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Showing papers on "Mortar published in 2010"


Journal ArticleDOI
TL;DR: In this article, the effect of elevated temperature on geopolymer paste, mortar and concrete made using fly ash as a precursor was investigated and it was shown that aggregate sizes larger than 10 mm resulted in good strength performances in both ambient and elevated temperatures.

691 citations


Journal ArticleDOI
TL;DR: In this paper, a powder obtained as a byproduct of marble sawing and shaping was characterized from a chemical and physical point of view in order to use it as mineral addition for mortars and concretes, especially for self-compacting concrete.

364 citations


Journal ArticleDOI
TL;DR: In this paper, the properties of MPC mortars with different magnesium to phosphate (M/P) molar ratios and sand to binder (S/B) weight ratios have been investigated.

313 citations


Journal ArticleDOI
TL;DR: It was concluded that there is a potential for the use of shredded waste PET granules as aggregate in the production of structural lightweight concrete due to its low unit weight which results in a reduction in the death weight of a structural concrete member of a building.

279 citations


Journal ArticleDOI
TL;DR: In this paper, it has been shown that the contraction of a mortar caused by air entrainment offsets the thermal expansion mismatch stress sufficiently to prevent cracking, and the magnitude of the contraction in air-entrained mortar is shown to account for a reduction of salt scaling damage.

235 citations


Journal ArticleDOI
TL;DR: In this article, the usability of waste marble dust (WMD) as an additive material in blended cement has been investigated, and it was shown that 10% WMD can be used as additive material for cement manufacturing.

202 citations


01 Jan 2010
TL;DR: Rice Husk Ash (RHA) is a byproduct material obtained from the combustion of rice husk which consists of non-crystalline silicon dioxide with high specific surface area and high pozzolanic reactivity as mentioned in this paper.
Abstract: In the last decade, the use of supplementary cementing materials has become an integral part of high strength and high performance concrete mix design. These can be natural materials, by-products or industrial wastes, or the ones requiring less energy and time to produce. Some of the commonly used supplementary cementing materials are fly ash, Silica Fume (SF), Ground Granulated Blast Furnace Slag (GGBFS) and Rice Husk Ash (RHA) etc. RHA is a by-product material obtained from the combustion of rice husk which consists of non-crystalline silicon dioxide with high specific surface area and high pozzolanic reactivity. It is used as pozzolanic material in mortar and concrete, and has demonstrated significant influence in improving the mechanical and durability properties of mortar and concrete. This paper presents an overview of the work carried out on the use of RHA as partial replacement of cement in mortar and concrete. Reported properties in this study are the mechanical, durability and fresh properties of mortar/concrete.

192 citations


Journal ArticleDOI
TL;DR: In this article, a new class of composites based on using basalt fibers bonded with a cement-based matrix as an innovative strengthening material for confinement of reinforced concrete members is proposed.
Abstract: This paper aims to appraise the opportunities provided by a new class of composites based on using basalt fibers bonded with a cement-based matrix as an innovative strengthening material for confinement of reinforced concrete members. The effectiveness of the proposed technique is assessed by comparing different confinement schemes on concrete cylinders: (1) uniaxial glass-fiber-reinforced polymer (FRP) laminates; (2) alkali-resistant fiberglass grids bonded with a cement-based mortar; (3) bidirectional basalt laminates preimpregnated with epoxy resin or latex and then bonded with a cement-based mortar; and (4) a cement-based mortar jacket. The study showed that confinement based on basalt fibers bonded with a cement-based mortar could be a promising solution to overcome some limitations of epoxy-based FRP laminates.

182 citations


Journal ArticleDOI
TL;DR: The pore structure of mortar was examined using thermoporometry (TPM), nitrogen adsorption/desorption (NAD), and mercury intrusion porosimetry (MIP).

165 citations


Journal ArticleDOI
TL;DR: In this paper, 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.

