Theses supervised by Tülin Akçaoğlu
10 theses · Eastern Mediterranean University
Effects of Limestone Powder, Olive Waste Ash and Sea Sand Powder on Properties of Self Compacting Concrete
Utilization of standardized local and waste resources is of great importance to the economic development in the world. Besides, application of waste material results in more eco-friendly concrete at the same time. In this study, the effects of two different new fillers, named as sea sand powder (SS), as a local available material and olive waste bottom ash, (OW) as a waste material of different proportions incorporated with two different quantities of superplasticizer (SP), on physical and mechanical properties of SCC were aimed to be investigated and compared to those of limestone powder (LS) as a common filler. For these aimes rheology of fresh concrete, compressive and tensile strengths, initial defects, fracture energy and volume changes during hydration were measured. Results showed that there is no considerable difference in hardened properties of SCC by using SS instead of LS; however, differences in volumetric shrinkage and rheological properties, especially for bleeding and segregation, were more pronounced. On the other hand, OW mixes show different outcomes. OW gives more viscosity to SCC mixes and eliminates segregation and bleeding of the mixes containing this filler. Nevertheless, reduced compressive strength and fracture energy and increased volumetric shrinkage and porosity in these mixes were noticeable compared to LS mixes; however, when 5% OW was used, the results found to be more tolerable. Keywords: Self-consolidated concrete, Olive waste ash, Sea sand powder, Limestone powder, Compressive strengths, Fracture energy
Influence of Matrix Quality and Environmental Conditions on Volume Change and Microcracking Behavior of Concrete
Concrete is a highly complex and heterogeneous engineering material. In its complex composite structure, it is not easy to understand its behavior either during hydration process or loading the material. Particularly the volume change during hydration results in initial defects and at the end these defects may influence its mechanical behavior under load. Individual properties of different phases like aggregate, matrix and the interfacial transition zone (ITZ) between the two, plays an important role on the microcracking behavior of the concrete. In this study, various techniques were used in determining the effect of hydration shrinkage crack on the microcracking behavior of the concrete including w/c ratio, silica fume and environmental conditions. Direct measurement by means of optical processing through Scanning Electron Microscope (SEM) is a way. On the other hand, the indirect measurements dealt with an overall study of the material by means of the tensile and the compressive strength measurements, the length and the volume change measurements and the prediction of the critical crack load from stress-strain diagrams. Conclusions were drawn from the direct and the indirect methods. The ultimate purposes of all the performed tests were used to measure the initial defects either in the ITZ or the matrix and their effect on the whole microcracking behavior of concrete. Keywords: SEM, ITZ, Cracks density, Compressive strength, Tensile strength, Volume change, Shrinkage.
Effects of Waste Marble and Glass Powders on Concrete Properties and Performance
Concrete, consisting primarily of cement, water and aggregates, is the most used construction material all over the world and plays an important role in the growth of infrastructure and industrial sectors. Cement manufacturing industry is one of the carbon dioxide producing sources that is caused global warming. However, using the waste materials and by-products as cement replacement materials become an attractive alternative because it helps to reduce the cost of concrete and cement manufacturing, also has numerous indirect benefits such as saving energy, reducing landfill cost and protecting the environment from possible pollution effects. Nowadays, marble dust and waste glass powders are two of the most polluting waste materials for the world environment. For this reason, in this thesis; the marble dust (MD) was examined as a partial cement replacement material with seven proportions as 0%, 10%, 20%, 30%, 40%, 50%, 60% and the glass powder (GP) was used as an additive material, 8% by cement weight, in a 0.55 water-binder ratio (w/b) concrete. Finally; experimental results indicated that MD can be used as a cement replacement material up to 10% replacement and with the use of GP both physical and mechanical properties of concrete can be improved. Keywords: Concrete, Marble dust, Glass powder, Cement replacement materials, Mechanical properties, Workability, Durability, Compressive strength, Sulphate resistance.
