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Showing papers on "Mortar published in 2005"


Journal ArticleDOI
TL;DR: In this paper, a thermophilic anaerobic microorganism is incorporated at different cell concentrations with the mixing water, and a 25% increase in 28 day compressive strength of cement mortar was achieved with the addition of about 105 cell/ml of mixing water.

366 citations


Journal ArticleDOI
TL;DR: In this article, the authors presented the experimental investigations of the resistance to impact loading of cement mortar slabs reinforced with four natural fibres, coir, sisal, jute, hibiscus cannebinus, and four different fibre contents (0.5, 1.0%, 1.5% and 2.5%) and three fiber lengths (20mm, 30mm and 40mm) were considered.
Abstract: This paper presents the experimental investigations of the resistance to impact loading of cement mortar slabs (1:3, size: 300 mm × 300 mm × 20 mm) reinforced with four natural fibres, coir, sisal, jute, hibiscus cannebinus and subjected to impact loading using a simple projectile test. Four different fibre contents (0.5%, 1.0%, 1.5% and 2.5%—by weight of cement) and three fibre lengths (20 mm, 30 mm and 40 mm) were considered. The results obtained have shown that the addition of the above natural fibres has increased the impact resistance by 3–18 times than that of the reference (i.e. plain) mortar slab. Of the four fibres, coir fibre reinforced mortar slab specimens have shown the best performance based on the set of chosen indicators, i.e. the impact resistance (Ru), residual impact strength ratio (Irs), impact crack-resistance ratio (Cr) and the condition of fibre at ultimate failure.

297 citations


Journal ArticleDOI
TL;DR: In this article, a concise summary of several investigations is presented to establish the influence of sisal and coconut fibres on the free and restrained plastic shrinkage, early drying shrinkage cracking, crack self-healing and long-term drying shrinking of mortar matrices.
Abstract: Many investigations are realized to establish the basic mechanical properties of vegetable fibre reinforced composites (VFRC) but not their shrinkage and creep behaviour. Some works have been realized to establish the shrinkage of cement mortar matrices reinforced with cellulose fibres, but very few results has been published with regards to shrinkage of VFRC with short sisal and coconut fibres. In this paper a concise summary of several investigations is presented to establish the influence of sisal and coconut fibres on the free and restrained plastic shrinkage, early drying shrinkage cracking, crack self-healing and long-term drying shrinkage of mortar matrices. The free and restrained shrinkage were studied by subjecting the specimens to wind speed of 0.4–0.5 m/s at 40 °C temperature for up to 280 min. The self healing of cracks of the VFRC was studied by using the same specimens as for the study of restrained shrinkage which were kept further in a controlled environment with 100% relative humidity and temperature of 21 °C for up to 40 days. Drying shrinkage tests were carried out at room temperature with about 41% relative humidity for 320 days. The influence of curing method, mix proportions and partial replacement of ordinary Portland cement (OPC) by ground granulated blast-furnace slag and silica fume on the drying shrinkage of VFRC was also investigated. Finally, based on the obtained results on drying shrinkage an equation using the recommendation of ACI model B3 was adjusted and compared well with the obtained experimental data.

241 citations


Journal ArticleDOI
TL;DR: In this article, the results of the variation in chemical composition and tensile strength of coir, sisal, jute and Hibiscus cannabinus fibres, when they are subjected to alternate wetting and drying and continuous immersion for 60 days in three mediums (water, saturated lime and sodium hydroxide) were determined after 28 days of normal curing.
Abstract: This paper presents the results of the variation in chemical composition and tensile strength of coir, sisal, jute and Hibiscus cannabinus fibres, when they are subjected to alternate wetting and drying and continuous immersion for 60 days in three mediums (water, saturated lime and sodium hydroxide). Compressive and flexural strengths of cement mortar (1:3) specimens reinforced with dry and corroded fibres were determined after 28 days of normal curing. From the results it is observed that there is substantial reduction in the salient chemical composition of all the four fibres, after exposure in the various mediums. Coir fibres are found to retain higher percentages of their initial strength than all other fibres, after the specified period of exposure in the various mediums. The compressive and flexural strengths of all natural fibre reinforced mortar specimens using corroded fibres are less than the strength of the reference mortar (i.e. without fibres) and fibre reinforced mortar specimens reinforced with dry natural fibres.