158 citations


Journal ArticleDOI
TL;DR: The physical properties, mechanical strength, and compatibility of lime mortar were found to be significantly improved by the introduction of sticky rice, suggesting that sticky rice-lime mortar is a suitable material for repairing mortar in ancient masonry.
Abstract: Replacing or repairing masonry mortar is usually necessary in the restoration of historical constructions, but the selection of a proper mortar is often problematic. An inappropriate choice can lead to failure of the restoration work, and perhaps even further damage. Thus, a thorough understanding of the original mortar technology and the fabrication of appropriate replacement materials are important research goals. Many kinds of materials have been used over the years in masonry mortars, and the technology has gradually evolved from the single-component mortar of ancient times to hybrid versions containing several ingredients. Beginning in 2450 BCE, lime was used as masonry mortar in Europe. In the Roman era, ground volcanic ash, brick powder, and ceramic chip were added to lime mortar, greatly improving performance. Because of its superior properties, the use of this hydraulic (that is, capable of setting underwater) mortar spread, and it was adopted throughout Europe and western Asia. Perhaps because o...

Journal ArticleDOI
TL;DR: In this paper, the influence of chemical nature and fineness of the fillers on the hydration process and on the compressive strength development of Portland Cement has been investigated.
Abstract: This paper focuses on the influence of the chemical nature and the fineness of the fillers on the hydration process and on the compressive strength development. Four different types of fillers are considered in combination with Portland cement: quartzite filler, alumina filler, limestone filler, and silica fume. The study deals with blended mortars having a 0.45 water to powder (cement and filler) ratio with a 10% substitution of cement by filler. Quartzite fillers do not seem to accelerate the hydration process in a significant way. No positive effect is noticed on the strength development either. The presence of a fine inert alumina powder increases the rate of early hydration of Portland cement. The greater the fineness, the faster the rate of hydration heat development. This reactivity leads to an increase in the compressive strength at early age for mortar containing the finest alumina powders. In case of coarse alumina powder, no acceleration effect is obtained. Finely ground limestone (calcite) fillers promote heterogeneous nucleation of hydrates which significantly accelerates hydration. At early age, this also results in an increased mortar compressive strength in comparison with the control mortar. From the obtained results, it is clear that both chemical natures as well as fineness are important with regard to the accelerating effect of the hydration process. With increasing fineness, the accelerating effect increases. For powders with comparable fineness, it is clear that limestone powder has a more significant accelerating effect than silica fume and alumina filler. Quartzite filler seems to have no significant effect.

Journal ArticleDOI
TL;DR: In this paper, the value of granite sludge wastes (GS) in cement-based mortar formulations was examined by assessing their potential as structural components and pigments, and they were found to be an effective filler or pozzolanic material for mortars.
Abstract: The value of granite sludge wastes (GS) in cement-based mortar formulations was examined by assessing their potential as structural components and pigments. Full characterization of GS was accomplished by X-ray fluorescence (XRF), X-ray diffraction (XRD), laser diffraction and scanning electron microscopy. GS were found to be an effective filler or pozzolanic material for mortars. Also, GS were easily converted into a reddish pigment by calcination at low temperatures (700–900 °C) for a short time. UV–Vis–NIR spectra, colourimetric parameters and XRD analysis confirmed the presence of α-Fe2O3 in the pigment. Therefore, the preparation of coloured mortar with good compressive strength can be an attractive, environmentally friendly method of managing granite sludge wastes.

Journal ArticleDOI
TL;DR: New bacterial genera that are capable of improving the compressive strength of concrete mortar are discovered that are partially identified as Sporosarcina soli, Bacillus massiliensis, and Lysinibacillus fusiformis.
Abstract: Microbiological calcium carbonate precipitation (MCP) has been investigated for its ability to improve the compressive strength of concrete mortar. However, very few studies have been conducted on the use of calcite-forming bacteria (CFB) to improve compressive strength. In this study, we discovered new bacterial genera that are capable of improving the compressive strength of concrete mortar. We isolated 4 CFB from 7 environmental concrete structures. Using sequence analysis of the 16S rRNA genes, the CFB could be partially identified as Sporosarcina soli KNUC401, Bacillus massiliensis KNUC402, Arthrobacter crystallopoietes KNUC403, and Lysinibacillus fusiformis KNUC404. Crystal aggregates were apparent in the bacterial colonies grown on an agar medium. Stereomicroscopy, scanning electron microscopy, and x-ray diffraction analyses illustrated both the crystal growth and the crystalline structure of the CaCO3 crystals. We used the isolates to improve the compressive strength of concrete mortar cubes and found that KNUC403 offered the best improvement in compressive strength.

