Papers by Keyword: Workability

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Authors: Zhi Shan, Jian Jun Shi, En Xiong, Xian Lei Wu
Abstract: The usual research method, on rheology of fresh self-compacting concrete, is that the regression models between rheological parameters and workability were established, and then the rheological test was operated to control fresh SCC. But, there is no rheometer used widely on site, already. So this paper developed an adaptive neuro-fuzzy inference approach of the back analysis of workability on fresh SCC rheology, and workability tests can be taken to inverse the rheological parameters, by adaptive neuro-fuzzy inference system. In order to check the correctness of this approach, a rheological problem of fresh SCC was solved by it, and the inversion results were in good agreement with the rheological parameters, and the predication accuracy of ANFIS models was quite sufficient to meet the engineering requirement.
Authors: Gai Fei Peng, Zhan Qi Guo, Piet Stroeven, Ri Gao, Guang Hua Huang
Abstract: A literature review was carried out to identify advances in research on workability of fresh concrete via both experimental tests and modeling, especially high performance concrete and self-compacting concrete. It is concluded that, in order to achieve better understanding of fresh concrete, especially self-compacting concrete (SCC) and high-performance concrete (HPC), a clear methodology of research should be established as the first step. It is suggested that there is no unique workability test method suitable for all the range of fluidity of fresh concrete, and a specific method should be identified for a proper range of fluidity. As to the relationship between fluidity of concrete and that of paste, future research can be conducted in two aspects, i.e. one is the influence of the quantity of paste in concrete, and another is the influence of fluidity of paste affected by a couple of factors.
Authors: Gai Fei Peng, Zhan Qi Guo, Piet Stroeven, Ri Gao, Jiu Feng Zhang
Abstract: A literature review was carried out to identify advances in research on workability of fresh concrete via both experimental tests and modeling, especially high performance concrete and self-compacting concrete. As to the relationship between fluidity of concrete and that of paste, future research can be conducted in two aspects, i.e. one is the influence of the quantity of paste in concrete, and another is the influence of fluidity of paste affected by a couple of factors. Most literature proved that the flow of concrete depends both on positive effect and negative effect, the former promote fluidity, such as dispersing, filling and lubricating, and the latter restricts fluidity, such as formation of particle coagulation, an increase of wettable surface of solid particles and mechanical interlock.
Authors: Xiu Shi Wang, Jian Guo Wang, Pei Xiang He
Abstract: This paper addresses mainly workability of dry-mixed self-compacting concrete (DSCC) based on the experimental study. Ten mix proportions for DSCC are designed by the orthogonal test method with fixed fine and additive content when coarse aggregate content and water content are used as variables. The workability (including filling ability, passing ability and segregation resistance) of fresh DSCC is quantitatively evaluated by slump flow, L-box, U-box and circular steel column of stability tests. It is found that DSCC of 13% water content has better fluidity, deformability and filling ability than DSCC of 12% water content and better uniform aggregate distribution and segregation resistance than DSCC of 14% water content based on the experimental results. It can be concluded that DSCC of 13% water content presented in this paper satisfy various requirements for workability and can be used for the design of practical concrete structures.
Authors: D.S. Vasilega, V.A. Zyryanov
Abstract: The results of experimental studies of the different machinability group materials’ characteristics, including tool steel DIN C125W, heat-resistant steel (C - 0.1%, Si - 0.6%, Cu - 0.3%, W - 0.1%, Mn - 0.4%, Ni - 23%, P - 0.01%, Cr - 12%, S - 0.01%, V - 0.01, Mo - 1.5%, Ti - 3%, V - 0.001%, Al - 0.6), nickel-based superalloy (Fe - 4%, C - 0.1%, Si - 0.6%, Mn - 0.5%, S - 0.01%, P - 0.01%, Cr - 15%, Ce - 0.01%, Mo - 4%, W - 6%, V - 0.3%, Ti - 2%, Al - 2%, B - 0.01%), the changes in the minimum surface wear, maximum cutting path, and cutting temperature in the processing of these materials, as well as the experimental data analysis showed that the extreme values of changes in the materials’ physical and mechanical properties under the temperature impact can be defined as the minimum surface wear temperature and maximum cutting path temperature, that is, the conditions corresponding to the maximum workability of the materials. It is possible to use the materials physical and mechanical property dependence on temperature for defining the maximum material workability temperature when processing it by cutting. The article suggests a method to define the maximum material workability temperature.
