Sulfate Attack on Concrete - Chapter 5

Consequences of sulfate attack on concrete - Như đã thảo luận trong chương trước, cụ thể để tấn công có sulfate trải qua một tổ chức lại tiến bộ và sâu sắc của vi cấu trúc nội bộ của mình. Những thay đổi này có hậu quả trực tiếp trên những đặc tính kỹ thuật của vật liệu. Như sẽ được nhìn thấy trong đoạn văn sau đây, cụ thể trải qua tấn công sulfate thường được tìm thấy bị sưng, spalling và nứt. Có bằng chứng mạnh mẽ cho thấy rằng suy thoái cũng góp phần làm giảm. | 5 Consequences of sulfate attack on concrete INTRODUCTION As discussed in the previous chapter concrete subject to sulfate attack undergoes a progressive and profound reorganization of its internal microstructure. These alterations have direct consequences on the engineering properties of the material. As will be seen in the following paragraphs concrete undergoing sulfate attack is often found to suffer from swelling spalling and cracking. There is overwhelming evidence to show that the degradation also contribute to significantly reduce the mechanical properties of concrete. Many structures affected by sulfate degradation often need to be repaired or in the most severe cases partially reconstructed. The various consequences of sulfate attack on concrete are reviewed in the following sections. Throughout the text distinction is made between concrete suffering from internal sulfate degradation and that affected by external sulfate attack. The behavior of hydrated cement systems tested under well-controlled laboratory conditions is also distinguished from the performance of concrete in service. EXTERNAL APPEARANCE AND VOLUME STABILITY OF CONCRETE ATTACKED BY SULFATE As emphasized in Chapter 4 it is now well established that hydrated cement systems subject to sulfate attack often sustain damage as a result of excessive volume change. For instance the swelling behavior of concrete suffering from internal sulfate attack has been the subject of numerous reports Day 1992 Diamond 1996 Lawrence 1995a b . The volume instability of mortar and concrete mixtures exposed sulfate solutions is also well documented Gollop and Taylor 1992-1996 Mehta 1992 Odler and Jawed 1991 Thor-valdson 1952 . For additional information see Thorvaldson et al. 1925 1927 1928 and Tuthill 1936 . 2002 Jan Skalny Jacques Marchand and Ivan Odler The macroscopic manifestations of both types of degradation will be reviewed in separate sections. The volume instability of concrete subjected to .