaviour and porosity of grouts based on CEMI 42.5R, proportioned with a polycarboxylate-based high range water reducer. Preliminary tests were conducted to focus on the grout best able to fill a fibrous network since the goal of this study was to develop an optimized grout able to be injected in a mat of steel fibers for concrete strengthening. The grout composition was developed based on criteria for fresh state and hardened state properties. For a CEMI 42.5R based grout different high range water reducer dosages (0%, 0.2%, 0.4%, 0.5%, 0.7%) and silica fume (SF) dosages (0%, 2%, 4%) were tested (as replacement of cement by mass). Rheological measurements were used to investigate the effect of polycarboxylates (PCEs) and SF dosage on grout properties, particularly its workability loss, as the mix was to be injected in a matrix of steel fibers for concrete jacketing. The workability behaviour was characterized by the rheological parameters yield stress and plastic viscosity (for different grout temperatures and resting times), as well as the procedures of mini slump cone and funnel flow time. Then, further development focused only on the best grout compositions. The cement substitution by 2% of SF exhibited the best overall behaviour and was considered as the most promising compared to the others compositions tested. Concerning the fresh state analysis, a significant workability loss was detected if grout temperature increased above 35 °C. Below this temperature the grout presented a self-levelling behaviour and a life time equal to 45 min. In the hardened state, silica fumes increased not only the grout’s porosity but also the grout’s compressive strength at later ages, since the pozzolanic contribution to the compressive strength does not occur until 28 d and beyond.
Citations
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Journal ArticleDOI
Shucai Li1, Fei Sha1, Rentai Liu1, Qingsong Zhang1, Zhaofeng Li1 
TL;DR: In this article, the properties of six different MC grouts (three portland-based and three slag-blended) and two ordinary Portland cements (ASTM I and III) are measured.

45 citations

Journal ArticleDOI
TL;DR: In this article, the development of coated pellets as a self-healing system in cement-based materials was described, which was utilised for producing pellets from three different powder minerals as potential healing agents: reactive magnesium oxide (MgO), silica fume and bentonite.

38 citations

Journal ArticleDOI
TL;DR: It is important to choose grouting materials that are soft and fine enough to penetrate into the discontinuities in voids, cracks, or cavities to fill them to improve the mechanical properties and impermeability of a particular system.
Abstract: Grout is a binding agent or binder often used with building materials to improve their durability functions. It may be organic or inorganic material used for sealing or consolidation of cracks, pores, or voids in order to improve the mechanical properties and impermeability of a particular system, whether soil, cementitious or of other building materials. Grouts act as dispersion agents where dispersed particles form a network responsible for the effectiveness of grouting properties. Chemical grouts are the most common and well-known grouting materials used for sealing sand, soil, or other matrices. However, this is an expensive technique and it also affects the environment because chemical grouts based on acrylamides, lignosulfonates, and polyurethane are toxic and environmentally harmful. Thus, it is necessary to find new grouting materials and methods of injection. It is important to choose grouting materials that are soft and fine enough to penetrate into the discontinuities in voids, cracks, or cavities to fill them (Bras et al., 2013).

32 citations


Cites background from "Development of an injectable grout ..."

  • ...It is important to choose grouting materials that are soft and fine enough to penetrate into the discontinuities in voids, cracks, or cavities to fill them (Bras et al., 2013)....

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  • ...A novel grout should have a self-leveling behavior in addition to a high compressive strength and low shrinkage, be easy to inject, and have good durability (Bras et al., 2013); this can be achieved using biogrout....

    [...]

Journal ArticleDOI
TL;DR: In this article, the main effects of high water content on the microstructure and mechanical properties of the materials, looking at physical and chemical aspects, were investigated using scanning electron microscopy and chemical phase analysis.
Abstract: Geopolymers have gained much interest recently as a promising alternative to cementitious materials in some applications. However, research is still needed to use this technology for soil reinforcement grouts. The specifications of grouts mainly consist in rheological properties, strength and permeability. Grouting actually requires a low viscosity, and thus higher water content. The influence of relatively high water content on the other properties of the material, i.e. strength and microstructure, has been investigated. This effect highly depends on the concentration of the activator (sodium silicate solution) and the precursor (metakaolin, fly ash or blast furnace slag) associated with the activator. This paper deals with the main effects of high water content on the microstructure and mechanical properties of the materials, looking at physical and chemical aspects. Scanning electron microscopy and chemical phase analysis were used to highlight the nuances that are related to the precursors used, espec...

