Concrete structures cannot efficiently perform their functions over time due to chemical and physical external effects. Thus, enhancing the relationship between repair and aged structures, and also improving the durability properties of concrete is crucial in terms of sustainability. However, high costs, negative environmental effects, and incompatibility problems occur in repair/retrofit applications. Furthermore, three-quarters of the failures in the repaired/retrofitted structures are caused by a lack of repair durability. The need for repair in pavement/bridge decks is also frequently encountered, and early-age performance problems with repair materials cause pavement/bridge decks to be unavailable for certain periods of time. Engineered Cementitious Composite (ECC) can be effectively used as repair/retrofit and pavement/bridge deck material. It also has a minimal need for repair/retrofit thanks to its high durability properties. This article presents state-of-the-art research regarding the application of ECC as a repair/retrofit and pavement/bridge deck material. Studies in the literature show that the repair/retrofit properties of ECC outperform conventional concrete and steel fiber-reinforced concrete. ECC can be a solution to high early strength and drying shrinkage problems frequently encountered in the use of repair materials. It could also be used for different repair applications such as cast, sprayed, and trenchless rehabilitation. Moreover, ECC might fulfill specific requirements for pavement, pavement overlay, tunnel pavement, airfield pavement, and bridge deck. These superior performances are attributed to ECC’s kink-crack trapping mechanism, uniquely large inelastic strain capacity, strain hardening, high tensile strain capacity, and multiple microcracking and ductile behaviors, especially bonding behavior and self-healing.

Production of cement and aggregate used in cement-based composites causes many environmental and energy problems. Decreasing the usage of cement and aggregate is a crucial and currently relevant challenge to provide sustainability. Inert materials can also be used instead of cement and aggregates, similar to pozzolanic materials, and they have positive effects on cement-based composites. One of the inert materials used in cement-based composites is wollastonite (calcium metasilicate-CaSiO₃), which has been investigated and attracted attention of many researchers. This article presents state-of-the-art research regarding fibrous concretes produced with wollastonite, such as mortars, conventional concrete, engineered cementitious composites, geopolymer concrete, self-compacting concrete, ultra-high-performance concrete and pavement concrete. The use of synthetic wollastonite, which is a novel issue, its high aspect ratio and allowing the use of waste material are also evaluated. Studies in the literature show that the use of wollastonite in different types of concrete improves performance properties, such as mechanical/durability properties, and provides environmental–economic efficiency. It has been proven by studies that wollastonite is a material with an inert structure, and, therefore, its behavior is similar to that of a fiber in cementitious composites due to its acicular particle structure.

The acquisition and transportation of aggregate exacerbate the negative impact of concrete on the environment, and waste materials are considered an effective solution to this crucial problem. One of these waste materials is waste ballast (WB), which is needed for new infrastructure along with increasing rail track technology. In this study, the effect of WB aggregate (which is basalt-based) on the mechanical and durability properties of standard concrete was examined. Coarse aggregate was replaced with WB aggregate at the rates of 50%, 75% and 100%. The slump, compressive strength, flexural strength, capillary water absorption, rapid chloride permeability and water penetration tests on the mixtures were performed. According to the results of this study, the utilization of WB improved the compressive strength and flexural strength of the mixtures by about 15% and 7%, respectively. Moreover, the capillary water absorption, rapid chloride permeability and water penetration values of all the concrete mixtures with WB were lower than the control mixture. In addition, the correlation relations between the mechanical and durability properties indicated that they have a strong relationship with each other. All the results of this study demonstrated that the utilization of WB instead of coarse aggregate improved the mechanical and durability properties of concrete. WB can also provide a more sustainable material formation by minimizing the negative environmental effects of concrete production.

