亞煙燃煤飛灰應用於普通混凝土之性質研究

發表於台電工程月刊，第738期，民國99年2月

亞煙燃煤飛灰應用於普通混凝土之性質研究

A Study on the Properties of Normal Concrete Containing Sub-bituminous Coal Fly Ash

黃兆龍*	江奇成**		林峰立**		賴正義*
Hwang, Chao-Lung	Chiang, Chu-Chan		Lin, Feng-li		Lai, Cheng-I
郭麗雯***		許讚全***		邱善得***
Quo, Lih-Wen		Hsu, Zan-Cyuan		Chyou, San-Der

（～97~98年度研究計畫論文～）

摘　要

本文採用美國混凝土協會規範之配比設計方法，以亞煙燃煤飛灰(C類飛灰)取代部分水泥，探討不同水膠比與飛灰取代量對混凝土新拌、硬固及微觀等性質的影響。研究結果顯示，摻用C 類飛灰可增加混凝土的流動性，改善工作性，但會產生緩凝的現象，抗壓強度在齡期91 天時略高於未摻用飛灰之混凝土，另由表面電阻、氯離子電滲與裂縫敏感度等試驗結果可知，摻用C類飛灰有助於混凝土內部孔隙的填塞，提升抗滲透以及減少混凝土表面裂縫的產生。但是，摻用過量的C類飛灰可能導致部分性質產生折損的現象，須視工程的性能需求，並經嚴密計算後再加以應用，才能發揮C類飛灰的效益。本研究建議C類飛灰取代水泥量不宜超過30%，避免影響混凝土初期的各項性能。

Abstract

In this paper the mixture design algorithm regulated by American Concrete Institute is adopted and sub-bituminous coal fly ash (Class C fly ash) is used to substitute part of cement. The effects of various water-to-binder ratio and substitution percentage of cement by fly ash on the properties of fresh as well as hardened concrete and the micro structure of fly ash along with concrete are studied. The test results indicate that the application of Class C fly ash into concrete can improve flowability and workability but result in longer setting time. The compressive strength of age 91 days is slightly higher than the concrete without fly ash. According to the test results of surface electrical resistance, chloride ion penetration current and crack sensibility, in addition, the utilization of Class C fly ash in concrete can block the pores inside concrete, enhance the resistance to penetration, and mitigate the occurrence of surface cracks. However, exceeding amount of Class C fly ash in concrete may be detrimental to a few performances of concrete and its usage has to be evaluated carefully to bring in full effects based on the requirements of construction. It is suggested that no more than 30% cement is substituted by Class C fly ash to maintain the concrete performances at the early age.