UGANDA STANDARD  
  DUS 2115  
First  Edition  
2018 -10-19 
 
 
 Reference number  
DUS 2155: 2018  
© UNBS 2018   
  
Fly ash used for cement and concrete  
 DUS 2115 : 2018  
ii © UNBS 2018  – All rights reserved  
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible for its correct ap plication  
© UNBS yyyy  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, including photocopying and microfilm, without prior written 
permission from UNBS.  
Requests for permission to reproduce this document should be addressed to  
The Executive Director  
Uganda National Bureau of Standards  
P.O. Box 6329  
Kampala  
Uganda  
Tel: +256 41 4 333 2 50/1/2/3  
Fax: +256 41 4 286 123  
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  DUS 2115: 2018  
© UNBS 2018  – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ .............................  v 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Classificat ion ................................ ................................ ................................ ................................ .........  2 
5 Grade  ................................ ................................ ................................ ................................ ......................  2 
6. Technical requirements  ................................ ................................ ................................ ........................  3 
6.1 Physical and che mical property requirements  ................................ ................................ ..................  3 
6.2 Radioactivity  ................................ ................................ ................................ ................................ ..........  4 
6.3 Alkali content  ................................ ................................ ................................ ................................ .........  4 
6.4 Calcium Sulfate Hemihydrate content  ................................ ................................ ................................ . 4 
6.5 Uniformity  ................................ ................................ ................................ ................................ ...............  4 
7 Test Methods  ................................ ................................ ................................ ................................ .........  4 
7.1 Fineness  ................................ ................................ ................................ ................................ .................  4 
7.2 Water content ratio  ................................ ................................ ................................ ................................  5 
7.3 Ignition Loss, Sulfur Trioxide, Free Calcium Oxide, Silicon Diox ide, Aluminum Oxide, 
Ferric Oxide, Alkali Content  ................................ ................................ ................................ .................  5 
7.4 Water content  ................................ ................................ ................................ ................................ .........  5 
7.5 Calcium Sulfate Hemihydrate  ................................ ................................ ................................ ...............  5 
7.6 Density  ................................ ................................ ................................ ................................ ....................  5 
7.7 Stability  ................................ ................................ ................................ ................................ ...................  5 
7.8 Strength activity index  ................................ ................................ ................................ ..........................  5 
7.9 Radioactivity  ................................ ................................ ................................ ................................ ..........  5 
8 Inspection rules  ................................ ................................ ................................ ................................ ..... 5 
8.1 Numbering and sampling  ................................ ................................ ................................ .....................  5 
8.2 Delivery inspection  ................................ ................................ ................................ ................................  6 
8.3 Type inspection  ................................ ................................ ................................ ................................ ..... 6 
8.4 Acceptance rules  ................................ ................................ ................................ ................................ ... 6 
8.4.1  Delivery inspection  ................................ ................................ ................................ ................................  6 
8.4.2  Type inspection  ................................ ................................ ................................ ................................ ..... 6 
8.5 Inspection report  ................................ ................................ ................................ ................................ ... 7 
8.6 Arbitration  ................................ ................................ ................................ ................................ ..............  7 
9 Packing, Marking, Transport and Storage  ................................ ................................ ..........................  7 
9.1 Package  ................................ ................................ ................................ ................................ ..................  7 
9.2 Signs  ................................ ................................ ................................ ................................ .......................  7 
9.3 Transport and storage  ................................ ................................ ................................ ..........................  7 
Annex  A (norm ative)  Fly ash water content ratio test method  ................................ ................................ ..... 8 
A.1 Scope  ................................ ................................ ................................ ................................ ......................  8 
A.2 Principle  ................................ ................................ ................................ ................................ .................  8 
A.3 Material  ................................ ................................ ................................ ................................ ...................  8 
A.4 Instrument and equipment  ................................ ................................ ................................ ...................  8 
A.5 Test procedures  ................................ ................................ ................................ ................................ ..... 8 
A.6 Result calculation  ................................ ................................ ................................ ................................ .. 9 
Annex  B (Normative)  Fly ash water content test method  ................................ ................................ ...........  10 
B.1 Scope  ................................ ................................ ................................ ................................ ....................  10 
B.2 Principle  ................................ ................................ ................................ ................................ ...............  10 
B.3 Instrument and equipment  ................................ ................................ ................................ .................  10 DUS 2115 : 2018  
iv © UNBS 2018  – All rights reserved  
 B.3.1  Drying box  ................................ ................................ ................................ ................................ ...........  10 
B.3.2  Balance  ................................ ................................ ................................ ................................ ................  10 
B.4 Test steps  ................................ ................................ ................................ ................................ ............  10 
B.5 Result calculation  ................................ ................................ ................................ ...............................  10 
Annex  C (Normative)  Fly ash strength activity index test method  ................................ ............................  11 
C.1 Scope  ................................ ................................ ................................ ................................ ...................  11 
C.2 Principles  ................................ ................................ ................................ ................................ .............  11 
C.3 Material  ................................ ................................ ................................ ................................ ................  11 
C.4 Instrument and equipment  ................................ ................................ ................................ .................  11 
C.5 Test procedures  ................................ ................................ ................................ ................................ .. 11 
C.6 Result calculation  ................................ ................................ ................................ ...............................  12 
Bibliography  ................................ ................................ ................................ ................................ .....................  13 
 
