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1.
《Composites Part A》2000,31(2):97-106
Recycling industrial wastes as filler components and/or aggregates in polymer mortars makes these materials very interesting from an ecological and safety point of view. In addition, the resulting materials have useful physical and mechanical properties. Four recycled fillers (powdered rubbers, tyre rubbers, micronized tyre fibers and milled electrical cable wastes) have been used to formulate new polymer mortars. The comparison of their mechanical properties and microstructures with those of a plain polymer mortar indicates that the presence of recycled waste affects the physical–mechanical behavior (compressive and flexural strengths, microstructure). The use of silane coupling agents has been also considered and its effect in leading to more compact materials is reported and discussed.  相似文献   

2.
《Composites Part A》2002,33(2):205-211
A promising application for polymer mortars and concretes is for machine tool structures: for this purpose, composite materials with good mechanical properties and high damping characteristics are required. Accordingly, four recycled fillers (powdered rubber, tyre rubber, micronized tyre fibres and milled electrical cable waste) have been used to formulate new polymer mortars. The internal energy dissipation and relaxation processes of the different materials, studied by the combined use of both dynamic mechanical and dielectric analysis, are compared thus showing the effect of the powdered rubber based filler as a damping promoter. The use of silane coupling agents has also been investigated and its effect in leading to stiffer materials is reported and discussed.  相似文献   

3.
Masonry mortars made with Portland cement, sand, water and white recycled polyurethane foam from industrial waste are examined in this study. Different mixtures were firstly prepared through the substitution of different amounts of sand by equivalent volumes of polyurethane and then, with different ratios of cement/aggregates. The comparative study was carried out on the effect that different ageing tests have on the mechanical properties of these mortars under flexion and compression. For this purpose, the samples were exposed to different corrosion and hardness tests: resistance to dry heat, hot water, salt spray test and Kesternich testing. After ageing, a small reduction in compressive strength was observed. However, in all the samples, the strength values were sufficiently high to consider that these types of recycled materials remain practically unaffected when compared with the reference specimens. Finally, alkali-silica reaction tests were performed to determine the chemical stability of these mortars.  相似文献   

4.
The effect of polymer addition on the rate and the extent of alkali silica reactions in mortars containing high alkali conceptrations has been investigated. A bicomponent epoxy resin was added to the mortars formulation up to a 20 wt% of cement content. Mortars of the same composition, but formulated without reactive aggregates, were also cast and subjected to the same curring procedure. Their microstructure, mechanical properties, dimensional stability and calcium hydroxide content were thus investigated. As the polymer content increases, mortar expansion is reduced: hypotheses for this behaviour, based on the microstructural characteristics of the composites, are proposed.
Résumé On a évalué l'effet de l'ajout des polymères sur la vitesse et l'étendue des réactions alcali-silice dans les mortier contenant une concentration élevée d'alcalis. Une résine à deux composants a été ajoutée à la formulation des mortiers jusqu'à 20% en poids sur le ciment. Les mortiers ont été soumis à une maturation accélérée à 80°C; on a aussi confectionné des mortiers de la même composition, mais sans granulats réactifs. On a ensuite étudié la microstructure, les propriétés mécaniques et les modifications dimensionnelles. Jusqu'ici, les résultats montrent que la hausse de la quantité de polymères augmente la stabilité dimensionnelle des mortiers. On propose une hypothèse pour ce comportement, laquelle est fondée sur les caractéristiques microstructurelles des échantillons.
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5.
Masonry mortars made with Portland cement, sand, water and white recycled polyurethane foam from industrial waste are examined in this study. Different mixtures were firstly prepared through the substitution of different amounts of sand by equivalent volumes of polyurethane and then, with different ratios of cement/aggregates. The comparative study was carried out on the effect that different ageing tests have on the mechanical properties of these mortars under flexion and compression. For this purpose, the samples were exposed to different corrosion and hardness tests: resistance to dry heat, hot water, salt spray test and Kesternich testing. After ageing, a small reduction in compressive strength was observed. However, in all the samples, the strength values were sufficiently high to consider that these types of recycled materials remain practically unaffected when compared with the reference specimens. Finally, alkali-silica reaction tests were performed to determine the chemical stability of these mortars.  相似文献   

