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GB/T 27690-2011 English PDF (GBT27690-2011)

GB/T 27690-2011 English PDF (GBT27690-2011)

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GB/T 27690-2011: Silica fume for cement mortar and concrete

This Standard specifies the terms and definitions, classification and labels, requirements, test methods, inspection rules, packaging, marks, transport and storage of silica fume for cement mortar and concrete. This Standard is applicable to silica fume for cement mortar and concrete.
GB/T 27690-2011
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 91.100.10
Q 12
Silica fume for cement mortar and concrete
ISSUED ON. NOVEMBER 21, 2011
IMPLEMENTED ON. AUGUST 01, 2012
Issued by. General Administration of Quality Supervision, Inspection and Quarantine;
Standardization Administration Committee.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 5
4 Classification and labels ... 5
5 Requirements ... 5
6 Test methods ... 6
7 Inspection rules ... 7
8 Packaging, marks, transport and storage ... 8
Annex A (normative) Inspection method for solid content of silica fume slurry ... 10
Annex B (normative) Test method for activity index ... 12
Annex C (normative) Test method for inhibition of alkali aggregate reaction.. 15 Silica fume for cement mortar and concrete
1 Scope
This Standard specifies the terms and definitions, classification and labels, requirements, test methods, inspection rules, packaging, marks, transport and storage of silica fume for cement mortar and concrete.
This Standard is applicable to silica fume for cement mortar and concrete. 2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 176, Method for Chemical Analysis of Cement
GB/T 2419, Test method for fluidity of cement mortar
GB 6566, Limit for Radionuclides in Building Materials
GB 8076-2008, Concrete Admixtures
GB/T 12573, Sampling method for cement
GB/T 19587, Determination of the specific surface area of solids by gas absorption using the BET method
GB/T 1767-1999, Method for exterior exposure testes of paint films
GB/T 18736-2002, Mineral admixtures for high strength and high-
performance concrete
GB/T 50082-2009, Standard for test methods of long-term performance and durability of ordinary concrete
JC/T 420, Method for chemical analysis of chloride for cement raw material JC/T 681, Mixer for mixing mortars
Radioactivity Ira???1.0 and Ir???1.0
Inhibition of alkali aggregate reactivity 14d expansion rate?€?s reduction value ???35% Resistance to chloride ion permeability 28d electric flux ratio ???40%
NOTE 1. Silica fume slurry is converted into solid content and tested according to this table.
NOTE 2. The inhibition of alkali aggregate reactivity and chloride ion permeability resistance is a selective test project, which is determined by both parties. 6 Test methods
6.1 SiO2 content
In accordance with Annex A of GB/T 18736-2002.
6.2 Chlorine content
In accordance with JC/T 420.
6.3 Water content, loss on ignition, total alkali content
In accordance with GB/T 176.
6.4 Solid content
In accordance with Annex A.
6.5 Water demand ratio
In accordance with Annex C of GB/T 18736-2002.
6.6 Specific surface area
In accordance with GB/T 19587.
6.7 Activity index
In accordance with Annex B.
6.8 Radioactivity
In accordance with GB 6566.
6.9 Inhibition of alkali aggregate reactivity
In accordance with Annex C.
6.10 Resistance to chloride ion permeability
Perform according to Clause 7 of GB/T 50082-2009. The resistance to chloride ion permeation is expressed by the ratio of the tested concrete to the reference concrete flux. Concrete mix ratio materials shall meet the requirements of GB 8076-2008. The reference concrete mix ratio of cement is 400 kg/m3 ?? 5 kg/m3. Sand rate is 36%~40%. Slump is controlled at 80mm ?? 10mm. Incorporate 10% silica ash into the tested concrete (accounting for the total proportion of cementitious materials). Use naphthalene-series high-efficiency water-reducing admixture that meets requirements for standard high-efficiency water-reducing admixture in GB 8076-2008 to adjust the slump of testing concrete. The water reducing rate of the water-reducing admixture is required to be greater than 18%.
NOTE. The method for preparing silica fume slurry is carried out according to the method specified in Annex A.
7 Inspection rules
7.1 Batch number, sampling and sample retention
7.1.1 Batch number
Take 30t of the same type of silica fume/silica fume slurry as an inspection lot. When it is less than 30t, it shall be regarded as an inspection batch.
7.1.2 Sampling
Sampling is according to GB/T 12573. The sampling shall be representative. The sampling can be continuous. The same quantity of samples may be taken from more than 10 different parts. The total shall be at least 5 kg. The silica fume slurry shall be at least 15 kg. The sample shall be evenly mixed.
7.1.3 Sample retention
The same batch of silica fume samples of manufacturer shall be divided into two equal portions. One is for product exit-factory inspection. The other is sealed and stored for 6 months for re-inspection or arbitration.
7.2 Inspection
7.2.1 Exit-factory inspection
The exit-factory inspection items of each batch of silica fume include SiO2 content, water content (solid content), water demand ratio, and loss on ignition. 7.2.2 Type inspection
The type inspection items include all performance indexes in Clause 5 of this Standard. Type inspection shall be performed in one of the following situations. a) trial model identification for new product or old product produced in transferred plant;
b) great changes in material, technique after official production which may affect product performances;
c) at least once for every-year during normal production;
d) production resumed after log-term discontinued production;
e) great difference between exit-factory inspection results and previous type inspection results;
f) required by national quality supervision organization.
7.3 Rules for determination
7.3.1 Exit-factory inspection
The inspection results of SiO2 content, water content (solid content), water demand ratio and loss on ignition shall meet the requirements of Clause 5. If one of the inspection results does not meet the requirements, it shall be unqualified product and cannot be delivered.
