• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.325-332
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• 2020

In the safety diagnosis of fire-damaged concrete structures, it is difficult to evaluate the strength and changes in materials due to high temperatures with the existing durability analysis method. In particular, the compressive strength of specimen with different damage levels by thickness is used as a representative value for reducing the compressive strength of the structural member. In this study, a heating experiment was performed with only top face heating and fully heating conditions at 400℃ to 800℃. After heating, splitting tensile test and color analysis were performed to sliced specimens with a thickness of 20mm accompanied by the compressive test of a fully heated specimen. As a result of the experiment, the compressive strength reduction rate calculated from the splitting tensile strength of every sliced specimen appeared to be within 10% of the fully heated specimen on aver age, and the hue value analysis showed consistent color values were observed by red at 400℃-600℃ and gray at 700℃ or above. It follows that the techniques proposed in this study are reasonably assessable to estimate heated temperature and residual compressive strength and damage depth of concrete.

• Economic and Environmental Geology
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• v.38 no.6 s.175
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• pp.675-687
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• 2005

The rocks of the five storied stone pagoda in the Jeongrimsaji temple site are 149 materials in total with porphyritic biotite granodiorite. They include pegmatite veinlet, basic xenolith and evenly developed plagioclase porphyry. This stone pagoda has comparably small fracture and cracks which are farmed in the times of rock properties, but surface exfoliation and granular decomposition are in process actively since the rocks are generally weakened from the influence of air contaminants and acid rain. Structural instability of constituting rocks in the 4th roof materials are observed to occur from distortion and tilt. Such instability is judged to threat stability of the upper part of the stone pagoda. Also, chemical weathering is operating even more as the contaminants, ferro-manganese hydroxides eluted from water-rock interaction on the rock surface. Most of the rock surface is covered with yellowish brown, dark black and light gray contaminants, and especially occur in the lower part of the roof rocks on each floor. The roof underpinning rocks are severe in surface pigmentation from manganese hydroxides and light gray contaminants. The surface of rocks lives bacteria. algae, lichen, or moss and diverse productions in colors of light gray, dark Bray and dark green. Grayish white crustose lichen grows thick on the surface with darkly discolored by fungi and algae in the first stage on basement rocks, and weeds grows wild on the upper part of each roof rocks. This stone pagoda must closely observe the movements of the upper part rock materials through minute safety diagnosis and long term monitoring for structural stability. Especially since the surface discoloration of rocks and pigmentation of secondary contaminants are severe, establishment of general restoration and scientific conservation treatment are necessary through more detailed study for this stone pagoda.