화강암질(花崗岩質) 풍화토(風化土)의 시멘트에 의한 안정처리(安定處理)에 관(關)한 연구(硏究) (내구성(耐久性)을 중심(中心)으로)

도덕현 ( Duk Hyun Do ) 한국농공학회 1980 韓國農工學會誌 : 전원과 자원 Vol.22 No.3

Soil-cement mixtures involve problems in it's durability in grain size distribution and mineral composition of the used soils as well as in cement content, compaction energy, molding water content, and curing. As an attempt to solve the problems associated with durability of weathered granite soil with cement treated was investigated by conducting tests such as unconfined compression test, it's moisture, immers, wet-dry and freeze-thaw curing, mesurement of loss of weight with wet-dry and freeze-thaw by KS F criteria and CBR test with moisture curing on the five soil samples different in weathering and mineral composition. The experimental results are summarized as follows; The unconfined compressive strength was higher in moisture curing rather than in the immers and wet-dry, while it was lowest in freeze-thaw. Decreasing ratio of unconfined compressive strength in soil-cement mixtures were lowest in optimum moisture content or in the dry side rather than optimum moisture content with freeze-thaw. The highly significant ceofficient was obtained between the cement content and loss of weight with freeze-thaw and wet-dry. It was possible to obtain the durability of soil-cement mixtures, as the materials of base for roads, containing above 4% of cement content, above 30kg/㎠ of unconfined compressive trength with seven days moisture curing or 12 cycle of freeze-thaw after it, above 100% of relative unconfined compressive strength, 80% of index of resistance, below 14% of loss of weight with 12 cycle of wet-dry and above 1.80g/㎤ of dry density.

花崗岩質風化土의 CBR 特性

都德鉉(Do Duk Hyun) 대한토목학회 1979 대한토목학회지 Vol.27 No.2

道路基層 安定處理에 關한 試驗硏究 (Ⅰ)

都德鉉(Do Duk Hyun),李在顯(Lee Jai Hyeon) 대한토목학회 1978 대한토목학회지 Vol.26 No.2

첨가제(添加劑)에 의한 Soil-Cement의 성질(性質) 개량(改良)

도덕현 ( Duk Hyun Do ) 한국농공학회 1979 韓國農工學會誌 : 전원과 자원 Vol.21 No.1

Six kinds of weathered granite soils whose degree of weathering and mineral compositions are different, were tested in order to improve the soil-cement. by performing compression test, durability (freezing-thawing) test and mesurement of shrinkage are made. From result of the tests as mentioned above, the following conclusions are drawn. The unconfined compressive strength of seondary additives containing soil-cement mixtures and their resistance against freezeing-thawing are more increased and shrinkage is more decreased than soil-cement mixtures only in case opitimun quantity of additives are added to soil-cement mixtures, and according as types of soils.

제주도(濟州道) "송이"의 시멘트안정처리(安定處理) 효과(效果)에 관(關)하여

신광식 ( Kwang Sik Sin ),도덕현 ( Duk Hyun Do ),이성태 ( Seong Tae Lee ) 한국농공학회 1981 韓國農工學會誌 : 전원과 자원 Vol.23 No.4

This experiment was carried out to find out the effectiveness of soil cement stabilization about the Song-I in Cheju province. The results are summarized as follows; 1. The increasing ratio of unconfined compressive strength according to the increment of cement content was markedly low compared with the weathered granite soil, so the effect of stabilization was low. 2. The moisture content of the sample of Song-I indicates the maximum unconfined compressive strength showed at the 5% or so of dry side than the optimum moisture content and the change of the unconfined compressive strength according to the change of moisture content was not sensitive compared with the weathered granite soil. 3. Generally the primary strength of curing age within 7 days of the sulfate resisting cement was low compared with the normal portland cement and the strength of 28 curing days showed a similar tendency, especially in case of Song-I, and it seemed that the sulfate resisting cement was a little more effective than the normal portland cement. 4. As the unconfined compressive strength of grain size controlled Song-I was low compared with the weathered granite soil, so the rate of weight loss by the durability test was great, therefore it was thought that the durability was weak.

불포화(不飽和) 점성토(粘性土)의 전단강도(剪斷强度) 특성(特性)에 관(關)한 연구(硏究)

유범식 ( Beom Sik Yoo ),도덕현 ( Duk Hyun Do ) 한국농공학회 1981 韓國農工學會誌 : 전원과 자원 Vol.23 No.3