 DUS 2115: 2018  
© UNBS 2018  – All rights reserved  v 
 Foreword  
Uganda Nation al Bureau of Standards (UNBS) is a parastatal under the Ministry of Trade , Industry and 
Cooperatives established under Cap 327 , of the Laws of Uganda , as amended .  UNBS is mandated to co -
ordinate the elaboration of standards and is  
(a) a member of Internation al Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT  Agreement  of the World Trade Organisation (WTO).  
The work of preparing Uganda Standards i s carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a given field or area and consists of key stakeholders 
including government, academia, consumer groups, private sector and other interested parti es.  
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Stan dards by the National Standards Council.  
The committee responsible for this document is Technical Committee UNBS /TC ###, [name of committee] , 
Subcommittee SC ##, [name of subcommittee] . 
This second/third/… edition cancels and replaces the first/second/… edition ( US nnn-n:yyyy), which has been 
technically revised.  
US nnn consists of the following parts, under the general title Introductory element — Main element :  
  Part n: Part title  
  Part [n+1]: Part title  
  Part [n+2]: Part title  
 DUS 2115 : 2018  
vi © UNBS 2018  – All rights reserved  
  
 UGANDA STANDARD  DUS 2115: 2018  
 
© UNBS 2018  – All rights reserved  1 
 Fly ash used for  cement and concrete  
1 Scope   
The Standard specifies the terms and definition, classification, grade, technical requirements, test method, 
inspection rules, packaging, marking, transportation and storage of the fly ash used for cement and concrete.  
The St andard is applicable to the fly ash used as admixture at time of mixing mortar and concrete, and fly ash 
used as active addition at time of cement production.  
2 Normative references   
The following referenced documents referred to in the text in such a way that some or all of their content 
constitutes requirements 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.  
US 310 -1: 2016, Por tland cement - Ordinary Portland cement  
US 100 -2: 2016 , Test methods - Part 2 - Chemical analysis  
ASTM D6023 – 16, Standard Test Method for Density (Unit Weight), Yield, Cement Content, and Air Content 
(Gravimetric) of Controlled Low -Strength Material (CLS M) 
US 100 -6: 2016 , Cement -Test -Methods  - Determination of fineness  
EAS 148 -3: 2017,  test methods - determination of setting times (2)  
ASTM C1437 – 15, Standard Test Method for Flow of Hydraulic Cement Mortar  
ASTM C471M - 17ae1, Standard Test Methods for  Chemical Analysis of Gypsum and Gypsum Products 
(Metric)  
DUS 2109: 2018, Radionuclide limitations  
EAS 18 -2: 2017, Part 2 Conformity evaluation  
EAS 148 -1: 2017,  cement - test methods - part 1 determination of strength  
DUS 2108: 2018, Sand for construction  
ASTM C311 / C311M – 17, Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for 
Use in Portland -Cement Concrete  
3 Terms and definitions   
For the purposes of this document, the following terms and definitions apply.   
2 © UNBS 2018  – All rights reserved  
 ISO and IEC main tain terminological databases for use in standardization at the following addresses:  
— ISO Online browsing platform: available at http://www.iso.org/obp  
3.1  
fly ash  
Powder collected in power plant pulverized coal furnace flue gas.  
Note  the fly ash does n ot include the followings:(1) When the coal is burnt with urban garbage or other wastes; (2) 
when the industrial or urban garbage is burnt in the incinerator; (3) the powder collected at time of combustion of the 
circulating fluidized bed boiler.  
3.2 
refer ence cement  
The Portland cement or ordinary Portland cement conforming to provisions of EAS 100 -1, or conforming to 
provisions of US 310 -1 and satisfying the strength grade 42.5 required in relevant requirements in the 
Standard.  
3.3 
testing sample  
The refe rence cement and fly ash to be inspected are mixed in the mass ratio 7:3.  
3.4 
reference mortar  
The reference cement and normal sand with specified grading are mixed in the mass ratio 1:3.  
3.5 
testing mortar  
The testing sample and normal sand with specified  grading are mixed in the mass ratio1: 3.  
3.6 
strength activity index  
The compressive strength ratio between the testing mortar and reference mortar in specified age is expressed 
in percentage.  
4 Classification   
4.1 According to the category of coal, the f ly ash is divided into type F fly ash (fly ash collected from 
anthracite or bituminous coal burning) and type C fly ash (fly ash collected from lignite or sub -bituminous coal 
burning, with calcium oxide content generally more than or equal to 10%).  
4.2 According to the purpose, the fly ash can be divided into the fly ash for mixing mortar and concrete and 
the fly ash as cement active addition.  
5 Grade   
The fly ash for mixing mortar and concrete is divided into three grades: grade I, II and III.  
The fly ash as cement active addition is not graded.  DUS 2115: 2018  
© UNBS 2018  – All rights reserved  3 
 6. Technical r equirements  
6.1 Physical and chemical property r equirements  
The fly ash for mixing mortar and concrete shall conform to the requirements of table1, and the fly ash as 
cement shall conform to the requir ements of table 2.  
Table 1  The physical and chemical property requirements of the fly ash for mixing mortar and 
concrete  
Item Physical and Chemical 
Performance Requirement  
Grade I  Level II  Level III  
Fineness (45μm square hole sieve screen residue)/%  Type F fly ash  ≤12.0  ≤30.0  ≤45.0  
 Type C fly ash     
Water Demand Ratio (%)  Type F fly ash  ≤95 ≤105  ≤115  
 Type C fly ash     
Ignition loss (Loss)/%  Type F fly ash  ≤5.0 ≤8.0 ≤10.0  
Type C fly ash     
Water content/%  Type F fly ash  ≤1.0 
 Type C fly ash   
Sulfur trioxide (SO 3) mass fraction/%  Type F fly ash  ≤3.0 
 Type C fly ash   
Item Physical and Chemical 
Performance Requirement  
 Grade I  Level II  Level III  
Free calcium oxide (f -CaO) mass fraction/%  Type F fly ash  ≤1.0 
 Type C fly ash  ≤4.0 
Total mass fraction of silicon dioxide (SiO 2), aluminum 
oxide (A1 2O3) and iron sesquioxide (Fe 2O3)/% Type F fly ash  ≥70.0  
 Type C fly ash  ≥50.0  
Density (g/cm3) Type F fly ash  ≤2.6 
 Type C fly ash   
Stability (Le c hatelier soundness test)/(mm)  Type C fly ash  ≤5.0 
Strength activity index  Type F fly ash  ≥70.0  
 Type C fly ash   
  
