RESUMEN
The paper describes the mechanical behavior of fine recycled concrete aggregate (FRCA) concrete according to the mineral admixtures. Three types of the mineral admixtures, i.e., fly ash (FA), ground-granulated blast-furnace slag (GGBS), and silica fume (SF), are used and the replacement ratios of FRCA are 50% and 100%. The dosages of the admixtures of FA, GGBS, and SF are determined with the normal dosage (30%, 40%, and 5.0%, respectively) based on the ACI committee reports (No. 232, 233, and 234) and half-normal dosage. The mechanical performance is investigated with the compressive and splitting tensile strength, and elastic modulus. Additionally, the total porosity is measured in natural fine aggregate (NFA) and FRCA 100% replaced specimens by mercury intrusion porosimetry (MIP) for investigating the relationship with the compressive strength. Based on the experimental test results, the mineral admixtures improve the mechanical performance of FRCA concrete. The effective dosages of FA, GGBS, and SF for FRCA concrete are investigated according to the replacement ratio of the FRCA. In particular, FRCA 100% replaced concrete may be possible to be used for the structural concrete members with the specific dosage of the mineral admixtures. The prediction of the splitting tensile strength and the elastic modulus by the codes or previous formulas exhibits underestimated and overestimated results, respectively. The relationship between the total porosity and the compressive strength of the FRCA concrete should be modified with more experimental tests.
RESUMEN
BACKGROUND AND PURPOSE: Wandering is one of the most common behavioral and psychological symptoms of dementia, and associated with some of the adverse outcomes in dementia, such as getting lost or even death. The etiology of wandering is not yet clearly known. As depression and wandering are both very common among the patients with dementia, this study examined the relationship between the depression and wandering among the community dwelling patients with dementia. METHODS: Fifty community dwelling patients diagnosed with dementia were included in this study if they had primary family caregiver, older than age 18 in Seoul, South Korea. The Geriatric Depression Scale, Korean Version (GDS-K), Korean Version of the Mini-Mental State Examination (K-MMSE) and Korean Version of Revised Algase Wandering Scale-Community Version (K-RAWS-CV) were used to measure the severity of depression, cognitive function and wandering. RESULTS: Thirty percents of the patients showed wandering. Mean score of GDS-K was significantly higher in wanderers than non-wanderers. Severity of depression was significantly correlated with the total score of K-RAWS-CV and subscales of persistent walking, repetitive walking, eloping behavior, and mealtime impulsivity in whole sample. K-MMSE score also was related to wandering behavior. The prevalence odds ratio for wandering in depressed patients compared with undepressed group was 8.386 (95% confidence interval: 1.978-35.561). CONCLUSIONS: This study implicates that not only cognitive impairment but also psychosocial aspects should be considered in wandering patients with dementia and suggests assessing the depression in patients would be helpful in identifying the causes of wandering.
RESUMEN
The main objective of this study is to develop an eco-friendly and a large recycling technique of flotation Tailings from korea (TK) from metal mines as construction materials such as admixtures for high-fluidity concrete (HFC). TK used in this study was obtained from the Korea Molybdenum Corporation in operation. TK was used as the alternative material to adjust flowability and viscosity of HFC in the form of powder agent which enables adjustment of concrete compressive strength. In this study, we have performed concrete rheological tests and concrete flowability tests to obtain the quality characteristics of TK for using as the admixture in producing HFC. The results indicated that the adequate mix ratio of cement to TK should be 8:2 (vol%). It is more effective to use the TK as admixture to control flowability, viscosity and strength of HFC than the normal concrete. It was found that TK could be recycled construction materials in bulk such as admixture for HFC, in terms of the economic and eco-friendly aspects.