The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Fernando M A Henriques - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the Grout injectability and types of resistance to Grout flow
Construction and Building Materials, 2016Co-Authors: Fernando Jorne, Fernando M A HenriquesAbstract:Abstract Grout injection is an efficient technique commonly used for structural consolidation of multi-leaf stone masonries, which often present high porosity (especially in the inner core) due to the presence of internal voids. Since porosity and void size distribution are not constant within masonry, the efficiency of Grouting varies along the injection. Thus, it is essential to study the injectability of Grouts in porous media with different characteristics along the height of injection. To evaluate the efficiency of Grout injection this work used 11 different porous media, in the shape of small scale cylinders. For each porous medium, Grout injection velocity and injected mass were measured. The reliability of various rules of thumb used to check Grout injectability was also verified. From the injection tests different resistances to Grout penetration were detected, created by the porous medium to the flow. The knowledge of these resistances is crucial to estimate the Grout penetration in the internal voids. In contrast with literature, the injection tests show that Darcy’s law and front resistance are not adequate to estimate the Grout injection. Therefore, an additional resistance is introduced (resistance of suspension – Rs). This resistance, as well as the overall resistance to Grout flow are reduced when the pre-wetting of the porous medium (before Grout injection) is done. The performance of the Grout injection performance was also analysed in the hardened state with ultrasonic tomography.
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Influence of superplasticizer, temperature, resting time and injection pressure on hydraulic lime Grout injectability. Correlation analysis between fresh Grout parameters and Grout injectability
Journal of Building Engineering, 2015Co-Authors: Fernando Jorne, Fernando M A Henriques, Luis G BaltazarAbstract: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.
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combined effect of superplasticizer silica fume and temperature in the performance of natural hydraulic lime Grouts
Construction and Building Materials, 2014Co-Authors: Luis G Baltazar, Fernando M A Henriques, Fernando Jorne, Maria Teresa CidadeAbstract:Abstract Grouting is a current repair technique for consolidating and strengthening old masonry buildings. Grouts can be seen as mixtures of binder with water, admixtures and/or additives, which should present low viscosity and high penetrability. The Grout specification involves the knowledge of the flow capacity within the masonry inner core and physic-chemical compatibility with the original materials. Nevertheless, the Grout properties are affected by a large number of parameters, including binder type and composition, mixing procedure, type and dosage of admixture, environmental conditions such as temperature that may lead to different Grout injection capacities, as reported by several authors. This paper deals with the effect of environmental temperature over superplasticized hydraulic lime-based Grouts with partial replacement of lime by silica fume. Grout performance was analysed in fresh and hardened state by testing its rheological behaviour, injectability as well as its hydration reactions kinetics. In spite of the considerable amount of information that exists for cement based mixtures with superplasticizers, there is little information about the effects of superplasticizers when used in natural hydraulic lime mixtures proportioned with silica fume. This study aims to contribute to a better understanding of the behaviour that superplasticized hydraulic lime Grouts present under different temperatures. The results showed that hydraulic lime Grouts performance could be improved, regarding rheological parameters and strength capacity if they are properly design and a suitable processing temperature were ensured.
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Rheology of Grouts for Masonry Injection
Key Engineering Materials, 2014Co-Authors: Luis G Baltazar, Fernando M A HenriquesAbstract:Grout injection technique applied in a multiple leaf masonry walls aims at increasing the compactness of the masonry and, therefore, improving their monolithic behaviour by bonding the separated segments together without compromising the architectural value of the masonry building. The success of the injection Grouts depends mainly on their rheological properties. This means that the flow properties of fresh Grouts are as important as their properties in the hardened state, since they govern the ability of the Grout to flow and fill the voids within masonry. In practice, the variability of voids within masonry requires ability to fine tune the rheological properties of the Grout, in order to optimal fill all voids with Grout. So, models were developed with the main purpose of predict and control the rheological properties of Grouts just performing simple flow tests traditionally used in the field. It is well known that flow tests commonly performed (such as Marsh cone and slump test), which try to describe the workability of cementitious materials, only give a qualitative result that can not be expressed in physical rheological units. However, the proposed models allow calculating a physical parameter (e.g. viscosity) instead of an empirical one (e.g. fluidity). This research shows the effect of Grout design variables on the properties of natural hydraulic lime Grouts based on the correlation between rheometry measurements and simple flow tests. Furthermore, the proposed models can be very useful to smooth the Grout design methodology, since these models enable the prediction of rheological properties of the Grout without the need for expensive and complex equipment, such as rheometers or viscometers.