Journal ArticleDOI
TL;DR: In this article, the authors extended the concept of water film thickness (WFT) of the solid-water mixture of sand with a maximum size of 1·18 mm to evaluate the effect of water content, packing density, and rheological properties on the fresh properties of cement paste and sand mortar.
Abstract: It is well known that the fresh properties of cement paste and cement–sand mortar are governed mainly by three parameters: water content, packing density and solid surface area. However, these parameters vary simultaneously upon any change in the mix composition and hence the evaluation of their individual and combined effects has been a difficult task. Recently, the authors have found that the effects of these parameters on the flowability and rheological properties of cement paste may be evaluated in terms of the water film thickness (WFT) of the solid–water mixture. Herein, this concept of WFT is extended to cement–sand mortar made of sand with a maximum size of 1·18 mm. A number of mortar samples proportioned with different water contents and different sand gradings were produced for packing density, flowability and rheological properties measurements. From the results, the WFT of each sample was determined and the effects of the WFT on the flowability and rheological properties of the mortar were inv...

Journal ArticleDOI
TL;DR: In this paper, the performance of fly ash based geopolymer mortar specimens in Magnesium Sulphate solution was evaluated in terms of visual appearance, variation of pH of solution, change in weight and change in compressive strength over the exposure period.
Abstract: An experimental investigation was conducted to study the performance of fly ash based geopolymer mortar specimens in Magnesium Sulphate solution. Specimens were manufactured from low calcium fly ash by activation with a mixture of Sodium Hydroxide and Sodium Silicate solution and cured thermally. 10% by weight Magnesium Sulphate solution was used to soak the specimen up to 24 weeks. Performance of the specimens was evaluated in terms of visual appearance, variation of pH of solution, change in weight, and change in compressive strength over the exposure period. White deposits occurred on the surface of specimen which was initially soft but later converted to hard crystals. pH of solution increased noticeably during the initial weeks which indicate migration of alkalis from mortar specimens. At the end of 24 weeks samples experienced very little weight gain and recorded a loss of compressive strength by up to 56%.

Journal ArticleDOI
TL;DR: In this article, the effects of water content, packing density and solid surface area on the rheology of CSF mortar were evaluated in terms of the water film thickness (WFT).
Abstract: In a recent study, the authors have demonstrated that the combined effects of water content, packing density and solid surface area on the rheology of cement–sand mortar may be evaluated in terms of the water film thickness (WFT). The present study aims to extend the concept of WFT to mortar containing condensed silica fume (CSF). For the study, mortar samples with various CSF and water contents were made for packing density, flowability and rheology measurements. It was found that although the effects of adding CSF are fairly complicated, the WFT is still the single most important parameter governing the rheology of CSF mortar. However, the rheological properties are dependent also on the CSF content. Correlations of the rheological properties to both the WFT and CSF content yielded R2 values of at least 0.896.

Journal ArticleDOI
TL;DR: In this article, a textile-mortar reinforced masonry (TRM) wall specimens failed in a combination of transverse detachment of the textile-masonry matrix due to the transverse displacement of the blocks relative to each other and combined transverse shear-tension fracturing of textile fibers.
Abstract: The work presented in this paper is a part of a comprehensive research project aimed at developing and testing a system for strengthening historical buildings. The system is composed of a combination of textile mesh and mortar. Representative wall specimens were tested for their out-of-plane flexural behavior under static and cyclic loadings. The parameters investigated include the types of masonry wall (concrete block, sandstone, and brick), mortar (natural lime and cement-based), and textile (bitumen coated E-glass, basalt, or coated basalt fibers). Companion specimens, strengthened using a steel wire mesh, were also tested for comparison. All textile-mortar reinforced masonry (TRM) wall specimens failed in a combination of transverse detachment of the textile-mortar matrix due to the transverse displacement of the blocks relative to each other, and combined transverse shear-tension fracturing of the textile fibers. Regardless of the mode of failure, the TRM specimens developed a substantial increase in their out-of-plane load and displacement capacities under static loading, and low stiffness and strength degradation, and considerable displacement capacities under cyclic loading. The wire mesh-mortar reinforced masonry specimens developed the highest load capacity but were the least ductile when compared to the TRM specimens.

