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Bu çalışmada endüstriyel işlem sonrası açığa çıkan atık poliüretanın hafif harç imalatında kullanımı araştırılmıştır. Hali hazırda hafif harç üretiminde kullanılan EPS (Expanded polystyren foam) ve atık poliüretan kullanılarak hafif harç numuneler üretilmiştir. Üretilen numuneler eşdeğer birim ağırlıklarına göre karşılaştırılarak, atık poliüretanın hafif harç imalatında kullanımı araştırılmıştır. Çalışma kapsamında EPS ve atık poliüretan agrega ile hacimce %20, %40, %60, %80, %100 oranlarında yer değiştirilerek kullanılmış ve 40x40x160 mm’lik prizmatik harç numuneler üretilmiştir. Üretilen harç numunelerin birim ağırlık değerleri, ultrasonik atımlı dalga hızları, ısı iletkenlik katsayıları ile eğilme ve basınç dayanımları ölçülmüştür. Ayrıca hem EPS hem de atık poliüretan ile üretilmiş harç numuneler 300⁰C, 600⁰C, 900⁰C’de yüksek sıcaklığa tabi tutulmuş ve sonrasında numunelerin mekanik dayanımları ile içyapıları incelenmiştir. İçyapı incelemeleri hamur numuneler üzerinde FESEM görüntüleri ile gerçekleştirilmiştir. Elde edilen verilere göre hem orta mukavemetli hafif beton sınıfına giren harçlarda, hem de taşıyıcı hafif beton sınıfına giren harçlarda atık poliüretan ile imal edilen harçların EPS’li harçlara göre daha iyi performans gösterdiği sonucuna varılmıştır. Özellikle yüksek sıcaklık sonrası mekanik dayanımlar incelendiğinde atık poliüretanlı harç numunelerin, EPS’li numunelere oranla daha yüksek eğilme ve basınç dayanımları verdiği tespit edilmiştir.

In this study, in order to observe the mechanical and physical properties of normal screed, sandy-lightweight screed and lightweight screed samples, expanded polystyrene (EPS) was used as fine aggregate and lightweight screed systems was produced by replacing sand at 100%, 50% and 0% by weight. Samples of cement dosages of 250, 300, 350 kg/m3 were produced for lightweight screeds, sandy-lightweight screeds and normal screeds. Unit weight, water absorption capacity, flexural strength, compressive strength, fire resistance, abrasion and thermal conductivity tests were performed on the produced screed systems. As a result of the research, it was determined that as EPS ratio increases in screed system; unit weights decreased, water absorption rates increased. Besides, the flexural and compressive strengths, fire and abrasion resistance are also decreased. However, it was observed that the thermal conductivity coefficient reduced with the increment of EPS particles in the screed. In normal, sandy-lightweight and lightweight screeds, it was determined that as the cement dosage increased; the unit weights, flexural and compressive strengths, fire and abrasion resistance increased, water absorption capacity and the thermal conductivity coefficient decreased.

There are very few studies in the literature on the usage of CKD in cementitious systems. This article presents the laboratory study results on the influence of cement kiln dust (CKD) on the properties of mortar made with cement kiln dust and Portland cement. The article aims to prevent CKD's (known as a hazardous waste product) damage to nature by utilizing CKD in cementitious systems and contributing to sustainability by reducing cement amount in the cementitious system. For this purpose, 5%, 10%, 15%, and 20% of CKD were replaced with cement and binary cementitious systems were formed. For all mortar mixes, the water/binder ratio was kept constant at 0.5, and the sand/binder ratio was 3. Workability, dry unit weight, water absorption ratio and porosity, flexural strength, compressive strength, abrasion, carbonation, and high-temperature resistance tests were performed on the mortar specimens. Based on the results of laboratory work, it was observed that the replacement of CKD with cement reduces the workability of fresh mortar. Compressive and flexural strengths of CKD-added mixtures were found to be equivalent or insignificantly lower than that of the control sample. The addition of CKD had a negligible effect on water absorption and porosity of samples. Besides, the residual compressive strength determined after the elevated temperature test for the sample made with CKD were found to be equivalent or higher compared to the control sample. Present laboratory studies showed that utilization of CKD in cementitious mortar system is feasible in terms of testing conducted.

