The study of the microstructure and the chemistry of hydration of the Portland cement, main hydraulic binder since the 19th century, have led to the development of novel cements with environmental sustainability (Moranville- Regourd, 1999; Roy, 1994; Roy, 1991). Cement has been partially replaced by active nano powders or supplementary cementing materials, such as ground granulated blast furnace slag (GBFS), silica fume (SF), rice husk ash (RHA), meta kaolin (MK) or fly ash (FA). These are examples of those new binders and constitute a significant contribution to the eco-efficiency of the global economy (Moranville- Regourd, 1999; Roy, 2003; Tailing, 1997; Van Loo, 2003). Other materials are those called the chemically bonded ceramics (CBC), the macro defect free cements (MDF) and the densified systems which contain homogeneously arranged ultrafine particles (DSP) (Moranville-Regourd, 1999; Roy, 1991; Roy, 1994). These new binders, which are alternative materials to traditional and blended cements and concretes, are obtained by the alkaline activation or geopolymerization of different industrial by-products (blast furnace slag and/or fly ashes). The provision of new types of cements is an ongoing research topic for the scientific community (Glukhovsky, 1983; Puertas, 1995; Roy, 1992; Shi, 2000; Wang, 1995b).
Egyptians has developed this concept of using the fibres in the concrete mix as a reinforcing material. Before they used to mix the straw and hairs of animals in the concrete as a material of reinforcement for fixing of bricks in walls. The production offibres is also in less percentage and to give potentiality to this by providing a land to improve this is very necessary. So that there is a similar way is to extracting the fibre is the major problem. To that problem the only solution is these bamboo fibres. This is bamboo is not grass or not a wood, but it is having the characteristics of both the grass and wood. In the recent years the concept of fibre reinforcement concrete is a great development to enhance effectiveness and grater performance related results in concrete it is much necessary to produce the high strength, performance and durability with desirable aspect ratio from which the effectiveness and the good results ofperformance are to developed in the concrete. The main reason of using the natural fibres to providing the greater strength and good resistance capacity to structures and to achieve the greater performances from it by making the structures rigid. The fibres are mixed randomly in the concrete mix with the calculated percentages of contents of the fibre reinforced concrete. The characteristics of the fibres and materials should effects on the results of fibre reinforced concrete. Whereas results are depends on the types offibres used, shape offibres, percentage content mix in concrete and the method of mixing fibres in concrete, the size of the aggregate , shape and texture of the aggregate. The fibres are the pieces of small size materials used for reinforcement which may be available naturally or manufactured artificially. The fibres may be flat in shape, triangle or may be in circular shape. The property of the fibre is often defined by the parameter which is known as “Aspect Ratio”. The ratio of fibre length to the fibre diameter is called as aspect ratio. The length of the fibre is decided by the multiplying the diameter to the aspect ratio. This length will be influences on the strength offibres which may in flexure, compression and may be tension.
Some previous research indicates that shear resistance of SCC and HPC is lesser than in current concretes (Schiessel, 2001). This author defends that this happens due to a better arrangement of the particles, as a consequence of the smaller dimensions of the aggregates and volume of voids, and also caused by the smoother surfaces of failure in case of High Resistance Self-Compacting Concrete. In the other hand, the shear formulations of the actual normative still treating this phenomenon with semi-empirical expressions, varying the theoretical basis and taking into account the material properties, the level of prestressed reinforcement, the shear reinforcement, and the supports (Cladera, 2004). The major part of the complexity is in accurate the contribution ofconcrete in the general shear resistance (Ma, 1997). In addition, the contribution of steel fibres in the shear resistance is still not well dominated.
This study examines the performanceof reinforcements of 100 tex hemp yarns and hybrid yarns reinforcements with same hemp yarns and glass fibres’ (136 Tex) in warp direction (25 % or 50 %) interwoven with hemp yarns. The industrial loom CTБ-175 and craftsman’s loom, plain weaving technique for production of reinforcements with surface density in range of 91-246 g/m2 were used in the production. Tensile strength of hemp reinforcement on warp direction is 241.7N-279.8N and tensile modulus 218.48MPa-271.24MPa.The measurement of fabric thickness and physical-mechanical properties of reinforcements were carried out according to ISO 5084:1996 and LVS EN ISO 13934-1-2001 standards. One and two layer composites of woven reinforcements of hemp and polypropylene yarns were produced with Laboratory Press LP_S_50/SASTM. The surface density of one layer composite is 311.2 g/m2 and 608.4 g/m2 of two layers composite. The tensile strength of same composites is 303.1N and 599.5N, the tensile stress is 35.66 MPa and 40.65 MPa. The elastic modulus of one layer composites is 908.2 MPa and 1152.5MPa for two layers composite. The mechanical properties of composites were established according to ISO 527-5:2009 standard.
flexural strength is observed by 20.31 % for mix MS75N25 with respect to reference mix. It is also seen that the addition of nylon fibres increase the flexural strength. The modulus of rupture of steel fibers is more as compare to nylon fibers. Therefore steel fibers are effective to arrest the macro cracks and undergo ductile failure while nylon fibers are only effective to arrest the micro cracks and undergoes brittle failure. Therefore steel-nylon combination also shows better performance during flexural strength test. Figure 6 states that combination of steel and nylon fibres are beneficial for increasing flexural strength.
