What Marx is concrete ? Many people do not understand what is the concrete grade and how to get the desired grade concrete . There are many ways determine the standard grade concrete . Within the scope of this article we show how to determine the easiest grade concrete .
To determine the actual incidence concrete , minimum should have a group of samples from the field , including 3 concrete homogeneous sample ( location and method of sampling , curing conditions ) . For large structures , the organization on the same template structure must be in different locations and their numbers large enough to be representative for the whole structure there. The average value of the compressive stress at the time of destruction ( by compressed samples ) of the samples in group 3 samples were taken to determine the concrete grade ( age 28 days ) . If time is not compressed form groups 28 days after concrete setting (usually 3 or 7 days later ) , the concrete grade is determined indirectly through charts concrete strength development standards respectively . The results of the sample compressed at age 3 or 7 days is the rapid test results , not officially . Results compressed samples at 28 days to be considered actual grade of concrete . Structural concrete in place is considered satisfactory grade design ( design rules ) while the average value of each sample group ( the actual label ) is not smaller label design, but at the same time not samples in the sample group of test results less than 85 % marks design .
When it comes to label refers to concrete compression resistance of concrete samples . According to current construction standards of Vietnam ( TCVN 3105:1993 , TCVN 4453:1995 ) , the sample used to measure the strength of a concrete cube sample size of 150 mm × 150 mm × 150 mm , was raised households in standard conditions specified in ISO 3105:1993 , in 28 days time after concrete setting . Then fed into the compressor to measure the compressive stress -destructive ( which determine the compressive strength of concrete ) , unit in MPa ( N / mm ² ) or daN / cm ² ( kg / cm ² ) .
As a rule of structural concrete construction shall be subject to a lot of different effects : compressive , bending , pulling , sliding , in which pressurized the biggest advantages of concrete . Therefore, people often take the compressive strength is characterized targets to assess the quality of concrete , concrete known as labels .
Mark Concrete is classified into several categories from 100 , 150 , 200 , 250 , 300 , 400 , 500 and 600 . When the label says 200 concrete is said to destroy the compressive stress of the concrete sample size standards , are curing in standard conditions , is compressed at the age of 28 days , to 200 kgf / cm ² . Also calculate the compressive strength of concrete is only 90 marks 200 kgf / cm ² ( is taken to calculate the concrete structural design according to the first limit state ) . Today, with the development of technology , we can produce concrete has very high intensities up to 1000kg/cm ² .