235 citations


Journal ArticleDOI
TL;DR: In this paper, the use of expanded polystyrene (EPS) beads as lightweight aggregate, both in concrete and mortar, has been investigated, and the compressive strength of the EPS concretes containing fly ash showed a continuous gain even up to 90 days.

234 citations


Journal ArticleDOI
TL;DR: In this article, the impact of polymer modification on the physical properties of cementitious mortars was investigated using a multimethod approach, where the identification and quantification of different polymer components within the cementitious matrix was put into consideration.

219 citations


Journal ArticleDOI
TL;DR: No reaction has been detected with particle size up to 100mum thus indicating the feasibility of the waste glass reuse as fine aggregate in mortars and concrete, and waste glass seems to positively contribute to the mortar micro-structural properties resulting in an evident improvement of its mechanical performance.

212 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of bond strength on masonry compressive strength has been examined through an experimental program using local bricks and mortars, and the results clearly indicate that an increase in bond strength, while keeping the mortar strength constant, leads to a significant increase in the compressive strengths of masonry.
Abstract: This paper focuses on some issues pertaining to brick-mortar bond and masonry compressive strength Failure theories for masonry under compression make the assumption that the bond between brick and mortar remains intact at the time of failure of the brick or mortar The influence of bond strength on masonry compressive strength is not fully accounted for in these failure theories In this investigation, the influence of bond strength on masonry compressive strength has been examined through an experimental program using local bricks and mortars Masonry prism compressive strength has been determined when the brick-mortar bond strength is varied over a wide range without altering the strength and deformation characteristics of the brick and mortar Brick-mortar bond strength has been determined through flexure bond strength and shear bond strength tests A relationship between the masonry prism compressive strength and bond strength has been obtained The results clearly indicate that an increase in bond strength, while keeping the mortar strength constant, leads to an increase in the compressive strength of masonry

207 citations


Journal ArticleDOI
TL;DR: In this article, a mortar-based formulation for the solution of two-dimensional frictional contact problems involving finite deformation and large sliding is presented, with particular emphasis on key aspects of the linearization procedure and on the robust description of the friction kinematics.
Abstract: This paper presents a mortar-based formulation for the solution of two dimensional frictional contact problems involving finite deformation and large sliding. As is widely recognized, traditional node-to-surface contact formulations have several drawbacks in solution of deformable-to-deformable contact problems, including lack of general patch test passage, degradation of spatial convergence rates, and robustness issues associated with the faceted representation of contacting surfaces. The mortar finite element method, initially proposed as a technique to join dissimilarly meshed domains, has been shown to preserve optimal convergence rates in tied contact problems (see (Discretization Methods and Iterative Solvers Based on Domain Decomposition, Springer-Verlag, Heidelberg, 2001) for a recent review), and is examined here as an alternative spatial discretization method for large sliding contact. In particular, a novel description for frictional sliding conditions in large deformation mortar formulations is proposed in this work. In recent years, the mortar element method has already been successfully implemented to solve frictional contact problems with linearized kinematics (see (Int. J. Numer. Meth. Engng 1993; 36: 3451)). However, in the presence of large deformations and finite sliding, one must face difficulties associated with the definition and linearization of contact virtual work in the case where the mortar projection has a direct dependence on the tangential relative motion along the interface. In this paper, such a formulation is presented, with particular emphasis on key aspects of the linearization procedure and on the robust description of the friction kinematics. Some novel techniques are proposed to treat the non-smoothness in the contact geometry and the searching required to define mortar segments. A number of numerical examples illustrate the performance and accuracy of the proposed formulation. Copyright © 2004 John Wiley & Sons, Ltd.

198 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the effect of a limestone filler addition in superplasticized cement mortar and proposed a mathematical model that can be used to predict the viscosity of such mixtures.

191 citations


Journal ArticleDOI
TL;DR: In this paper, the authors explored the question of whether reinforcing steel can be protected with activated fly ash cement as effectively as with Portland cement, and found that activated fly-ash mortars can passivate steel reinforcement as speedily and effectively as Portland cement mortars, giving no cause to fear that corrosion may limit the durability of reinforced concrete structures built with these new types of activated fly -ash cement.

