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为了评定塑性混凝土的长期渗流稳定性和使用年限,结合当地原材料的情况,采用膨润土、黏土、水泥、骨料、水和减水剂等来制备塑性混凝土,试验测定了完整或含孔洞塑性混凝土的长期渗流稳定性和使用年限。经过多次试配试验,选定配合比并制作试件,该试件在标准养护28 d后,其抗压强度为1.25 MPa。分别制备、使用2组共12个试件进行溶蚀试验或冲淋试验。溶蚀试验表明,在溶蚀试验的测试初期,渗透系数是不断变化的,尤其在试验前30~40 d是比较明显的,但均在10-7 cm/s数量级。随溶蚀时间的延长,混凝土试件中被溶蚀Ca O的数量呈线性递减关系,直至降低到自来水所含Ca O的浓度范围,而渗透系数在150~180 d时增至3.0×10-7 cm/s,且逐渐趋于稳定。经180 d的渗流溶蚀作用后,塑性混凝土会产生剪损裂缝和拉断裂缝,甚至有较大的塑性变形,导致试件顶面平均上升位移值高达38.5 mm。通过溶蚀试验计算该塑性混凝土的渗透系数和Ca O含量,然后计算塑性混凝土防渗墙使用年限为37.1~60.7 a。冲淋试验表明:水流会在含孔洞的混凝土中产生集中冲刷且局部混凝土中的Ca O被溶蚀并随水流携带走,经过测定分析,水流从孔中冲蚀出的白色沉淀物为碳酸钙,另有少量的Na+、微量黏土和膨润土颗粒,从而降低了混凝土的质量。在恒压水流作用下,水流对已含孔洞混凝土的冲刷较弱,混凝土中被溶蚀并携带走的Ca O较少,即使冲淋197 d后,其前后的质量的损失较小,相对损失不超过1%,但其强度损失较大,高达25.4%。综合研究表明:采用黏土和膨润土制备的塑性混凝土符合土石坝防渗墙防渗的特点,具有水泥用量小、强度低、高抗渗性和使用年限长的特点。
In order to evaluate the long-term seepage stability and service life of plastic concrete, the plastic concrete is prepared by using bentonite, clay, cement, aggregates, water and water reducer in combination with the local raw materials. Long-term seepage stability and service life. After several trial tests, the selection of the ratio and the production of specimens, the specimen after 28 days of standard conservation, the compressive strength of 1.25 MPa. Were prepared, the use of two groups of 12 specimens for corrosion test or shower test. The dissolution test shows that the permeability coefficient is changing at the beginning of the test of erosion test, especially 30 ~ 40 days before the test, but both are on the order of 10-7 cm / s. With the prolongation of corrosion time, the amount of dissolved CaO in concrete specimens decreases linearly until the concentration of CaO in tap water decreases, while the permeability coefficient increases to 3.0 × 10-7 cm / s, and gradually stabilized. After 180 days of seepage erosion, the plastic concrete will produce shear fracture and fracture, and even larger plastic deformation, resulting in an average upward displacement of the specimen up to 38.5 mm. Calculate the permeability coefficient and CaO content of the plastic concrete through the corrosion test, and then calculate the service life of plastic concrete cutoff wall is 37.1 ~ 60.7 a. The results of shower experiment show that the water flow will concentrate and scour in the concrete with holes and the CaO in the concrete is dissolved and carried along with the water flow. After the analysis and analysis, the white precipitate eroded from the holes by the water flow is calcium carbonate, Another small amount of Na +, trace clay and bentonite particles, thereby reducing the quality of concrete. Under the action of constant pressure water flow, the scouring of water flow to the concrete containing the hole is weak. The CaO that is corroded and carried in the concrete is less, and the loss of mass before and after the showering for 197 d is small, the relative loss is not More than 1%, but its intensity loss is larger, up to 25.4%. The comprehensive study shows that the plastic concrete made of clay and bentonite is in accordance with the seepage prevention of earth-rock dam cut-off wall and has the characteristics of small amount of cement, low strength, high impermeability and long service life.