4 © UNBS 2018  – All rights reserved  
 Table 2  The Physical and chemical property requirements of the fly ash as cement active addition  
Item Physical and 
Chemical 
Performance 
Requirement  
Ignition loss (Loss)/%  Type F fly ash  
≤8.0 
Type C fly ash  
Water content/%  Type F fly ash  
≤1.0 
Type C fly ash  
Sulfur trioxide (SO 3) mass fraction/%  Type F fly ash  
≤3.5 
Type C fly ash  
Free calcium oxide (f -CaO) mass fraction/%  Type F fly ash  ≤1.0 
Type C fly ash  ≤4.0 
Total mass fraction of silicon dioxide (SiO 2), aluminum oxide (Al 2O3) and 
iron sesquioxide (Fe 2O3)/% Type F fly ash  ≥70.0  
Type C fly ash  ≥50.0  
Density/(g/cm3) Type F fly ash  
≤2.6 
Type C fly ash  
Stability (Le chatelier soundness test)/mm  Type C fly ash  ≤5.0 
Strength activity index  Type F fly ash  
≥70.0  
Type C fly ash  
6.2 Radioactivity   
Conform to the requirements of specified index of the main materials for building of the building in DUS 2109 . 
6.3 Alkali  content  
Expressed in Na 2O+0.658K 2O calculation value. When there is alkali content requirement in the fly ash 
application, it shall be determined through negotiation between the supply and requisitioning parties.  
6.4 Calcium Sulfate Hemihydrate c ontent  
For the fly ash discharged by the dry method or semi -dry desulphurization process, the calcium sulfate 
hemihydrate content is required to be tested (CaSO 3•1/2H 2O), which shall be not more than 3.0%.  
6.5 Uniformity  
Characterized by fineness, the fineness of s ingle sample shall be not more than the maximum deviation of the 
average fineness value of previous 10 samples (average value of all aforementioned samples, if the sample 
size is less than 10), the maximum deviation scope shall be determined through negoti ation between the 
buyer and seller.  
7 Test m ethods  
7.1 Fineness  
Carry out as per the 45μm negative pressure screen analysis method in US 100 -6, with the screen analysis 
time of 3 min.  DUS 2115: 2018  
© UNBS 2018  – All rights reserved  5 
 The screen shall be calibrated by the standard sample specified in ASTM C311/C311M - 17 or other standard 
sample of same grade, carry ou t screen calibration after screening for 100 samples, and the result treatment 
is same as that specified in US 100 -6. 
7.2 Water content r atio 
Carry out as per Appendix A.  
7.3 Ignition Loss, Sulfur Trioxide, Free Calcium Oxide, Silicon Dioxide, Aluminum Oxi de, 
Ferric Oxide, Alkali Content  
Carry out as per US 100 -2, among them, aluminum oxide shall be measured by copper sulfate back titration 
method or x -ray fluorescence analysis method, in case of any dispute, the copper sulfate back titration method 
shall p revail.  
7.4 Water c ontent  
Carry out as per Appendix B.  
7.5 Calcium Sulfate Hemihydrate  
It is determined according to relevant standards  
7.6 Density  
It is determined according to ASTM D6023 - 16. 
7.7 Stability  
The testing sample shall be prepared as per  3.3, and stability test shall be carried out as per US 100 -3. 
7.8 Strength activity i ndex  
Subject to Appendix C.  
7.9 Radioactivity  
Mix the fly ash with the Portland cement required in US 310 -1 as per the mass ratio 1:1 well, and test as per 
DUS 2109 . 
8 Inspec tion r ules 
8.1 Numbering and s ampling  
The fly ash shall be numbered and sampled on basis of same category and grade before delivery. The bulk fly 
ash and bagged fly ash shall be numbered and sampled respectively. One number refers to the quantity less 
than 500 t onnes , and each number represents one sampling unit. When the capacity of the bulk fly ash is 
more than the number of tons of delivery number specified by the factory, it is allowed that the quantity of the 
number exceeds the number of tons specified  for sampling. The fly ash mass shall be calculated as per the 
dry ash (water content less than 1%) mass.  
Sampling method shall be as per US 310 -2. Sampling shall be representative, sampling can be made 
continuously, or samples of equivalent amount can be taken from more than 10 different positions, with total 
amount less than 3kg.   
6 © UNBS 2018  – All rights reserved  
 Note  for the fly ash for mixing concrete and mortar, when necessary, the buyer can carry out random sampling and 
inspection.  
8.2 Delivery i nspection  
8.2.1  For the fly ash for mix ing concrete and mortar, the delivery inspection items are all items other than 
the ignition loss and strength activity index in table 1 in 6.1; for the fly ash discharged by dry method or semi -
