控制性低強度材料（CLSM）為結構填充、鋪面底層、基礎以及管溝回填的重要材料，其工程特性主要為自黏結與良好流動性，可用於替代回填級配料。但是目前現場可供判斷CLSM凝固狀況之試驗方法卻無法有效地發揮作用，甚至於被忽略不做，導致CLSM的特性無法發揮，反而成為施工品質不良的元兇，因此CLSM強度發展之監測成為本文研究之重點。本研究以動態圓錐貫入儀（DCP）進行CLSM強度評估之研究，找出CLSM可繼續施工之平均貫入比(APR)臨界值，並進行現場試驗驗證。 本研究實驗室作業主要以不同單位水泥量及W/C進行CLSM之拌製，進行ASTM C403貫入阻抗試驗檢驗其可繼續施工之時間，抗壓強度及規範內其他條件，再從符合規範之配比中找出DCP之可繼續施工臨界值APR值。本研究另外於現場進行DCP試驗以及CLSM採樣之ASTM C403試驗，評估實驗室內所訂定之臨界值於現場施工品質管理之成效。最後再比較DCP在CLSM與傳統級配料之差異，並以CLSM之DCP試驗數據，代入DCP與土壤CBR值之關係式中，求得CLSM之DCP結果相較於傳統級配料之CBR值。主要試驗結果討論如下： 1.本研究早強型CLSM大多能符合規範要求之工作性與強度，在實驗室之CLSM配比(S/A=1.0)中，經由ASTM C403以及DCP試驗結果，建議APR值26.3mm/blow為該材料之可繼續施工臨界值。 2.上述之建議值與現場採樣所進行之ASTM C403試驗結果顯示，試體達400psi時間（292min）與本研究建議可繼續施工之時間（約300min）相近。 3.將CLSM（S/A=1.0）試體經過DCP試驗後，取其表面完整者，再進行貫入試驗所得到之結果多大於400psi，平均值為473.2psi，可能ASTM C403貫入試驗結果受到試體深度、表面積、養護溫度、擾動與擠壓等外在條件而影響。 4.本研究之CLSM顯示抗壓強度隨著時間而增加，APR值則隨時間減少之結果。早強型CLSM（S/A=1.0）之12小時APR與28天抗壓強度試驗結果中，兩者之關係同時受到W/C與單位水泥量之影響，W/C較高者有較低之晚期抗壓強度與較高之APR值，單位水泥量較高者則有較高之晚期抗壓強度與較低之APR值。 Controlled Low Strength Materials (CLSM) is a self-compacted, cementitious material, and the primary application is as structural fill or backfill in place of compacted soil. However, there was no efficient way to check the setting time and the hardening of in-situ CLSM. Thus, it was necessary to develop an effective method to monitor the setting time of CLSM and determine when to construct the next layer. The research work of this study included: preparing CLSM mixtures with different W/C ratios and cement contents, comparing the results from ASTM C403, DCP and compressive strength tests, and determining the critical value of APR for the construction of next layer. In-situ DCP tests were performed in two projects to verify the laboratory results. CBR values were also estimated using DCP-CBR relationships provided by the DCP manufacture. Major findings of this study are summarized as follows: 1.For high-early-strength CLSM (S/A=1.0), the critical APR value for the construction of next layer was recommended as 26.3mm/blow. 2.Results of field verification showed that the average time (292min) that reached 400psi of ASTM C403 test was comparable to that (300min) of DCP tests. 3.Test of ASTM C403 performed on specimens that were done with DCP test showed higher readings which were probably due to the influence of specimen thickness, surface area, curing temperature, and disturbing of DCP testing. 4.Results of this study showed that compressive strength increased with time, while APR decreased with time. CLSM mixtures with higher W/C ratio generally had lower compressive strength and higher APR, while mixtures with higher cement content generally had higher compressive strength and lower APR.
