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GB/T 177-1985 (GBT177-1985)

GB/T 177-1985_English: PDF (GBT 177-1985, GBT177-1985)
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Standard ID GB/T 177-1985 (GB/T177-1985)
Description (Translated English) Test method for strength of hydraulic cement mortar
Sector / Industry National Standard (Recommended)
Classification of Chinese Standard Q11
Classification of International Standard 91.100.10
Word Count Estimation 4,447
Date of Issue 1985/6/29
Date of Implementation 1985/10/1
Older Standard (superseded by this standard) GB 177-1977
Regulation (derived from) National Standard Committee Bulletin (2005 No. 146)
Proposing organization State Building Materials Industry Bureau
Issuing agency(ies) National Bureau of Standards

Standards related to: GB/T 177-1985

GB/T 177-1985
ICS 13.030.20
Z 63
Test method for strength of
hydraulic cement mortar
October 1, 1985 Implemented
Table of Contents
Test method for strength of hydraulic cement mortar ... 3 
1 Instrument ... 3 
2 Materials ... 5 
3 Temperature and humidity ... 5 
4 Specimen moulding ... 6 
5 Curing ... 7 
6 Strength test ... 7 
Additional Information... 9 
Test method for strength of hydraulic cement mortar
This method is applicable to flexural and compressive strength tests of Portland
cement, common Portland cement, slag cement, limestone cement, and coal ash
cement. For other type of cements that are designated to adopt this method, after the
water-cement ratio is experimentally determined, it may also applicable.
1 Instrument
1.1 Mortar mixer
Mortar mixer is in type of blades double-turning; the stirring blades and stirring bowl
are turned in reverse direction. Blades and bowl are made of wear-resistant metallic
material; the gaps BETWEEN blades AND bowl-bottom and bowl-wall are 1.5 ±
0.5mm. The manufacturing quality shall comply with provisions of GB3350.1-82
“Apparatus for physical test of cement - -Mixer for mixing mortars”.
1.2 Mortar vibrostand
Mortar vibrostand (Figure 1) is vibrated by an electrical motor that is mounted with 2
symmetrical laterality wheels. When using, fix it to the concrete base and comply with
the provisions of GB 3350.2-82 "Apparatus for physical test of cement - Vibrator for
compacting mortar specimen".
1.3 Mould and baiting funnel
1.3.1 Mould is detachable triple-mould; it is consisted by partition-plates, end-plates,
and base etc. The manufacturing quality shall comply with provisions of GB 3350.5-82
“Apparatus for physical test of cement - Specimen mould for use in testing mortar
strength”. For the mould in use, the mould-cavity height must not be less than 39.8mm,
mould-cavity width must not be greater than 40.2mm.
1.3.2 Baiting funnel (Fig. 2) is consisted of funnel and die ring. Funnel is made of
0.5mm galvanized iron sheet, the feeding mouth’s width is generally 4-5mm. Die ring’
height is 25mm, made of metal material. Baiting hopper’s weight is 2.5 ~ 2.0kg.
1.4 Flexural testing machine
Flexural testing machine generally uses double-level type; it may also adopt others of
which the performance meets the requirements. Flexural jig shall comply with the
requirements of 2.5 ~ 2.9 in GB 3350.3-82 "Apparatus for physical test of cement -
Electrically driven flexure testing device".
Loading and support cylinder must be made of hard steel material, After abrasion, the
allowed dimensions of the cylinder is.
10- mm.
1.5 Compressive testing machine and compression jig
1.5.1 Tonnage of compressive testing machine should be to 20 ~ 30t, the error must
not exceed ± 2.0%.
1.5.2 Compressive jig is made of hard steel material, and complies with GB 3350.4-82
" Apparatus for physical test of cement compression jig".
1.6 Calibrating knife
Calibrating knife’s section is an equilateral triangle, the effective length is 26mm.
2 Materials
2.1 Cement specimen shall be fully mixed, pass through 0.9mm square-hole sieve,
and record the sieve residues.
2.2 Standard sand shall comply with the quality requirements of GB178-77 "Standard
sand for cement strength test".
2.3 Test water must be clean, fresh water.
3 Temperature and humidity
3.1 Test chamber’s temperature is 17 ~ 25°C (including strength test chamber); the
relative humidity is greater than 50%. Temperature of cement specimen, standard
sand, mixing water and mould shall be the same as the chamber temperature.
3.2 Curing oven’s temperature is 20 ± 3°C; the relative humidity is greater than 90%.
Curing water’s temperature is 20 ± 2°C.
in 2 age-periods.
4.7 When changing cement before test, it must clean the mixing bowl, blades and
baiting funnel etc.
5 Curing
5.1 After numbering, place the test moulds into curing oven. The grate plate in curing
oven must be level. Take out after 24 ± 3h; demould it; when demoulding, it shall
prevent to damage the test specimen. For slower hardening cement, it allows to delay
the demoulding, however, the demoulding time must be recorded.
5.2 After the specimen is demoulded, place in water tank for curing. There shall have
gap in between the specimens; water surface is at least 2cm above the specimen; the
curing water is changed for every 2 weeks.
6 Strength test
6.1 Each age-period’s specimen must be conducted for strength test, within the
following time.
Age-period Time
3d 3d ± 2h
7d 7d ± 3h
28d 28d ± 3h
After specimens are removed from water, they shall be covered with damp cloth
before the strength test.
6.2 Flexural strength test.
6.2.1 Fro each age-period, take out 3 specimens to conduct flexural strength test.
Before test, wipe away water and sand on the specimens’ surface; remove the debris
adhered on jig’s cylindrical surface; place the specimen into the flexural jig; it shall
make its side to contact with the cylinder.
6.2.2 When using leveraged flexural test machine to conduct the test, before the
specimen is placed, it shall make the lever into equilibrium. After the specimen is
mounted, adjust the jig, so that the lever is at equilibrium state as possible, when the
specimen is fractured.
6.2.3 Loading speed of flexural test is 5 ± 0.5kgf / s.
6.2.4 Flexural strength is calculated according to equation (1).
S ─ compressive area, that is 4cmx6.25cm.
Compressive strength is calculated to 1kgf / cm2.
6.3.4 In 6 compressive strength results, discard the largest and the smallest 2 values;
compressive strength test result is based on the mean of the remaining 4 values. If it
is less than 6 values, take the mean.
Additional Information.
This Standard was proposed by State Bureau of Building Materials Industry.
This Standard shall be administered by Building Materials Science and Technology
Research Institute.
This Standard was responsibly revised by Building Materials Academy.
The main drafters of this Standard. Zhao Fuxin, Zhang Datong, and Fan Jiquan.
This Standard was first published in 1962.