GB/T 27690-2023 PDF English
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| GB/T 27690-2023 | English | 230 |
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Silica fume for cement mortar and concrete
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| GB/T 27690-2011 | English | 85 |
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Silica fume for cement mortar and concrete
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GB/T 27690-2023: Silica fume for cement mortar and concrete---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT27690-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 91.100.10
CCS Q 12
Replacing GB/T 27690-2011
Silica fume for cement mortar and concrete
Issued on: MARCH 17, 2023
Implemented on: OCTOBER 01, 2023
Issued by. State Administration for Market Regulation;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword... 3
1 Scope... 6
2 Normative references... 6
3 Terms and definitions... 6
4 Classification and marking... 7
5 Requirements... 7
6 Test methods... 8
7 Inspection rules... 10
8 Packaging, labeling, transportation and storage... 11
Annex A (normative) Test method for bulk density... 12
Annex B (normative) Test methods for water demand ratio and activity index... 14
Annex C (normative) Test method for inhibition of alkali-aggregate reactivity... 17
Silica fume for cement mortar and concrete
1 Scope
This document specifies the classification and marking, requirements, test methods,
inspection rules, packaging, labeling, transportation and storage of silica fume for
mortar and concrete.
This document applies to silica fume for 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, Methods for chemical analysis of cement
GB/T 1345, The test sieving method for fineness of cement
GB/T 2419, Test method for fluidity of cement mortar
GB 6566, Limits of radionuclides in building materials
GB 8076, Concrete admixtures
GB/T 17671, Test method of cement mortar strength (ISO method)
GB/T 19587, Determination of the specific surface area of solids by gas adsorption
using the BET method
GB/T 50082, Standard for test methods of long-term performance and durability of
ordinary concrete
JC/T 681, Planetary cement mortar mixer
JGJ 63, Standard of water for concrete
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 silica fume
When smelting ferrosilicon alloy or industrial silicon, the silicon vapor discharged
through the flue is collected to obtain a powder material with amorphous silicon dioxide
as the main component.
3.2 non-densified silica fume
Silica fume that is directly collected without densification treatment and has a bulk
density not exceeding 350 kg/m3.
3.3 densified silica fume
Silica fume that the non-densified silica fume is densified and the bulk density is
increased to more than 350 kg/m3.
4 Classification and marking
4.1 Product classification
4.1.1 According to the silicon dioxide content, it is divided into grade 85 silica fume
(code SF85) and grade 90 silica fume (code SF90).
4.1.2 According to the bulk density, it is divided into non-densified silica fume (code is
R) and densified silica fume (code is D).
4.2 Product marking
The product mark consists of the silica content classification code, bulk density
classification code and standard number.
Example. The marking for grade 90 densified silica fume is as follows.
SF90-D GB/T27690
5 Requirements
5.1 Bulk density
The bulk density of non-densified silica fume shall not be greater than 350 kg/m3.The
bulk density of densified silica fume shall be greater than 350 kg/m3.
5.2 Technical requirements
The performance indicators of silica fume used in mortar and concrete shall comply
with the requirements of Table 1.
Table 1 -- Performance indicators of silica fume for mortar and concrete
cement content of the reference concrete mix ratio shall be 400 kg/m3 ±5 kg/m3.The
sand content shall be 38%±2%. The slump is adjusted by the amount of water. The
slump is controlled at 80 mm±10 mm. 10% silica fume is added to the tested concrete
(an equal amount replaces cement). The tested concrete has the same mix ratio as the
reference concrete. The slump of the tested concrete is adjusted by using a standard
high-efficiency water-reducing agent or a standard high-performance water-reducing
agent that complies with the provisions of GB 8076.
7 Inspection rules
7.1 Batch number, sampling and sample retention
7.1.1 Batch number
40 t of the same type of silica fume is considered as one inspection batch. If it is less
than 40 t, it is considered as one inspection batch.
7.1.2 Sampling
The sampling shall be representative. It can be continuous or equal amount of samples
can be taken from more than 10 different parts. The total amount shall be at least 5 kg.
The specimens shall be mixed evenly.
7.1.3 Sample retention
The same batch of silica fume specimens from the manufacturer shall be divided into
two equal parts. One part is used for product inspection before leaving the factory. The
other part 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 for each batch of silica fume include bulk density,
silicon dioxide content, moisture content, loss on ignition, fineness, water demand ratio
and activity index.
7.2.2 Type inspection
Type inspection shall include all items in Chapter 5.Type inspection shall be carried
out in any of the following cases.
a) Pre-production and testing of new products or old products for transfer to other
factories.
b) After formal production, if there are major changes in materials and processes,
which may affect product performance.
c) During normal production, inspection shall be carried out at least once a year.
d) When the product is resumed after long-term suspension of production.
e) When the exit-factory inspection results are significantly different from the last
type inspection.