Journal ArticleDOI
TL;DR: In this article, the use of rigid polyurethane foam wastes with cement-based mixtures to produce lightweight mortar was investigated and several mortar grades were obtained by mixing cement with different amounts of polyurethethane, aggregate and water.
Abstract: This paper presents results of an experimental study on the use of rigid polyurethane foam wastes with cement-based mixtures to produce lightweight mortar. Several mortar grades were obtained by mixing cement with different amounts of polyurethane, aggregate and water. Dosages were varied to replace aggregates with recycled polyurethane, while the amount of water was optimized to obtain good workability. Rigid polyurethane was ground to particle sizes of less than 4 mm prior to use as an aggregate substitute. The characteristics of the test specimens were defined and they were tested in both a fresh and a hardened state. Results show that an increase in the amount of polyurethane affects the mortar, decreasing its density and mechanical properties while increasing its workability, permeability, and occluded air content. These results confirm that mortar produced with recycled polyurethane is comparable to lightweight mortar made with traditional materials.


Journal ArticleDOI
TL;DR: In this paper, the authors provided the first report of impact damage self-sensing in cement-based materials and demonstrated that the surface resistance of the surface receiving the impact is an effective indicator of the damage, even for minor damage without cracking.
Abstract: Damage monitoring of the civil infrastructure is critically needed. This article provides the first report of impact damage self-sensing in cement-based materials. Cement mortar reinforced with short (57 mm) carbon fiber and in bulk or coating (510 mm thick) form is effective for sensing its own impact damage through DC/AC electrical resistance measurement, provided that the region of resistance measurement contains the point of impact. The mortar resistivity needs to be 10 4 10 5 X cm, as provided by pitch-based fiber (15mm diameter, unsized) at 0.5% or 1.0% by mass of cement, or type A PAN-based fiber (7mm diameter, desized) at 0.5%. Due to the low mortar resistivity of 10 3 X cm, pitch-based fiber at 1.5% and type B PAN-based fiber (7mm diameter, unsized) at 0.5% are less effective. Without fiber, there is no sensing ability. The surface resistance of the surface receiving the impact is an effective indicator of the damage, even for minor damage without cracking, inflicted by impact at 880 J. The oblique or longitudinal volume resistance is much less effective. The surface resistance increases abruptly upon impact, but it decreases abruptly upon impact after 540 impacts (number decreasing with increasing impact energy) have been inflicted. Key Word: cement, concrete, carbon fiber, sensing, damage, impact, electrical resistance, electrical resistivity.

Journal ArticleDOI
TL;DR: In this article, a microfocus X-ray CT (micro-CT) scanner was used for the nondestructive 3D imaging of internal air voids or cracks at a spatial resolution of the order of 10 microns.
Abstract: This paper presents our findings on the application of X-ray microtomography to characterize the internal structure of mortars that were exposed to freezing-thawing action. A microfocus X-ray CT (micro-CT) scanner was used for the nondestructive 3D imaging of internal air voids or cracks at a spatial resolution of the order of 10 microns. Four different types of mortar specimens (i.e., non-air-entrained and air-entrained Portland cement mortar, and non-air-entrained and air-entrained fly ash mortar) were scanned after being subjected to different numbers of freeze-thaw cycles. Coupled with image analysis, the void space obtained from micro-CT was characterized in three dimensions (3D) in terms of void fraction and air void size distribution, as well as, the crack width and tortuosity of the connected crack network. Results suggest that the initial air voids follow a lognormal distribution with the highest population of modal size around 30-50 μm, irrespective of the type of mortar. As the distributed air voids of non-air entrained mortars were relatively few in numbers, the fly ash mortar in particular was the least resistant against frost damage as shown by the formation of internal cracks that meander around the weaker paste-aggregate interface. Indications also suggest that these cracks are well connected and anisotropic in 3D.

Journal ArticleDOI
TL;DR: In this paper, the authors measured the bond strength of natural hydraulic-lime (NHL) mortars, to further characterise their properties and enhance their use in building, and they concluded that the 185mm flow results in the strongest bond, simultaneously providing the highest water retention and best workability.
Abstract: This paper measures the bond strength of natural hydraulic-lime (NHL) mortars, to further characterise their properties and enhance their use in building. An additional objective is to correlate bond strength with mortar hydraulicity, water content, workability and water retention, to develop mortars of high bond strength that would improve the quality of masonry. To this aim, the flexural bond strength of masonry, built with mortars of three hydraulic strengths-each including the water amount required to attain three specific flows (165, 185 and 195 mm), was measured with the bond wrench test. The results suggest that NHL mortars possess high water retention, and this enables a strong bond that compares well to that of Portland cement and cement/lime mortars. The results also indicate that bond strength is not determined by the binder’s hydraulic strength, but it increases proportionally to the mortar’s water retention. The paper concludes that for the NHL5 mortars, the 185 mm flow results in the strongest bond, simultaneously providing the highest water retention and best workability. However, for the lower strengths (NHL 2 and NHL 3.5 mortars), the water content required to attain the flows that provide an optimum workability (165 and 165–185 mm, respectively) does not lead to the strongest bond, but it is the highest flow values that provide the NHL2 and NHL3.5 mortars with the strongest bond and, in most instances, the highest water retention.