7.3.2 Type inspection
If all the inspection items comply with the provisions of Clause 5, it shall be accepted. Should one index fail to meet the requirements of this Standard, it shall be rejected.
7.4 Re-inspection
During the product storage period, when the user disputes the product quality, the re-inspection can be performed. Re-inspection can be carried out with the same number of sealed samples. If the user requests on-site sampling, it shall be specified in the supply contract in advance. The production plant shall, within 7 days of receiving the user's notice, sample together with the user and send it to the quality supervision and inspection agency for inspection. If the production plant shall not go to the site within the specified time, the user may take samples with the quality inspection agency and the results are equally effective. 8 Packaging, marks, transport and storage
8.1 Packaging
Silica fume can be packed or bulk. Silica fume slurry is packaged in sealed containers. Environmental considerations shall be considered. The net mass of Annex A
(normative)
Inspection method for solid content of silica fume slurry
A.1 Method summary
Put a sample of silica fume slurry into a constant weighing bottle and bake it to a constant temperature at a certain temperature.
A.2 Apparatus
The apparatus shall meet the following requirements.
a) oven - temperature control range is 105??C ?? 5??C;
b) balance ?€? weight-range is 100g, the sensitivity is 0.0001g;
c) weighing bottle with lid - 25mm??65mm;
d) dryer - containing color changing silica gel.
A.3 Test steps
A.3.1 Put the cleaned weighing bottle with lid into the oven for 30 min at 100??C ~105??C. Cool for 30 min and weigh. Repeat the above process until constant weight, the mass is m0.
A.3.2 Put 5.000g ~ 10.000g of silica fume slurry into a constant weight weighing bottle. Cover the lid. Weigh the total mass of the silica fume slurry and weighing bottle m1.
A.3.3 Put the weighing bottle containing silica fume slurry into the oven. Remove the lid. Heat to 100??C ~ 105??C for drying. Cover the lid and place it in the dryer for 30 min, weigh. Repeat the above process until constant weight, the mass is m2.
A.4 Results representation
The solid content of silica fume slurry is determined by formula (A.1), to the nearest of 0.1%.
Xsolid
Annex C
(normative)
Test method for inhibition of alkali aggregate reaction
C.1 This test method adopts the rapid cement mortar rod method for testing the alkali aggregate reaction. The inhibition of the reaction of the silica fume to the alkali aggregate is tested by manually setting the conditions of the alkali aggregate reaction.
C.2 Apparatus
The apparatus shall meet the following requirements.
a) oven - temperature control range is 105??C ?? 5??C;
b) balance - weighing 1000g, the resolution is 0.1g;
c) test sieve ?€? square-hole sieves with a nominal diameter of 4.75mm,
2.36mm, 1.18mm, 600??m, 300??m and 150??m, respectively;
d) length measuring instrument - measurement range of 275mm ~ 300mm,
precision of 0.01mm;
e) cement mortar mixer - meet the requirements of JC/T 681;
f) constant temperature curing box or water bath - temperature control range is 80??C ?? 2??C;
g) curing cylinder - made of alkali-resistant and high-temperature resistant material, no water leakage, sealing, preventing the humidity inside the container from falling, the volume of the cylinder can ensure that the test piece is completely immersed in the water. A test piece holder is
arranged in the cylinder, and the test piece is placed perpendicular to the sample holder;
h) test mode - metal test mode, size of 25mm??25mm??280mm, small hole in
the center of the test die, equipped with stainless steel probe; file, boring bar, measuring cylinder, dryer, etc.
C.3 Raw materials
C.3.1 Aggregate. quartz glass granules (level meets the requirements of Table C.1), aggregates shall be washed and dried.
Place the curing tube in an oven or water bath at a temperature of 80??C ?? 2??C for 24 h. Test pieces made of the same aggregate are placed in the same curing cylinder.
C.6.3 Then take the curing cylinders one by one. Take one test piece from the curing cylinder each time. Dry the surface with a rag. Immediately test the base length (L0) of the piece with the length gauge. Repeat test at least twice for each test piece. Take the average of the two readings within the accuracy of the instrument as the length measurement (to the nearest of 0.02mm). The
measurement direction of each test piece shall be consistent. Remove, dry the test piece and complete reading within 15s ?? 5s. After the reading, the test piece is covered with a damp cloth. After measuring the reference length of all the test pieces, place the test piece in a curing cylinder containing a concentration of 1 mol/L sodium hydroxide solution, and ensure that the test piece is completely immersed. The solution temperature shall be kept at 80??C ?? 2??C. Put the curing cylinder back in the oven or water bath.
NOTE. When measuring the length of any test piece with the length measuring instrument, the zero point of the length measuring instrument shall be adjusted first. C.6.4 From the date of measuring the reference length, the length (Lt) is measured separately on the 3rd d, 7th d, 10th d, and 14th d. The length measurement method is the same as the base length measurement method.
After each measurement, the test piece shall be turned into the original curing tube, the cover shall be covered. Put back into the oven or water bath at 80??C ?? 2??C. Continue to be cured to the next test age. Prevent splashing of sodium hydroxide solution during operation to avoid burning skin.
C.6.5 During the measurement, the deformation, cracks, exudates, etc. of the test piece shall be observed. In particular, the presence or absence of colloidal substances shall be observed and detailed records shall be made.
C.7 Results calculation
C.7.1 The expansion ratio of the test piece shall be calculated according to formula (C.1) to the nearest 0.01%.
Where,
Et - expansion rate of test piece at td age, %;
Lt - length of the test piece at td age, in millimeters (mm);

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