Journal ArticleDOI
TL;DR: In this article, the effect of particle size of fly ash on packing effect and pozzolanic reaction of mortar when 20% of fly ashes is used to replace Portland cement type I was studied.

Journal ArticleDOI
TL;DR: In this paper, the effect of metakaolin addition on the corrosion resistance of cement mortar is studied, where a poor Greek kaolin with a low kaolinite content was thermally treated and the produced metakaolis (MKC) was ground to the appropriate fineness.
Abstract: In this paper the effect of metakaolin addition on the corrosion resistance of cement mortar is studied. A poor Greek kaolin with a low kaolinite content was thermally treated and the produced metakaolin (MK) was ground to the appropriate fineness. In addition, a commercial metakaolin (MKC) of high purity was used. Several mixture proportions were used to produce mortar specimens, where metakaolin replaced either sand or cement. Mortar specimens were then exposed to the corrosive environment of either partial or total immersion in 3.5% w/w NaCl solution. For the evaluation of the performance of metakaolin, the following methods were used: compressive strength, corrosion potential, mass loss, electrochemical measurements of the corrosion rate by the Linear Polarization method, carbonation depth and porosity. It is concluded that metakaolin improves the compressive strength and the 10% w/w addition shows the optimum contribution to the strength development. In addition, the use of metakaolin, either as a sand replacement up to 20% w/w, or as a cement replacement up to 10% w/w, improves the corrosion behavior of mortar specimens, while when metakaolin is added in greater percentages there is no positive effect.

Journal ArticleDOI
TL;DR: In this paper, a conventional mortar was compared with ones incorporating rubber tyre particles, partly replacing the natural sand aggregates, and the compressive and tensile properties of these cement composites were investigated.

Journal ArticleDOI
TL;DR: In this paper, restoration mortars with analogous chemical composition of binders, aggregates and mineral additions, derived from the study of historic mortars, were evaluated regarding the strength development and the lime reaction, up to 15 months of curing.
Abstract: In this research, restoration mortars with analogous chemical composition of binders, aggregates and mineral additions, as they derive from the study of historic mortars, were evaluated regarding the strength development and the lime reaction, up to 15 months of curing. For this purpose several mixtures were tested in laboratory regarding their chemical and mechanical characteristics. The obtained results show that most of them present a slow rate of chemical and mechanical evolution, with the exception of hydraulic lime mortar and mortar with lime putty–natural pozzolanic addition. The best mechanical behavior was observed in mortars with lime powder and lime powder–artificial pozzolanic addition. These materials present also a low ratio of compressive to flexural strength ( f c / f f ). Further investigations on these materials would determine the time where their chemical and mechanical characteristics become stable. Only at that time, it would be possible to compare the compatibility characteristics of the restoration mortars with those employed in the past.

Journal ArticleDOI
TL;DR: In this article, the effect of pozzolans such as silica fume (SF), fly ash (FA), and metakaolin (MK) on the properties of fiber-reinforced mortars was investigated.
Abstract: Randomly oriented short fibers have been shown to increase tensile strength and retard crack propagation of cement based materials such as fiber-reinforced mortars for diverse applications, especially in aggressive environments. In the case of reinforced concrete, it is very important to produce a “high quality” cover in order to prevent corrosion of the rebars. In order to obtain a high performance material the use of a pozzolan is advisable because low permeability is achieved. The objective of this research was to determine the effect of pozzolans such as silica fume (SF), fly ash (FA), and metakaolin (MK) on the properties of fiber-reinforced mortars. Different types of natural and synthetic fibers were used. A superplasticizer was used to keep the same workability as that of the control mortar. Results of the mechanical and durability properties of the fiber-reinforced mortars are reported. The results show that a loss of resistance due to embedding fibers in mortar is compensated for by the increase in strength caused by silica fume or metakaolin additions to the mortar. The addition of 15% of SF or MK produces an improvement of up to 20% and 68%, respectively, when compared with those mortars without addition. There is a significant decrease in the coefficient of capillary absorption and chloride penetration when a highly pozzolanic material is incorporated into the matrix. In general, these materials, especially SF and MK, improve the mechanical performance and the durability of fiber-reinforced materials, especially those reinforced with steel, glass or sisal fibers. The fly ash addition had a different performance, which could be attributed to its low degree of pozzolanicity.