Journal ArticleDOI
TL;DR: In this paper, numerical simulations are carried out to estimate the response and damage of unreinforced brick masonry walls subjected to explosive blast loading based on the transient dynamic finite element program LS-DYNA.

Journal ArticleDOI
TL;DR: In this paper, an experimental study was conducted on the high strength flowable mortar reinforced by the different percentages of steel fiber (0.2%), palm fiber ( 0.1%), and the hybridization of these two fibers with 2% volumetric fractions to determine the density, compressive strength, flexural strength and toughness.

Journal ArticleDOI
TL;DR: In this article, a meso-scale model is presented, suitable to interpret delamination phenomena of FRP strips glued to masonry, and the overall response and the collapse mechanism are investigated, induced by different boundary conditions and mechanical properties of constituent materials.

Journal ArticleDOI
TL;DR: In this paper, the effects of lightweight natural fillers, such as vermiculite and perlite, on the properties of a mixed-binder mortar based on a cement/lime/sand formulation with a typical ratio of 1:1:6.
Abstract: This work presents a study on the effects of lightweight natural fillers, such as vermiculite and perlite, on the properties of a mixed-binder mortar based on a cement/lime/sand formulation with a typical ratio of 1:1:6. This kind of mortar may be used for indoor and outdoor rehabilitation purposes. Mortars with different contents of the above-mentioned fillers were prepared and their effect on the fresh and hardened product characteristics was evaluated. In the fresh state condition, properties such as apparent density, air content and water retention ability were measured. In what concerns the hardened product characteristics, evaluation was based on the variations of mechanical properties, open porosity and capillarity. It is observed that both the content and the nature of the lightweight filler determine the final characteristics of the mortar. This is particularly enhanced, for instance, by the relationship between hardened product physical properties, microstructure and porosity distribution.

Journal ArticleDOI
TL;DR: In this paper, the effect of chemical and mineral admixtures, including superplasticizer, viscosity modifying agent (VMA), limestone powder and fly ash in different W/C on fluidity, visco-ciality, and stability of self-consolidating mortar is investigated and proper workability regions for the prepared mixtures are presented.

Journal ArticleDOI
TL;DR: In this article, the authors present a novel technique which is suitable to measure the coefficient of thermal expansion (CTE) of hardening materials with high accuracy starting from casting time, which consists of casting a small amount of cement paste or mortar into flexible membranes.

Journal ArticleDOI
TL;DR: In this paper, the authors reported the testing of 12 alkali-activated (AA) mortars and six AA concretes using lightweight aggregates and found that the compressive strength of AA mortar decreased linearly with the increase of the replacement level of lightweight fine aggregates, regardless of the water-binder ratio.
Abstract: This study reports the testing of 12 alkali-activated (AA) mortars and six AA concretes using lightweight aggregates. These tests aimed to explore the significance and limitations of the development of lightweight AA mortar and concrete. Ground granulated blast-furnace slag, which was used as source material, was activated by sodium silicate powder. The main parameter investigated was the replacement level of lightweight fine aggregates to the natural sand. The effect of the water–binder ratio on the compressive strength development was also studied in AA mortars. Initial flow and development of compressive strength were recorded for the lightweight AA mortar. For the lightweight AA concrete, many factors were measured: the variation of slump with elapsed time, the development of compressive strength, splitting tensile strength, moduli of rupture and elasticity, stress–strain relationship, bond strength and shrinkage strain. Test results showed that the compressive strength of AA mortar decreased linearly with the increase of the replacement level of lightweight fine aggregates, regardless of the water–binder ratio. The compressive strength of AA concrete, however, sharply decreased when the replacement level of lightweight fine aggregates exceeded 30%. In particular, the increase in the discontinuous grading of lightweight aggregate resulted in the deterioration of the mechanical properties of AA concrete.