A study on test methods for static and dynamic elastic modulus of soil-cement specimens

[[abstract]]本研究以水泥含量為10%、20%、30%三種不同配比的土壤水泥試體為主，分別以動力試驗與靜力試驗，找出土壤水泥的力學參數，並探討相關性。動力試驗參考CNS 1239-A3052之“混凝土試體縱向基本頻率試驗法”進行試驗，藉由小鋼球撞擊力輸入試體內激發共振頻率，並由加速規量測時間域訊號，然後經過傅立葉分析運算，最後求得動力之彈性模數。靜力試驗則依照ASTM D4832-02之“控制性低強度材料CLSM標準圓柱試體試驗法”進行試驗，由抗壓機進行抗壓試驗，並架設測微計量測變形，並經由荷重-位移之線性回歸曲線圖上的斜率，求得靜力之彈性模數。 在進行動力試驗與靜力試驗前先進行儀器之查驗，而查驗動力與靜力試驗儀器時，皆須以一標準件當作查驗基準。動力試驗以鋼筋的彈性模數與密度，比對敲擊時基本縱向頻率，查驗動力試驗設備的準確性。靜力試驗則以標準壓力環與測微計進行抗壓試驗機之荷重與位移查驗。藉由動力試驗求得的彈性模數與靜力試驗求得的彈性模數比較，得知動力試驗的彈性模數比靜力試驗彈性模數較高;且在量測彈性模數過程中，動力試驗的數據重複性比靜力試驗較穩定。[[abstract]]The study conducts static and dynamic tests on soil-cement samples mixed by three levels of cement contents: 10% 20% and 30% Test results are used to identify the relevancy of mechanical properties Dynamic testing follows a CNS 1239-A3052 method for determining longitudinal natural frequencies of ordinary concrete samples; excitation of soil-cement samples are introduced by small steel balls and waveforms recorded by accelerometer in time are analyzed by Fourier analysis to generate the dynamic modulus of elasticity Static testing is based on ASTM D4832-02 method for determining the compressive strength of controlled low strength materials; extensometers are used to measure deformations and the slope of load-deformation curves by linear regression produces the static modulus of elasticity Test equipment need be examined in advance with standard samples Dynamic test procedure is validated by examining the natural frequency of various steel bars having given modulus of elasticity and density Static test procedure is validated by standard load cells and Vernier scale The test results for all soil-cement samples indicate that dynamic test is more consistent and dynamic modulus of elasticity is higher than static modulus with their difference reducing when cement ratios increas