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The use of rheology in the study of the composition effects on the fresh behaviour of hydraulic lime Grouts for injection of masonry walls
Rheologica Acta, 2013Co-Authors: Luis G Baltazar, Fernando M A Henriques, Fernando Jorne, Maria Teresa CidadeAbstract:The injection of Grouts inside multi-leaf stone masonries is a technique widely used for structural consolidation. To ensure an adequate flow of the Grout inside the masonry, it is crucial to assure good fresh Grout properties, such as good rheological behaviour. The scope of this paper is to provide preliminary indications and valuable data about the effects of specific hydraulic lime Grout composition on their rheological behaviour with the purpose of a successful injection process. Through the use of rotational rheometer together with the Taguchi method, it was possible to study the influence of water/binder ratio, the type and dosage of superplasticizer and the partial replacement of hydraulic lime by silica fume, upon the Grout rheological properties. The study leads to the conclusion that polycarboxylate-based superplasticizers present better performance from a rheological point of view than the naphthalene-based superplasticizer and that the water/binder ratio and superplasticizer dosage are the most determinant factors in the fresh Grout rheological behaviour. On the other hand, silica fume dosage turned out to be the factor with the least contribution to improve the Grout rheological behaviour compared to the other two factors reported in this study. The results summarised in this paper are part of a larger study and precede the analysis of the performance of those Grouts when injected into different porous media that simulate old masonries.
Luis G Baltazar - One of the best experts on this subject based on the ideXlab platform.
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Influence of superplasticizer, temperature, resting time and injection pressure on hydraulic lime Grout injectability. Correlation analysis between fresh Grout parameters and Grout injectability
Journal of Building Engineering, 2015Co-Authors: Fernando Jorne, Fernando M A Henriques, Luis G BaltazarAbstract: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.
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combined effect of superplasticizer silica fume and temperature in the performance of natural hydraulic lime Grouts
Construction and Building Materials, 2014Co-Authors: Luis G Baltazar, Fernando M A Henriques, Fernando Jorne, Maria Teresa CidadeAbstract:Abstract Grouting is a current repair technique for consolidating and strengthening old masonry buildings. Grouts can be seen as mixtures of binder with water, admixtures and/or additives, which should present low viscosity and high penetrability. The Grout specification involves the knowledge of the flow capacity within the masonry inner core and physic-chemical compatibility with the original materials. Nevertheless, the Grout properties are affected by a large number of parameters, including binder type and composition, mixing procedure, type and dosage of admixture, environmental conditions such as temperature that may lead to different Grout injection capacities, as reported by several authors. This paper deals with the effect of environmental temperature over superplasticized hydraulic lime-based Grouts with partial replacement of lime by silica fume. Grout performance was analysed in fresh and hardened state by testing its rheological behaviour, injectability as well as its hydration reactions kinetics. In spite of the considerable amount of information that exists for cement based mixtures with superplasticizers, there is little information about the effects of superplasticizers when used in natural hydraulic lime mixtures proportioned with silica fume. This study aims to contribute to a better understanding of the behaviour that superplasticized hydraulic lime Grouts present under different temperatures. The results showed that hydraulic lime Grouts performance could be improved, regarding rheological parameters and strength capacity if they are properly design and a suitable processing temperature were ensured.
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Rheology of Grouts for Masonry Injection
Key Engineering Materials, 2014Co-Authors: Luis G Baltazar, Fernando M A HenriquesAbstract:Grout injection technique applied in a multiple leaf masonry walls aims at increasing the compactness of the masonry and, therefore, improving their monolithic behaviour by bonding the separated segments together without compromising the architectural value of the masonry building. The success of the injection Grouts depends mainly on their rheological properties. This means that the flow properties of fresh Grouts are as important as their properties in the hardened state, since they govern the ability of the Grout to flow and fill the voids within masonry. In practice, the variability of voids within masonry requires ability to fine tune the rheological properties of the Grout, in order to optimal fill all voids with Grout. So, models were developed with the main purpose of predict and control the rheological properties of Grouts just performing simple flow tests traditionally used in the field. It is well known that flow tests commonly performed (such as Marsh cone and slump test), which try to describe the workability of cementitious materials, only give a qualitative result that can not be expressed in physical rheological units. However, the proposed models allow calculating a physical parameter (e.g. viscosity) instead of an empirical one (e.g. fluidity). This research shows the effect of Grout design variables on the properties of natural hydraulic lime Grouts based on the correlation between rheometry measurements and simple flow tests. Furthermore, the proposed models can be very useful to smooth the Grout design methodology, since these models enable the prediction of rheological properties of the Grout without the need for expensive and complex equipment, such as rheometers or viscometers.
