高流動性應變硬化鋼纖維混凝土之配比設計與力學性質研究

A Study on Mix Design and Mechanical Behavior of Highly Flowable Strain Hardening Steel Fiber Reinforced Concrete

高唯淵(Wei-Yuan Kao)

指導教授 ： 廖文正

國立臺灣大學/工學院/土木工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.03186

摘要

本研究參考自充填混凝土配比設計概念與緻密堆積理論，並配合坍流度預測模型及最小鋼纖維添加量演算公式，提出一套高流動性應變硬化纖維混凝土（Highly Flowable Strain Hardening Fiber Reinforced Concrete, HF-SHFRC）配比設計流程。HF-SHFRC是一種擁有自充填混凝土（Self-Compacting Concrete, SCC）在新拌時的自充填高流動性，及高性能纖維水泥質複合材料（High Performance Fiber Reinforced Cementitious Composites, HPFRCC）硬固後受直拉張力作用下呈應變硬化之力學行為的混凝土。利用受拉應變硬化最小纖維添加量演算公式，求得使混凝土達到拉力應變硬化行為之纖維添加量，以利於發展SHFRC之配比；同時針對鋼纖維混凝土（Fiber Reinforced Concrete, FRC）流動性之不足，配合坍流度預測模型調整砂漿與混凝土性質，以完成HF-SHFRC之配比設計。
經由本研究建議的配比設計流程，已建立出不同目標抗壓強度（30 ~ 60 MPa）的HF-SHFRC本土化配比，並進行坍流度、抗壓強度、直接拉力與乾燥收縮試驗。此外，針對不含粗骨材之砂漿配比，進行新拌性質試驗及纖維拉拔試驗。坍流度試驗結果顯示其充填性能表現佳，且具有高流動性。從直接拉力試驗結果可觀察其力學性質表現優秀，不論在應變硬化的行為發展上，還是韌性、延展性與應變容量的表現，相較於一般混凝土皆優越許多。

關鍵字

應變硬化 ； 自充填混凝土 ； 鋼纖維混凝土 ； 高性能纖維水泥質複合材料 ； 配比設計 ； 彎鉤型鋼纖維

並列摘要

This study aims to develop a comprehensive mix design process for highly flowable strain hardening fiber reinforced concrete (HF-SHFRC). The proposed method is developed based on mix design concept of self-compacting concrete (SCC), dense packing theory, and critical volume fraction of fibers of high performance fiber reinforced cementitious composites (HPFRCC). The HF-SHFRC has good workability in the fresh state similar to SCC and exhibits the strain-hardening and multiple cracking characteristics of HPFRCC under tensile forces in the hardened state. In order to achieve the tensile strain-hardening, this study applies the calculation formula of critical volume fraction of fibers. Moreover, the slump flow prediction model is also applied to design HT-SHFRC mixtures for target flowability.
By following mix design process proposed by this study, mixtures of different compressive strength targets (from 30 to 60 MPa) have been successfully developed. The slum flow test results show excellent flowability (slump flow more than 500mm) even with addition of steel hooked fiber of 1.5% volume fraction. In terms of mechanical properties, results of direct tensile tests show that all mixtures satisfy the strain-hardening characteristics of HPFRCC while maintaining 80% of maximum tensile stress capacities up to 0.5% tensile strains. To sum up, the test results show good agreement with performance targets in terms of flowability, strength and tensile strain hardening characteristics.

並列關鍵字

Strain Hardening ； SCC ； FRC ； HPFRCC ； Mix Design ； Hooked Steel Fibers

參考文獻

[120] 杜俊穎（詹穎雯指導），「鋼纖維在蒸壓條件下對活性粉混凝土之加勁機理」，碩士論文，國立台灣大學土木工程研究所，2008。

[121] 林靖淳（詹穎雯、廖文正指導），「碳纖維水泥複合材料受力應變與電阻特性之探討」，碩士論文，國立台灣大學土木工程研究所，2011。

[2] Naaman, A. E., and Reinhardt, H. W., “Characterization of High Performance Fiber Reinforced Cement Composites—HPFRCC,” High Performance Fiber Reinforced Cement Composites 2, Proceedings of the Second International RILEM Workshop, Ann Arbor, MI, pp. 1-24, 1996.

[3] Chao, S.-H., Liao, W.-C. and Naaman, A. E., “Large Scale Tensile Tests of High Performance Fiber Reinforced Cement Composites”, RILEM PRO53 High Performance Fibre Reinforced Composites HPFRCC5, pp. 77-86, 2007.

[7] Wu Yao, Jie Li, and Keru Wu, “Mechanical Properties of Hybrid Fiber-reinforced Concrete at Low Fiber Volume Fraction”, Cement and Concrete Research, Vol. 33, pp.27-30, 2003.