Showing papers on "Mortar published in 2008"
TL;DR: In this article, a study of the strength, porosity and corrosion resistance of mortars made with ternary blends of ordinary Portland cement (OPC), ground rice husk ash (RHA), and classified fly ash (fine fly ash, FA).
330 citations
TL;DR: In this article, a study of the resistance to chloride penetration of blended Portland cement mortar containing ground palm oil fuel ash (POA), ground rice husk ash (RHA), and fine fly ash (FA) is presented.
296 citations
TL;DR: The effects of nano-SiO(2) on three ash particle sizes in mortar were studied by replacing a portion of the cement with incinerated sewage sludge ash and results indicate that the amount of water needed at standard consistency increased and a reduction in setting time became noticeable for smaller ash particles.
296 citations
TL;DR: In this paper, the authors compared the properties of 12 alkali-activated mortars and a control ordinary portland cement (OPC) mortar, and found that the compressive strength development of alkali activated mortar was significantly dependent on the proposed alkali quality coefficient.
252 citations
TL;DR: In this article, the influence of crushed fine aggregate on the rheological properties of the mortar phase of concre... is investigated. But the results from a laboratory study are limited.
Abstract: This paper presents results from a laboratory study on the influence of crushed fine aggregate on the rheological properties, i.e., yield stress and plastic viscosity, of the mortar phase of concre ...
212 citations
TL;DR: In this article, the authors described the mechanical effects of rust layer formed in reinforced mortar through accelerated tests of corrosion, and the morphological and physico-chemical properties of the corrosion system were characterized at different stages by using optical microscope and scanning electron microscope coupled with energy dispersive spectroscopy.
209 citations
TL;DR: The relationship between crack opening and chloride-ion diffusion along a crack is discussed in this paper, where it is shown that crack opening significantly affects chloride diffusion along the crack path and that self-healing could reduce chloride diffusion in cracks.
190 citations
TL;DR: In this article, an experimental study was done to examine the chloride permeability and microstructure of portland cement mortar with nanomaterials admixed at 1% by weight of cement.
Abstract: Chloride permeability of concrete has been recognized as a critical intrinsic property affecting the durability of reinforced concrete. An experimental study was done, designed to examine the chloride permeability and microstructure of portland cement mortar with nanomaterials admixed at 1% by weight of cement. The electromigration test showed that, for cement mortars of the same mix design, the incorporation of nanoparticles (Fe2 O3, Al2O3, TiO2, and SiO2) and nanoclays (montmorillonite) improved the chloride penetration resistance of the mortar, as indicated by the reduced apparent diffusion coefficients of chloride anion. The nanomaterials also reduced the general ionic permeability of the mortar, as indicated by the reduced electric charge passing through. Such improvements were especially significant when using nano-SiO2 and nanoclays. The electrochemical impedance spectroscopy test indicated that incorporation of nanomaterials in cement mortar significantly increased its ionic transport resistance a...
189 citations
TL;DR: Results showed that sludge/fly ash can make the crystals of cement hydration product finer, which implies that the addition of nano-SiO(2) to mortar can improve the influence of sludge-fly ash on the development of the early strength of the mortar.
187 citations
TL;DR: In this paper, the authors used thermogravimetric-differential scanning calorimetry (TG-DSC) and X-ray diffraction (XRD) techniques to identify the formation of dehydrated and transformed phases of preheated FRCA.
178 citations
Posted Content•
TL;DR: In this article, the influence of aggregate size and volume fraction on shrinkage induced micro-cracking and permeability of concrete and mortar was investigated, based on a 2D lattice approach in which aggregates were simplified as monosized cylindrical inclusions.
Abstract: In this paper, the influence of aggregate size and volume fraction on shrinkage induced micro-cracking and permeability of concrete and mortar was investigated. Nonlinear finite element analyses of model concrete and mortar specimens with regular and random aggregate arrangements were performed. The aggregate diameter was varied between 2 and 16 mm. Furthermore, a range of volume fractions between 0.1 and 0.5 was studied. The nonlinear analyses were based on a 2D lattice approach in which aggregates were simplified as monosized cylindrical inclusions. The analysis results were interpreted by means of crack length, crack width and change of permeability. The results show that increasing aggregate diameter (at equal volume fraction) and decreasing volume fraction (at equal aggregate diameter), increases crack width and consequently greatly increases permeability.