Journal ArticleDOI
TL;DR: The results of an investigation on the effect of dry and prewetted lightweight aggregate aggregates on the microstructure and durability of mortar are presented in this paper, where the results are compared with those obtained for normal aggregate mortar.

Journal ArticleDOI
TL;DR: In this paper, a meso-scale analysis of concrete is carried out, which is necessary for the quantitative evaluation of concrete behavior especially in compression, and failure behaviors and strengths in compression and tension of mortar and concrete are predicted well by the analysis.
Abstract: Concrete is a heterogeneous material consisting of mortar and aggregate at the meso scale. Evaluation of the fracture process at this scale is useful to clarify the material characteristic of concrete. The authors have conducted meso scale analysis of concrete over a past few years by Rigid Body Spring Model (RBSM). In this study, three-dimensional analyses of mortar and concrete are carried out, which is necessary for the quantitative evaluation of concrete behavior especially in compression. Constitutive models at the meso scale are developed for the 3D RBSM analysis. Failure behaviors and strengths in compression and tension of mortar and concrete are predicted well by the analysis. In biaxial compression test of concrete, crack in normal direction to plane of specimen is simulated that cannot be presented by two-dimensional analysis.

Journal ArticleDOI
TL;DR: In this paper, the results of round robin tests comparing two nondestructive, ultrasonic techniques: the wave transmission method using P-waves and the wave reflection method using S-waves were reported.
Abstract: This paper reports on results of round robin tests comparing two nondestructive, ultrasonic techniques: the wave transmission method using P-waves and the wave reflection method using S-waves. The experiments were conducted within the activities of the RILEM Technical Committee TC ATC-185 with the objective to evaluate the ability of these methods to continuously monitor the setting and hardening process of cementitious materials. In total, eight different mortar and concrete mixtures were subjected to the ultrasonic tests. Additionally, experiments were conducted to determine the penetration resistance (ASTM C 403), the in-situ temperature rise, the adiabatic heat release, and the chemical shrinkage (of the cement paste phase) of the investigated materials. The results revealed that, originating from the different wave types, the two ultrasonic methods monitor the setting process of mortar and concrete in significantly different ways. Despite these differences, the comparison of the ultrasonic test results with the development of the adiabatic heat and the chemical shrinkage has proven that P-wave velocity and reflection loss, as the parameters measured by the two methods, have a consistent and direct relationship to the cement hydration process.

Journal ArticleDOI
TL;DR: A comparative study of the microstructure of both new and in-use aged blast-furnace slag cement coir reinforced composite was performed in this article, where both internal and external walls of a 12-y...
Abstract: A comparative study of the microstructure of both new and in-use aged blast-furnace slag cement coir reinforced composite was performed. Aged samples came from internal and external walls of a 12-y ...

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the use of ultrasound measurements for monitoring setting and hardening of mortar containing different accelerating admixtures for shotcrete, and evaluated the sensitivity to accelerator type (alkaline aluminate or alkali-free) and dosage, and accelerator-cement compatibility.

Journal ArticleDOI
TL;DR: In this article, the ability of a shear wave reflection (WR) method to monitor microstructural changes of Portland cement mortar during hydration was investigated, and it was shown that the wave reflection measurements are governed primarily by the degree of the interparticle bonding of the cement particles as calculated from the specific contact area of a simulated microstructure.

Journal ArticleDOI
TL;DR: In this article, the compressive strength and elastic modulus of MPSC mortars with different fine aggregates, and different water contents were investigated, and it was found that the change of mechanical properties was mainly controlled by increase of total porosity which was determined by water content.
Abstract: Properties of magnesium phospho-silicate cement (MPSC) mortars with different fine aggregates, and different water contents were investigated in the present work. Three types of fine aggregates, natural sand, dead burnt magnesia and alumina particles were used. Two types of hard burnt magnesia powder with MgO content 89.51 and 71.50 wt.% were used as binder. Compressive strength of MPSC mortar with different water/binder ratios were determined at ages of 1, 3, 7, and 24 h. The 3, 7, and 28 day compressive strength and modulus of elasticity were also tested. It was found that the compressive strength of MPSC mortar decreases with the increase of sand content, regardless of sand type. However, the strength reduction of MPSC mortars formed with magnesia and alumina sand was much smaller than that of mortars formed with natural sand. Moreover, in spite of the raw materials, compressive strength and elastic modulus of MPSC decreased with the increase of water/binder ratio at all ages. The hydrate products were analysed by XRD and TG-DTA, and the porosity of MPSC mortar was analysed by MIP. Results showed total porosity increased with the increase of water content. The content of hydrate product of MPSC, phosphate hexahydrate, also increased with the increase of water content. However, it seems that the change of mechanical properties of MPSC is mainly controlled by increase of total porosity which was determined by water content.