Bu çalışmada alkali ile aktive edilmiş cüruflu harçlarda ırmak kumu ile EPS (Genleştirilmiş polistiren) ikameedilerek hafif harç numuneleri üretilmiştir. EPS granülleri ırmak kumu ile hacimce yüzde 20-40-60-80-100oranlarında yer değiştirilerek karışıma dâhil edilmiştir. Çalışmada aktivatör olarak sodyum silikat kullanılmış veüretilen numuneler 28 gün havada kür edilmiştir. Kür süresini dolduran alkali ile aktive edilmiş cüruflu harçlarınbirim ağırlık, ultrasonik atımlı dalga hızı, ısı geçirimlilik özellikleri ile eğilme ve basınç dayanımları belirlenmiştir.Ayrıca 28 gün kür süresi sonrası 300⁰C, 600⁰C ve 900⁰C sıcaklıklara maruz bırakılan numunelerin yüksek sıcaklığakarşı dirençleri ve içyapı özellikleri araştırılmıştır. Elde edilen sonuçlara göre EPS ikamesi ile numunelerin birimağırlık, ultrasonik atımlı dalga hızı değerleri ile eğilme ve basınç dayanım değerleri düşerken, yalıtımperformansının ise arttığı görülmüştür. Irmak kumu ile ikame edilen EPS miktarı arttıkça numunelerin eğilme vebasınç dayanımlarında meydana gelen kayıplar artmıştır. Ayrıca EPS ikame oranı arttıkça özellikle 600⁰C ve 900⁰Csıcaklık sonrasında basınç dayanımlarında ciddi oranda kayıplar yaşanmıştır. Buna paralel olarak yüksek sıcaklıketkisine maruz kalan numunelerin içyapıları daha boşluklu ve çatlaklı bir yapıya dönüşmüştür.&nbsp

It is known that nano-and microparticles have been very popular in recent years since their advantages. However, due to the very small size of such materials, they have very high tendency to agglomeration particularly for nanoparticles. Therefore, it is critical that they are properly distributed in the system to which they are added. This paper investigated the effects of dry particle coating with nano-and microparticles to solve the agglomeration problem. For a clear evaluation, paste samples were preferred to detemine the compressive strength. Nano-SiO2and nano-CaCO3, micro-CaCO3and micro-SiO2, also known as silica fume, were selected as particulate additives. It was studied by the addition of various percentages (0.3, 0.7, 1, 2, 3 and 5%) of nano-and microparticles in cementitious systems, replacing cement by weight with and without dry particle coating. Dry particle coating was made by using a high-speed paddle mixer. Portland cement and additive particles were mixed at 1500 rpm for 30 seconds in high-speed powder mixer designed for this purpose. The 3-day compressive strength of the cement-based samples to which particles were added at the specified rates was determined and the effect of the dry particle coating on the early strength was investigated. According to the results, it was observed that the production of paste with the dry particle coating technique gave higher compressive strength compared to the production of paste directly in early period. Especially with dry particle coating, compressive strength increased more than 100% in paste samples containing 0.3% nano-SiO2compared to direct addition without coating.