dry desulphurization process, the calcium sulfate hemihydrate content item in 6.4 is added (CaSO 3 • 1/2H 2O). 
8.2.2  For the fly ash as the cement active addition, the delivery inspection items are all items other than the 
strength activity index in table 2 in 6.1; for the fly ash discharged by dry method or semi -dry d esulphurization 
process, the calcium sulfate hemihydrate content item in 6.4 is added (CaSO 3 • 1/2H 2O). 
8.3 Type i nspection  
8.3.1  The type inspection items of the fly ash for mixing concrete and mortar shall be  as specified in table 1 
in 6.1 , 6.2 and 6.4.  
8.3.2  The type inspection items of the fly ash as the cement active addition shall be as specified in table 2 
in 6.1, 6.2 and 6.4.  
8.3.3  In case of any of the following conditions, carry out type inspection:  
a) When the raw materials and process have signific ant changes, which may affect product 
performance;  
b) During normal production, inspect half a year (except the radioactivity);  
c) When production resumes after long shutdown;  
d) When the delivery inspection result is greatly different from last type inspection;  
e) When the type inspection is required by national quality supervision and inspection agency.  
8.4 Acceptance r ules 
8.4.1  Delivery i nspection  
8.4.1.1  When the delivery inspection items of the fly ash for mixing concrete and mortar conform to the 
technical requ irements in table 1 in 6.1 and 6.4, it shall be judged as qualified in the inspection. If any one item 
does not conform to the requirements, it is allowed to carry out sampling again in the same number to carry 
out re -inspection of all items, to judge by t he re -inspection result.  
8.4.1.2  When the delivery inspection items of the fly ash as cement active addition conform to the 
technical requirements in table 2 in 6.1 and 6.4, it shall be judged as qualified in the inspection. If any one item 
does not confor m to the requirements, it is allowed to carry out sampling again in the same number to carry 
out re -inspection of all items, to judge by the re -inspection result.  
8.4.2  Type i nspection  
8.4.2.1  When the type inspection items of the fly ash for mixing concre te and mortar conform to the 
technical requirements in table 1 in 6.1, 6.2 and 6.4, it shall be judged as qualified in the type inspection. If any 
one item does not conform to the requirements, it is allowed to carry out sampling from the reserved sample i n 
the lot to carry out re -inspection of all items, to judge by the re -inspection result.  
8.4.2.2  When the type inspection items of the fly ash as cement active addition conform to the technical 
requirements in table 2 in 6.1, 6.2 and 6.4, it shall be judge d as qualified in the type inspection. If any one item DUS 2115: 2018  
© UNBS 2018  – All rights reserved  7 
 does not conform to the requirements, it is allowed to carry out sampling from the reserved sample in the lot to 
carry out re -inspection of all items, to judge by the re -inspection result.  
8.5 Inspecti on report  
The inspection report shall include delivery number, delivery inspection item, classification and grade. When 
the user requires, the producer shall send the results of various inspections other than the strength activity 
index within 7d ays since the fly ash delivery, and report the strength activity index inspection result within 
32days. 
8.6 Arbitration  
In case of dispute for the fly ash quality, relevant organization shall sign and seal the recognized sample and 
send to the quality supervision an d inspection agency at or above provincial level recognized by the state for 
arbitration inspection.  
9 Packing, marking, transport and s torage  
9.1 Package  
The fly ash can be put in bulk or bag, and net content of each bag is 25 kg or 40 kg, and net content  of each 
bag shall be not less than 99% of mark mass. Other package specifications shall be determined through 
negotiation between the buyer and seller.  
9.2 Signs  
Card shall be provided for bulk fly ash, including product name, classification, grade, net c ontent, lot number, 
number of standard implemented, manufacturer name and address and date of production.  
The bagged fly ash bags shall indicate the content same as those on the bulk fly ash card.  
9.3 Transport and s torage  
During transportation and storage , the fly ash shall not be wetted and mixed with impurities, and 
environmental pollution shall be prevented .   
8 © UNBS 2018  – All rights reserved  
 Annex  A 
(normative)  
 
