防腐處理對木質構造建築地檻材之耐久性

Abstract

本研究針對於ACQ、AAC防腐處理材及其經淋失處理後，對白蟻（Coptotermes formosanus Shiraki）、白腐菌（Lenzites betulina）及褐腐菌（Laetiporus sulphureus）抵抗效能進行研究。此外，亦探討防腐處理對鐵件的腐蝕性與防腐處理對木材力學性質之影響。 抗白蟻、白腐菌及褐腐菌試驗，使用杉木（Cunnignhamia lanceolata）心材、北美鐵杉（Tsuga heterophylla）心材、柳杉（Cryptomeria japonica ）心材、落葉松（Larix leptolepis）心材及台灣杉（Taiwania cryptomerioides）邊材共計五樹種。抗白蟻試驗結果顯示，各組防腐試材重量損失率不超過1%，即使淋失處裡後，試材重量損失率不超過2%，防腐劑ACQ、AAC皆能有效抗白蟻。抗白腐菌（L. betulina）試驗結果顯示，台灣杉與落葉松經ACQ、AAC防腐處理均明顯提升抗腐效能，杉木與北美鐵杉使用AAC作為木材防腐劑時效果較ACQ佳。抗褐腐菌（L. sulphureus）試驗結果顯示，除了柳杉心材外，ACQ、AAC防腐處理均能顯著提高各樹種抵抗褐腐菌能力。 防腐材對表面處理鍍鋅鋼釘腐蝕性不具顯著影響，但防腐材對低碳鐵釘腐蝕性具有顯著影響。使用於ACQ防腐材，鐵件腐蝕重量損失率為低碳鐵釘（1.93 %）＞表面處理鍍鋅鋼釘（1.41 %），使用於AAC防腐材則為低碳鐵釘（3.78 %）＞表面處理鍍鋅鋼釘（1.24 %）。 防腐處理後，藥劑吸收達ACQ-K2、-K3以及-K4級吸收量之台灣杉、柳杉以及 杉木試材，平均抗彎彈性模數（MOE）/比重與平均抗彎破壞模數（MOR）/比重之比強度，分析結果顯示其強度變化不顯著（除了台灣杉K2組MOE/比重之比強度會顯著降低外），MOE與MOR變動值約在10%左右。 CO2減量效益方面，建築物若加以適當的木材防腐後，以台灣杉試材經AAC防腐，所改善的試材重量損失率為例，一棟面積為136 m2木質構造建築物之地檻材部分，可減少因台灣家白蟻啃蝕造成木材中固定的CO2約43.72 kg返還大氣；抵抗白腐菌及褐腐菌侵害而言，減少129.90及123.50 kg的CO2返還大氣。

The main purposes of this study are to investigate the effects of wood preservation on the resistances to Coptotermes formosanus Shiraki, Lenzites betulina, and Laetiporus sulphureus. Additionally, the effects of wood preservation on metal corrosiveness and strength properties of wood are also studied. The resistances to Coptotermes formosanus Shiraki, Lenzites betulina, and Laetiporus sulphureus are tested by the heartwoods of Cunnignhamia lanceolata、Tsuga heterophylla、Cryptomeria japonica 、Larix leptolepis and the sapwood of Taiwania cryptomerioides which were treated with the following absorbing capacity of ACQ-K2(1.3 kgf/m3), ACQ-K3(2.6 kgf/m3), ACQ-K4(5.2 kgf/m3), AAC-K2(2.3 kgf/m3), AAC-K3(4.5 kgf/m3), and AAC-K4(9.0 kgf/m3) as specified in CNS 3000. On the termite resistances test, the weight loss of treated wood did not exceed 1% and the weight loss didn’t exceed 2 % even after weathering test. On the decay resistances test, all of the treated specimens were well protected against L. Sulphureus（except Cryptomeria japonica specimens）. And the treated Taiwania cryptomerioides Hayata and Larix leptolepis specimens were well protected against L. betulina. The treated wood did not exert significant effect on the surface Zinc-plated steel nail corrosiveness, however, the treated wood had significant effect on the low-carbon nail corrosiveness. When ACQ was used, the weight loss of low-carbon nail (1.93 %) > the weight loss of surface Zinc-plated steel nail (1.41 %). When AAC was used, the weight loss of low-carbon nail (3.78 %) > the weight loss of surface Zinc-plated steel nail (1.24 %). After the preservative treatment, Taiwania cryptomerioides, Cryptomeria japonica,and Cunnignhamia lanceolata specimens which absorbed ACQ and reached the grade ACQ-K2、ACQ-K3 and ACQ-K4, the results showed that MOE/specific gravity and MOR/specific gravity did not change significantly (except the MOE/specific gravity of K2 group of Taiwania cryptomerioides reduced significantly), and the values of MOE and MOR change were about 10%. Taking Taiwania cryptomerioides as an example, as estimation, the preservation treated sill of one wooden construction building with a floor area of 136 m2 could reduce 43.72 kg CO2 which fixed in the wood would return to the atmosphere by the gnawing of termite. And it would reduce 129.90 kg and 123.50 kg of CO2 caused by the infringement of Lenzites betulina and Laetiporus sulphureus respectively.