In this context and in order to contribute to the state of the art of this subject, this paper aims at evaluating the structural performanceof reinforced concrete beams whose bonding component is the geo- polymer cement. Also, it gives a step forward in utilization of such cement in elements with structural purpose, advancing the work de- veloped by the authors on the characterization of the micromechani- cal behavior ofgeopolymer cement pastes/mortars . The main idea here is to identify if the properties ofgeopolymer cement, such as ductility and tensile strength, contribute to the structural perfor- mance of beams. In order to accomplish this goal, first, the mechani- cal behavior of the geopolymerconcrete is evaluated by pursuing compressive strength, steel-concrete bond and elastic modulus experiments. Then, a 4 point bending test is developed in order to measure the structural performanceof the geopolymer reinforced concrete beam. In both cases, mechanical characterization of the concrete and of the beam, specimens are fabricated with Portland cement to serve as reference results. Finally, a non-linear finite ele- ment model of the geopolymer beam is built using the experimental data (acquired in the geopolymerconcrete experiments) and its re- sults are compared to the experimental ones.
In construction sector there is always a growing demand for finding a suitable material which could effectively replace cement and fine aggregate since manufacture of cement causes environmental pollution and lacking of natural resources to a greater extent. (Okan.K et.al, 2007) have studied about concrete containing fly ash of 0%, 15% and 30% and steel fibresof volume fraction 0%, 0.25%, 0.5%, 1% and 1.5% found steel fibre improves the tensile strength, drying shrinkage, freeze – thaw resistance and reduce the workability. The addition of fly ash increase workability reduces unit weight ofconcrete. They finally concluded addition of 1% volume fraction of fibre increases in compressive strength 15%, tensile strength 30%. (G.M.Ganesh et.al, 2011) added fly ash and silica fume on high strength concrete. They found addition of silica fume provides an early strength and fly ash provides long term strength. The addition of 6% silica fume to different fly ash proportion has a high compressive strength than 10% silica fume. (Ward et.al, 2002) have studied the effect of silica fume and fly ash on heat of hydration of Portland cement. Silica fume simply went up the stack as smoke vented into the atmosphere. Silica fume is a by-product produced from silicon metal or ferrosilicon alloys. Silicon metal and alloy are produced in electric- arc furnaces the raw intensity and durability it also can improve the material overall performance as filler. Measurements of heat of hydration were carried out under isothermal conditions. The test results indicate that silica fume accelerates cement hydration at high water/Cement ratio and retards hydration at low water/cement ratio. The addition of silica fume alters the hydration process in the period of 2- 20 hours after the start of hydration. Initial hydration of the cement is usually accelerated by the presence of silica fume. (Ribakov et.al, 2009) have studied with utilising three different fibres. From experimental
The problems related to environmental issues have motivated the research about eco-friendly materials. This fact combined with the relatively high binder percentage and with the need to improve the mixtures durability has led to the additives incorporation like the fibres, not only in asphalt mixtures but also in stone matrix asphalt and asphalt concrete. A wide variety of fibre types has been used in asphalt mixtures, including cellulose, mineral, synthetic polymer, glass fibres, newsprint, carpet fibres and recycled tire fibres [28–36]. Cellulosic fibres are the most commonly used addi- tives [37–42]. The current study uses cellulosic fibres to improve porous asphalt performance. These fibres present a set of impor- tant advantages, such as wide availability at relatively low cost, recycling ability, biodegradability, non-hazardous nature, zero car- bon footprint, and interesting physical and mechanical properties (low density and well-balanced stiffness, toughness and strength) [43,44]. One of the main objectives of cellulosic fibres is to stop binder drainage preventing its loss during storage and transport .
This research presents an experimental study on the spalling of self-compacting concrete (SCC) with and without polypropylene (PP) fibres subjected to elevated temperatures and at 2 and 4 hour exposure times. The results showed spalling occurred in all specimens that did not contain PP fibre in the concrete mixture above 400 o C. On the other hand, spalling did not occur in specimens containing PP fibres above 0.05 % by volume. Spalling resistance performance was significantly improved. The hardened densities, weight losses, permeability, and scanning electron microscopy tests showed that the main cause for spalling was the low permeability of the SCC and the presence of water inside the concrete. Vapour developed inside the concrete during a fire finds it difficult to escape and will produce high internal stresses that lead to spalling. Statistical models were devised for the above test. Keywords: Spalling; Polypropylene; ISAT; Weight Loss; Self-Compacting Concrete.
