Group company IKK Corporation (hereinafter "IKK") is working with Tekken Construction Co., Ltd. (hereinafter "Tekken Construction") to conduct various performance evaluation tests, including acid resistance tests (hydrogen sulfide) for the geopolymer concrete "Cemenon®." The full-scale application of Cemenon® segments to a sewerage pipe construction project ordered by Suita City, Osaka Prefecture, was completed in October 2024, and performance evaluation tests confirmed that the segments have significantly greater durability than conventional cement concrete segments.
This shows its potential as an effective solution to the serious problem of sewer deterioration.
■ About geopolymer concrete "Semenon®"
Geopolymer concrete is a solidified body produced by the condensation polymerization reaction of powders (active fillers) such as metakaolin and fly ash, which undergo a chemical reaction in an alkaline environment, with an alkaline silica solution such as water glass.
Geopolymer concrete "CemenonⓇ"*1 is classified as a pure geopolymer *2 among alkali activated materials (AAMs) that contains almost no calcium (Ca) components, and has high resistance to acid deterioration environments in which calcium (Ca) dissolves.
■ Acid resistance test (hydrogen sulfide): Approximately 17 times stronger than conventional cement concrete segments
In this test, based on the "Manual for Corrosion Inhibition and Prevention Technologies for Sewerage Concrete Structures," a φ100 x 200 mm test specimen, which is in line with the actual segment manufacturing process, was immersed in a sulfuric acid solution for 112 days to check the mass change rate. As a result, while the mass change rate of conventional concrete was -42.2%, that of Cemenon® was -2.4%, demonstrating that it has approximately 17 times the acid resistance (Photo 1, Figure 1).
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- Photo 1: Test specimen for acid resistance test (hydrogen sulfide)
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- Figure 1 Acid resistance test (hydrogen sulfide)
■ Abrasion resistance test: Approximately 1.2 times stronger than conventional cement concrete segments
This test was conducted in accordance with ASTM C779-05 "Standard Test Method for Abrasion Resistance of Horizontal Concrete Surfaces (Method A: Rotating Disc Machine)" and measured the abrasion depth after 60 minutes. The results showed that Cemenon® has approximately 1.2 times the abrasion resistance of conventional concrete (Figure 2).
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- Figure 2. Abrasion resistance test
■ Other (ongoing performance evaluation tests)
(1) Deterioration measurement test
This accelerated test involved immersing a φ100 x 200 mm specimen in a 5% sulfuric acid solution to measure the amount of deterioration in one direction. The amount of deterioration is the sum of the "amount of corrosion" and the "depth of internal deterioration," and will be used to design corrosion protection layers based on predictions of future long-term deterioration (Figure 3).
In addition, we plan to simultaneously conduct exposure tests inside actual sewer pipe facilities, and believe that Cemenon® 's high acid resistance will contribute to solving the problem of sewer deterioration.
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- Figure 3: Image of the degradation measurement test
(2) Long-term durability
We are currently conducting various long-term durability tests with an eye toward future expansion of applications.
At the Tekken Construction Technology Center, a segment mockup with an outer diameter of 3,100 mm has been installed to conduct verification under conditions close to the real environment, such as long-term durability in natural environments (Photo 2).
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- Photo 2: Tekken Construction Co., Ltd. Construction Technology Center (Narita City, Chiba Prefecture)
(Front: Cemenon® segment, Back: Conventional cement segment)
■ Future application
Semenon® segments have the same strength and load-bearing capacity as conventional products, and have been installed as segments in public sewerage facilities. We have also established a production and sales system for nationwide expansion.
IKK and Tekken Construction will contribute to the realization of a sustainable society by actively proposing the application of "Cemenon®," a geopolymer concrete that can significantly reduce CO₂ emissions and has high acid (hydrogen sulfide) resistance, to structures that require corrosion resistance, such as sewerage pipelines (segments for shield tunneling).
*1 "Cemenon®"is a geopolymer concrete developed by IHI Corporation, IKK Corporation, Yokohama National University, and Advan Engineering Co., Ltd.
*2Based on the classification of the Japan Society of Civil Engineers Concrete Committee's "Research Subcommittee on Infrastructure Construction in a Low-Carbon Society Using New Alkali-Activated Materials (Committee 233)."