Fly ash water content ratio test m ethod   
A.1 Scope  
The Appendix is applicable to the fly ash water content ratio measurement.  
A.2 Principle  
Measure the mortar fluidity of the testing mortar and reference mortar as per ASTM C1437 - 15, the water 
addition ratio when both meet the specified fluidity scope is the fly ash water content ratio.  
A.3 Material  
A.3.1  Reference cement: The Portland cement or ordinary Portland cement conforming to provisions of US 
310-1, or conforming to the strength grade 42.5 specified in US 310 -1, and the fluidity of the reference mortar 
prepared as per table A.1 is  (L0) within 145mm -155 mm.  
A.3.2  Testing sample: the reference cement and fly ash to be inspected are mixed as per the mass ratio 7: 
3. 
A.3.3  Normal sand: the medium sand conforming to 0 .5 mm -1.0 mm specified in US 100 -2. 
A.3.4  Water: clean fresh water.  
A.4 Instrument and e quipment  
A.4.1  Balance  
The range shall be not less than1 000 g, and the division value shall be not more than 1 g.  
A.4.2  Mixer  
The mixer for mixing mortars as specified in US 100 -2. 
A.4.3  Fluidity jumping table  
As specified in ASTM C1437 - 15. 
A.5 Test p rocedures  
A.5.1  mortar pr oportion shall be as per A.1.  
 DUS 2115: 2018  
© UNBS 2018  – All rights reserved  9 
 Table A.1  Fly ash water content ratio testing mortar p roportion  
Mortar c ategory  Reference cement  Testing s ample  
Normal s and 
Reference c ement  Fly a sh 
Reference mortar  250 ― ― 750 
Testing mortar  (gram)  - 175 75 750 
A.5.2  The reference mortar and testing mortar are mixed as per provisions of US 100 -2. 
A.5.3  The fluidity of the reference mortar and testing mortar after mixed shall be tested as per ASTM C1437 
- 15. When the testing mortar fluidity reaches ±2 mm of the r eference mortar fluidity (L 0), record the water 
addition (m) at this time; when the testing mortar fluidity exceeds ±2 mm of the reference mortar fluidity (L 0), 
adjust the water addition again, until the testing mortar fluidity reaches ±2 mm of the referen ce mortar fluidity 
(L0). 
A.6 Result c alculation  
A.6.1  The water content ratio shall be calculated as per formula (A.1), and the result is reserved to 1%.  
1. ..... .......... .......... .......... .......... 100125A xmX
 