6.
The electricla behavior of polymer-modified cement mortars has been evaluated as a function of the polymer and the evaporable water contents. The effects have been correlated to microstructural changes induced by the addition of an acrylic polymer and an epoxy resin purposely formulated for cement-based composites. Moreover, the effect of the addition of pulverized fly ash, which has proved to be beneficial on many of the cement composite properties, has also been studied. Polymer modified cement mortar composites exhibit a tendency towards insulating behavior which is greatly enhanced by water losses: the electrical properties must thus be carefully evaluated when static charge accumulation is not desired. The addition of pulverized fly ash to ordinary Portland mortars slightly influences the electrical behaviour, but strongly enhances the insulating behaviour of polymer modified cement mortars.  相似文献   

7.
Higher cement and fines content is needed in self-compacting mortars (SCMs) to increase their flowability and stability. Different inert fillers and supplementary cementitious materials are usually added. The use of sands rich in fines may be a cost effective alternative source of filler. This paper presents the results of an experimental study on the rheological and mechanical properties of self-compacting mortars (SCMs) made with various types of sands: crushed sand (CS), river sand (RS), dune sand (DS) and a mixture of different sands. The mini-slump flow, V-funnel flow time and viscosity measurement tests were used to study the rheological properties. The experimental results indicate that the rheological properties and strength improve with mixtures of crushed and river sands but decrease with mixtures of crushed and dune sands especially for higher dune sand content. Crushed sand with (10–15%) of limestone fines can be used successfully in production of SCM with good rheological and strength properties. However, a reduction in compressive strength with increasing dune sand content (up to 50%) in mortar with binary and ternary sands was observed.  相似文献   

8.
Higher cement and fines content is needed in self-compacting mortars (SCMs) to increase their flowability and stability. Different inert fillers and supplementary cementitious materials are usually added. The use of sands rich in fines may be a cost effective alternative source of filler. This paper presents the results of an experimental study on the rheological and mechanical properties of self-compacting mortars (SCMs) made with various types of sands: crushed sand (CS), river sand (RS), dune sand (DS) and a mixture of different sands. The mini-slump flow, V-funnel flow time and viscosity measurement tests were used to study the rheological properties. The experimental results indicate that the rheological properties and strength improve with mixtures of crushed and river sands but decrease with mixtures of crushed and dune sands especially for higher dune sand content. Crushed sand with (10–15%) of limestone fines can be used successfully in production of SCM with good rheological and strength properties. However, a reduction in compressive strength with increasing dune sand content (up to 50%) in mortar with binary and ternary sands was observed.  相似文献   

9.
In recent years, there has been an increasing interest in seeking the potential applications of recycled mixed plastic wastes in building and construction sectors to relieve the pressure on landfills. This paper presents the recent developments and applications of composite materials made from recycled mixed plastics and glass fibre. Some of the first uses for such composites are as an alternative to non-load bearing applications like park benches and picnic tables. With its inherent resistance to rot and insect attack, these composites can in fact be used as a replacement for chemically treated woods in various larger-scale outdoor applications such as railroad crossties and bridges. However, the properties of the structural components made from recycled mixed plastics are not well understood. Information on the behaviour of such composites under applied loading and at different environmental conditions such as elevated temperature and ultraviolet rays are crucial for the utilisation of recycled mixed plastic materials in construction. This paper presents an overview of the mechanical properties and durability of recycled mixed plastic waste composites. The paper identifies research needs critical in the effective design and utilisation of these composite materials in civil engineering and construction.  相似文献   

10.
Glass fiber-reinforced polymer (GFRP) composites and carbon fiber-reinforced polymer (CFRP) composites were recycled using superheated steam. Recycled glass fibers (R-GFs) and recycled carbon fibers (R-CFs) were surface treated for reuse as fiber-reinforced polymer (FRP) composites. Treated R-GFs (TR-GFs) and treated R-CFs (TR-CFs) were characterized by scanning electron microscopy (SEM) and remanufactured by vacuum-assisted resin transfer molding (VARTM). Most residual resin impurities were removed by surface treatment. Analysis indicated no adverse effect of surface treatment on bending strength. The mechanical properties of the TR-GF reinforced polymer (TR-GFRP) and TR-CF reinforced polymer (TR-CFRP) composites were determined and compared with those of R-GF reinforced polymer (R-GFRP) and R-CF reinforced polymer (R-CFRP). The bending strengths of R-GFRP (26%) and R-CFRP (49%) were very low, compared to that of virgin glass fiber-reinforced polymer (V-GFRP) and that of virgin carbon fiber-reinforced polymer (V-CFRP). The bending strength of TR-GFRP composites was improved to about 90% of that of V-GFRP, and the bending strength of TR-CFRP composites was improved to about 80% of that of V-CFRP.  相似文献   