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The use of rheology in the study of the composition effects on the fresh behaviour of hydraulic lime Grouts for injection of masonry walls
Rheologica Acta, 2013Co-Authors: Luis G Baltazar, Fernando M A Henriques, Fernando Jorne, Maria Teresa CidadeAbstract:The injection of Grouts inside multi-leaf stone masonries is a technique widely used for structural consolidation. To ensure an adequate flow of the Grout inside the masonry, it is crucial to assure good fresh Grout properties, such as good rheological behaviour. The scope of this paper is to provide preliminary indications and valuable data about the effects of specific hydraulic lime Grout composition on their rheological behaviour with the purpose of a successful injection process. Through the use of rotational rheometer together with the Taguchi method, it was possible to study the influence of water/binder ratio, the type and dosage of superplasticizer and the partial replacement of hydraulic lime by silica fume, upon the Grout rheological properties. The study leads to the conclusion that polycarboxylate-based superplasticizers present better performance from a rheological point of view than the naphthalene-based superplasticizer and that the water/binder ratio and superplasticizer dosage are the most determinant factors in the fresh Grout rheological behaviour. On the other hand, silica fume dosage turned out to be the factor with the least contribution to improve the Grout rheological behaviour compared to the other two factors reported in this study. The results summarised in this paper are part of a larger study and precede the analysis of the performance of those Grouts when injected into different porous media that simulate old masonries.
Fernando Jorne - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the Grout injectability and types of resistance to Grout flow
Construction and Building Materials, 2016Co-Authors: Fernando Jorne, Fernando M A HenriquesAbstract:Abstract Grout injection is an efficient technique commonly used for structural consolidation of multi-leaf stone masonries, which often present high porosity (especially in the inner core) due to the presence of internal voids. Since porosity and void size distribution are not constant within masonry, the efficiency of Grouting varies along the injection. Thus, it is essential to study the injectability of Grouts in porous media with different characteristics along the height of injection. To evaluate the efficiency of Grout injection this work used 11 different porous media, in the shape of small scale cylinders. For each porous medium, Grout injection velocity and injected mass were measured. The reliability of various rules of thumb used to check Grout injectability was also verified. From the injection tests different resistances to Grout penetration were detected, created by the porous medium to the flow. The knowledge of these resistances is crucial to estimate the Grout penetration in the internal voids. In contrast with literature, the injection tests show that Darcy’s law and front resistance are not adequate to estimate the Grout injection. Therefore, an additional resistance is introduced (resistance of suspension – Rs). This resistance, as well as the overall resistance to Grout flow are reduced when the pre-wetting of the porous medium (before Grout injection) is done. The performance of the Grout injection performance was also analysed in the hardened state with ultrasonic tomography.
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Influence of superplasticizer, temperature, resting time and injection pressure on hydraulic lime Grout injectability. Correlation analysis between fresh Grout parameters and Grout injectability
Journal of Building Engineering, 2015Co-Authors: Fernando Jorne, Fernando M A Henriques, Luis G BaltazarAbstract: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.