Where;  
X Water content ratio, %  
m The water addition when the testing mortar f luidity reaches ±2 mm of the reference mortar 
fluidity (L 0), the unit is gram (g);  
125 reference mortar water addition, in gram (g).  
A.6.2  When the test result is in conflict or requires arbitration, the reference cement shall preferably be the 
cement stan dard sample for strength inspection in US 310 -2. 
  
10 © UNBS 2018  – All rights reserved  
 Annex  B 
(Normative)  
 
Fly ash water content test m ethod   
B.1 Scope  
This Appendix is applicable to determination of fly ash water content.  
B.2 Principle  
Put the fly ash into the drying box with specified temperature for drying to constant weight, to determine the fly 
ash water content by the mass difference before and after drying and mass ratio before drying.  
B.3 Instrument and e quipment  
B.3.1  Drying b ox 
The c ontrollable temperature is 105°C -110°C, and minimum division value shall be not more than 2°C.  
B.3.2  Balance  
The range shall be not less than 50g, and minimum division value shall be not more than 0.01 g.  
B.4 Test s teps 
B.4.1  Weigh the fly ash sample for a bout 50g, to the accuracy of 0.01 g, and put into the evaporating dish 
dried to constant weight for weighing (m 1), to the accuracy of 0.01 g.  
B.4.2  Put the fly ash sample into 105°C -110°C drying box for drying to constant weight, and take it out and 
place it in the dryer and cool to room temperature, and then weigh (m 0), to the accuracy of 0.01 g.  
B.5 Result c alculation  
Water content is calculated as per formula (B.1), and the result is reserved to 0.1%.  
1. ...... .......... .......... .......... 100
10 1B xmmmw
 
