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Investigation on the effect of silane coupling agent treatment of steel fibers on the durability of UHPC

Du Shuang, Luan Congqi, Yuan Lianwang, Du Peng, Zhou Zonghui, Wang Jinbang

Archives of Civil and Mechanical Engineering

2023

Vol. 23, no. 2

art. no. e118, 2023

Ultra-high performance concrete (UHPC) is a type of cementitious material that has been specifically engineered to achieve exceptional mechanical properties and durability through optimized particle filling. However, the addition of steel fibers to the UHPC matrix creates a transitional region at the interface. Previous research has indicated that the use of silane coupling agents (SCA) on the surface of steel fibers is a promising approach for improving the bonding properties between the fibers and the matrix. This study aims to explore the impact of varying amounts of untreated steel fibers versus those that have undergone SCA treatment on the durability of UHPC. The findings indicate that treating steel fibers with SCA significantly narrows the pore space between the matrix and steel fibers, as well as enhances the production of hydration products on the steel fiber surface. Furthermore, this treatment facilitates the formation of a compact transition zone between the UHPC matrix and steel fibers. The electrochemical corrosion resistance, chloride ion penetration resistance, frost resistance, and sulfate erosion resistance of UHPC are all enhanced by this method. As a result, the durability of UHPC is significantly improved, making it an extremely promising avenue of research.

Preparation and characterization of attapulgite microcapsules coated with acrylic polymer

Song Lining, Li Zhenxu, Yang Lina, Wang Ning, Zhao Jie, Gu Zheng

Polimery

2021

T. 66, nr 2

112--118

The attapulgite core-shell microcapsule type flame retardant was prepared by in situ polymerization. Attapulgite (ATP) was used as a core material with poly(methyl methacrylate) (PMMA) and poly(methyl methacrylate-co-acrylic acid) [P(MMA-co-AA)] as shell materials. The attapulgite was modified by the silane coupling agent. The effects of different shell materials and modification methods on the structure and properties of attapulgite core-shell microcapsules were studied by scanning electron microscopy, particle size distribution, infrared analysis and thermogravimetric analysis. The results showed that the coating effect was best when the amount of silane coupling agent was 1% of the attapulgite mass. The particle size of the microcapsule prepared with PMMA as shell material was uniform and the coating efficiency was better. After the copolymerization of acrylic acid (AA) in MMA shell materials, the cladding efficiency was improved. At the same time, the thermal decomposition temperature of the microcapsule shell material was greatly reduced, which is beneficial to the performance of attapulgite flame retardant.

Metodą polimeryzacji in situ otrzymano uniepalniające attapulgitowe mikrokapsułki o budowie typu rdzeń-otoczka. Rdzeń stanowił attapulgit (ATP) modyfikowany silanowym środkiem sprzęgającym, a poli(metakrylan metylu) (PMMA) lub poli(metakrylan metylu-co-kwas akrylowy) [P(MMA-co-AA)] – otoczkę. Wpływ rodzaju użytego materiału powłokowego i metody modyfikacji na strukturę i właściwości otrzymanych mikrokapsułek oceniano metodą skaningowej mikroskopii elektronowej, na podstawie rozkładu wielkości cząstek, analizy widm w podczerwieni i analizy termograwimetrycznej. Najlepsze właściwości wykazywała otoczka attapulgitowego rdzenia otrzymana z zastosowaniem środka sprzęgającego w ilości 1% mas. ATP. Wielkość mikrokapsułek wytworzonych z udziałem PMMA była jednorodna, a efektywność powlekania ATP modyfikowanego silanowym środkiem sprzęgającym była większa. Wydajność powlekania za pomocą kopolimeru P(MMA-co-AA) była lepsza niż w wypadku PMMA, a znacznie niższa temperatura rozkładu termicznego kopolimeru stanowiącego otoczkę mikrokapsułki stwarza korzystne warunki dla uniepalniającego działania attapulgitu.

Preparation of nanosized NaA zeolite and its surface modification by KH-550

Hou J., Jiang Q.

Materials Science Poland

2018

Vol. 36, No. 4

638--643

Nanosized NaA zeolite was successfully synthesized by hydrothermal method using tetraethyl orthosilicate (TEOS) and aluminum isopropoxide (AIP) as the main raw materials. The surface modification of NaA zeolite was carried out by silane coupling agent 3-aminopropyltriethoxysilane (KH-550). The effects of silane coupling agent dosage, reaction temperature, reaction time, hydrolysis time and pH value on grafting rate of NaA zeolite were investigated in detail. The zeolites were characterized by XRD, SEM-EDS, FT-IR and TG-DTA. The results showed that the surface of NaA zeolite was modified successfully by KH-550. The optimal modification conditions obtained were as follows: the dosage of coupling agent in 95 % ethanol – 1.6 %, reaction temperature − 70 °C, reaction time – 2 h, hydrolysis time – 20 min, and pH value – 3.5. Under these conditions, the grafting rate of modified NaA zeolite was 3.95 %.