In order to investigate the characteristics of the shear strength of the unsaturated cohesive soils which has mean characters of sand and clay widely used for banking, I selected soil samples from An-sung district and, against it, performed direct shear test and unconfined compression test changing grain size, compaction energy and moisture content and also performed triaxial compression test under optimum moisture content. The results are as follows; 1. As the passing percent of the No. 200 sieve increased from 23.6% to 56.1%, cohesion increased from 0.202kg/㎠ to 0.398kg/㎠ under the direct shear test and from 0.38 kg/㎠ to 1.05kg/㎠ under the tria4al compression test, internal friction angle decreased from 44. 78° to 34.34° under the direct shear test and from 31.88° to 13.31° under the triaxial compression test. 2. Cohesion showed it's maximum value around OMC and internal friction angle showed a tendency to increase according to the decrease of water content but it's increasing ratio was relatively slow. 3. Decreasing ratio of cohesion and internal friction angle was relatively sensitive according to the decrease of compaction energy. 4. The smaller of the vertical stress and the coarser of the grain size of samples, changing of the volume showed a tendency to increase and as the increase of water content, the shear displacement (d_h) at failure shear stress (τ_f) showed maximum and the τ_f-d_h curve was gentle. 5. To synthesize the results of the direct shear test and the triaxial compression test, cohesion showed higher under the triaxial compression test and internal friction angle showed a tendeney to appear higher under the direct shear test. It seems that we can get correspondent results by removing the side friction of mold with soils and adjusting the vertical stress and shearing speed under the direct shear test.

화강토(花崗土)의 풍화도(風化度)가 수분흡착(水分吸着) 및 침투성(浸透性)에 미치는 영향(影響)

이대훈 ( Lee Dae Hoon ),도덕현 ( Do Duk Hyun ) 한국농공학회 1984 韓國農工學會誌 : 전원과 자원 Vol.26 No.3

To examine the moisture adsorption and permeability characteristics, weathered granite soils of different degrees of weathering, cultivated upland soils and sands of Han-river were sampled. The results are as follows: 1. In case that the mother rock was same, the pF values under same moisture content decreased according as the grain size of soil became finer by the weathering process. 2. In case that the mother rock was different, the pF value varied by the behavior of clay minerals, and the cultivated upland soils showed more sensitive reaction than sands and fresh granite soils. 3. The pF value changed by the difference of primary moisture content and also influenced by soil structure, testing method and etc. 4. The pF value and compaction curve had close relation, however under same moisture content, the pF value decreased by the increment of density. 5. The permeability depend on the available void ratio between the soil particles according to the degree of weathering, and the pF value of available void water between the soil particles which related directly to permeability was about 3.3 except the void water holded in the soil particles. 6. As the above, the pF value and permeability were differentiated by degree of weathering, primary moisture content, density and etc. Therefore it is considered unreasonable to define uniformly by soil texture.

지연(遲延)다짐이 Soil-Cement의 압축강도(壓縮强度)에 미치는 영향(影響)

정일웅 ( Jeong Il Woong ),김문기 ( Kim Moon Ki ),도덕현 ( Do Duk Hyun ) 한국농공학회 1986 韓國農工學會誌 : 전원과 자원 Vol.28 No.4

This study was attempted to investigate the effects of delayed compaction on the unconfined compressive strengh and dry density of Soil-cement mixtures. Soil-cement construction is a time-consuming procedure. Time-delay is known as a detrimental factor to lower the quality of soil-cement layer. A laboratory test was performed using coarse and fine weathered granite soils. The soils were mixed with 7% cement at optimum moisture content and excess moisture content in part. Secondary additives such as lime, gypsum-plaster, flyash and sugar were tried to counteract the detri-mental effect of delayed compaction. The specimens were compacted by Harvard Miniature Compaction Apparatus at 0,1,2,4,6 hors after mixing. Two kinds of compactive efforts(9^kgf and 18^kgf tamper) were applied. The results were summarized as follows: 1. With the increase of time delay, the decrease rate of dry density of the specimen compacted by 9^kgf tamper was steeper than that of the specimen compacted by 18^kgf tamper. In the same manner, soil-B had steeper decreasing rate of dry density than soil-A. 2. Based on the results of delayed compaction tests, the dry density and unconfined compressive sterngth were rapidly decreased in the early 2 hours delay, while those were slowly decreased during the time delay of 2 to 6 hours. 3. The dry density and unconfined compressive strength were increased by addition of 3% excess water to the optimum moisture content during the time delay of 2 to 6 hours. 4. Without time delay in compaction, the dry densities of soil-A were increased by adding secondary additives such as lime, gypsum-plaster, flyash and sugar, on the other hand, those of soil-B were decreased except for the case of sugar. 5. The use of secondary additives like lime, gypsum-plaster, flyash and sugar could reduce the decrease of unconfined compressive strength due to delayed compaction. Among them, lime was the most effective. 6. From the above mentioned results, several recommendations could be suggested in order to compensate for losses of unconfined compressive strenght and densitv due to delayed compaction. They are a) to use coarse-grained granite soil rather than fined-grained one, b) to add about 3% excess compaction moisture content, c) to increase compactive effort to a certain degree, and d) to use secondary additives like line gypsum-plaster, flyash, and sugar in proper quantity depending on the soil types.