本文針對花蓮溪河川骨材進行岩種辨別及各岩種所佔比例計算，發現除了含大理岩、石英脈、燧石、片岩等岩種，尚含有具鹼反應性之安山岩 (約4.6%) 存在。就此情形本研究再針對花蓮港北岸疑似具鹼-骨材反應裂化之波消溾進行鑽心取樣，並就鑽心試體進行骨材種類辨別及統計，結果發現所得之岩石種類和比例皆與花蓮港溪之骨材相似。花蓮地區之砂石來源主要由花蓮溪及木瓜溪河川骨材所供應，兩河川砂石骨材種類大致相同，惟花蓮溪骨材具少量安山岩出現，而木瓜溪則否，故花蓮港北岸之消波塊骨材來源可能取自花蓮溪，而花蓮溪骨材有導致鹼-骨材反應的潛能。因此本文針對花蓮溪骨材，利用調整鹼含量及安山岩含量的方式，進行ASTM C 227水泥砂漿棒試驗、ASTM C 1293混凝土角柱試驗，探討安山岩在花蓮溪骨材鹼-矽反應過程中，所產生的悲極效應 (pessimum effect) 及膨脹行為。 根據研究結果，發現改變水泥砂漿棒中的鹼含量及安山岩骨材含量等參數時，可發生悲極效應的現象，並且安山岩骨材之悲極比例 (pessimum proportion) 將會隨著水泥鹼含量的增加而增加。另外，就研究顯示，花蓮溪骨材中的安山岩含量對膨脹量影響甚鉅，只要微量增加安山岩含量，即可令花蓮溪骨材之膨脹量大幅成長。因此雖然安山岩骨材在花蓮溪骨材中所佔比例不多，但對於整體花蓮溪骨材之鹼-骨材反應性具有關鍵之影響，故安山岩在花蓮溪骨材中所產生的悲極效應問題不可不注意。 Rocks identifying and counting were carried out to aim to the aggregates in the Hua-Lein River in this paper. The results were showed that besides marble, quartz vein, chert and schist, a few reactive andesite (about 4.6%) exist in the Hua-Lein River. At this point, the study cored the concrete blocks that were suspected to the potential for alkali-aggregate reaction and at the north coast in the Hua-Lein Port. Also, aim to these cores distinguishing the kinds of aggregates and counting the rocks was carried out. It was found that whatever the kinds of rocks and the proportion of rocks were the same as the aggregates in the Hua-Lein River. In Hua-Lein area, the supplied of aggregates are mainly from the Hua-Lein River and the Mu-Gua River. The aggregates in the Hua-Lein River and the Mu-Gua River are the same in substance, but andesites existing in the Hua-Lein River are only the difference between the two rivers. Hence, the aggregates in the concrete blocks that are at the north coast in the Hua-Lein Port possibly were from the Hua-Lein River, and the aggregates have the potential for alkali-aggregate reaction. Therefore, the alkali content and the andesite content were changed in the mortar bar test (ASTM C227) and the concrete prism test (ASTM C1293) to study the pessimum effect and expansion behavior of andesite in the Hua-Lein River aggregates in this paper. The results were showed that when the alkali content and the andesite content were changed in the mortar bars, the pessimum effect would occur and the pessimum proportion of andesite would increase with the alkali content of cement. Besides, the andesites content have great influence on expansion. Only a few andesites it would produce great expansion. Thus, the andesitic aggregates have a great effect upon all the Hua-Lein River aggregate even though there are a few andesites.in the Hua-Lein River. According to all of the above, the pessimum effect of andesites in the Hua-Lein River aggregates must be careful.
