plastic shrinkage cracks การใช้

• Effects of water - cement ratio on plastic shrinkage cracking of concrete
• 4 ) the effects of fly ash and silica fume on plastic shrinkage cracking were related to the actual w / b ratio of concrete mixture
• The judge criterion of plastic shrinkage cracking for cement based material was studied through the testing of plastic tensile strength and plastic shrinkage capillary stress of cement mortar and concrete
• The trends of plastic shrinkage cracking in concretes made with the same water or cement paste content per cubic meter are similar with the above case , but the critical w / c ratio is about 0 . 45 - 0 . 4 and 0 . 4 , respectively
• There was a borderline w / b ratio , above which concretes containing fly ash or silica fume were more sensitive to plastic shrinkage cracking than that of concretes without fly ash or silica fume , and below which fly ash or silica fume high performance concretes can restrain the plastic shrinkage cracking
• In the paper the effects of the made parameters , the main materials and environmental conditions on plastic shrinkage cracking were investigated . it can be concluded as following : 1 ) there was a critical w / c ratio of maximum plastic shrinkage cracking between lower and higher w / c ratio of concrete mixtures made with the same cement content per cubic meter , concretes with lower or higher w / c ratio being less prone to plastic shrinkage cracking and the w / c critical ratio critical of maximum plastic shrinkage cracking being about 0 . 5
• The proportion of plastic shrinkage cracking is rather high in early cracking . the plastic shrinkage cracking would effect construction appearance and promote the propagation of drying shrinkage cracking or other types cracking , but also provide a passage for aggressive agents penetrating and moving to the concrete mass
• The results shows that the combined use of fibers and expansions was superior to the use of fibers or expansion agents alone in reducing the amounts of plastic shrinkage cracks and diminishing the size of cracks , and it improved the resistance to plastic shrinkage crack extremely
• 2 ) to a certainty of sand percentage , concretes with moderate critical sand percentage which changed in about 36 % - 43 % were more sensitive to plastic shrinkage cracking than concretes with lower or higher sand percentage . 3 ) concrete made with lower strength grading cement was more prone to plastic shrinkage cracking than that of concrete made with higher strength grading cement