-
combined effect of superplasticizer silica fume and temperature in the performance of natural hydraulic lime Grouts
Construction and Building Materials, 2014Co-Authors: Luis G Baltazar, Fernando M A Henriques, Fernando Jorne, Maria Teresa CidadeAbstract:Abstract Grouting is a current repair technique for consolidating and strengthening old masonry buildings. Grouts can be seen as mixtures of binder with water, admixtures and/or additives, which should present low viscosity and high penetrability. The Grout specification involves the knowledge of the flow capacity within the masonry inner core and physic-chemical compatibility with the original materials. Nevertheless, the Grout properties are affected by a large number of parameters, including binder type and composition, mixing procedure, type and dosage of admixture, environmental conditions such as temperature that may lead to different Grout injection capacities, as reported by several authors. This paper deals with the effect of environmental temperature over superplasticized hydraulic lime-based Grouts with partial replacement of lime by silica fume. Grout performance was analysed in fresh and hardened state by testing its rheological behaviour, injectability as well as its hydration reactions kinetics. In spite of the considerable amount of information that exists for cement based mixtures with superplasticizers, there is little information about the effects of superplasticizers when used in natural hydraulic lime mixtures proportioned with silica fume. This study aims to contribute to a better understanding of the behaviour that superplasticized hydraulic lime Grouts present under different temperatures. The results showed that hydraulic lime Grouts performance could be improved, regarding rheological parameters and strength capacity if they are properly design and a suitable processing temperature were ensured.
-
The use of rheology in the study of the composition effects on the fresh behaviour of hydraulic lime Grouts for injection of masonry walls
Rheologica Acta, 2013Co-Authors: Luis G Baltazar, Fernando M A Henriques, Fernando Jorne, Maria Teresa CidadeAbstract:The injection of Grouts inside multi-leaf stone masonries is a technique widely used for structural consolidation. To ensure an adequate flow of the Grout inside the masonry, it is crucial to assure good fresh Grout properties, such as good rheological behaviour. The scope of this paper is to provide preliminary indications and valuable data about the effects of specific hydraulic lime Grout composition on their rheological behaviour with the purpose of a successful injection process. Through the use of rotational rheometer together with the Taguchi method, it was possible to study the influence of water/binder ratio, the type and dosage of superplasticizer and the partial replacement of hydraulic lime by silica fume, upon the Grout rheological properties. The study leads to the conclusion that polycarboxylate-based superplasticizers present better performance from a rheological point of view than the naphthalene-based superplasticizer and that the water/binder ratio and superplasticizer dosage are the most determinant factors in the fresh Grout rheological behaviour. On the other hand, silica fume dosage turned out to be the factor with the least contribution to improve the Grout rheological behaviour compared to the other two factors reported in this study. The results summarised in this paper are part of a larger study and precede the analysis of the performance of those Grouts when injected into different porous media that simulate old masonries.
Ana Bras - One of the best experts on this subject based on the ideXlab platform.
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natural hydraulic lime based Grouts the selection of Grout injection parameters for masonry consolidation
Construction and Building Materials, 2011Co-Authors: Ana Bras, Fernando M A HenriquesAbstract:Abstract The goal of this research was to develop a methodology for Grout composition optimization concerning specific applications. It could be developed for masonry consolidation or bonded prestressed tendon Grout, pre-placed aggregate Grout, among others. The Grout development does not only depend on its intrinsic properties but also on the nature and features of the support. The purpose of a Grout injection technique applied in a multiple leaf wall is to increase the compactness and create links between the internal and external leaves, which improve not only shear and flexural resistance but also the compressive strength. In practice, the variability of voids within masonries requires an ability to fine tune the rheological properties of the Grout in order to optimally fill the voids. The methodology proposed here for testing Grout injectability in a porous media like masonry is a logical tool to use in Grout optimization. It shows that several Grout parameters should be controlled for a successful injection. Concerning the support and its typology, the mortar between stones plays a fundamental role in the effectiveness of the intervention, due to its reduced porosity and composition. Besides that, earth and mortar, for example, can be present in the interior of masonry and make difficult, with their absorption, the injection. Thus, the water retention capacity of Grout should be controlled to prevent that problem, as it was made in this work, using the optimized mixing procedure that takes into account that and other fresh Grout properties. This study analyses some relevant Grout properties such as yield stress, plastic viscosity, flowability and injectability for natural hydraulic lime based Grouts in different porous media. The research shows that there are differences in the Grout behaviour, especially in rheological properties, when different mixing procedures and/or Grout composition (different water/binder or fly ash/binder ratios) are used and that fresh Grout properties may be optimized for injection purpose.
