How to sample concrete How to sample a test block of shotcrete

Concrete is mixed on site.

According to the "Code for Acceptance of Construction Quality of Concrete Structure Engineering" (GB 50204-2002) and "Concrete Strength Inspection and Evaluation".

According to the provisions of GBJ107 87, the specimens used to check the concrete strength of structural components should be poured in concrete.

The location of the building is randomly selected. Sampling and specimen retention shall comply with the following provisions:

1. For every 100 trays of concrete mixed but not more than 100 cubic meters of concrete with the same mix ratio, the number of sampling times shall not be less than once;

2. When the concrete of the same mix ratio is less than 100 trays mixed in each working shift, the number of sampling shall not be less than once;

3. When a continuous pouring exceeds 1000 cubic meters, the sampling of concrete of the same mix ratio shall not be less than every 200 cubic meters.

on a single occasion; 4. For concrete on the same floor and with the same mix ratio, sampling shall not be less than once;

5. At least one group of standard curing specimens should be retained for each sampling, and the number of retention groups for curing specimens under the same conditions should be based on actual needs. Are you sure.

According to the provisions of the Code for Acceptance of Construction Quality of Concrete Structure Engineering (GB 50204-2002) and the Standard for Inspection and Evaluation of Concrete Strength (GBJ107 87), the specimens used to check the concrete strength of structural components should be randomly selected at the pouring site of concrete. Sampling and specimen retention shall comply with the following provisions:

1. For every 100 trays of concrete mixed but not more than 100 cubic meters of concrete with the same mix ratio, the number of sampling times shall not be less than once;

2. When the concrete of the same mix ratio is less than 100 trays mixed in each working shift, the number of sampling shall not be less than once;

3. When a continuous pouring exceeds 1,000 cubic meters, the sampling of concrete with the same mix ratio shall not be less than once every 200 cubic meters;

4. For concrete on the same floor and with the same mix ratio, sampling shall not be less than once;

5. At least one group of standard curing specimens should be retained for each sampling, and the number of retention groups for curing specimens under the same conditions should be determined according to actual needs.

Does the supervisor have a supervision certificate? If he didn't, he beat him up, he had itchy skin to beg for daytime.

The number of indwelling groups for the same condition (600 days) specimens should be determined according to the actual needs. The number of retention specimens of the same strength grade under the same conditions should be determined according to the quantity and importance of concrete engineering, and should not be less than 10 groups and should not be less than 3 groups.

A group of impermeable specimens should be retained every 500m for continuous pouring of impermeable concrete, and each project shall not be less than two groups. In winter construction to test the impermeability of concrete mixed with antifreeze, the specimen should be cured under the same conditions as the project for 28 days, and then the impermeability test should be carried out after standard curing for 28 days.

Conservation purposes. After the concrete is poured, if the climate is hot and the air is dry, if the maintenance is not carried out in time, the moisture in the concrete will evaporate too quickly, forming a dehydration phenomenon, which will make the cement particles that have formed a gel body can not be fully hydrated, can not be converted into stable crystals, lack of sufficient cohesion, and will appear flake or powder on the surface of the concrete.

The standard method for the preparation of shotcrete test blocks is "spraying large slabs", the large slab test mold (45 35 12cm) is leaned against the wall, the trial mold is sprayed full with a concrete spray gun, sprayed solid, the test mold is flattened, the excess concrete is shoveled away, the surface is roughly smoothed and not squeezed, the mold is dismantled for 24 hours, the large plate test block is moved into the standard maintenance room for maintenance, and the general 7 10d is cut into 6 10 10 10cm test blocks, and then cured to 28d, and 3 test blocks that are not damaged in the cutting process are selected for compressive testing.

The sample of the test block of sprayed concrete is generally taken 10 * 10, according to the different local regulations, the inspection is generally 100m in a group.

However, the general spraying concrete is mixed by itself, and this mix ratio should be tested by the quality supervision station, and you have to send the cement, sand, gravel, and admixtures for inspection respectively, and the test block should also be sent twice, once for compressive strength, and once for the mix ratio.

For concrete sampling, the Code for Acceptance of Construction Quality of Concrete Structure Engineering stipulates that "when a continuous pouring exceeds 1000m3, the concrete of the same mix ratio shall be sampled less than once every 200m3." ”

So here comes the question:

When pouring 1100m3 of concrete at one time, is it taken once every 100m3? Or 200m3 once? Or press 100m3 within 1000m3? Outside press 200m3? ”

In the interpretation of the provisions of the "Concrete Strength Inspection and Evaluation Standard" GB T 50107-2010, it is explained:

When the concrete with the same mix ratio is continuously poured at one time exceeds 1000m3, the whole batch of concrete should be sampled every 200m3 should not be less than once. ”

For example, if 1850m3 is poured continuously, at least 10 groups of specimens should be retained; If 1050m3 is washed continuously, at least 6 sets of trial key companions should be retained.

According to the "Concrete Strength Inspection and Evaluation Standard for Pure Lead".

The sampling of concrete test blocks and the retention of test blocks should comply with the following regulations.

1. No more than 100 cubic meters of hail gear with the mix ratio of concrete, sampling shall not be less than once;

2. When the concrete of the same mix ratio is less than 100 trays mixed in each working shift, the sampling shall not be less than once;

3. When a continuous pouring exceeds 1000 cubic meters, sampling is taken every 200 cubic meters; For each floor, the concrete of the same mix ratio shall be sampled not less than once;

4. At least one group of standard curing test blocks should be retained for each sampling, and the number of retention groups for curing test blocks under the same conditions should be determined according to actual needs.

Sampling unit, quantity:

The construction unit shall not be less than one group per working shift; Not less than one group per 100m3 of mixing;

When the amount of concrete engineering for continuous pouring is less than the above quantity, a group of test blocks should also be left; When the mix ratio changes, a group of test blocks need to be left for each mountain shelter mix ratio;

According to the construction requirements (demoulding, hoisting), the number of test blocks retained shall be specified in the construction plan. 4 groups were made for each sampling (2 groups with the same conditions, 1 group of standard maintenance, and 1 group of standby).

Ordinary concrete sampling standards for the same part, the same number, the same production process, continuous pouring of concrete every 100 square retaining not less than a group of 7 days and a group of 28 days test block, less than 100 square meters according to 100 square indwelling test block.

Concrete, for short"Concrete (tóng).": refers to the general term of engineering composite materials that cement aggregates into a whole by cementitious materials. The word concrete usually refers to the use of cement as cementitious material, sand and stone as aggregates; Cement concrete, also known as ordinary concrete, is widely used in civil engineering engineering when it is mixed with water (which can contain admixtures and admixtures) in a certain proportion and is mixed to obtain cement concrete.

History. Archaeologists have found that 5,000 years ago, the ancestors of Lingjiatan were not only able to make exquisite jade tools, but also began rice farming, raising or hunting pigs, deer, birds and poultry and other animals to enrich the diet of varieties. In addition, in the construction of houses, they have learned similar to the steel and concrete spikes

digging grooves to fill the soil, wooden bones to support the mud wall".

5,000 years ago, the Lingjiatan people did not simply build houses, it has been proved that the Lingjiatan people at that time had already understood the construction process of "digging grooves and filling the soil, and supporting the mud walls with empty bones of wooden guessing stoves", which is very similar to today's reinforced concrete.

The staff said that the primitive ancestors used the fire-burned soil as the filling material for the foundation groove and the wall, used wooden sticks as the support column of the wall in the foundation groove, and then filled the red-boiled soil clods, and applied thick clay on the surface of both sides of the wall, and even some of them may be reinforced with reed rods.