TL;DR: In this paper, an experimental method is proposed to determine the residual mortar content (RMC) of concrete aggregates, which comprises a combination of mechanical and chemical stresses that disintegrate residual mortar and destroy the bond between the mortar and the natural aggregates.
Abstract: Recycling concrete from demolition of existing structures and using it as recycled concrete aggregates (RCAs) in structural-grade concrete have significant economic and environmental benefits. Currently, only a small portion of the concrete waste is reused in building construction, while most of it is used as either pavement base course or sent to landfills for disposal. The lack of confidence in the material properties of the concrete produced with RCAs is generally the main reason for its under-utilization in structural concrete. It has been demonstrated in the literature that the amount of residual mortar attached to the original (or “virgin”) aggregate particles is one of the factors affecting the material properties of RCAs. Therefore, before using RCAs in new concrete, it is crucial that the residual mortar content (RMC) is determined accurately; however, currently there is no standard procedure to determine this quantity. In this paper, an experimental method is proposed to determine the RMC of RCAs. The method comprises a combination of mechanical and chemical stresses that disintegrate the residual mortar and destroy the bond between the mortar and the natural aggregates. The mechanical stresses are created through subjecting RCA to freeze-and-thaw action, while the chemical degradation is achieved through exposure of the RCA to a sodium sulphate solution. The results of the proposed test procedure are validated by means of comprehensive image analysis. With the proposed approach, the attached residual mortar can be adequately removed, and the residual mortar content can be determined.
TL;DR: In this article, three different sand gradings were used to examine the workability, strength, water retentivity, drying shrinkage and stress-strain characteristics of two types of mortars and soil-cement block masonry.
TL;DR: In this article, the effect of curing conditions on properties of mortars with and without ground granulated blast furnace slag (GGBFS) was studied, and the results indicated that elevated temperature increases performance of mortar at early ages but decreases at later ages, and this affect is more significant at slag replaced mortars.
TL;DR: Three types of wastes, metallurgical slag from Pb production (SLG), the sand-sized fraction of MSWI bottom ash from a grate furnace (SF), and boiler and flyAsh from a fluidised bed incinerator (BFA), were characterized and used to replace the fine aggregate during preparation of cement mortar.
TL;DR: In this article, the effects of low-calcium fly ash (FA), limestone (LS), and dolomitic limestone (DLS) on the properties of cement and mortar have been investigated through a number of tests.
Abstract: The effects of low-calcium fly ash (FA), limestone (LS), and dolomitic limestone (DLS) on the properties of cement and mortar has been investigated through a number of tests. Composition of cement hydration products in cement paste and mortar were made with clinker (PC), gypsum (G), FA, LS and DLS. The binders employed were Portland cement (OPC), fly ash–portland cement (FA–OPC), FA–LS–OPC, and FA–DLS–OPC blends with a maximum PC replacement level of 40%, FA level of up to 40%, LS and DLS levels of up to 15%. The hydration rate and products were studied by means of X-ray diffraction (XRD) and Fourier transforms infrared spectroscopy (FTIR). The results showed that the FA, LS and DLS prolong the setting time of the cements. Relative to OPC, in FA–OPC system expansion decreases as the fly ash content of the cement increases. Ternary system, FA–DLS–OPC produces a marked fall in the expansion of the tested specimens.
TL;DR: In this article, the authors present data on engineering properties such as compressive strength, visual change and expansion of mortar specimens incorporating limestone filler subjected to severe sulfate attack at ambient temperature.
TL;DR: In this article, a 3D multi-scale modelling of mechanical properties of cement-based materials approach is presented, which provides a quantitative means to estimate and predict the mechanical properties, taking into account the eventual changes in the micro-structure.
TL;DR: In this article, the effects of high temperatures up to 900°C on the mechanical properties and the microstructure of pumice mortars incorporating different amounts of ground granulated blast furnace slag (GGBFS) were investigated.
TL;DR: In this article, petrographic analysis of Roman mortars has been used to reveal the composition and origin of raw materials, pozzolanic additions and mortar hydraulicity.
