中華民國內政部建築研究所中華民國內政部建築研究所

一、研究緣起
混凝土是一種脆性材料，具有良好的抗壓強度，但其抗拉強度較差。傳統上，會將抗拉強度極佳的鋼筋放置於混凝土結構中的適當位置，使混凝土具有承受拉應力和剪應力的能力。然而，依據工商時報2021年11月24日的報導，隨著全球原物料成本增加，未來鋼鐵價格將遠高於過去10年的水準，往後幾年熱軋鋼平均價每公噸達600美元以上，甚至上千美元都有可能。此外，鋼筋外型細長、重量重，運送不易且成本高，加上工地現場尚需進行焊接及綁紮，需大量專業施工人員才能完成，隨著台灣建築施工從業人員嚴重老化及不足，此類專職人員越來越少，已成為國家整體建設發展中急待克服的問題。
過往研究指出，於混凝土中添加適量的纖維，可有效控製混凝土開裂，增加混凝土的韌性，隨著混凝土科技的進步，各式混凝土用纖維逐漸增加，含纖維高流動性混凝土的研究也逐漸被探討，使得利用此類新纖維混凝土以減少鋼筋的使用變得可行，不過混凝土的耐久性也是決定纖維混凝土是否可更加廣泛應用的重要指標，然而有關纖維混凝土耐久性的研究不多，且多為含纖維普通混凝土的探討，針對含纖維高強度、高性能混凝土的探討仍相當的少。因此，本研究即在探討具有高流動性、高強度含纖維混凝土之耐久性，以期建立本土化纖維混凝土新的產製技術。
二、研究方法及過程
本研究主題為纖維混凝土耐久性的探討，規劃試驗變數包含混凝土水膠比為0.4，飛灰及爐石粉分別取代水泥重量之0%、30%及60%，鋼纖維與聚丙烯纖維添加量分別為每立方公尺混凝土體積的0%、0.15%及0.3%，並添加適量強塑劑改善混凝土的坍度及坍流度，使混凝土具有良好的工作性。採用淡水養護和鹽水養護兩種方式，比較對纖維混凝土抗壓強度、劈裂強度及抗彎強度等工程性質的影響，並進行混凝土透水及快速氯離子滲透等試驗，瞭解纖維混凝土的耐久性。
三、重要發現
鹽水養護之混凝土抗壓強度高於淡水養護者，纖維混凝土抗壓強度高於無纖維混凝土，隨混凝土強度的增加，纖維對混凝土強度的貢獻逐漸不明顯，其中爐石粉混凝土的抗壓強度最高，飛灰混凝土的強度最低。鹽水養護之聚丙烯纖維混凝土之劈裂強度最高，混合纖維混凝土次之，飛灰混凝土的強度最小。鹽水養護對高強度纖維混凝土抗彎強度的影響不明顯，其中添加0.3%聚丙烯纖維混凝土之劈裂強度高於其他纖維混凝土。經鹽水養護的鋼纖維混凝土有出現生鏽的狀況，聚丙烯纖維無明顯腐蝕情形產生。爐石粉混凝土的滲透率最小鹽水養護之混凝土透水率低於淡水養護者，纖維混凝土的透水率高於無纖維混凝土。水泥混凝土通過的總電荷最多、耐久性較差，鋼纖維混凝土通過的電荷數比其他種類的纖維混凝土高，鹽水養護之混凝土通過總電荷數比淡水養護者高。
四、主要建議事項
纖維混凝土的工程性質比普通混凝土佳，若可簡化其製程、改善其工作性，將有助於實務的推廣應用，減少普通混凝土的用量，降低混凝土產製過程中的能源消耗及二氧化碳的排放量。以下分別從立即可行建議及中長期建議加以列舉。
立即可行之建議—鋼纖維混凝土耐久性的探討
主辦機關：內政部建築研究所
協辦機關：無
現行纖維混凝土的應用以鋼纖維混凝土的數量最多，就本研究成果可知，鋼纖維混凝土有生鏽腐蝕的問題，有必要針對更多種類的鋼纖維混凝土耐久性進行研究，包含鋼纖維的整類、卜作嵐材料的類型、齡期長短及養護環境等課題的釐清，找出改善鋼纖維混凝土耐久性的對策，將有助於提升纖維混凝土技術及應用層面。
長期性建議—預鑄纖維混凝土耐久性的探討
主辦機關：內政部建築研究所
協辦機關：無
為因應現場施工人員老化及短缺等問題，國家積極推廣預鑄混凝土工法，以簡化現場施工的程序，降低施工人員的需求，而纖維混凝土非常適合以預鑄工法進行製作，不過預鑄混凝土的關鍵技術為高溫蒸氣養護，該養護過程對纖維混凝土的耐久性影響值得研究，包含高溫及水分是否會造成鋼纖維腐蝕生鏽，以及高溫高壓養護方式對聚丙烯纖維等化學纖維的影響，也須深入瞭解，建置合宜的預鑄纖維混凝土養護方式，以利該類混凝土的推廣應用。

1.Purpose of Research
Concrete is a brittle material with good compressive strength but poor tensile strength. Traditionally, rebar with excellent tensile strength has been placed in place in the concrete structure to give the concrete the ability to withstand both tensile and shear stresses. However, according to a report by Business Times on November 24, 2021, with the increase in global raw material costs, the future steel price will be much higher than the level of the past 10 years. Even thousands of dollars are possible. In addition, steel bars are slender and heavy, which are difficult to transport and cost high. In addition, welding and tying still need to be carried out on the construction site, which requires a large number of professional construction personnel to complete. With the serious aging and shortage of construction workers in Taiwan, such full-time professionals Fewer and fewer personnel have become an urgent problem to be overcome in the overall construction and development of the country.
