Mitsuo Ozawa, Gyu-Yong Kim, Gyeong-Choel Choe, Min-Ho Yoon, Ryoichi Sato and Keitetsu Rokugo
The behavior of high-performance concrete (HPC) at high temperatures is very complex and also affects the global behavior of heated HPC-based structures. Researchers have also…
Abstract
Purpose
The behavior of high-performance concrete (HPC) at high temperatures is very complex and also affects the global behavior of heated HPC-based structures. Researchers have also reported how various types of fibers affected the mechanical properties of cement-based materials at high temperatures. This study aims to discuss the effects of high temperatures on the compressive strength and elastic modulus of HPC with polypropylene (PP) and jute fiber.
Design/methodology/approach
Adding synthetic fiber (especially the PP type) to HPC is a widely used and effective method of preventing explosive spalling. Although researchers have experimentally determined the permeability of heated PP-fiber-reinforced HPC, few studies have investigated how adding natural fiber such as jute to this type of concrete might prevent spalling. In this study, the effects of high temperatures on the compressive strength and elastic modulus of HPC with PP and jute fiber (jute fiber addition ratio: 0.075 vol.%; length: 12 mm; PP fiber addition ratio: 0.075 vol.%; length: 12 mm) were experimentally investigated.
Findings
The work was intended to clarify the influence of elevated temperatures ranging from 20°C to 500°C on the material mechanical properties of HPC at 80 MPa. HSC with jute fiber showed a compressive strength loss of about 40 per cent at 100°C before recovering to full strength between 200°C and 300°C.
Originality/value
The elastic modulus of high-strength concrete decreased by 10-40 per cent between 100°C and 300°C. At 500°C, the elastic modulus was only 30 per cent of the room temperature value. The thermal expansion strain of all specimens was 0.006 at 500°C.
Details
Keywords
In an economy with a developed financial system, wages and salaries are not the only source of income for households. Capital markets allow households to invest their saving and…
Abstract
In an economy with a developed financial system, wages and salaries are not the only source of income for households. Capital markets allow households to invest their saving and earn interest and return. An accumulation of wealth is greater for households with higher incomes, who then earn more interest and returns from their wealth, leading to more inequality of income among households. The recent financial crisis experienced in Japan, characterized by a substantial decrease in stock and real estate prices, should have had a reversing effect on the income distribution among Japanese households. Time-series data of quintile income shares and a measure of income inequality in Japan are used to analyze the effects of the financial bubble of the late 1980s and the financial crisis of the 1990s on the income distribution in Japan. The result reveals a significant de-equalizing effect of rising asset prices on income distribution in Japan. However, the equalizing effect of the falling prices of stocks and real estate was partially offset by the de-equalizing effect of rising unemployment in the late 1990s. Furthermore, taking into account the effect of the financial market condition, the income distribution fluctuates less pro-cyclically than previous studies indicated.