Effects of Waste Glass as a Partial Replacement of Coarse Aggregate on Concrete Performance
[Abstract Not Available]
Effects of Glass Powder as a Partial Cement Replacement on Mechanical Properties and Behaviour of Concrete
Concrete is the most used construction material all over the world and cement as the most valuable component in concrete affects both concrete price and quality. On the other hand, cement manufacturing industry is one of the carbon dioxide producing sources, that is caused global warming. However, using the waste materials and byproducts as cement replacement materials become an attractive alternative because it helps to reduce the cost of concrete and cement manufacturing, also has numerous indirect benefits such as saving energy, reducing landfill cost and protecting the environment from possible pollution effects. Nowadays, waste glass is one of the most polluting waste materials for the world environment. For this reason, in this thesis, the glass powder (GP) of waste glass was examined as a partial cement replacement material in concrete with five different proportions (0%, 10%, 20%, 30% and 40%) for three water-binder ratios (w/b) (0.4, 0.5 and 0.6). Finally, experimental results indicated that GP can be used as a cement replacement material and it can improve both physical and mechanical properties of concrete for all three different w/b tested in this study.
Effects of Glass Powder as a Supplementary Cementitious Material on the Performance of High Strength Mortars
Concrete, is the most widely used engineering material in construction. Since around 11 billion tons of concrete is used each year all over the world, considerable amount of cement is required for its production. This results in high production of carbon dioxide which is one of the main reasons of global warming. Therefore, in the last few years, there is a growing interest in using waste pozzolanic admixtures as a supplementary cementitious material. Using these kind of admixtures as a part of cement replacement reduces the air pollution, cost and also enhances some properties of mortars and concretes. Among the other waste natural pozzolans, glass powder becomes important due to its high content of silica, availability and cost. These motivate lots of researchers to evaluate the effects of glass powder as a cement replacement material. In this study, effects of three different types (colors) of glass powders with different quantities used as cement replacement on the workability and mechanical properties of high strength mortars were evaluated. For this purpose, the flow table test for workability, flexural and compressive strength tests, modulus of elasticity measurement, rapid chloride test for permeability were performed to determine the effects of water binder ratio on high strength mortars performance. Moreover, the effect of curing temperature on the performance of high strength mortars modified with glass powders was also investigated. Finally, comparison is done between the results of control, silica fume and glass powder specimens. It is important to note that glass powder addition as a pozzolanic material has a considerable influence on compressive strength and permeability at low water binder ratio specimens under high curing temperature. Keywords: glass powder, curing temperature, water-binder ratio, workability, compressive and flexural strength, modulus of elasticity, permeability
Effect of Supplementary Cementitious Materials on Mechanical Properties and Self-Healing Efficiency of Engineered Cementitious Composite
Concrete is considered as a fundamental construction material as it has high compressive strength and fairly low cost. However, brittleness behavior and limited tensile strength can be remarkably observed in conventional concrete and accordingly, crack formation easily occurs. Many researchers have dedicated considerable efforts to adjust the brittleness characteristic and other weak points of conventional concrete and thus, they come up with the development of a new type of concrete, which is named engineered cementitious composite (ECC). In this experimental study, it is aimed to investigate the effects of replacing slag (S) 100% with fly ash (FA), in different proportions with limestone powder (LSP), and glass powder (GP); on workability, mechanical properties, microcracking behavior and self-healing efficiency of ECC. For this purpose eight different ECC mixtures were prepared; at first reference sample is produced with a certain amount of cement and slag as a binder, then slag is replaced 100% with fly ash, 5, 20 and 40% with LSP and 20, 40 and 60% with GP by total mass of slag. In order to determine and compare the effects of slag, fly ash, LSP and GP on workability, mechanical properties and behavior and self-healing efficiency of ECC; flow test, compressive and splitting tensile strength tests at different compressive loading levels, stress-strain diagrams tests under compression were conducted. In addition, self-healing efficiency of eight different ECC produced were determined by means of ultrasound readings and stereomicroscope measurements. Here, cracks were created on the surface of specimens by preloading them up to ultimate splitting tensile strength. After that, microscope and ultrasonic test were utilized to observe and determine the self-healing recovery rate. Overall, replacing slag with LSP up to 5% and with GP up to 20% displayed significant improvement on mechanical properties of ECC and a high relative comparative of self-healing efficiency with ECC-Ref. Calcium carbonate and C-S-H gels were observed to be the prominent healing products.