This paper reports on the research work conducted on the PSSDB floor system introduc- ing geopolymerconcrete (Abdullah et. al. 2011) infill in the trough of the PSS, as an alterna- tive to the previously adopted normal concrete. The geopolymerconcrete, in addition to being eco-friendly is high strength and expected to improve the structural performanceof the PSSDB floor system in terms of stiffness and strength. Previous research involving normal concrete infill in PSSDB floors have been reported in Shodiq (2004), Wan Badaruzzaman et al. (2003), Seraji et al. (2013), and Gandomkar et al. (2011 and 2012). Shodiq (2004) has demonstrated that the stiffness and strength of the PSSDB floor system with normal concrete infill is 20.2% and 61.0% higher than the one without infill. This was due to the increased stiffness contribut- ed by the concrete infill and its effect in delaying the onset of local buckling of the upper flange under compression of the PSS.
with a high performance composite based on Portland cement and short steel fibers, intended to constitute the called transition layer. After the performanceof several steps of experimental and theo- retical analysis, it can be concluded that the technique proposed – even with the possibility of further improvements, as any other technique – proved to be efficient both in the reconstitution of ten- sile zone of RC beams and in the improvement of beam perfor- mance as a whole, particularly in a more efficient exploration of the resistance properties of strengthening with sheets of PRFC. The research was not limited to simple testing and comparison of strengthened and non-strengthened beams, but aimed to cover several scientific foundations and evaluations that focused on the problem in question. From the joint analysis of all results obtained, it could be concluded that the intended objective was reached. Finally, it is highlighted a synthesis of the partial conclusions and complementary comments on each specific study produced: the addition of steel microfibers to conventional fibers enhances the contribution of the matrix to the composite resistance and the im- provement in the mechanism of stress transfer from matrix to fibers; with the matrix cracking, the stress transfer was facilitated by the steel microfibers which, in large amount in the matrix, led to the progress of cracking with the increase in the loading level; the flexural strengthening of beams through the external bonding of CFRP sheet to a transition layer constitutes an efficient strategy with practical application in engineering;
The influence of aluminium (added in quantity from about 0.6% to about 2.8%) on both the alloy matrix and the shape of graphite precipitates in cast iron treated with a fixed amounts of cerium mischmetal (0.11%) and ferrosilicon (1.29%) is discussed in the paper. The metallographic examinations were carried out for specimens cut out of the separately cast rods of 20 mm diameter. It was found that the addition of aluminium in the amounts from about 0.6% to about 1.1% to the cast iron containing about 3% of carbon, about 3.7% of silicon (after graphitizing modification), and 0.1% of manganese leads to the occurrence of the ferrite-pearlite matrix containing cementite precipitates in the case of the treatment of the alloy with cerium mischmetal . The increase in the quantity of aluminium up to about 1.9% or up to about 2.8% results either in purely ferrite matrix in this first case or in ferrite matrix containing small amounts of pearlite in the latter one. Nodular graphite precipitates occurred only in cast iron containing 1.9% or 2.8% of aluminium, and the greater aluminium content resulted in the higher degree of graphite spheroidization. The noticeable amount of vermicular graphite precipitates accompanied the nodular graphite.
This article deals with the question if the innovative JCs produced by EESC, UJs and ShJS are able to maintain the traditional performanceof JPCPs. Accordingly, the aim of the paper is to analyze the effects of the JB on the performanceof the JPCPs with EESC, UJs and ShJS. For that the JB is characterized by joints activation, opening, deterioration and LTE, not in an isolated but in a comprehensive way to determine not only the complete JB, but their effects on the JPCPs performance, so at the end upon the users. The paper contributes not only with a comprehensive analysis of the JCs, but also with new field experiences. Furthermore, all studies of the literature review regarding to the evaluation of EESC referred to traditional JPCPs, but not to JPCPs with ShJS. All these allow concluding that the innovative JCs contribute to a sustainable infrastructure as they can maintain, and even improve, the traditional life-cycle performanceof CPs if the design hypotheses are valid. With this purpose, for the analyzed conditions, it is recommended to cut the joints at least at 30% of the JPCPs thickness in order to assure % joints activation, joints opening . mm, so LTE %. UJs with thin blade mm and limited fines in the base % passing µm can be used in JPCPs applications as streets, low volume roads, parking lots, bus corridors (moderate rainfall) and any JPCP where the seals do not work well enough. Even an extrapolation to more exigent cases could be possible with stricter specifications for saw- cuts width . mm , base fines content % and the use of JPCPs with ShJS to obtain smaller joint openings.
