현무암 석분슬러지의 공학적 특성 및 활용 방안 연구

Abstract

According to the Unified Soil Classification System (USCS), Jeju powdered basalt sludge that is produced during the stone treatment process is similar to ML & CL. The materials found from our surroundings such as site soil, cement (hardening material), compounds (quick setting admixtures), fly-ash and sand were mixed with the Jeju powdered basalt sludge. The strength test results for these mixed materials showed that the intensity decreased as the powdered basalt sludge content increased. As the curing day extended the intensity also increased. The most mixtures with powered basalt sludge were satisfied with the standard intensity of the water-stop material, except when the mixtures were used as following percentages: the powdered basalt sludge below 18%, cement below 2%, fly-ash and sand over 80%. With the soil ratio over 20%, the formation did not occur during the test of water curing, and because it is hard to manifest over the regular intensity, the test results concluded that it cannot be utilized as the water stop material. The tensile strengths of mixtures were found about 9-14% of the compressive strength, although they can be different depending on the curing condition. After compaction the powered basalt sludge, the coefficient of permeability was 4.67E-06cm/sec. The permeability test results for the combination of various samples and powered basalt sludge showed that the permeability decreased as the powered basalt sludge content decreased and as the cement content and curing day increased. Also, when the amount of the used powered content was below 50%, the coefficient of permeability was very small changed. The mixtures formed with the ratio of powdered content below 83%, and cement content over 17% showed the permeability standard of the water-stop material in satisfactory with the coefficient of permeability below 1.00E-07cm/sec. The mixtures formed with the powered sludge below 50%, fly-ash, and cement below 50%, were not satisfied with the standard permeability as a water-stop material. In addition, in case with the site soil mixture testing, it was found that the sample formation was difficult to do conducting tests. However, for the mixed proportion ratio for the powdered sludge and site soil with 4:6, it was considered as being close to the permeability standard of water-stop material. The strength test result for the powered basalt sludge, cement, and compounds (quick setting admixtures) after freezing and thawing showed that its resistance dropped as the content of powdered sludge increased. While the change of the coefficient of permeability was relatively small with increasing the content of cement to before and after freezing and thawing, the coefficient of permeability was increased as the content of powered sludge increased. This is because of the increase in gap that is caused by the expansive force and moisture in the process of freezing and thawing. In the weight change testing, 9% of the weight dropped as the content of powered sludge increased. The examination of Pozzolan reaction revealed that with the increase of cement content, the combination was good and the size of gap was small, but as the content of powered sludge increased, the size of gap was larger. Also, during the crack & length change test that is based on the drying shrinkage, the shrinkage amount was high, and the number of cracks was low as the content of powered sludge increased. The adsorption tests were conducted to determine the detergency of powered sludge. The test results for each of the heavy metal, pH, and sample amount revealed that whole eliminate efficiency resulted pb2+> Cd2+>Cr, and the eliminate efficiency increased as pH increased. In order to develop a water-stop method by utilization of the powdered basalt sludge, the permeability tests were conducted on pecimens formed the conditions of sedimentation and dryness for seven days after dropped the mixed sample from the water. As results, the permeability was very low with the ratio of powered sludge 50%, cement 10%, and fly-ash 40%. But as the use of site soil increased, the permeability tended to be higher. In case with the combination of powdered sludge, cement, and sand, if the mix proportion ratio of the powered sludge and cement was high, the result of permeability was low. Thus, it was concluded that the proposed method could be applicable to the water-stop method. There are many other ways to recycle the powdered sludge: it can be used as impermeability material for filling holes after drilling; filling material for the underground water pumping facility; grouting material for surrounding space, and for the small scaled pond ground construction.