Effects of Polypropylene Waste Plastic as a Replacement to Coarse Aggregate on Mechanical Behavior of Self Compacting Concrete
In recent years, the usage of recycled plastic aggregates as a replacement to aggregate has been taken into consideration to decrease the environmental effects of both concrete and waste plastics. Recycled plastic aggregate concrete, has come to be recognized as a distinctly promising technology capable of making useful contributions to resource performance in the production industry This thesis outlines an experimental study on the physical and mechanical properties of 0.45 w/b self-compacted concrete (SCC) manufactured using recycled polypropylene (PP) waste plastic as a replacement to natural coarse aggregates. It analyzes the effects of five different percentages (0, 5, 10, 15, 20 and 25%) of PP as a replacement to natural coarse aggregates on compressive strength, flexural strength, splitting tensile strength, workability, weight, ultrasonic pulse velocity and flexural toughness of SCC. It also studies the weight loss, pulse velocity, compressive, splitting and flexural strength changes, when specimens are exposed to two different temperatures as100℃ and 200℃. Experimental results show that; SCC mechanical and physical properties decreased with increased PP percentage up to 25%, because the mechanical and physical properties of SCC concretes, incorporated with PP are lower than those of concretes formed with natural aggregate. Polypropylene aggregates at high level (25%), has a positive effect on flexural toughness because they were used in small sizes, which could improve flexibility. Keywords: Self Compacted Concrete, Polypropylene waste plastic, lightweight aggregate, compressive strength, splitting tensile strength, flexural strength, workability, flexural toughness, Heat degradation.
Effects of Polyvinyl Chloride as a Partial Aggregate Replacement on Mechanical Properties and Behavior of Self Compacted Concrete
These days, concrete is one of the main construction materials used the world ever. Aggregates are considered the most important component of concrete volume because they account for three quarters of the volume of any normal concrete. All over the world, more than 22 million tons of polyvinyl chloride (PVC) are presently produced per year. Such a large level of PVC production has a negative effect on environmental pollution in the society. For this reason, in this thesis, the waste plastic light weight aggregate PVC was tested examined as a replacement for natural aggregate in six different percentages starting from 0, 10, 20, 30, 40 and 60%. The study also examined the production of self-compacting concrete (SCC) at a constant water binder ratio of 0.45, using Master Glenium 27 as 1.7% of the mixture and silica fume at 10% of the weight of the cement. The workability of the SCC was tested with L-box, V-funnel flow time and slump flow methods. Results showed that the PVC plastic content successfully achieved SCC until a 60% ratio. They also show that, the use of PVC waste plastic as a partial replacement of natural aggregate has negative effect on the physical and mechanical properties of concrete, including: flexural strength, compressive strength, splitting tensile strength, weight, and ultrasound pulse velocity before and after degradation.
Effect of W/C Ratio and Replacement Materials on Fracture Behavior of Concrete - Via Computed Tomography Method
Nowadays, with the advancements in all fields of science and technology, use new numerical and experimental methods are made possible in the construction industry. X-rays and CT (Computed Tomography) scans are two of the direct methods developed to evaluate the microcracking behavior of concrete. The aim of this study was to evaluate the effect of water/cement ratio and mineral admixtures on microcracking behavior of concrete. For this purpose, total of 12 specimens were produced using three different w/c ratios and four different admixtures. To be able to determine the effects of these differences on both compressive strength and microcracking behavior, first the specimens were subjected to compressive stress loading and then to CT (Computed Tomography) scans to obtain 2D and 3D images. CT (Computed Tomography) scans were taken for different loading levels corresponding the ultimate strength. It was found that out of all specimens, the one containing metakaolin admixture with low w/c ratio has a considerable influence on the microcracking behavior of concrete under compressive stress loading. Although the crack rate of propagation is slow up to 80% of the ultimate stress, cracking accelerates after 80% of loading of metakaolin specimens.