Journal ArticleDOI
B. Rongbing1, S. Jian1
TL;DR: In this article, a chemical process called ethoxylation was used to synthesize a shrinkage-reducing admixture (SRA), which reduced free drying shrinkage (FDS) rate with the increment of dosage for both mortar and concrete.

Journal ArticleDOI
TL;DR: The changes in mechanical properties of portland cement mortars due to the addition of carbon fibres (CF) to the mix have been studied in this paper, where compression and flexural strength have been determined in relation to the amount of fibres added to mix, water/binder ratio, curing time and porosity.

Journal ArticleDOI
TL;DR: The main characteristics of the mortar element method are described, together with the usual arguments for its numerical analysis in an abstract framework, and three examples of recent applications, concerning the treatment of non homogeneous media, eddy currents in moving conductors, and finite element mesh adaptivity are given.
Abstract: We describe the main characteristics of the mortar element method, together with the usual arguments for its numerical analysis in an abstract framework. We illustrate this presentation by focussing on mortar spectral element and mortar finite element methods. We give three examples of recent applications, concerning the treatment of non homogeneous media, eddy currents in moving conductors, and finite element mesh adaptivity. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Journal ArticleDOI
TL;DR: In this article, the authors used optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermal analysis (differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) to characterize the mortar of the Roman Colosseum and a Roman cistern from Albano Laziale.

Journal ArticleDOI
TL;DR: In this article, short fibers of shape memory alloy (SMA) wires were embedded in mortar and the wires had been shaped by inelastic elongation into loop-and star-shaped fibers.
Abstract: Mortar and concrete exhibit low tensile strengths. Hence, cracks develop easily due to shrinkage and external actions. They can be prevented by applying prestress, thus obtaining crack-free products. Such products exhibit a high bending and tensile strength, are leak proof and of high durability. Prestress can be realized using external or internal wires or cables. In thin walled products, however, this is not feasible. For this purpose, short fibers of shape memory alloy (SMA) wires were embedded in mortar. The wires had been shaped by inelastic elongation into loop-and star-shaped fibers. After hardening of the mortar, the specimens were heated up in order to activate the tensile stress in the fibers, thereby causing a prestress of the surrounding mortar. The effect was monitored by length measurements both on specimens with and without fibers. Compression stresses in the cement mortar were estimated by multiplying the difference in strain between fiber-reinforced and reference prisms by the Young's modulus. Thus, compression of some 7 MPa was reached in the experiments. For practical applications, alloys with suitable temperature domains of austenitic and martensitic transformation, most likely Fe-based, and efficient methods for the production of such fiber mortars are to be developed.

Journal ArticleDOI
TL;DR: In this paper, an experimental study on the magnesium sulfate resistance of mortar and paste specimens incorporating 0, 5, 10% and 15% metakaolin (MK) was performed using visual examination, reduction in compressive strength and expansion measurements.

Journal ArticleDOI
TL;DR: In this paper, a modified two-dimensional dual mortar method for piecewise linear finite elements is developed that overcomes this deficiency and is demonstrated on a model problem, and mathematical analysis is provided to demonstrate the optimal convergence and stability of the new method.
Abstract: Dual mortar method formulations have shown to be a very effective and efficient way for interfacing (e.g. tying, contacting) dissimilar meshes. On the other hand, we have recently found that they can sometimes perform quite poorly when applied to curved surfaces in some solid mechanics applications. A new modified two-dimensional dual mortar method for piecewise linear finite elements is developed that overcomes this deficiency and is demonstrated on a model problem. Furthermore, mathematical analysis is provided to demonstrate the optimal convergence and stability of the new method. Copyright © 2005 John Wiley & Sons, Ltd.