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Natural hydraulic lime based Grouts – The selection of Grout injection parameters for masonry consolidation
Construction and Building Materials, 2011Co-Authors: Ana Bras, Fernando M A HenriquesAbstract:Abstract The goal of this research was to develop a methodology for Grout composition optimization concerning specific applications. It could be developed for masonry consolidation or bonded prestressed tendon Grout, pre-placed aggregate Grout, among others. The Grout development does not only depend on its intrinsic properties but also on the nature and features of the support. The purpose of a Grout injection technique applied in a multiple leaf wall is to increase the compactness and create links between the internal and external leaves, which improve not only shear and flexural resistance but also the compressive strength. In practice, the variability of voids within masonries requires an ability to fine tune the rheological properties of the Grout in order to optimally fill the voids. The methodology proposed here for testing Grout injectability in a porous media like masonry is a logical tool to use in Grout optimization. It shows that several Grout parameters should be controlled for a successful injection. Concerning the support and its typology, the mortar between stones plays a fundamental role in the effectiveness of the intervention, due to its reduced porosity and composition. Besides that, earth and mortar, for example, can be present in the interior of masonry and make difficult, with their absorption, the injection. Thus, the water retention capacity of Grout should be controlled to prevent that problem, as it was made in this work, using the optimized mixing procedure that takes into account that and other fresh Grout properties. This study analyses some relevant Grout properties such as yield stress, plastic viscosity, flowability and injectability for natural hydraulic lime based Grouts in different porous media. The research shows that there are differences in the Grout behaviour, especially in rheological properties, when different mixing procedures and/or Grout composition (different water/binder or fly ash/binder ratios) are used and that fresh Grout properties may be optimized for injection purpose.
Maria Teresa Cidade - One of the best experts on this subject based on the ideXlab platform.
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combined effect of superplasticizer silica fume and temperature in the performance of natural hydraulic lime Grouts
Construction and Building Materials, 2014Co-Authors: Luis G Baltazar, Fernando M A Henriques, Fernando Jorne, Maria Teresa CidadeAbstract:Abstract Grouting is a current repair technique for consolidating and strengthening old masonry buildings. Grouts can be seen as mixtures of binder with water, admixtures and/or additives, which should present low viscosity and high penetrability. The Grout specification involves the knowledge of the flow capacity within the masonry inner core and physic-chemical compatibility with the original materials. Nevertheless, the Grout properties are affected by a large number of parameters, including binder type and composition, mixing procedure, type and dosage of admixture, environmental conditions such as temperature that may lead to different Grout injection capacities, as reported by several authors. This paper deals with the effect of environmental temperature over superplasticized hydraulic lime-based Grouts with partial replacement of lime by silica fume. Grout performance was analysed in fresh and hardened state by testing its rheological behaviour, injectability as well as its hydration reactions kinetics. In spite of the considerable amount of information that exists for cement based mixtures with superplasticizers, there is little information about the effects of superplasticizers when used in natural hydraulic lime mixtures proportioned with silica fume. This study aims to contribute to a better understanding of the behaviour that superplasticized hydraulic lime Grouts present under different temperatures. The results showed that hydraulic lime Grouts performance could be improved, regarding rheological parameters and strength capacity if they are properly design and a suitable processing temperature were ensured.
-
The use of rheology in the study of the composition effects on the fresh behaviour of hydraulic lime Grouts for injection of masonry walls
Rheologica Acta, 2013Co-Authors: Luis G Baltazar, Fernando M A Henriques, Fernando Jorne, Maria Teresa CidadeAbstract:The injection of Grouts inside multi-leaf stone masonries is a technique widely used for structural consolidation. To ensure an adequate flow of the Grout inside the masonry, it is crucial to assure good fresh Grout properties, such as good rheological behaviour. The scope of this paper is to provide preliminary indications and valuable data about the effects of specific hydraulic lime Grout composition on their rheological behaviour with the purpose of a successful injection process. Through the use of rotational rheometer together with the Taguchi method, it was possible to study the influence of water/binder ratio, the type and dosage of superplasticizer and the partial replacement of hydraulic lime by silica fume, upon the Grout rheological properties. The study leads to the conclusion that polycarboxylate-based superplasticizers present better performance from a rheological point of view than the naphthalene-based superplasticizer and that the water/binder ratio and superplasticizer dosage are the most determinant factors in the fresh Grout rheological behaviour. On the other hand, silica fume dosage turned out to be the factor with the least contribution to improve the Grout rheological behaviour compared to the other two factors reported in this study. The results summarised in this paper are part of a larger study and precede the analysis of the performance of those Grouts when injected into different porous media that simulate old masonries.
