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Activated Low Clinker Slag Portland Cement and Concrete on Its Basis
Published in Leonid Dvorkin, Vadim Zhitkovsky, Mohammed Sonebi, Vitaliy Marchuk, Yurii Stepasiuk, Improving Concrete and Mortar Using Modified Ash and Slag Cements, 2020
Leonid Dvorkin, Vadim Zhitkovsky, Mohammed Sonebi, Vitaliy Marchuk, Yurii Stepasiuk
According to the results of previous studies, it was found that combined SFA activation is the most effective of all considered activation types. The effect of the activated LSC and various plasticizing additives content on the water demand of concrete mixtures and the strength of concrete was studied. A three-level two-factor plan was implemented [40]. Experimental planning conditions are listed in Table 2.8. All concrete mixes were made based on the same binder of the following composition: clinker, 12%; slag, 8%, FG, 7.5% (SO3, 4.5%). To ensure SFA activation, in addition to the binder, lime was introduced in the amount of 3% by the binder weight, and sodium silicon fluoride (Na2SiF6) in the amount of 2%. The strength of the binder with a specific surface of 453 m2/kg was 45 MPa. Plasticizing additives were technical lingosulfonate (LST), naphthalene-formaldehyde SP-1 type superplasticizer, and polycarboxylic superplasticizer Sika VC 225.
The Use of Superplasticizers in High Performance Concrete
Published in Yves Malier, High Performance Concrete, 2018
In concrete plants, the superplasticizer dosage has to be known in liters of commercial solution per cubic meter of concrete, in contrast to the scientific practice of expressing superplasticizer dosage in terms of solid content.
Material properties
Published in Charles E. Reynolds, James C. Steedman, Anthony J. Threlfall, Reynolds's Reinforced Concrete Designer's Handbook, 2007
Charles E. Reynolds, James C. Steedman, Anthony J. Threlfall
A flowing concrete is usually obtained by first producing a concrete whose slump is in the range 50-90 mm, and then adding the superplasticizer, which increases the slump to over 200 mm. This high consistence lasts for only a limited period of time: stiffening and hardening of the concrete then proceed normally. Because of this time limitation, when ready-mixed concrete is being used, it is usual for the superplasticizer to be added to the concrete on site rather than at the batching or mixing plant. Flowing concrete can be more susceptible to segregation and bleeding, so it is essential for the mix design and proportions to allow for the use of a superplasticizer. As a general guide, a conventionally designed mix needs to be modified, by increasing the sand content by about 5%. A high degree of control over the batching of all the constituents is essential, especially the water, because if the consistence of the concrete is not correct at the time of adding the superplasticizer, excessive flow and segregation will occur.
Permeation-durability properties of metakaolin blended concrete containing rubber
Published in European Journal of Environmental and Civil Engineering, 2022
Noor Azline Mohd Nasir, Nabilah Abu Bakar, Nor Azizi Safiee, Farah Nora Aznieta Abdul Aziz
Despite all rubberized concretes’ strength surpassed the control (Non-RC0%SP), the rate of strength increment decreased with increasing of superplasticizer levels beyond 0.50%. The rubberized concrete with 0.50% superplasticizer level had a high compressive strength, which is about 43 N/mm2. The strength of rubberized concrete with rubber treated and metakaolin was enhanced with the use of superplasticizer, where more water available from the deflocculation of binder particles that accelerated the binder hydration reactivity and consequently improved the microstructure of the concrete. In contrast, a systematic reduction in compressive strength, which about −10.5 to −5.5%, was observed on rubberized concrete with the superplasticizer level beyond 0.50%. Nonetheless, the strength was beyond 40 N/mm2, which is the common strength used in construction application. Despite the strength improvement with the increase in the superplasticizer content, excessive superplasticizer dosage may adversely affect the compressive strength of the concrete. Beyond the optimum limit of superplasticizer content, more water is available for the hydration process and will also cause entrapped water, which creates more capillary pores. At this point, excessive superplasticizer content may cause bleeding and segregation, which consequently affects cohesiveness and uniformity of the rubberized concrete.
The mechanical and durability behaviour of sustainable self-compacting concrete partially contained waste plastic as fine aggregate
Published in Australian Journal of Civil Engineering, 2022
Nahla Hilal, Taher A. Tawfik, Hadi Hemdan Edan, Nadhim Hamah Sor
In this study, two different series of mixes along with total cementitious (cement and waste ceramic powder) of 585 kg/m3 and a constant water-cementitious ratio of 0.38 (w/cm) were prepared. The first series included the reference SCC mix preparation with 0% of waste LDP (LDP0). While, the second series involved the self compact concrete preparation including different waste LDP percentage which is considered as a recycled aggregate that is used as a replacement fractions of sand volume with percentages 0, 6, 12, 18, 24 and 30% in the concrete mixtures. Therefore, six different mixtures were created which are shown in Table 5. The prepared concrete mixes were casted and constant dosages of superplasticizer were utilized 1.538 % by the total cementitious content weight after some trials to obtain the optimum dosage (Sor 2018).
Self-compacting cement-bound pavement foundations for road tunnels: performance assessment in field trials
Published in International Journal of Pavement Engineering, 2022
Ezio Santagata, Eldho Choorackal, Pier Paolo Riviera
Water-to-cement ratio of the mixtures was defined by referring to a surrogate parameter, the water-to-powder ratio (w/p), which is more frequently used in the design of SCC mixtures which contain a relevant quantity of very fine particles (Shi et al.2015). In the case of the SC-CBMs, ‘powder’ is the term which is used to collectively indicate Portland cement and mineral sludge, which jointly contribute to paste fluidity and void filling effects. As proven by the mix design studies previously carried out by the Authors (Choorackal et al.2019b), in order to achieve satisfactory flowability characteristics while guaranteeing an adequate stability, it is recommended to use w/p values of the order of 0.75–0.80. This optimal range was identified by referring to powder pastes containing the same polycarboxylate superplasticizer employed in the research project described in this paper (with a dosage of 0.5% by weight of cement). For the SC-CBMs produced and laid in the field trials, the value of w/p was fixed at 0.80 except for the case of the mixtures with 200 kg/m3 cement, for which it was reduced to 0.75. The dosage of superplasticizer was in most cases fixed at 0.5% by weight of cement although it was increased to 0.75% for the mixtures laid in field trials 3, characterised by cement dosages of 150 kg/m3 ad 200 kg/m3.