Where;  
W water content, %;  
m1 mass of the sample before drying, in gram (g);  
m0 mass of the sample after drying, in gram (g).  DUS 2115: 2018  
© UNBS 2018  – All rights reserved  11 
 Annex  C 
(Normative)  
 
Fly a sh strength activity index test m ethod   
C.1 Scope  
This Appendix is applicable to de termination of the fly ash strength activity index.  
C.2 Principles  
Measure the 28d compressive strength of the testing mortar and reference mortar as per US 100 -2, and  
determine the strength activity index of the fly ash by the ratio of the two.  
C.3 Materi al 
C.3.1  Reference cement: the Portland cement or ordinary Portland cement conforming to provisions of US 
310-1, or conforming to the strength grade 42.5 specified in US 310 -1.  
C.3.2  Testing sample: reference cement and fly ash to be inspected are mixed a s per the mass ratio 7: 3.  
C.3.3  Normal sand: as specified in DUS 2108 . 
C.3.4  Water: clean fresh water.  
C.4 Instrument and e quipment  
Balance,  mixer, jolting table or vibrating table, compressive strength tester and other shall be as specified 
in US 100 -2. 
C.5 Test p rocedures  
C.5.1  Mortar proportion shall be as specified in C.1.  
Table C.1  Strength activity index testing mortar p roportion  
Mortar c ategory  Reference c ement  Testing s ample  Normal s and Water  
  Reference c ement  Fly Ash    
Reference mortar  (gram)  450 — — 1 350  225 
Testing mortar  (gram)  ― 315 135 1 350  225 
C.5.2  Carry out mixing, test piece formation and curing of the reference mortar and testing mortar as per US 
100-1 respectively.  
C.5.3  Cure the specimen for 28 d ays, and measure the compressive  strength of the reference mortar and 
testing mortar as per US 100 -1 respectively.   
12 © UNBS 2018  – All rights reserved  
 C.6 Result c alculation  
C.6.1  The strength activity index shall be calculated as per formula (C.1), and the result is reserved to 1%.  
)1. ...( .......... .......... .......... .......... 100
028 C xRRH
 
Where;  
H28 stren gth activity index, %  
R Testing mortar’ s 28days compressive strength, in Mega Pascal  (MPa);  
R0 Reference mortar’s 28d ays compressive strength, in Mega Pascal  (MPa).  
C.6.2  When the test result is in conflict or requires arbitration, the reference cement sha ll preferably be the 
cement standard sample for strength inspection in US 310 -2 DUS 2115: 2018  
© UNBS 2018  – All rights reserved  13 
 Bibliography  
[1] GB/T 1596: 2017 , Fly ash used for cement and concrete   
 
 DUS  2115: 2018  
© UNBS 2018  – All rights reserved  15 
 Certification marking  
Products that conform to Uganda standards may be marked with Uganda National Bu reau of Standards 
(UNBS) Certification Mark shown in the figure below.  
The use of the UNBS Certification Mark is governed by the Standards Act, and the Regulations made 
thereunder. This mark can be used only by those licensed under the certification mark scheme operated by 
the Uganda National Bureau of Standards and in conjunction with the relevant Uganda Standard. The 
presence of this mark on a product or in relation to a product is an assurance that the goods comply with the 
requirements of that standard  under a system of supervision, control and testing in accordance with the 
certification mark scheme of the Uganda National Bureau of Standards. UNBS marked products are 
continually checked by UNBS for conformity to that standard.  
Further particulars of t he terms and conditions of licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
 DUS 2115 : 2018    
 
ICS nn.nnn.nn  
Price based on nn pages  
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