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 LONG-LIFE AND ECO-FRIENDLY CONCRETE STRUCTURES WITH INDUSTRIAL WASTES AND BY-PRODUCTS - ADVANCED APPLICATIONS IN JAPAN -
Tác giả hoặc Nhóm tác giả: Akira Hosoda, Phan Thanh Ngoc, Hiroshi Kazama
Nơi đăng: VANJ Conference 2022 – Diversity for an Inclusive Society; Số: S06-01;Từ->đến trang: 20;Năm: 2022
Lĩnh vực: Chưa xác định; Loại: Báo cáo; Thể loại: Quốc tế
TÓM TẮT
The applications of industrial wastes and by-products have been developed in a wide range of concrete structures in Japan for sustainable society, not only as eco-friendly materials but also for obtaining long-life of the structures. The presentation consists of three main parts including the invention of innovative porous concrete and liquified stabilized soil, the durability design of RC deck slab utilizing ground granulated blast furnace slag (GGBS) and expansive additive (EA), and the utilization of fly-ash (FA) for mitigating corrosion and alkali-silica reaction (ASR) in concrete structures. In order to effectively reuse the remained wastes in ready-mixed concrete plants in Japan, wastes and by-products such as steel slags and granulated blast furnace slags were applied with seawater to make porous zero cement concrete. The concrete which is more durable than weed control sheets can be used as a base layer in pavements. Moreover, the remained wasted ready-mixed concrete is also converted into granulated dry materials which can be utilized as liquified stabilized soil in many practical applications. In recent years, a new durable concrete design accounting for multiple protection countermeasures including low water-to-cement ratio, blast furnace slag or fly ash, expansive additive, anti-corrosion rebar, increased entrained air (around 6% of air content), and sufficient curing has been applied to many bridges in Tohoku region of Japan to enhance the reliability of durable RC deck slabs. However, it should be concerned that those highly durable concrete specifications may conversely increase the risk of early-age cracking in RC deck slabs. Early age cracks may provide a rapid route for harmful agents to reach the reinforcing bars and may exaggerate the deterioration due to frost and fatigue damages causing loss of serviceability and increasing maintenance costs. According to our studies, several crack control designs including an effective stepwise construction strategy, the application of expansive additive (20 and 25 kg/m³), effective curing methods and a new arrangement of a joint system in parapet walls were developed to improve the durability design for RC deck slabs in Tohoku region. Several technical reports stated that the RC structures in Okinawa Island of Japan experienced severe corrosion due to the combined effect of chloride attack from non-washed sea sand and ASR. According to our investigations, FA can be utilized as cement replacement or as fine aggregate in the concrete mix design of bridge piers or girders to control chloride ion penetration and suppress ASR.
ABSTRACT
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