
聚甲醛纤维对自密实混凝土工作性能和力学性能影响
刘恒, 贺晶晶, 冯兴国, 崔海鹏
聚甲醛纤维对自密实混凝土工作性能和力学性能影响
Influence of Polyoxymethylene Fiber on Workability and Mechanical Properties of Self-Compacting Concrete
针对聚甲醛(POM)纤维自密实混凝土开展性能试验研究,分析纤维几何特性、纤维掺量对自密实混凝土(SCC)的工作性能的与力学性能的影响规律及机理。研究表明:纤维长度一定时,掺量在0.8~2.4 kg/m3范围内增加时,SCC坍落扩展度下降,SCC的力学性能呈先增后减的趋势;纤维掺量一定时,纤维长度6~20 mm范围内增大时,SCC坍落扩展度变化不大,SCC力学性能呈先增后减的趋势。掺量1.6 kg/m3、长度12 mm的圆柱状纤维对SCC抗压强度提升幅度最大,较素SCC的28 d强度提升了3.6%;长度12 mm扁平状纤维与长度6 mm圆柱状纤维混杂,掺量为1.6 kg/m3时,SCC的28 d劈裂抗拉强度提高14.52%。POM的掺入,使得对SCC微观结构更为密实,纤维与胶凝体紧密结合可有效吸收破坏产生能量,实现宏观力学性能提升。研究结论可为POM纤维自密实混凝土工程应用提供参考。
The performance test of polyoxymethylene (POM) fiber self-compacting concrete(SCC) was carried out, and the influence law and mechanism of fiber geometric characteristics and fiber content on the working performance and mechanical properties of SCC were analyzed. The results show that when the fiber length is constant and the content is increased in the range of 0.8~2.4 kg/m3, the slump spread of SCC decreases, and the mechanical properties of SCC increase first and then decrease. When the fiber content is constant and the fiber length increases within the range of 6~20 mm, the slump spread of SCC does not change much, and the mechanical properties of SCC increase first and then decrease. The cylindrical fibers with a dosage of 1.6 kg/m3 and a length of 12 mm has the largest improvement on the compressive strength of SCC, which is 3.6% higher than that of plain SCC at 28 d. The 28 d splitting tensile strength of SCC is increased by 14.52% when the flat fiber with a length of 12 mm and the cylindrical fiber with a length of 6mm are mixed, and the dosage is 1.6 kg/m3. The addition of POM makes the microstructure of SCC more compact, and the close combination of fiber and gel can effectively absorb the energy generated by damage and improve the macro-mechanical properties. The research conclusion can provide a reference for the engineering application of POM fiber self-compacting concrete.
自密实混凝土 / 聚甲醛纤维 / 坍落扩展度 / 抗压强度 / 劈裂抗拉强度 / 微观结构 {{custom_keyword}} /
self-compacting concrete / polyoxymethylene fiber / slump-flow / compressive strength / splitting tensile strength / SEM {{custom_keyword}} /
表1 水泥物理性能Tab.1 Cement physical properties |
密度ρ/(g·cm-3) | 标准稠度用水量/% | 凝结时间/min | 抗压强度/MPa | 抗折强度/MPa | |||
---|---|---|---|---|---|---|---|
Initial set | Final set | 3 d | 28 d | 3 d | 28 d | ||
3.05 | 27.9 | 173 | 227 | 28.5 | 51.0 | 6.2 | 8.6 |
表2 粉煤灰化学组成 (%)Tab.2 Chemical composition of fly ash |
化学组成 | |||||||||
---|---|---|---|---|---|---|---|---|---|
SiO2 | Al2O3 | Fe2O3 | CaO | MgO | CaO | SO3 | Cl- | K2O | Na2O |
51.19 | 20.49 | 8.05 | 10.76 | 2.50 | 0.94 | 1.01 | 0.013 | 1.35 | 1.38 |
表3 SCC配合比Tab.3 Mixture proportion of SCC |
配合比/(kg | 水胶比 | |||||
---|---|---|---|---|---|---|
水 | 水泥 | 粉煤灰 | 砂 | 石 | 减水剂 | |
180 | 411 | 103 | 832 | 854 | 0.93 | 0.35 |
表4 不同组SCC掺入纤维情况 (kg/m3)Tab.4 Situation of different groups of SCC mixed with fiber |
组 | F-POM | C-POM | 混杂POM | 混杂比 |
---|---|---|---|---|
JZ | - | - | - | - |
F-POM-6 | 0.8/1.6/2.4 | - | - | - |
F-POM-12 | 0.8/1.6/2.4 | - | - | - |
F-POM-20 | 0.8/1.6/2.4 | - | - | - |
C-POM-6 | - | 0.8/1.6/2.4 | - | - |
C-POM-12 | - | 0.8/1.6/2.4 | - | - |
C-POM-20 | - | 0.8/1.6/2.4 | - | - |
F-C-12-6 | - | - | 0.8/1.6/2.4 | 1∶1 |
F-C-20-6 | - | - | 0.8/1.6/2.4 | 1∶1 |
F-C-20-12 | - | - | 0.8/1.6/2.4 | 1∶1 |
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