In this study, the determination of flexural tensile strength of concrete kerbstone is investigated. Currently, the flexural tensile strength of concrete kerbstone is determined using simple bending formula. However, due to the unsymmetrical cross-section of kerbstone, the bending take place on the section of kerbstone is not simple bending but bi-axial bending. The study shows how the flexural tensile strength for unsymmetrical sections should be determined. Additionally, flexural strength results obtained using the simple bending formula suggested by certain specifications and bi-axial bending formula used in the study were compared. As a result of the study, it was found that bi-axial bending formula gave higher values than that of the simple bending formula., Bu çalışmada, beton bordür taşının eğilmede çekme dayanımının belirlenmesi konusu araştırılmıştır. Günümüzde, beton bordür taşının eğilmede çekme dayanımı, basit eğilme formülü kullanılarak belirlenmektedir. Ancak, bordür taşının simetrik olmayan enine kesitinden dolayı, bordür taşı kesitinde meydana gelen eğilme, basit bir eğilme değil, iki eksenli bir eğilme olmaktadır. Çalışma da, simetrik olmayan kesitler için eğilmede çekme dayanımının nasıl belirlenmesi gerektiği teorik olarak gösterilmiştir. Ek olarak, standartların önerdiği basit eğilme formülü ve çalışmada kullanılan iki eksenli eğilme formülü kullanılarak elde edilen eğilme dayanımı sonuçları karşılaştırılmıştır. Çalışma sonucuna göre, iki eksenli eğilme formülü ile basit eğilme formülüne göre daha yüksek eğilmede çekme dayanımı değerleri elde edildiği tespit edilmiştir.

In this study, fly ash-based geopolymer light mortars were produced using expanded polystyrene (EPS). EPS aggregated geopolymer mortars were produced by replacing the river sand with 20%, 40%, 60%, 80%, 100% by volume. Geopolymer mortars with EPS were subjected to a temperature heat curing at 75 ° C for 24 and 48 hours by activating the F class fly ash with NaOH at a fixed rate. Physical properties, mechanical properties, and thermal conductivity properties of geopolymer lightweight mortar samples after heat curing were investigated. In addition, the flexural, compressive strength of geopolymer mortars after high temperatures at 300 ° C, 600 ° C, 900 ° C, and the microstructure of geopolymer pastes were investigated. According to the results, the unit weights of light geopolymer mortars subjected to 24 hours of heat curing are between 1.93 and 0.61 g/cm3, and the unit weights of light geopolymer mortars subjected to 48 hours of heat curing are between 1.87 and 0.66 g/cm3 has been seen. The compressive strength loss of geopolymer mortars with 20% and 40% EPS replacement (EUK 20, EUK40) after the high temperature was determined to be less than the reference geopolymer sample. The porous structure that causes loss of strength after high temperature and NASH gel structure that maintains the existing strength are displayed in FESEM images. Highly linear between unit weight and compressive strength (R2 = 0.9191), heat transmission coefficient (R2 = 0.9787), ultrasonic transmission velocity (R2 = 0.9082), and split tensile strength (R2 = 0.9191) It has been concluded that there is a relationship., Bu çalışmada genleştirilmiş polistiren (EPS) kullanılarak uçucu kül tabanlı geopolimer hafif harçlar imal edilmiştir. EPS hacimce %20, %40, %60, %80, %100 oranlarında ırmak kumu ile yer değiştirerek, EPS agregalı geopolimer harçların üretimi gerçekleştirilmiştir. EPS’li geopolimer harçlar, F sınıfı uçucu külün sabit oranda NaOH ile aktive edilmesiyle, 75 °C’de 24 ve 48 saat sıcaklık kürüne tabii tutulmuştur. Sıcaklık kürü sonrası geopolimer hafif harç numunelerin fiziksel özellikleri, mekanik özellikleri ve ısıl geçirimlilik özellikleri araştırılmıştır. Ayrıca 300 °C, 600 °C, 900 °C’de yüksek sıcaklık sonrası geopolimer harçların eğilme, basınç dayanımları ve geopolimer hamurların mikro yapısı incelenmiştir. Elde edilen sonuçlara göre 24 saat sıcaklık kürüne tabii tutulan hafif geopolimer harçların birim ağırlıkları 1,93 ile 0,61 g/cm3 arasında, 48 saat sıcaklık kürüne tabii tutulan hafif geopolimer harçların birim ağırlıkları 1,87 ile 0,66 g/cm3 arasında olduğu görülmüştür. Yüksek sıcaklık sonrası %20 ve %40 EPS ikameli (EUK 20, EUK40) geopolimer harçların basınç dayanımındaki kayıp oranları, referans geopolimer numuneye göre daha az olduğu belirlenmiştir. FESEM görüntülerinde yüksek sıcaklık sonrası dayanım kaybına yol açan gözenekli yapı ve mevcut dayanımı devam ettiren NASH jeli yapısı görüntülenmiştir. Birim ağırlık ile basınç dayanımı (R2=0,9008), ısı geçirgenlik katsayısı (R2=0,9787), ultrasonik geçiş hızı (R2=0,9082), ve yarmada çekme dayanımı (R2=0,9191) arasında yüksek oranda doğrusal ilişki olduğu sonucuna ulaşılmıştır.