TL;DR: In this article, an experimental investigation was performed to measure the restrained and unrestrained plastic shrinkage properties of small mortar specimens containing short flax fibres in amounts ranging from 0.05% to 0.3% by volume.
Abstract: An experimental investigation was performed to measure the restrained and unrestrained plastic shrinkage properties of small mortar specimens containing short flax fibres (10–38 mm in length) in amounts ranging from 0.05% to 0.3% by volume. Based on the number of cracks, total crack area, and maximum crack widths produced within the first 24 h after casting and exposure to hot, dry, and windy conditions, flax fibres were found to be slightly more effective in controlling restrained plastic shrinkage cracking than commercially available polypropylene and glass fibres for the mortar mixture studied. At a flax fibre volume fraction of 0.3%, total crack areas were reduced by at least 99.5% relative to plain mortar specimens and maximum crack widths were reduced by at least 98.5% to less than 0.022 mm. Fibre length did not significantly influence cracking behaviour, nor did the presence of flax fibres significantly influence the free plastic shrinkage strains observed.
TL;DR: It is seen that over 20% FA and 2% Li(2)CO(3) replacements are required to produce mortars which have expansion values below the 0.2% critical value when exposed to ASR, however, usages of these admixtures reduce expansions occurring because of ASR.
TL;DR: In this paper, the authors investigated the strain rate effect on masonry materials, such as clay bricks and mortar mixed with cement, lime and sand, using uniaxial compression tests.
Abstract: It is well known that most construction materials behave differently under highspeed and static loading conditions. The strain rate effect on many materials, such as metals, concrete and rock, has been intensively investigated. However, the strain rate effect on masonry materials, such as clay bricks and mortar mixed with cement, lime and sand, cannot be found in open literature. Understanding the strain rate effects on masonry materials is important for accurately modelling masonry structure damage to high-velocity impact and blast loads. This paper reports experimental results of the strain rate effect on clay bricks and mortar materials. Uniaxial compression tests were carried out on brick and mortar specimens at various strain rates ranging from quasi-static (10-6 /s) to dynamic up to a strain rate of 200 /s. The strain rate effect on the yield and ultimate strength, yield and ultimate strain, elastic modulus, and Poisson's ratio of clay brick and mortar material are determined from the testing results. Empirical relations of dynamic increase factors (DIF) for the material properties are derived and presented. Discussions and comparisons of the DIF of brick and mortar obtained in this study are also made with other geomaterials, such as concrete and rock.
TL;DR: In this article, the effects of carbon dioxide on chloride penetration and chloride ion diffusion coefficient of blended Portland cement mortar containing ground palm oil fuel ash (POA), ground rice husk ash (RHA), and classified fly ash (fine fly ash, FA).
TL;DR: In this article, the authors proposed prediction relations for the compressive strength of foam concrete by extending two of the well-known relations available for cement paste, mortar and normal concrete, viz., Balshin's strength-porosity model and Power's gel-space ratio equation.
Abstract: There are several strength prediction relations developed for plain cement paste, mortar and concrete. In concrete where air voids contribute significantly to volume of voids (like aerated and foam concrete), more general expressions including the volume of air voids is to be developed as the better alternative. The objective of this paper is to propose prediction relations for the compressive strength of foam concrete by extending two of the well-known relations available for cement paste, mortar and normal concrete, viz., Balshin’s strength-porosity model and Power’s gel-space ratio equation. For this, theoretical equations were derived for porosity and gel-space ratio relating it to the density, proportion of ingredients in the mix and material characteristics like specific gravity. Foam concrete with fly ash showed lesser dependency on pore parameters than cement-sand mixes. As both the prediction relations developed in this study consider the effect of composition on the strength, it can serve as a simple tool for predicting the strength of foam concrete. But strength-porosity model stands out compared to gel-space model as it correlates well with the measured strength and also because of its ease in application since it employs the composition of constituents and easily measurable parameters.
TL;DR: In this article, nonlinear wave modulation spectroscopy (NWMS) was used to quantitatively track the evolution of microcracks in Portland cement mortar samples and quantitatively assess the deterioration of cement-based materials.
