Study on the Engineering Properties of Hardened and Durability of Concrete Containing Stainless Steel Slag

• Main Authors: HSIEH, YI-TA, 謝易達
• Other Authors: Wang, Her-Yung
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/59r9st

碩士 === 國立高雄科技大學 === 土木工程系 === 107 === This study is based on stainless steel reducing slag and replaces cement with 5 different substitutions(0%、5%、10%、15%、20%) to make concrete. The slump will increase as the amount of substitution increases, effectively improving workability. A concrete cylindrical specimen make in size of ∅10×20cm was prepared and cured to a hardness and durability properties after 1、3、7、28、56 days of ageing. The hardness properties is determined by the compressive and splitting strength as a basis for judging whether stainless steel is suitable for general proportion design and engineering materials. The ultrasonic wave velocity is used to detect whether the wave velocity change and the compressive strength are consistent, so as to evaluate the internal compactness of the concrete and detect the surface resistance as the basis of the surface porosity. The autoclave test, sulfate-resistant and high-temperature fire damage tests can predict the materials positive impact on concrete in high-pressure, high-erosion and high-temperature environments. The results show that the stainless steel reduction concrete with the age of 28 days has a compressive strength of 34.6MPa~27.65MPa with the substitution amount, which is 27.44MPa (about 280kgf/m3) and the splitting strength is 15.34MPa~12.81MPa. The ratio is 44~47, indicating that the strength decreases with the increase of the substitution amount and has a good relationship between the compressive strength and the splitting strength. At this time, the ultrasonic wave velocity growth condition is 4762m/s~4361m/s, and the R2 of the compressive strength is 0.9 or more, which shows that the density of each substitution can achieve better compactness and similar growth trend with compressive strength. The surface resistance is 9.87kΩ-cm~9.08 kΩ-cm, which shows that the surface porosity and the variation due to the substitution amount are not large. In terms of durability, the high temperature 200 °C fire damage has catalytic effect on quality, compressive strength and electrical resistance, but the ultrasonic wave velocity is reduced. After the high temperature 600℃ and 800℃ fire damage, the weight change is -1.8%~-4.5% and -3%~-7.1%, compressive strength decreased by 48%~57% and 76%~85%, respectively. The ultrasonic wave velocity cannot be transmitted under the partial replacement of 7 days of age, indicating that the higher the temperature, the greater the influence on the concrete and the poor resistance in the early age. The results of sulfate attack resistance show that the crystal formed during the soaking process will accumulate in the concrete pores and crack the concrete. The high substitution in the early stage of the cycle will make the concrete less likely to spall, and the cumulative weight will be higher than the control group after the fifth cycle. In the autoclave test, the expansion amount of 10% of the substitution amount of 56 days is 0.059%, which is 0.007% higher than that of the 28th day of age. It shows that the longer the age, the larger the expansion and the expansion of the replacement amount of 10%. The quantity does not exceed the specification value. The porosity of the section shows that 600℃ and 800℃ high temperature cause irreversible damage to the concrete structure, followed by sulfate erosion, and the greater the substitution amount, the greater the influence on the porosity.