폐콘크리트의 品質이 재생콘크리트의 特性에 미치는 影響 = Effects of the Quality of Waste Concrete on the Properties of Recycled Concrete

다국어 초록 (Multilingual Abstract)

A lot of buildings have been pulled down in the process of redevelopment of urbans, deterioration of buildings, rearrangement of environments and etc in recent years. It has been one of the serious problems in the sides of both society and economy that great amount of demolished concrete produced by being pulled down many buildings have increased all over the country. Moreover, for the environmental reasons, the number of accessible disposal areas near the demolition sites have decreased gradually. Therefore, it has been increasingly interested in the ways of recycling of demolished concrete as the sources because of their efficiencies in the prevention of pollution and the saving of resources. For the countermeasures against the exhaustions of natural aggregate resources, this study deals with the properties of recycled aggregates, which was produced by crushing demolition concrete with jaw crusher, and of cement mortar and concrete used recycled aggregates. The results of this study are as follows.
1) Grades of recycled fine aggregates shows a deviation from the standard range of grade. The grain shape, the ratios of absolute volume of grain, the passing amounts through No.200 sieve doesn't satisfy the limits of K.S. The shape modulus of recycled coarse aggregates has bad results with the increase of W/C ratio.
2) Specific gravity, unit weight and the ratio of absolute volume of recycled aggregates show lower values than those of river sand or crushed sand. They decreased with the increase of W/C ratio for the demolished concrete. Water absorption of recycled aggregates was higher than that of river sand, and increases with the increase of W/C ratio for the demolished concrete.
3) The values of flow of mortar of the recycled aggregates increase with the increase of W/C ratio. Air contents of mortar show a decline and unit weight increases compared with those of river sand mortar, which is related to the qualities of the recycled aggregates. Compressive strength of mortar used recycled aggregate was lower than that of river sand mortar by about 30∼40%.
4) Drying shrinkage of mortar used recycled aggregates shows the highest value among the mortars used river sand or crushed sand. Resistance against the freezing and thawing of recycled aggregate mortar was lower than that of river sand mortar. The permeability for recycled aggregate mortar was higher than that of river sand mortar.
5) Mortar digested in Na₂SO₄ showed a continuous increase in length change and weight loss with the time and carbonation, however mortar digested in HCl showed a steep decline. The deterioration of durability of neutralized mortar that strength of neutralized mortar is lower than that of sound mortar by about 60∼70% is confirmed.
6) Slump of recycled aggregate concrete showed a lower value than that of crushed aggregate concrete, and air contents showed reverse tendency.
7) Compressive strength of recycled aggregate concrete showed a lower value than that of crushed stone concrete and decreased with the decrease of compressive strength of demolished concrete.
8) Close relationship between experiment items is confirmed. Flow of the fresh mortar is highly influenced on the absorption ratios of recycled aggregates, and compressive strength of the hardened mortar on the ratio of absolute volume of grain.
9) Air content of the fresh mortar is highly correlated to unit weight and strength at hardened mortar to elasticity modulous. Air content of the fresh mortar has much influence on the strength.
10) Slump of the recycled concrete is highly correlated to the ratios of absolute volume of grain and unit weight, and air content to the unit weight. Correlation factor between specific gravity and compressive strength showed to be 0.97.
11) As compressive strength of the demolished concrete increases by 100kg/㎠, the strength of recycled aggregate mortar and concrete increased about 10% with the high strength mortar and concrete and about 5% with the normal strength.

목차 (Table of Contents)

• 목차
• 제1장 서론 = 1
• 제1절 연구배경 및 목적 = 1
• 제2절 연구범위 및 방법 = 2
• 제3절 연구동향 = 6
• 제2장 재생콘크리트에 관한 이론적 고찰 = 9
• 제1절 폐콘크리트의 발생 및 재활용 = 9
• 제2절 재생골재의 제조 = 13
• 제3절 재생골재의 특성 = 16
• 제4절 재생콘크리트의 특성 = 21
• 제3장 재생골재에 관한 실험 = 31
• 제1절 개요 = 31
• 제2절 실험계획 및 방법 = 31
• 제3절 잔골재 및 굵은골재의 발생비율 = 40
• 제4절 골재의 입자특성 = 42
• 제5절 골재의 물리적 특성 = 51
• 제4장 재생콘크리트에 관한 실험 = 57
• 제1절 개요 = 57
• 제2절 실험계획 및 방법 = 57
• 제3절 굳지않은 콘크리트의 특성 = 77
• 제4절 경화 콘크리트의 특성 = 85
• 제5절 내구성 특성 = 108
• 제5장 종합고찰 및 분석 = 127
• 제1절 개요 = 127
• 제2절 재생골재 특성간의 상관분석 = 127
• 제3절 재생골재 및 콘크리트간의 상관분석 = 129
• 제4절 폐콘크리트의 품질이 재생골재 및 콘크리트의 특성 = 131
• 제6장 결론 = 135
• ·참고문헌 = 139
• ·ABSTRACT = 143