11.
This study’s main objective is to show the viability of reducing the cement content of mortars by incorporating fine crushed concrete aggregates whilst simultaneously maintaining a good performance in terms of functional requisites. The advantages of this, if the results are positive, are both environmental and economic: less energy is consumed in cement manufacture and the mortars’ direct costs are lower. To evaluate the hypothetical binding characteristics of concrete fines incorporated in mortars, and thus allow a cement consumption reduction, various standard tests were performed to quantify their most important properties (e.g. mechanical strength, water-related performance, cracking susceptibility, shrinkage) and compare them with those of a reference mortar containing no recycled fines and not reducing the cement content.  相似文献   

12.
This paper presents the durability behavior of pultruded unidirectional carbon fiber reinforced polymer (CFRP) plates immersed in water and seawater at room temperature, under sustained bending strain of 30% and 50% ultimate strain. In this study, water absorption kinetics of CFRP composite and effects of moisture ingress on the mechanical properties, such as tensile properties and short beam shear strength, constitute integral parts of the investigation. The study reveals that seawater immersion leads to higher equilibrium moisture content than water immersion, due to the blister induced damages on the CFRP plate surfaces in seawater. However, diffusion coefficient in seawater immersion is shown to be lower compared to the water immersion, and is attributed to the high concentration of dissolved salts in seawater that retard water diffusion by osmosis. Increasing the bending strain reduces the free volume fraction of the resin matrix, which is responsible for the decreased water uptake and diffusion coefficient for both immersions. Immersion in both media leads to the pronounced degradation in the resin controlled property (i.e., short beam shear strength) of CFRP, but shows less or negligible effects on the fiber controlled properties (i.e., tensile strength and modulus). Both immersion media and 50% bending strain level show remarkable effects on the variation of the mechanical properties of CFRP.  相似文献   

13.
Mortars containing recycled aggregate, instead of quartz sand, were characterized to find an alternative application for the fine recycled-aggregate fraction coming from building debris processing. Tests on bond strength of mortar to masonry units were carried out, as well as tests on compressive and shear strengths of masonry assemblages. The results obtained were related to the mechanical properties of mortars and brick. On the basis of the characterization results and performance evaluations, recycled-aggregate mortar appears to be superior to ordinary mortars in terms of mortar–brick bond strength and shear strength of masonry assemblages. This improved performance is of particular interest for the masonry structures in zones of seismic activity. In addition, the use of fine recycled aggregate is in accordance with the sustainable development concept, where recycling of building rubble plays a key role in ending the building life cycle.  相似文献   

14.
Due to its superior damping ratio, high adhesion and fast curing, polymer concrete is used in manufacturing bases for a wide range of precision machines. The coefficient of thermal expansion for polymer concrete is one of the main parameters that can affect the level of accuracy in precision tool machines. Flexural strength is a fundamental strength of the base. In this study six aggregates (basalt, spodumene, fly ash, river gravel, sand and chalk) were investigated. Polymer concrete samples were prepared with different compositions of aggregates containing the same resin volume fraction (aggregates 83% and risen 17%). A four points flexural test was employed to measure the flexural strength of the polymer concrete samples. The coefficient of thermal expansion for polymer concrete was measured using a custom built device. The preliminary optimum composition, with the highest flexural strength and lowest thermal expansion coefficient, was found to be basalt, spodumene and fly ash. Basalt, sand and fly ash composition was the second in the rank. The second composition was nominated for further optimization in terms of resin volume fraction in consideration of its ability to adapt a smaller amount of resin. Different samples of polymer concrete were prepared with a variety of resin volume fractions as follows; 17%, 15% and 13%. The resin volume fraction has been demonstrated to have a significant effect on the coefficient of thermal expansion and flexural strength for polymer concrete. The final optimized composition was basalt, sand and fly ash (filler 87% and resin 13%). ANSYS 13 software was employed in visualizing the influence of polymer concrete compositions on the thermal expansion of the base and how it affected the level of precision of the tool machine.  相似文献   