Abstract: This paper presents the successful application of a nonlinear ultrasonic technique, nonlinear wave modulation spectroscopy (NWMS) to quantitatively track the evolution of microcracks in Portland cement mortar samples. The damage type considered in this study is microcracking due to alkali–silica reaction (ASR), a deleterious reaction occurring in concrete structures around the world. Nonlinear ultrasonic measurements are conducted on six different mortar specimens that are monitored from their initial, intact state up to their fully damaged state. The objective of this research is to determine the sensitivity and suitability of NWMS to quantitatively track this damage state throughout an entire life-cycle and to nondestructively identify the initiation time and the extent of microcracking in these mortar specimens. The nonlinear ultrasonic measurements are made with standard laboratory equipment, and the inherent high attenuation of cement-based materials is overcome with a procedure that uses the sideband energy instead of measuring peak amplitudes. The results show that the NWMS method can track the progressive damage in mortar, demonstrating the feasibility of using this nonlinear ultrasonic technique to quantitatively assess the deterioration of cement-based materials.
TL;DR: In this article, a homogenized continuum model based on simplified micromechanical hypoth- eses is presented to describe the anisotropic damage process and the dissipative behavior of masonry structures under static incremental and dynamic loads.
Abstract: The paper addresses the problem of describing the anisotropic damage process and the dissipative behavior of masonry structures under static incremental and dynamic loads. A homogenized continuum model, based on simplified micromechanical hypoth- eses, is presented. The plane stress is considered. The finite-element method is adopted as a framework for numerical implementation. Masonry is considered as a composite material made up of blocks, mortar bed joints, and mortar head joints. Mortar bed joints are schematized as interfaces characterized by cohesion, tensile strength and friction, whereas mortar head joints are considered as geometri- cal discontinuities. Internal symmetries of the material leads to distinguishing two couples of emisymmetric bed joints, characterized by equal state variables. The computation of the displacement jumps in these two couples of joints is sufficient to evaluate the displacement jumps of all the joints contained in the assumed unit cell. Constitutive equations consider the nonlinear stress-strain relation in terms of mean stresses and mean strains. The latter are produced by an elastic strain contribution and by different inelastic strain contributions depending on the damage in mortar joints and in blocks. The damage processes are described by means of an energetic approach. The hysteretic behavior is described by considering a Coulomb-type friction law on the mortar bed joints. The model is implemented in a general purpose finite-element code ANSYS. A simple example of a cyclic load history is presented in order to demonstrate the effectiveness of the model.
TL;DR: In this paper, a possible mechanism was suggested that biomineralization may occur during the carbonation of calcium hydroxide, where the sticky rice functions as a template and controls the growth of calcium carbonate crystal.
TL;DR: In this paper, the authors examined stabilization/solidification (S/S) techniques using a bentonite/cement mortar for the stabilization of sewage sludge containing heavy metals such as Cu, Zn, Pb.
Abstract: This study examines stabilization/solidification (S/S) techniques using a bentonite/cement mortar. These techniques are usually applied for the stabilization of sewage sludge, containing heavy metals such as Cu, Zn, Pb. Due to the high organic content of sludge, bentonite had been added in order to stabilize the system. For this purpose, 4 × 4 × 16 cm mortar prism samples were prepared. Their composition was: 50% w/w sewage sludge (primary sewage sludge from Psyttalia Athens and secondary biological sewage sludge from Metamorphosis Athens), 30% w/w cement CEMI 42.5 and finally 20% w/w bentonite. The samples were cured for 28 days at 25 °C and compressive strength was tested. Highest strength and lowest leachability were the criteria for selection of the optimum product by the S/S technique. An extensive study using several characterization techniques focusing on hydration reactions was carried out. The instrumental analysis included: X-ray diffraction analysis, thermal analysis (TGA, DTA), electron scanning microscopy (SEM), infrared analysis (FT-IR) as well as tests for the toxicity characteristic leaching procedure (TCLP). The S/S products had been proven throughout the study as a viable solution for stabilizing heavy metals. They can be used in many applications such as in landfill liners, slurry walls and building blocks.
TL;DR: In this article, the properties of cement-based mortars with waste glass (WG) and industrial by-products are examined. And the results showed that compressive strength was decreased as replacement level increased, and the same trend was also valid for durability properties examined in this study.