This study presents the resistance of sodium meta-silicate activated ground granulated blast furnace slag (GGBFS) to acidic and basic mediums.Geopolymer mortars were prepared with GGBFS activated by sodium meta-silicate activator having 4, 8, and 12% sodium concentrations by mass ofslag. These mortars were exposed to two types of acid solutions, H2SO4 and HCl with a 5% concentration of acid-water solution. Similarly, somespecimens were exposed to a basic medium composed of 25% NaOH solution with water. Exposure time for the acidic and basic mediums was setto one year. Comparison of results obtained from slag based geopolymer mortar was made with normal Portland cement control mortar. Normalcontrol samples lost compressive strength significantly after exposure to acidic and basic medium in comparison to alkali activated slag mortar.Particularly, after exposure to H2SO4, the compressive strength of the normal control samples decreased by about 40%. Contrary to this, the slagbased geopolymer mortar gained compressive strength after exposure to the acidic or basic mediums. An up to 21% strength increase was observedfrom the alkali activated slag mixtures made with 4% and 8% Na content.&nbsp

U radu se analizira alkalno aktiviranje mješavina morta koje sadrže mljevenu granuliranu zguru iz visokih peći i leteći pepeo, pri čemu se aktivacija odvija pomoću natrijevog metasilikata. Analiziraju se dvije serije te je izmjerena tlačna čvrstoća. Rezultati dobiveni za prvu seriju pokazuju da se tlačna čvrstoća bitno smanjuje sa smanjenjem omjera zgure i letećeg pepela. Trodnevna tlačna čvrstoća morta njegovanog pri temperaturi 100 °C donekle se povećava do omjera 60/40, ali se bitno smanjuje pri omjeru 40/60., The alkali activation of mortar blends containing Ground Granulated Blast Furnace Slag and Fly Ash, with activation based on sodium metasilicate, is investigated in this study. Two series are investigated, and compressive strength is measured. The results of the first series show that the compressive strength decreases considerably with a decrease in the slag and fly ash ratio. The 3-day compressive strength of mortar cured at the temperature of 100°C increases slightly up to the ratio of 60/40, but decreases considerably at the 40/60 ratio.

Behaviour of construction materials i.e. steel, concrete and mortar under elevated temperature is important. In the study, the variations in mass loss, and strengths of polypropylene fiber reinforced mortar subjected to elevated temperatures were examined. Mortar was made with CEM I 42.5R Portland cement, monofilament polypropylene fiber, fine aggregate and drinkable water. The sand-cement and water-cement ratio were chosen 3:1 and 1:2 for all mixtures, respectively. Mixes containing 0, 0.1, 0.2 and 0.3% polypropylene fiber in volume of solid matter of mixture were prepared. Mortars were exposed to 100, 200, 400, 600 and 800 degrees C temperatures and cooled down 23 +/- 2 degrees C in air and water. There was a difference between the temperatures at which the important reductions observed for flexural tensile and compressive strength. Significant reduction was observed at 400 degrees C for compressive strength and while it was 200 degrees C for flexural strength. No difference was observed between air cooling and water cooling regimes up to 600 degrees C; however, at 800 degrees C the residual compressive and flexural strength of water cooled mortar was about 40% of the air cooled mortar. Mortar containing polypropylene fiber presented better behaviour to elevated temperature in terms of relative residual strengths up to 400 degrees C.