15.
《Composites Part B》2013,44(8):3061-3068
Due to its superior damping ratio, high adhesion and fast curing, polymer concrete is used in manufacturing bases for a wide range of precision machines. The coefficient of thermal expansion for polymer concrete is one of the main parameters that can affect the level of accuracy in precision tool machines. Flexural strength is a fundamental strength of the base. In this study six aggregates (basalt, spodumene, fly ash, river gravel, sand and chalk) were investigated. Polymer concrete samples were prepared with different compositions of aggregates containing the same resin volume fraction (aggregates 83% and risen 17%). A four points flexural test was employed to measure the flexural strength of the polymer concrete samples. The coefficient of thermal expansion for polymer concrete was measured using a custom built device. The preliminary optimum composition, with the highest flexural strength and lowest thermal expansion coefficient, was found to be basalt, spodumene and fly ash. Basalt, sand and fly ash composition was the second in the rank. The second composition was nominated for further optimization in terms of resin volume fraction in consideration of its ability to adapt a smaller amount of resin. Different samples of polymer concrete were prepared with a variety of resin volume fractions as follows; 17%, 15% and 13%. The resin volume fraction has been demonstrated to have a significant effect on the coefficient of thermal expansion and flexural strength for polymer concrete. The final optimized composition was basalt, sand and fly ash (filler 87% and resin 13%). ANSYS 13 software was employed in visualizing the influence of polymer concrete compositions on the thermal expansion of the base and how it affected the level of precision of the tool machine.  相似文献   

16.
Polymer-based nanocomposites have shown superior mechanical, thermal, as well as multifunctional properties when compared to plain polymer matrices. This fact has lead to a great research activity focused on incorporating polymeric materials with nanoparticles over the last years. The present research investigates the influence of nanoparticles reinforcement on fracture properties of polymer mortars, with particular regards to fracture and toughening mechanisms. This investigation was carried-out for a series of polymer mortars, containing varying amounts of aluminum oxide (Al2O3) and iron oxide (Fe2O3) nanoparticles dispersed in epoxy matrices.  相似文献   

17.
The types of aggregate used play an important role in determining the effectiveness of X-ray radiation protection of cement mortars. Cement mortars were prepared using fine aggregates obtained from six different sources. The influence of aggregate type on X-ray shielding properties was studied. The results showed that mortars prepared with barite and lead-laden recycled cathode ray tube funnel glass provided better shielding properties than mortars prepared with natural sand, natural crushed fine stone or crushed beverage glass. This is attributed to the use of dense aggregates being able to interact with X-ray radiation, thus reducing the depth of penetration. Due to the superior shielding properties of the mortar containing barite, it can be used to replace traditional sand mortar for applications as rendering or plastering materials for the construction of medical diagnostic and CT scanner rooms.  相似文献   

18.
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.  相似文献   

19.
Simple-to-use models are presented in this paper for determining the residual tension, compression and flexural properties of burnt fibre reinforced polymer composite materials following a fire. The post-fire mechanical properties are calculated using analytical equations that combine the properties of the fire-damaged (i.e. char) and undamaged regions of a composite. Fire tests were performed on composites containing carbon, glass or Kevlar fibres with an epoxy, polyester, vinyl ester or phenolic resin matrix to assess the accuracy of the models. The composites were tested to a wide range of fire conditions with temperatures from 525 to 850 °C for times up to 30 min. It is found that the post-fire properties drop rapidly with increasing heat flux and duration of a fire due to the thermal degradation of the polymer matrix. It is shown that the reduction to the post-fire properties of the burnt composites can be accurately determined using the models. In almost all test cases, the agreement between the calculated and measured residual mechanical properties is within 10%.  相似文献   

20.
In order to find new application fields for either fine materials coming from building demolition or industrial byproducts, some mortars, in which fine recycled materials, obtained from a plant where rubble from building demolition are ground, are substituted to natural sand, were tested.Moreover, mortars containing either fly ash or ground brick powder as partial cement replacement were studied.Based on characterization results and performance evaluations, recycled-aggregate mortar seems to be superior in terms of mortar-brick bond strength, mainly because of its rheological properties.In addition, the use of fine recycled aggregate instead of natural sand is in accordance with the sustainable development concept, with recycling and reuse of building rubble playing a key role in meeting the need to complete the building life cycle.  相似文献   

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