Concrete Knowledge 100 Questions (7)

37, how to check the quality of concrete mold test?

A: Use vernier caliper to measure the length, width and height of the test die, 

allowing error ≤0.5mm. With caliper back and 0.02 ~ 1mm stainless steel gauge 

with measuring four inner surface flatness, allow error ≤0.05㎜ (standard method is 

card 100mm length); If test 150mm×150mm×150mm mold, quite good along the inner 

side of the diagonal full length stuck, and then use the ruler to measure the flatness, 

allowing error < 0.13mm, this method is more accurate than the standard method; When the 150mm×150mm×150mm test mold is qualified by the standard method, it is possible to produce 

the test block side flatness is not qualified. If you do not have a feeler, you can also use a shaving blade, 

as long as the blade does not fit into the caliper and the inside side of the die. Measure the Angle of each adjacent surface with a standard Angle ruler, and the allowable error is less than 0.3°; The standard drawing triangle plate can also be used to clamp the side of two adjacent surfaces from the inside, and the gap between the triangle plate and the other side end can be measured with a gauge. The allowable error is < 0.5mm (100mm×100mm×100mm), < 0.8mm (150mm×150mm×150mm). Most of the 150mm×150mm×150mm cast iron test moulds on the current market are side concave core, and most of the 150mm×150mm×150mm plastic test moulds are side convex core; So before buying carefully check the side flatness.

38, how is the standard maintenance?

Answer: The molding concrete test block into the temperature of 20±2℃, humidity is greater than 95% of the environment curing is standard curing.

39, what is the same condition maintenance?

Answer: The curing condition of the formed concrete test block is the same as the curing condition of the construction site component, which is called the same condition curing.

40, the common curing age of concrete has a few?

A: 3d, 7d, 14d, 28d, 60d, 90d. However, whether the concrete strength is qualified by the national standard is based on the strength of the standard test block of 28d. When the construction of mass concrete, can be indicated in the "construction organization design" to use 60d or 90d strength as the evaluation basis.

41, what is the compressive strength of concrete?

A: The standard method of production, maintenance, pressure test and the unit area can bear the damage load is called the compressive strength of concrete, the unit is MPa.

42, what is the flexural strength of concrete?

A: The strength obtained by the 150mm×150mm×550mm test block broken on the bending fixture after standard curing is called the bending strength, the unit is MPa. The flexural strength of concrete is required to be tested on the pavement of highway.