The demand forcement usage increases in the world, currently. It is known that using industrial waste materials in concrete as cement or aggregate replacement as part of waste management as well as conserving natural resourcesis getting wider. Due to thesefacts, in this work, an investigation was carriedout on the utilization of waste marble powders as cement replacement mineral materials. In this context, marble powder replaced cement at 5%, 10%, 15% and 20% in mass basis, and mortars were produced. In mortar mixtures, water-binder ratio was chosen as 0.5, and sand-binder ratio was taken as 3. Workability of fresh mortar was measured. Unit weight, water absorption,and porosity, compressive and flexuralstrengths, abrasion, carbonation and drying shrinkage measurements testing were carried out on hardened mortar specimens. Influence of elevated temperature on hardened mortar mixture was also investigated. As a result of laboratory study, it is concluded that replacing marble powder with cement result with a favourable contribution to workability of freshmortar, as well as resistance to elevated temperature. It also reduced drying shrinkage of mortar in comparison to reference mortar made without marble powder. However, it influenced water absorption, abrasion,and carbonation resistance of mortar, unfavourably. For short term curing duration, replacement of marble powder with cement reduced compressive strength insignificantly for 5% and 10%marble powder replacement, but,reduced itsignificantly for 15% and 20%. However, at long term curing at 90 days, the difference between strength of reference mortarand marble containing mortar was diminished, particularly formortar containing 5% and 10% marble powder

In this study, the influence of a pre-rest period before heat curing (as a new parameter), on the physical properties, flexural and compressive strength, and microstructure of geopolymer mortars and pastes produced with alkali activation of fly ash were investigated. In this context, geopolymer mortar and paste samples were prepared and pre-rested under laboratory conditions for 0, 1, 2, 3, 7, 14, and 28 days before heat curing. After the pre-rest period, the samples were subjected to heat curing at 75°C in an oven, for 2 days. Mortar and paste samples exposed to a pre-rest period while in the fresh state before heat curing were compared with control samples without pre-resting. Water absorption, porosity, specific gravity, capillarity, flexural strength, compressive strength, and abrasion resistance tests were conducted on the geopolymer mortar samples. A reaction kinetics study using an isothermal calorimeter, XRD, and SEM analyses were performed on the geopolymer paste samples for microstructural investigations. Based on the results obtained, it was observed that the mechanical strength of the samples subjected to the pre-rest period before heat curing increased considerably compared to the reference (without pre-resting) samples. In addition, because of pre-resting, the capillarity coefficient, water permeability, and porosity of the samples decreased compared to the reference samples, and it was concluded that pre-resting improves durability-related properties. Moreover, the reaction kinetics and SEM analysis results, supporting the above findings, showed that a pre-resting period increases the geopolymeric reaction products and causes a denser microstructure.

In the study, the influence of heat curing duration and rest period after heat curing duration on the strength and transport characteristics of alkali activated fly ash (AAFA) mortar were investigated. A local class F type fly ash, CEN reference sand, sodium hydroxide and potable water were used in preparation of cement-less fresh geopolymer mortar mixture. Mixture ratios (in mass basis) were 3, 1, 0.29, and 0.1 for sand, fly ash, water and sodium hydroxide, respectively. Some samples were cured at 75 degrees C temperature for 4 h, 1, 2, 3 and 7 days; then, they were tested after heat curing period. Additionally, some of the equivalent samples were kept in the laboratory at 23 +/- 2 degrees C temperature with 50 +/- 5% relative humidity, until 28 days after their initial heat curing period. Then, they were tested at 28 days for combined curing conditions. The measured properties of AAFA mortar were unit weight, porosity, capillary water absorption, water absorption capacity, flexural-bending and split tension strength, compressive strengths and abrasion resistance. It was observed that the strengths of mortar were significantly increased with the increase in heat curing duration. A significant strength development was also observed after rest period. As a result of the study, high strength and abrasion resistant AAFA geopolymer mortar was produced. However, transport properties of AAFA geopolymer mortar found to be not as good as mechanical properties. (C) 2017 Elsevier Ltd. All rights reserved.