Authors: Jin Huang, Hua You Su
Abstract: When the ordinary concrete is added to fly ash, the slump of concrete is increased and the workability and pumpability are also improved, which can meet the design requirement, reduce project costs, protect environment and save resources. Based on evaluation of the basic performance for raw materials of fly ash concrete, the improved mix design method for fly ash concrete is proposed. And then it is tested in practical project to verify the workability and feasibility and meanwhile some construction attentions are proposed. The results show that the fly ash can significantly improve the workability of cement concrete. The early strength of fly ash concrete is lower than ordinary concrete, but after 28 days, the compressive strength is similar with ordinary concrete, which provides a reference for design and construction of fly ash concrete.
Authors: Le Anh Tuan Bui, Chun Tsun Chen, Chao Lung Hwang, Mintar Fransiscus
Abstract: The residual RHA from Vietnam is used to test the likely application in cement and concrete. The characteristics, quality and influence of RHA on the quality of concrete are investigated in this investigation. The workability, strength and durability of concrete added with ground RHA satisfy with the relevant standards and requirements. It indicates that the ground RHA in this study can be used as a good supplementary cementious material. Therefore, it is possible to obtain RHA concrete with comparable properties than those of the control specimen (without RHA) with a lower consumption of cement, thus reducing the CO2 emissions during the production of cement and the environmental and disposal problem of the ash can also be diminished. Moreover, while the results will be able to substantiate the viability of application of RHA in concrete industry under the prevailing conditions in Vietnam, they are also expected to be especially useful for future studies on RHA in a specific condition in this country.
Authors: Ru Wang, Pei Ming Wang
Abstract: This paper summarizes the function of styrene-butadiene rubber (SBR) in cement-based materials, focusing on the achievements of the authors in recent years. The effect of SBR on the properties of cement mortar is introduced, i.e. the workability of fresh mortar such as the water-reduction and water-retention effects of SBR, the mechanical properties of hardened mortar such as the tensile bond strength, flexural and compressive strengths, flexibility and anti-impacting capacity, the waterproofness such as the capillary water adsorption and anti-penetration capacity, the microstructure such as the matrix structure and interface structure, and the cement hydration such as the calcium silicate hydrates, calcium aluminate hydrates and polymerization of [SiO4]4- tetrahedron.
Authors: Oluwarotimi M. Olofinnade, Julius M. Ndambuki, Anthony N. Ede, Colin Booth
Abstract: Use of waste materials in concrete is now a global trend for efficient waste management so as to achieve a sustainable green environment and with the added advantages of preserving the natural resources as well as producing a better performing concrete. This study examined the properties of concrete containing ground waste glass powder (GP) as partial replacement for cement. The waste glass was finely grounded into powder and the morphology imagery of the powder materials was carried out using scanning electron microscopy (SEM). Moreover, the chemical composition of the glass powdered material was determined using X-ray fluorescence (XRF). Laboratory tests were carried out to determine the strength activity index, workability, split tensile and compressive strength properties of the concrete with 0%, 15%, 18%, 21%, 24%, 27% and 30% partial replacement of cement with the ground waste glass powder. The results showed that the oxides composition of the glass powder meets the requirements for pozzolanic material, while the SEM morphology shows materials of amorphous flaky solid masses, and based on the 28-day strength activity index, concrete containing 21% cement replacement shows a higher strength index above therecommended 75%. It was also observed that workability of the concrete reduced with increase in percentage glass content while significant improvement of the compressive strength of the concrete was achieved at 21% cement replacement, after which a decrease in strength with increasing percentage glass content was observed. The revealed results were confirmed by the microstructural examination using SEM showing a denser concrete at 21% cement replacement but increase porosityas the glass content increases. However, a decrease in split tensile strength was observed with increasing glass content. The results clearly showed that it is possible to produce moderate strength sustainable concrete for structural application using 20% glass powder as cement replacement.
Authors: Shun Bo Zhao, Qi Guo, Guang Xin Li, Yan Feng Su
Abstract: Experimental study was carried out on the concrete mixed with machine-made sand and recycled coarse aggregate (MSRAC), three strength grades of concrete were designed by changing the water to cement ratio as 0.36, 0.45 and 0.55, while the sand ratio varied in a range of 32%~38%, 32%~42% and 38%~44% successively. The workability and the mechanical properties such as compressive and splitting tensile strengths and elastic modulus of MSRAC were tested. The results show that although the mechanical properties of MSRAC were influenced by sand ratio, they were still controlled by the water to cement ratio. The ratio of axial compressive strength to cubic compressive strength and the elastic modulus of MSRAC basically satisfy the specifications of the current design code for concrete structures. It should be noticed that the tensile strength of MSRAC is lower than current specification, and tends to reduce with the increase of water to cement ratio.
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