Figure - uploaded by Mehmet Uzun
Content may be subject to copyright.
Source publication
It is very important to save time during the assembly of prefabricated elements. In wet connection types, the setting time of the concrete might lead time lose. There are many studies investigates the methods to shorten the setting time of concrete. Especially in the recent years, there are accelerators developed to shorten concrete setting time wi...
Contexts in source publication
Context 1
... chemical and physical features of cement are given in Table 1. Table 2. The particle size distribution of silica sand is given in Figure 1. ...Similar publications
Concrete filled steel tubes are extensively used in high rise structures and bridges. The characteristics such as ease of construction, maintenance, resistance to corrosion makes the concrete filled steel tubes a potential application in many structures to satisfy the durability criteria. Extensive research was carried out in the past decades on th...
Citations
... They were used Taguchi-Grey relational analysis to investigate and optimize the effect of ground granulated blast furnace slag replacement, water to geopolymer solids ratio, molarity of NaOH solution, binder content and Na2SiO3 to NaOH solution ratio on setting time, workability and compressive strength of fly ash-based geopolymer concrete [28]. However, it is well documented that it has been utilized to optimize many other products and processes, these includes literature [29][30][31][32][33]. ...
Geopolymer is a promising eco-friendly material that can be produced with a variety of physical and mechanical properties through alerting the processing parameters. Obtaining Geopolymer with high compressive strength and high porosity may make this material a preferred candidate for many thermal and physicochemical applications. This research aims to identify the set of the processing parameters that yield such as these Geopolymer materials. Taguchi method combined with Grey relational analysis has been used to solve this multi-response trouble. The analysis and the experimental results showed that it is possible to achieve this aim by using a low amount of hydrogen peroxide as a foaming agent, a low amount of yeast as a catalyst, and a low amount of vegetable oil as a stabilizer. Furthermore, the polymerization time elapses before adding the foaming agent is found to be an important processing parameter. Also, the experimental results showed that high porosity and adequate compressive strength can be obtained at the same geopolymer body by choosing the suitable values of the processing parameters. Moreover, it has been found that the use of yeast as the catalyst and the polymerization time is important processing parameters. Also, it has been noticed that the amount of the vegetable oil, which is used as a stabilizer, should be kept in low values to obtain the optimal compressive strength and porosity.
Prefabricated buildings are highly preferred due to their many advantages such as rapid production, low cost. However, it has been seen with the earthquakes in the past years that prefabricated buildings are insufficient in terms of seismic performance because of connection problems of structural members. Therefore, studies about prefabricated connection types have increased in recent years. In this study, an innovative connection was proposed for prefabricated prestressed foundation-column connection that is easy to assemble, preventing workmanship errors, cost and time-effective compared with socket connection. In the study, samples were produced for 5 different connections. The produced 1/2 scale samples were tested under cyclic lateral loading. Structural parameters such as strength, stiffness degradation, ductility, energy dissipation capacity, equivalent viscous damping ratio were obtained from test results. The obtained parameters were interpreted, and the seismic behavior of the samples was compared. As a result, it was seen that the proposed connection provided structural parameters such as sufficient strength and rigidity that can be applied in seismic regions.
With the increasing effects of global warming, the use of natural materials in engineering studies is increasing. In engineering construction, on the other hand, the use of natural fibers as concrete additives in order to reduce carbon emissions and protect the green environment is the focus of the studies. It is possible to increase ductility with the use of fiber in self-compacting ultra high performance concrete. The use of natural fibers provides an environmentally friendly approach. Therefore, in this study, the effect of red pine needles on the mechanical properties of self-compacting ultra high performance concrete was investigated. Pine needles were divided into 30, 40 and 50 mm length. The red pine needles were purified from organic matter with alkaline solution. It was added into the self-compacting ultra high performance concrete at the rates of 0.25%, 0.50%, 0.75% and 1.00% by volume. Slump-flow test, v-funnel test, compressive strength test, flexural strength test, freeze-thaw test, sulfate attack test were applied to examine the mechanical properties of the samples. In the sample with a length of 30 mm and a fiber content of 0.50%, the slump-flow test results decreased from 738 mm to 723 mm compared to the reference sample. According to the V-funnel test results, the closest results to the reference sample were obtained. The sample with a length of 30 mm and a fiber content of 0.50% provided a 15.6% increase in the 28-day compressive strength. On the other hand, the flexural strength increased from 8.60 MPa to 22.46 MPa according to the reference sample. In the sulfate attack test and freeze-thaw test, the closest results to the reference sample were obtained with the 30 mm length sample with 0.50% fiber content. With the results obtained, it was seen that the use of pine needles as a natural fiber in self-compacting concrete was appropriate.
