Physical properties of high strength cement pastes

Abstract Recent developments in methods of processing ordinary Portland cement have shown that above average strengths (in flexure) are easily obtained without expending energy on high pressure compaction techniques. This paper reports strengths and other physical properties of both ordinary pastes and modified (macro defect free) pastes and attempts to compare and contrast the two types. The apparently greater notch sensitivity of the modified pastes is explained in terms of a reduced inherent flaw size. Optical microscopy shows that large pores are absent in the modified paste but transmission electron microscopy (TEM) shows that the fine scale microstructures of ordinary pastes and high strength pastes are very similar.