7.3 Judgment rules
7.3.1 Exit-factory inspection
If the inspection results of all exit-factory inspection items meet the requirements of
this document, the batch of products will be judged as qualified products. If the
inspection result of one item does not meet the requirements of this document, it will
be judged as unqualified products.
7.3.2 Type inspection
If the inspection results of the type inspection items all meet the requirements of this
document, the batch of products will be judged as qualified products. If one indicator
does not meet the requirements of this document, it will be judged as unqualified
products.
8 Packaging, labeling, transportation and storage
8.1 Packaging
Silica fume can be packed in bags or in bulk. The net weight of each bag of bagged
material shall not be less than 99% of the labeled weight. The total weight of 20 bags
randomly selected shall not be less than 100% of the total labeled weight. The net
weight of each ton bag packed in ton bags shall not be less than 100% of the labeled
weight. Bulk packaging shall be determined by negotiation between the supplier and
the buyer.
8.2 Labeling
The packaging bag of bagged silica fume shall clearly indicate the product name,
product mark, net content, manufacturer's name and address, batch number, and
production date. Bulk silica fume shall be submitted with a card with the same content
as the bagged label.
8.3 Transportation and storage
Silica fume shall not be exposed to moisture or mixed with foreign matter during
transportation and storage. Environmental pollution shall also be prevented. The storage
period is 180 d from the date of production. If the storage time exceeds the storage
period, re-inspection shall be carried out. It can only be used after passing the inspection.
Annex A
(normative)
Test method for bulk density
A.1 Instruments and equipment
A.1.1 Balance. the graduation value is 0.1 g.
A.1.2 Capacity cylinder. it is a cylindrical metal cylinder. Inner diameter is 108 mm.
Net height is 109 mm. Wall thickness is 2 mm. Bottom thickness is 5 mm. Volume is 1
L.
A.1.3 Oven. the temperature can be controlled at 105℃±5℃. The resolution of the
display device is 1℃.
A.1.4 Round steel bar. round steel with a diameter of 10 mm and a length of 500 mm.
A.1.5 Ruler, funnel or spoon, brush, enamel tray, etc.
A.2 Test steps
A.2.1 Take about 1000 g of sample and spread it evenly in an enamel dish. Place it in
an oven at 105℃ ± 5℃ for 2 h. Take it out and place it in a desiccator. Cool it for 30
min and weigh it. Repeat the above process until the difference in mass between two
consecutive weighings does not exceed 0.5 g.
A.2.2 Weigh the mass of the prepared volume cylinder as m1, accurate to 0.1 g. Use a
funnel or a spoon to slowly pour the sample from about 50 mm above the center of the
volume cylinder. Let the sample fall freely. Load the sample into the volume cylinder
twice. After the first layer is filled (about slightly above 1/2), place a round steel rod
with a diameter of 10 mm at the bottom of the cylinder. Press the cylinder. Hit the
ground alternately 5 times on the left and right sides. Then load the second layer. After
the second layer is filled, hit the ground in the same way. Add more sample until it
exceeds the mouth of the cylinder. Then use a ruler to scrape it flat on both sides along
the center line of the mouth of the cylinder. Use a brush to remove the silica fume stuck
to the outside of the volume cylinder.
A.2.3 Weigh the total mass m2 of the volumetric cylinder and the sample to an accuracy
of 0.1 g.
A.3 Result calculation
The bulk density of silica fume is calculated according to formula (A.1).
Annex B
(normative)
Test methods for water demand ratio and activity index
B.1 Instruments and equipment
B.1.1 Use the test instruments specified in GB/T 17671.
B.1.2 Use the test instruments specified in GB/T 2419.
B.1.3 Balance. graduation value is 0.01 g.
B.2 Raw materials
B.2.1 Cement
Use the reference cement specified in GB 8076.It is allowed to use ordinary Portland
cement with a strength grade greater than or equal to 42.5, which is made by grinding
clinker with a tricalcium aluminate (C3A) content of 6%~8% and a total alkali content
(Na2O% + 0.658K2O%) of no more than 1%, dihydrate gypsum and slag, but the
reference cement is still required for arbitration.
B.2.2 Sand
Use standard sand that complies with GB/T 17671.
B.2.3 Water
Use water that complies with the provisions of JGJ 63.
B.2.4 Water reducing agent
Use standard high efficiency water reducing agent or standard high performance water
reducing agent that complies with GB 8076.
B.3 Test conditions and methods
B.3.1 Test conditions
The test room shall comply with the provisions of GB/T 17671.Various materials and
tools for the test shall be placed in the test room for more than 24 h in advance to reach
the same temperature as the test room.
B.3.2 Test steps
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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