28 citations

Journal ArticleDOI
TL;DR: In this article, the authors evaluated the performance of grout injectability by checking the intrinsic properties of the grout and then by controlling the injectability through injection tests in porous media that simulate old masonries.
Abstract: The grout injection technique is commonly used for the consolidation of old stone masonries. In particular, the multi-leaf masonries which generally exhibit low compactness in the inner core and very few links between the internal and external leaves. Grouts are concentrated suspensions that can be seen as mixtures of binder with water, and special admixtures. To ensure an adequate flow of the grout and a correct filling of the internal voids inside the masonry, it is essential to assure good fresh grout properties. Thus, the evaluation of the performance of the grout injectability is firstly started by checking the intrinsic properties of the grout (namely rheological parameters) and then by controlling the injectability, through injection tests in porous media that simulate old masonries. The main goal of this paper is to provide indications and valuable data about the combined effect of superplasticizer dosage, environmental temperature, resting times (i.e. the time after the grout mixing had ended) and injection pressure on grout injectability, aiming at a successful injection process. The lack of information about the influence of the referred parameters on the injectability of hydraulic lime grouts enhances the importance of a detailed research on the subject.

26 citations

References
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Book
15 Jun 1989
TL;DR: In this article, the authors discuss the importance of non-linearity solids and liquids rheology is a difficult subject for rheological research, and present some demonstrations of high extensional viscosity behaviour.
Abstract: 1) What is rheology? historical perspective the importance of non-linearity solids and liquids rheology is a difficult subject components of rheological research. 2) Viscosity practical ranges of variables which affect viscosity the shear-dependent viscosity of non-Newtonian liquids viscometers for measuring shear viscosity. 3) Linear viscoelasticity the meaning and consequences of linearity the Kelvin and Maxwell models the relaxation spectrum oscillatory shear relationships between functions of linear viscoelasticity methods of measurement. 4) Normal stresses the nature and origin of normal stresses typical behaviour of N 1 and N 2 observable consequences of N 1 and N 2 methods of measuring N 1 and N 2 relationships between viscometric functions and linear viscoelastic functions. 5) extensional viscosity importance of extensional flow theoretical considerations experimental methods experimental results some demonstrations of high extensional viscosity behaviour. 6) Rheology of polymeric liquids general behaviour effect of temperature on polymer rheology effect of molecular weight on polymer rheology effect of concentration on the rheology of polymer solutions polymer gels liquid crystal polymers. molecular theories the method of reduced variables empirical relations between rheological functions practical applications. 7) Rheology of suspensions the viscosity of suspensions of solid particles in Newtonian liquids the colloidal contribution to viscosity viscoelastic properties of suspensions suspensions of deformable particles the interaction of suspended particles with polymer molecules also present in the continuous phase computer simulation studies of suspension rheology. 8. Theoretical rheology basic principles of continuum mechanics successful applications of the formulation principles some general constitutive equations constitutive equations for restricted classes of flows simple constitutive equations of the Oldroyd/Maxwell type solution of flow problems.

2,569 citations

Book
01 Jan 1970
TL;DR: The chemistry of cement and concrete as discussed by the authors, The chemistry of concrete and its properties, and the relationship between concrete and cement, is a classic example of such an approach. But it is not suitable for outdoor use.
Abstract: The chemistry of cement and concrete , The chemistry of cement and concrete , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

2,424 citations

Journal ArticleDOI
TL;DR: A history of thixotropy is given in this article, together with a description of how it is understood today in various parts of the scientific community, and a mechanistic description of the thixotropic system is presented.
Abstract: The ensuing mechanical response to stressing or straining a structured liquid results in various viscoelastic phenomena, either in the linear region where the microstructure responds linearly with respect to the stress and strain but does not itself change, or in the nonlinear region where the microstructure does change in response to the imposed stresses and strains, but does so reversibly. The complication of thixotropy arises because this reversible, microstructural change itself takes time to come about due to local spatial rearrangement of the components. This frequently found time-response of a microstructure that is itself changing with time makes thixotropic, viscoelastic behaviour one of the greatest challenges facing rheologists today, in terms of its accurate experimental characterisation and its adequate theoretical description. Here a history of thixotropy is given, together with a description of how it is understood today in various parts of the scientific community. Then a mechanistic description of thixotropy is presented, together with a series of applications where thixotropy is important. A list of different examples of thixotropic systems is then given. Finally the various kinds of theories that have been put forward to describe the phenomenon mathematically are listed.

1,367 citations

Journal ArticleDOI
TL;DR: In this article, the methods used to measure and model thixotropy of fresh concrete in the civil engineering field are described and a simple thixotropic model is presented, which is in agreement with the experimental observations that can be found in the literature.

570 citations

Journal ArticleDOI
TL;DR: In this paper, a thixotropic model is presented to predict the trends of the fresh behaviour of cement pastes in various flow situations, and its four parameters are identified experimentally for tested cement paste using coaxial viscometer test.

246 citations