Jones (2004) says that companies must constantly change or develop a way to use existing resources and capabilities to enhance the ability to create value and to develop its effectiveness. The amendment is intended to find improved performance. Performance is meant here is not the performance in the narrow sense that only limited to financial gain. Indeed, the advantage of course have to be hunted, because without profit companies will not be able to survive, but the goal of the company from a strategic management perspective is intended to Obtain and maintain a sustainable competitive advantage and Achieve superior performance. At first it only financial criteria used to assess whether or not the superior performanceof a company. Performance serves as an instrument to determine whether the company has the ability to going concern, as well as a basis for formulating operational planning company in the future and for the information of shareholders, stakeholders, customers, regarding the achievements and success of the company. There are many approaches, in defining the performance, according to Mulyadi (2007: 337). Performance is the success of personnel, team, or organizational unit in achieving the strategic objectives that have been set previously with the expected behavior. Mulyadi, also explained that the successful achievement of strategic objectives needs to be measured. That is why the strategic objectives that form the basis ofperformance measurement is necessary to determine its size, and determined initiative to realize the strategic objectives of an organization tersebut.Tercapainya purposes only possible because of the efforts of the actors that exist in the organization. Prawirosentono (2000), defines performance as: "The work that is accomplished by a person or group in an organization within a certain time, in accordance with the authority and responsibilities of each, in an effort to achieve the goals of the organization in question legally, do not violate the law and in accordance with moral and ethical. In the related literature, there are two approaches to measuring the company's performance advantage (Supratikno et.al, 2005).
The main objective of the treatment is the fibre superficial cleaning by the remove of some agents (grass, silica, etc.) that difficult the chemical reactions between the fibres and the matrix. Additionally, can remove the lignin and the hemicelluloses, responsible for some degradation mechanisms.
The fibre reinforcement efficacy of mortar is dependent upon many factors, including the properties of the matrix as well as the fibre geometry, size, type, volume and dispersion. Among the plastic fibres typically used in mortars, little or nothing is known about the rheological behaviour of acrylic fibres. Thus, in this study the influence of different acrylic fibres characteristics on the rheological behaviour of cement mortars was investigated. The method selected is based on factorial design of experiments in which the parameters considered are the length, diameter and acrylic fibre content. The test results indicate that Herschel-Bulkley model better simulate the rheological behaviour of acrylic fibres reinforced mortars. It was also observed that the yield stress increases with the reduction of fibre length and diameter and the plastic viscosity increases as the fibre length increases.
Modern concrete is a delegate with industrialized production of premixed concrete, with the change of the fineness of cement, mineral admixture and the use of high performance water reducing agent for the characteristics of the concrete. The characteristics of modern concreteperformance in the improvement of the permeability and the early strength ofconcrete, the hydration reaction time is shorter, reduce the reliance of the concrete strength for concrete strength, and its workability is invested by harsh concrete into the plastic concrete, make the rheological properties of modern concrete mixture more evident, under the same water cement ratio have higher strength and better compactness, thus ensuring workability and durability ofconcrete structure is increasing day by day. The most important characteristics is high homogeneity ,it can also according to the needs of the actual project to
capacity), and the development of pervious pavements. In turn, mi- cro- and macro-drainage measures include detention and retention strategies. Briely, detention is based on the use of dry basins de- signed as an integrating feature of urban landscapes, while retention works maintain a permanent pool and are used to not only control low peaks, but also assess water quality. However, the greatest diiculty in the design and construction of these reservoirs is the amount of lit- ter carried by stormwater lows, which obstructs drainage inlets [2,3]. In this scenario, pervious pavements stand as promising alterna- tives to reduce surface runofs, favoring seepage and water reten- tion in soils.
large precipitates in the size range of 100-200nm, present as single objects or as clusters, characterised by different shapes (oval and oblong), sizes and chemical compositions, fine-dispersed precipitates of carbides in the size range of
is formed by intertwined polypropylene and is currently patented as Marlex® (CR Bard, Branston, RI, USA), Prolene® (Ethicon, Somerville, NJ, USA) and Atrium® (Atrium Medical, Hudson, NH, USA). The use of a mesh preserves the elasticity of the abdominal wall as it allows proper tissue integration maintaining the necessary strength. Polypropylene meshes have good mechanical stability, reasonable elasticity and no tendency to degrade. The pores on this type of mesh, being rated as small (1-2 mm) produce a greater and longer-lasting foreign body inflammatory reaction. Such reaction depends exclusively on the amount of material and on the structure of the texture present on the mesh. Studies demonstrate that meshes have an excessive amount of material, contributing to the rigidity and restriction of the abdominal wall, as well as a greater foreign body reaction. 16 The polypropylene mesh was compared, in this