水泥使用要领（Essentials of cement）.docVIP

水泥使用要领（Essentials of cement） Often at the forum to see tiling related posts, many of the so-called experts, most posts is referenced, a lot of post is to confuse the concept of misleading to consumers, some said, must use high grade cement; some say No. 525 cement can not be used have said; best 325 cement; while not much attention or have real practical experience of people, will have a tiling of old master often dont have the time nor the Internet bubble, and the teacher may not always care about the cement national standard changes. What does cement mark represent? A class used to indicate the strength of cement, usually depending on the compressive strength of the 28 day period measured by the standard strength test method. For example, the number 425 refers to the cement cement samples according to the standard compressive strength measured 28 days 425-524 kg / cm 2, and the sample of 3 days, 7 days compressive strength and 3 days, 7 days, 28 days and flexural strength was subject to 425 cement standard. The cement division provides the basis for reasonable selection of cement grade, the higher the grade, the higher the strength Whats the difference between the same label 42.5 and 42.5R? R said the early strength. For 42.5 of ordinary cement, in the hardening process, compressive strength of 3 days is about 17 MPa, curing 28 days can reach 42.5 MPa; but for the early strength of cement, the compressive strength of 3 days up to 22 MPa, 42.5 MPA can be completely hardening. By contrast, early strength cement with R produces higher strength in the early stages. What kinds of cement can be roughly divided into? The country is divided into six kinds, referred to as common portland cement Portland cement, ordinary portland cement, slag Portland cement, Portland cement, fly ash volcano ash Portland cement, Portland cement, also formed six types of cement standard. Different varieties of cement with different packaging color word logo, Portland cement and ordinary port