Structures are exposed to various external effects and loads throughout their service life. Such a case then results in failure at a load lower than the design compressive strength. Although there is a cement-based healing system for repairing these damages, it is often insufficient. Therefore, a more effective autonomous healing system is needed, and microbial-induced calcite precipitation (MICP) was most of the time experimented with for this purpose. In this study, bacterial mortar samples were produced and loaded at different levels of their ultimate compressive stress. The effects of the loads were determined, and the effectiveness of bacterial treatments was also investigated. Crack healing, compressive strength, water absorption, ultrasonic pulse velocity (UPV), and high temperature effect experiments were conducted. In bacterial mortar samples, the MICP mechanism repaired about 3.5 times larger cracks than the control samples. While the treatment of cracks and damage observed at 90% and 100% loading levels were highly limited thanks to the autogenous system, some properties of bacterial mortars improved as the loading level increased. It was observed that the MICP mechanism was more effective, especially in damaged samples with high load levels. In addition, bacterial mortars demonstrated more advanced physical, mechanical, and durability properties at each loading level.
Bacterial concrete specimens were produced in this study to investigate the effects of microbially induced calcium carbonate precipitation (MICP) mechanism on concrete durability. Bacterial concrete (BC) samples were produced through supplementation of Bacillus megaterium bacteria into concrete mixture and curing water. However, control concrete (CC) samples were produced without bacteria. BC and CC were exposed to acid (HCl) and high temperature (400C) treatments. In the first phase of the study, 100×100×100 mm cube specimens were immersed into HCl solution for 10 days and compressive strengths and weight losses were determined. Compressive strength of acid-treated samples was measured as 25.08 MPa for BC samples and as 17.90 MPa for CC samples. Such values revealed that BC samples yielded 40.11% greater compressive strength. When CC samples lost 10.99% weight due to acid attack, BC samples lost 8.74% weight. In the second phase of the study, concrete specimens were exposed to 400℃ temperature and compressive strength of heat-treated samples was determined. As the result of high temperature, bacterial samples yielded 13.76% greater compressive strength against high temperature. Present findings revealed that CaCO3 formation on concrete improved concrete durability against attacks and high temperatures.
Concrete is exposed to a variety of stresses throughout its service life, which can result in cracks and damage. The use of fibers in concrete mixtures is known to improve the mechanical and durability properties of the concrete. In this study, glass fiber-reinforced concrete cube specimens were produced and stressed at 70 and 90 percent of their maximum compressive strength. The effects of stress loading-induced cracks and glass fiber reinforcements on mechanical and durability properties of concrete specimens were investigated using UPV, capillary water absorption, acid effect, and high-temperature effect tests. Glass fibers increased compressive strength and reduced water absorption in specimens that were not stressed. On the other hand, glass fibers increased the durability of stressed specimens at both degrees of compressive load stress. The bridging effects of glass fibers reduced crack creation, resulting in improved UPV test results. Glass fibers did not dissolve in acid solution due to their chemical resistance, resulting in less weight loss and higher compressive strength in concrete specimens. In the high-temperature effect tests, decreasing compressive strength values were observed as the stress load and temperature levels increased. However, such reductions were lower for glass fiber reinforced concrete than for control concrete without glass fiber. As a result of the present findings, glass fiber reinforcements prevent stress-induced cracks, making the concrete more durable and stronger against external forces.
Küresel ısınma sonucu insanların karşı karşıya kalacağı risklerin ve sera gazı salınımının azaltılması amacıyla iklim değişikliğine karşı dirençli kentlerin oluşturulması günümüzde tüm toplumların en öncelikli konuları arasındadır. Dirençli kentler oluşturmak amacıyla yenilenebilir enerji kullanımı, enerji verimliliği, yeşil alanların arttırılması, yaya ve bisiklet kullanımının yaygınlaştırılması, sürdürülebilir atık yönetimi gibi birçok alanda birçok uygulama yapılmaktadır. Atıkların geri dönüştürülmesi ve yeniden kullanımı sürdürülebilir atık yönetimi kapsamında olup doğal kaynak tüketiminin fazla olduğu beton endüstrisinde atık malzemelerin geri kazanılması bu açıdan oldukça önemlidir. Bu çalışmada, silis dumanı, kolemanit ve kolemanit atık kullanımının çimentolu sistemlerin basınç dayanımı ve su emme özelliklerine ayrı ayrı ve hibrid etkisi incelenmiştir. Bu kapsamda çimento ağırlığının %5, 10 ve 15 oranlarında silis dumanı, %0,5, 1, 1,5 ve 2 oranlarında kolemanit ve %1, 3, 5 ve 7 oranlarında kolemanit atığı ikame edilmiştir. Hazırlanan karışımların yayılma, 1, 28, 63 ve 90 günlük basınç dayanımı ile 63 ve 90 günlük su emme kapasiteleri belirlenmiştir. Deney sonuçlarına göre, mineral katkı kullanımı işlenebilirliği azaltmış dolayısıyla akışkanlaştırıcı katkı ihtiyacını arttırmıştır. Silis dumanı ve kolemanit atığının aksine kolemanit kullanımının işlenebilirliği kısmen iyileştirdiği belirlenmiştir. Dayanım sonuçlarına göre, kolemanit ve kolemanit atığı kullanımı karışımların basınç dayanımını ve su emme oranlarını olumsuz yönde etkilemiştir. Silis dumanı kullanımı ise kontrol karışımına kıyasla 1 günlük dayanımları düşürürken, nihai ve ileri yaş dayanımlarını arttırmıştır. Ayrıca silis dumanı ile kolemanit ve kolemanit atığının birlikte kullanımı sonucu kolemanit ve kolemanit atığının sebep olduğu dayanım kaybının silis dumanı ile telafi edilebildiği tespit edilmiştir.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.