In this laboratory work, high compressive and flexural tensile strength of alkali activated fly ash geopolymer mortars were presented. Class F fly ash was used throughout the study. NaOH was used as alkali medium that provides high pH value. Also, the factors influencing the compressive and flexural tensile strength were investigated. A total of 216 fly ash geopolymer mortar samples were prepared. Heat curing temperature, heat curing duration and alkali (Na) concentration were chosen as the influencing parameters of strengths. Mortar mixture parameters were 3 and 1/3 for sand-binder ratio, and water-binder ratio, respectively. Na concentrations of the mortar mixtures were changed from 4% to 20% with 2% increment step. Heat curing temperatures were changed from 45 to 115 degrees C with 10 degrees C increment step. Heat curing durations were chosen as 24, 48 and 72 h. For each combination of influencing parameter, three prismatic specimens with 40 mm x 40 mm x 160 mm dimensions were prepared using a three-cell mortar cast. After heat curing period in a laboratory oven, the samples were left to cool down to room temperature, then compressive and flexural strengths were measured as described in its respective standard. Very high compressive and flexural tensile strength obtained, which were as high as 120 and 15 MPa respectively. (C) 2015 Elsevier Ltd. All rights reserved.

This paper reports the results of an investigation on the influences of admixtures and curing conditions on some properties of Alkali-Activated Slag (AAS) mixtures with no cement. In the study, Shrinkage-Reducing (SRA) and superplasticizing and setretarding (WRRe) admixtures were used. For the slag activation, sodium metasilicate was used at two sodium concentrations, 4% and 6% by mass of slag. Setting time, flow loss of fresh mixtures, and shrinkage strain, carbonation, flexural and compressive strength of hardened mixtures were measured. The test results showed that the admixtures generally had no impact on the setting times of AAS pastes. WRRe increased the flow rate of AAS mortars while SRA partially affected the flow values of AAS mortars. WRRe and SRA did not produce an important difference on the carbonation depths of AAS mortars. However, WRRe and especially SRA admixtures decreased the shrinkage values of AAS mortars. Additionally, curing conditions had a significant effect on the mechanical behavior in the hardened state of AAS mortars compared to Normal Portland Cement (NPC) mortars, and the strength development of AAS mortars at early ages was very fast in comparison with NPC mortars when subjected to elevated temperature.

This paper presents the influence of shrinkage-reducing (SHR) and superplasticizing and set-retarding admixtures (SSRe) on the properties of slag pastes and mortars activated by liquid sodium silicate with different dosage and modulus ratio. Properties in the fresh and hardened state for these binders were investigated by means of measuring some properties including setting time, flowability, flexural strength, compressive strength, carbonation and shrinkage. In this study, fifteen pastes and mortars were prepared. Liquid sodium silicate was used to activate the slag at two sodium concentrations, 4% and 6% by mass of slag. Liquid sodium silicate and sodium hydroxide were blended to obtain 0.75 and 1 modulus ratio of SiO2/Na2O. Results showed that although the higher percentage of sodium in the activator produced a higher strength, workability and setting times rapidly decreased with the higher sodium concentration due to instantaneous reaction and quick hardening of slag activated by liquid sodium silicate. None of the admixtures generally had an impact on the setting times of alkali-activated slag (AAS) pastes. SSRe admixture increased the flow rate of AAS mortars while SHR admixture partially affected the flow values of AAS mortars. SHR admixture exhibited a slight decrease in the carbonation depths of AAS mortars. SSRe and particularly SHR chemical admixtures reduced the shrinkage of AAS mortars. However, the shrinkage values of AAS mortars still were higher than those of ordinary Portland cement (NPC) mortars. Curing conditions had a significant effect on the mechanical behavior in the hardened state of AAS mortars compared to NPC mortars. (C) 2012 Elsevier Ltd. All rights reserved.