En tr This study has been carried out to investigate the effect of Osmaniye basic pumice on the workability characteristics of self-compacting concrete (SCC). Self-compacting concrete incorporated basic pumice (SCCB) with a constant water / binder ratio (cement + fly ash) of 0.32 was produced at a fixed slump flow diameter of 690±20 mm by adjusting the amount of High-Range-Water-Reducing-Admixture (HRWRA). First, control concrete without basic pumice was produced at a constant water/binder ratio and then basic pumice replacing the coarse aggregate in the proportions of 20%, 30%, 40%, 50% and 60% was added to the mixture. To identify effects of basic pumice on properties in the fresh and hardened state of SCCB, slump flow diameter, T₅₀₀ flow time, V-funnel flow time, L-box height ratio and 28-day compressive strength tests were conducted. Increasing amount of the basic pumice in the SCC resulted in a gradual decrease of workability. Therefore, SCCB has been manufactured by adding basic pumice up to 60%. Due to the specific weight of basic pumice lower than that of crushed stone, compressive strength of SCC showed a decrease of 23%. Bu çalışma kendiliğinden yerleşen beton (KYB) üretiminde Osmaniye bazik pomzasının işlenebilirliğe olan etkisini araştırmak amacıyla gerçekleştirilmiştir. Bazik pomza katkılı kendiliğinden yerleşen beton (KYBB) üretimi 0,32 sabit su/bağlayıcı (çimento + uçucu kül) oranında, 690±20 mm sabit bir çökme akışıyla, yüksek oranda su azaltıcı katkı (akışkanlaştırıcı) kullanılarak gerçekleştirilmiştir. İlk olarak bazik pomza hiç katılmaksızın kontrol betonu sabit su/bağlayıcı oranı ile dökülmüş ve daha sonra bazik pomza %20, %30, %40, %50 ve %60 oranlarında her defasında iri agreganın yerine ikame edilerek karışıma eklenmiştir. Bazik pomzanın KYBB’lerin taze ve sertleşmiş haldeki özellikleri üzerine etkilerini tespit etmek amacıyla taze haldeki betonun çökme yayılma tablasında akış çapı ve T₅₀₀ süresi, V hunisinde boşalma süresi, L kutusunda yükseklik oranı testleri ve 28 günlük basınç dayanımı testi yapılmıştır. KYBB’de kullanılan bazik pomza miktarı arttıkça işlenebilirliğin giderek azaldığı tespit edilmiştir. Bu nedenle en fazla %60 oranında bazik pomza kullanılarak KYBB üretilebilmiştir. KYB’nin basınç dayanımı ise bazik pomzanın özgül ağırlığının kırma taştan düşük olmasından dolayı %23 oranında bir azalma göstermiştir.

The utilisation of waste bricks (WB) and waste marble (WM) in engineered cementitious composites (ECCs), which are high-ductility fibre-reinforced cementitious composites, was investigated in this work. To produce sustainable ECC, WB and WM were used as cement and sand replacements, respectively. Nine ECC mixtures were produced and evaluated through tests for fresh properties, compressive and flexural strength, mid-span beam deflection and ultrasonic pulse velocity, along with microstructural analyses (Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy). The results showed that the irregular shapes of WB and the high surface area of WM reduced the workability of the ECC. WB reduced hydration products (calcium silicate hydrate and calcium hydroxide) owing to its low reactivity, which weakened the matrix and lowered its mechanical strength. The incorporation of WM resulted in enhanced mechanical strength owing to its effective filling of voids. WB enhanced ductility, with the highest value at 30% replacement, whereas WM caused a slight reduction. Microstructural tests confirmed that WB increased internal voids, while the incorporation of WM led to a denser structure. The combined use of WB and WM resulted in lower mechanical performance than their individual use owing to competing microstructural mechanisms. Based on the overall mechanical, microstructural and sustainability performance, the most favourable results were obtained by using 30% WB instead of cement and 100% WM instead of sand.

Günümüzdeki zorlu işletim koşulları göz önüne alındığında, traversler ve balastsız üstyapı sistemlerinde yeni nesil kompozit malzemelerin kullanımı önemli bir araştırma konusudur. Yüksek deformasyon kapasitesi ve üstün mekanik özelliklere sahip Tasarlanmış Çimento Esaslı Kompozitler (Engineered Cementitious Composites, ECC), bu alanda potansiyel bir çözüm sunmaktadır. Bu çalışmada, ilk kez Atık Tuğla (AT), Atık Mermer (AM) ve farklı uzunluklarda hibritlenmiş Polipropilen (PP) liflerin ECC üretiminde kullanımı araştırılmıştır. Sürdürülebilir ECC üretimi amacıyla, çimento yerine AT, kum yerine AM ve PVA lif yerine 6 ve 12 mm uzunluğundaki hibrit PP lifler kullanılmıştır. Üretilen ECC numuneleri üzerinde mini-slump, basınç dayanımı, eğilme dayanımı, orta nokta sehim ve ultrasonik dalga hızı (UDH) testleri gerçekleştirilmiştir. Sonuçlar, AT ve PP kullanımının mekanik özellikleri azalttığını, buna karşın AM katkısının mekanik özellikleri artırdığını göstermiştir. AT sünekliği artırırken, AM ve PP kullanımının sünekliği azalttığı belirlenmiştir. UDH sonuçları mekanik özelliklerle pozitif korelasyon göstermiştir. Elde edilen bulgular, AT, AM ve PP katkılı ECC'nin sürdürülebilir üretimi mümkün kıldığını ve bu malzemenin travers ve balastsız üstyapı uygulamaları için potansiyel bir alternatif olabileceğini ortaya koymuştur.