Utilization of ceramic waste in the production of Khorasan mortar

Khorasan mortar was used in almost all of the historical structures in the geographical area of turkey. It is still used in the renovation of these structures. Water, lime, baked clay is used in the production of Khorasan by breaking and grinding. Crushed brick and tiles are preferred as baked clay. In this study, the usability of ceramic wastes as baked clay was investigated. An important part of ceramic production is made especially in Eskişehir and its vicinity. 10% of ceramic production shows up as wastes because of various reasons. These wastes which are under 20 mm are crushed in the jaw breakers and these which are under 150 mm are grinned in grinders, transformed to powder and then mixed with hydrated lime and water in various proportions, in this way Khorasan mortars are obtained. In mortar production, crushed ceramic-ceramic powder ratio, ceramic-lime ratio were changed and the most suitable ratios were tried to be found. Samples taken from these mortars which are 4 cm x 4 cm x 16 cm in size are removed after a day from the mold and kept in humid environment. Physical and mechanical properties such as unit weight, ultrasonic pulse velocity, bending strength, compressive strength of the mortar were determined. As a result of the experiments, the unit weights range was between 1.5–1.65 kg/dm3, the ultrasonic pulse velocity rates range from 1.3–1.9 km/h, the range of bending strengths was from 0.25–1.05 MPa, and compressive strength has changed in the range of 7.5–10.5 MPa. With the work done, it is recommended to use a high percentage of lime while using ceramic wastes in the process of producing Khorasan mortar

Numerical evaluation of reinforced concrete slabs with fixed support under impact load

Reinforced concrete (RC) structural members may be subjected to impact load besides quasi-static load or other dynamic loads like earthquake and wind loads in their service periods. Many research emphasized that although impact load acts on structural members for a short time, it caused considerable damage to these members or even collapses the whole structure. Thus, it becomes crucial to consider and accurately evaluate the impact load effect in the design process. The present study intends to introduce a finite element model (FEM) verified with the test data for the accurate evaluation of load-deflection behavior and damage patterns of the fixed supported RC slabs exposed to impact load. First, a nonlinear FEM including strain-rate effect for both concrete and steel reinforcement, and crack visualization algorithm has been established by using LS-DYNA software. Then, the dynamic responses obtained by the present FEM have been compared with the experimental data presented in a previous study existing in the literature and it is found that the present FEM yields accurate results for the RC slab subjected to impact load and it can be safely used in the design process. In the second part of the study, using the verified FEM, the effects of applied input impact energy, the application point of impact load, and hammer geometry on the dynamic responses and failure characteristics of the RC slabs exposed to the impact loading were investigated and interpreted in detail

On the evaluation of lateral-torsional buckling of web-tapered cantilevers with doubly symmetric I-section

Recently, structural engineers have tended to design stronger and lighter structures due to economic reasons, technical developments in computer-aided design, and improvements in manufacturing. The demand for designing stronger and lighter structures has led to the compulsory considering structural efficiency and stability loss at the design level. Lateral-torsional buckling (LTB) is a major stability loss for web-tapered cantilevers with doubly symmetric I-section, which are aesthetic and structurally efficient. The elastic LTB loads of these cantilevers should be calculated at the design level since the LTB may happen before bending stress reaches yield. Studies related to the LTB of cantilevers are rare and require numerical solutions since the LTB mode shape of cantilevers is complex compared to simply supported beams. The present study introduces an analytical procedure based on the energy method for calculating elastic LTB of web-tapered cantilevers with doubly-symmetric I-section in two different forms. The analytical model considers different transverse load types, positions of loads, and web tapering degrees. The analytical solutions were validated with one-dimensional finite element analysis using a beam element. Excellent accordance between results was demonstrated. The general LTB behavior of web-tapered cantilevers with doubly symmetric I-section was clarified with detailed comments based on results obtained from the presented analytical model

Effect of steam‒curing on the glass fiber reinforced concrete

Due to the increased need to use precast concrete to reduce construction duration and to accelerate the cement reaction process to achieve the required concrete resistance that enables the elements to gain the required strength to handle the loads generated by the transportation process, many companies use steam curing methods to expedite the hydration process. The steam curing process negatively affects the concrete strength, especially in the long term. Fibers of different types are used to improve the interior composition of concrete and increase its crack resistance. The purpose of the current study was to determine the effect of the glass fiber on the behavior of steam-cured concrete. In this study 90 concrete cubes were used with 15cm dimensions, three different weight ratios of glass fibers (0%, 0.12%, and 0.24%) with two curing methods standard curing in the water tank (water curing - WC) for 3, 7, and 28 days, and steam curing (SC) for 4 and 8 hours. Nine specimens of each mix were cast in 12 mm, and 24 mm fibers length and tested for each curing duration and method. The results of this study indicate that fiber glass addition to the steam-cured concrete has a positive effect on the concrete unit weight and the ultrasonic pulse velocity. Moreover, the result showed that the tensile and compressive strength of the concrete has been positively affected by the length of the fiber more than the fiber weight percentage

Effect of waste steel tire wired concrete on the mechanical behavior under impact loading

In this experimental study the effect of waste steel tire wire was investigated on the concrete bollards of mechanical behavior under impact loading. Concrete bollards were produced using three different dimensions with three different volumes of waste steel tire wire (0%, 5% and 10%). The concrete was 30 MPa strength. The concrete bollards were cast into molds with a size of 100x100 mm, 150x150 mm and 200x200 mm and standard length of 1100 mm prism. Nine cube specimens of three different dimensions are tested. 84 kg of an impact load is used with the drop height of 400 mm in this study. Compressive strength tests were achieved. Concrete bollards were kept in laboratory standard conditions. According to the results of study compressive strength of the concrete vary between 25-30 MPa. The use of waste steel tire wire in the concrete bollards contributes to the less crack, less deflection, more acceleration and more energy dissipation at the end of the specimens. The experimental test aimed to research the effect of waste steel tire wired concrete on the mechanical behavior under impact loading as a possible environmentally friendly and sustainable solution. It can be said that the results provide the potential usage of waste steel tire wire manufacturing friendly to nature and sustainability of the concrete bollards. Generally, the usage of waste steel tire wire in concrete could be an innovative method in the construction industry

Mechanical behavior investigation of rubberized concrete barriers in impact load

Approximately 1.5 million waste tires are produced annually. Waste tires in landfills and stocks cause toxic chemicals to pollute the soil and cause major fires. Waste tires are a global environmental problem. This problem gave an idea of recycling of waste tires instead of landfills and stocks. In this paper, an experimental study is conducted to review the behavior under impact load of rubberized concrete with conventional concrete. Three different mixes were made by adding crumb rubber (0%, 5% and 10%) by volume to the concrete. Nine cantilever column specimens of three type cross section (10x10, 15x15 and 20x20 cm2) were used to investigate the behavior under impact load. The specimens with higher rubberized concrete have longer impact load duration at the initial peak point. Specimens with rubber content become much flexible than normal specimens. Furthermore, the damage level of columns is greater with increasing rubber content. Therefore, the specimens with higher rubberized concrete absorb more impact energy. The barriers with higher rubber content minimize injury and demise when an accidental impact happens. Using concrete with rubber content reduces costs and produces an environmentally sustainable solution