GB 2938-2008Low heat expansive cement (English PDF)

4.1 Blast furnace slag

In line with GB/T 203 provisions of Excellence for granulated blast furnace slag.

4.2 Gypsum

Natural gypsum. meet Class A or Class G for more than two gypsum or anhydrite GB/T 5483 regulations.

Industrial by-product gypsum. industrial production to calcium sulfate as a byproduct main component. When using industrial by-product gypsum should be tested, certified Ming on the performance of cement harmless.

4.3 Portland cement clinker

By the mainly containing CaO, SiO2, Al2O3, Fe2O3 material, and an appropriate proportion of finely pulverized till the partial melting of the resulting calcium silicate-based to hydraulic binder material mineral composition. Wherein the mass fraction of the mineral calcium silicate is not less than 66%, calcium oxide and silicon oxide by mass is not less than 2.0. Clinker intensity level required to achieve 42.5 above; free calcium oxide content (mass fraction) shall not exceed 1.5%; MgO content (mass Volume fraction) should not exceed 6.0%.

4.4 Aids

Allow cement grinding aids added, the amount should not exceed 0.5% by mass of cement, grinding aids should be consistent with JC/T 667's Provisions.

4.5 Additive Material

By the supply and demand sides agreed to allow adding a small amount to improve the performance of cement expansion Additive Material.

6.1 Trioxide

Sulfur trioxide content (mass fraction) should be 4.0% to 7.0%.

6.2 The specific surface area the specific surface area of not less than 300m2/kg.

6.3 Setting Time

Initial setting no earlier than 45min, the final setting shall not be later than 12h, but also by the production units and the use of units agreed.

6.4 Stability

Boiling cooking method should test qualified.

6.5 Strength

Compressive strength and flexural strength of cement every age should not be less than the values in Table 1.

Table 1 cement grade and age strength

power level

32.5

Flexural strength/MPa 7d 28d 5.0 7.0 Compressive strength/MPa 7d 28d 18.0 32.5

6.6 Heat of hydration

Each age heat of hydration of cement should not be greater than the value in Table 2.

Table 2 age heat of hydration of cement

power level

32.5

Hydration heat/kJ/kg 3d 7d

6.7 Coefficient of linear expansion

Coefficient of linear expansion should meet the following requirements.

1d not less than 0.05%;

7d shall not be less than 0.10%;

28d shall not exceed 0.60%.

6.8 Chloride

Chloride ion content of cement (mass fraction) shall not exceed 0.06%.

6.9 Alkali content

Alkali content agreed upon by both parties. Alkali content (mass fraction) Press Na2O + 0.658K2O calculated values.

7.1 Sulfur trioxide (SO3), sodium oxide (N Rao 2O) and potassium oxide (K2O)

According to GB/T 176 performed.

7.2 The specific surface area According to GB/T 8074 carried out.

7.3 Setting time and soundness

According to GB/T 1346 carried out.

7.4 Heat of hydration

According to GB/T 2022 or GB/T 12959, and adopt the direct method of arbitration.

7.5 Coefficient of linear expansion

Press JC/T 313 performed, with the following additional provisions.

a) by the beginning of the test specimen 24h moisture conservation stripping length measurement, then in water conservation to 1d, 7d, 28d length measurement.

b) Final setting time exceeds 12h, moisture curing time by pressing the test specimen after the final setting time 12h First release length measurement.

7.6 Strength

According to GB/T 17671 performed.

7.7 Chloride

Press JC/T 420 test.

8.1 Number and sampling

Former cement factory by number and species with sampling. Bagged cement and bulk cement should be separately numbered and sampled. Each number is a take Sample units, cement factory numbered no more than 400t is a number.

Sampling method according to GB/T 12573 performed.

Sampling should be representative. Continuous take, also from more than 20 different parts of the sample taken the same amount of total at least 14kg.

Samples taken by the method specified in this standard Chapter 7 factory inspection.

8.2 Cement factory

Cement factory technical requirements of this standard shall comply with the technical requirements of Chapter 6 6.1 to 6.8.

8.3 Determine the rules

8.3.1 Qualified

Chapter 6 comply with the standard 6.1 to 6.8 of the technical requirements for qualified products.

8.3.2 Nonconforming

Any one does not meet the criteria in Chapter 6 6.1 to 6.8 of the technical requirements to be defective.

8.4 Test Report

Content test report shall include the technical requirements and test results of this standard, such as the use of aids, industrial by-product gypsum, it should say Clear its name and adding volume. Cement plant should be issued from the date of despatch except 28d 11d and 28d strength linear expansion coefficient of the test in the cement Test results. 28d and 28d strength linear expansion coefficient values should be reported immediately from the date of 32d within the cement.