Previous studies have pointed out that adding an appropriate amount of fiber to concrete can effectively control cracking of concrete and increase the toughness of concrete. , making it feasible to use this new fiber reinforced concrete to reduce the use of steel bars, but the durability of concrete is also an important indicator to determine whether fiber reinforced concrete can be more widely used. However, there are not many studies on the durability of fiber reinforced concrete, and most of them contain the discussion of fiber-reinforced ordinary concrete is still relatively small. Therefore, this study is to explore the durability of fiber-reinforced concrete with high fluidity and high strength, in order to establish a new production technology of localized fiber-reinforced concrete.
2.Methodology and Process
The subject of this research is the discussion of the durability of fiber reinforced concrete. The planned test variables include a concrete water-binder ratio of 0.4, fly ash and furnace stone powder to replace 0%, 30% and 60% of the cement weight, respectively, and the addition of steel fiber and polypropylene fiber. It is 0%, 0.15% and 0.3% of the concrete volume per cubic meter, and an appropriate amount of superplasticizer is added to improve the slump and slump flow of the concrete, so that the concrete has good workability. Two methods of fresh water curing and salt water curing were used to compare the effects on engineering properties such as compressive strength, splitting strength and flexural strength of fiber reinforced concrete, and tests such as concrete permeation and rapid chloride ion penetration were carried out to understand the durability of fiber reinforced concrete.
3.Important Findings
The compressive strength of salt water cured concrete is higher than that of fresh water curing, and the compressive strength of fiber-reinforced concrete is higher than that of non-fiber concrete. Fly ash concrete has the lowest strength. The splitting strength of the salt water cured polypropylene fiber concrete is the highest, followed by the mixed fiber concrete, and the fly ash concrete is the smallest. The effect of salt water curing on the flexural strength of high-strength fiber reinforced concrete is not obvious, and the splitting strength of 0.3% polypropylene fiber reinforced concrete is higher than that of other fiber reinforced concrete. The steel fiber reinforced concrete cured by salt water has a rust condition, and the polypropylene fiber has no obvious corrosion. The permeability of furnace stone powder concrete is the smallest. The permeability of concrete cured by salt water is lower than that of fresh water curing, and the permeability of fiber concrete is higher than that of non-fiber concrete. Cement concrete has the most total charges and poor durability. Steel fiber concrete has higher charges than other types of fiber concrete. The total charge of salt water curing concrete is higher than that of fresh water curing.
4.Major Recommedations
Immediate implementation:
Sponsor Agency: Architecture and Building Research Institute, Ministry of the Interior
Co-sponsor Agency:
The current application of fiber reinforced concrete is the largest number of steel fiber reinforced concrete. According to the results of this study, steel fiber reinforced concrete has the problem of rust and corrosion. It is necessary to study the durability of more types of steel fiber reinforced concrete, including the types of steel fiber, Pozzon materials, test ages and curing environment, and find out the countermeasures to improve the durability of steel fiber reinforced concrete, which will help to improve the technology and application level of fiber reinforced concrete.
Long-term implementation:
Sponsor Agency: Architecture and Building Research Institute, Ministry of the Interior 
Co-sponsor Agency: Architecture and Building Research Institute, Ministry of the Interior
In response to problems such as the aging and shortage of construction workers on site, the state actively promotes the construction method of Pingxuan concrete to simplify the procedure of on-site construction and reduce the demand for construction personnel. Fiber concrete is very suitable for the production of the construction method, but the key to concrete is the construction of Pingxuan. The technology is high-temperature steam curing. The effect of this curing process on the durability of fiber reinforced concrete is worth studying, including whether high temperature and moisture will cause corrosion and rusting of steel fibers, and the impact of high-temperature and high-pressure curing methods on synthetic fibers such as polypropylene fibers. Understand and establish a suitable curing method of Pingxuan fiber concrete to facilitate the popularization and application of this type of concrete.