UGANDA STANDARD  
  DUS 65  
Second  Edition  
2018 -09-10 
 
 
 Reference number  
DUS 65: 2018  
© UNBS 2018   
  
Precast concrete paving units — Specification  
 DUS 65: 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 c orrect application  
© 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 65:2018  
© UNBS 2018  – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ .............................  v 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Classification  ................................ ................................ ................................ ................................ .........  1 
4.1 Varieties  ................................ ................................ ................................ ................................ ..................  1 
2.2 Codes  ................................ ................................ ................................ ................................ ......................  2 
4.3 Specification  ................................ ................................ ................................ ................................ ..........  2 
4.4 Grade  ................................ ................................ ................................ ................................ ......................  2 
4.5 Marks  ................................ ................................ ................................ ................................ ......................  2 
4 General provisions  ................................ ................................ ................................ ................................  2 
4.1 Raw materials  ................................ ................................ ................................ ................................ ........  2 
5 Technical requirements  ................................ ................................ ................................ ........................  3 
5.1 Appearance quality  ................................ ................................ ................................ ...............................  3 
5.2 Dimensional deviation  ................................ ................................ ................................ ..........................  3 
5.3 Mechanical properties ................................ ................................ ................................ ...........................  3 
5.4 Physical prope rties  ................................ ................................ ................................ ...............................  4 
6 Test method  ................................ ................................ ................................ ................................ ...........  4 
6.1 Appearance quality  ................................ ................................ ................................ ...............................  4 
6.1.1  Measuring  gauges  ................................ ................................ ................................ ................................ . 4 
6.1.2  Measurement method  ................................ ................................ ................................ ...........................  5 
6.2 Specifications  ................................ ................................ ................................ ................................ ........  6 
6.2.1  Measuring gauges  ................................ ................................ ................................ ................................ . 6 
6.2.2  Measurement method  ................................ ................................ ................................ ...........................  6 
6.3 Mechanical properties ................................ ................................ ................................ ...........................  8 
6.4 Physical properties  ................................ ................................ ................................ ...............................  8 
6.4.1  Abrasive resistance  ................................ ................................ ................................ ...............................  8 
6.4.2   Water absorption  ................................ ................................ ................................ ................................ ... 8 
6.4.3   Frost resistance  ................................ ................................ ................................ ................................ .... 9 
7 Inspection rules  ................................ ................................ ................................ ................................ ..... 9 
7.1 Inspection classification  ................................ ................................ ................................ .......................  9 
7.2 Batch  ................................ ................................ ................................ ................................ .....................  10 
7.3 Sampling  ................................ ................................ ................................ ................................ ..............  10 
7.4 Judgment rules  ................................ ................................ ................................ ................................ .... 10 
7.4.1  Appearance quality  ................................ ................................ ................................ .............................  10 
7.4.2  Dimensional deviation  ................................ ................................ ................................ ........................  11 
7.4.3  Physical and mechanical properties  ................................ ................................ ................................ . 11 
7.4.4  Conclusions  ................................ ................................ ................................ ................................ .........  11 
8 Signs and operation instruction  ................................ ................................ ................................ ........  11 
8.1 Marking  ................................ ................................ ................................ ................................ .................  11 
8.2 Operation instruction  ................................ ................................ ................................ ..........................  11 
9 Packaging, transportation and storage  ................................ ................................ .............................  11 
9.1 Packing  ................................ ................................ ................................ ................................ .................  11 
9.2 Transportation  ................................ ................................ ................................ ................................ ..... 11 
9.3 Storage  ................................ ................................ ................................ ................................ .................  12 
Annex  A (normative)  Method for compressive strength test ................................ ................................ ...... 13 
A.1 Test equipment  ................................ ................................ ................................ ................................ .... 13 DUS 65: 2018  
iv © UNBS 2018  – All rights reserved  
 A.1.1   Testing machine ................................ ................................ ................................ ................................ . 13 
A.1.2  Pressure plate  ................................ ................................ ................................ ................................ ..... 13 
A.2 Test pieces  ................................ ................................ ................................ ................................ ..........  13 
A.3 Test steps  ................................ ................................ ................................ ................................ ............  13 
A.4 Result calculation and assessment  ................................ ................................ ................................ .. 14 
Annex  B (informative)  Method for rupture strength test  ................................ ................................ ............  15 
B.1 Test equipment  ................................ ................................ ................................ ................................ ... 15 
B.2 Test pieces  ................................ ................................ ................................ ................................ ..........  15 
B.3 Test steps  ................................ ................................ ................................ ................................ ............  15 
Bibliography  ................................ ................................ ................................ ................................ .....................  17 
 
 DUS 65:2018  
© UNBS 2018  – All rights reserved  v 
 Foreword  
Uganda National 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 .  UNB S is mandated to co -
ordinate the elaboration of standards and is  
(a) a member of International 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 is 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 parties.  
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the com ments before recommending the draft standards 
for approval and declaration as Uganda Standards 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 65: 2018  
vi © UNBS 2018  – All rights reserved  
  
 
 UGANDA STANDARD  DUS 65: 2018  
 
© UNBS 2018 – All rights reserved  1 
 Precast concrete paving units — Specification   
1 Scope   
The Standard specifies the classification, general provisions, technical requirements, test method, inspection 
rules, ma rking,  operation i nstruction, packaging, transport and storage of precast concrete paving units.  
The Standard applies to the blocks and slabs with cement and aggregate as main raw materials, produced 
through pressurization, vibration pressurization or other form ing processes, for paving concrete pavement and 
ground works for walkway, carriageway, square and warehouse (hereinafter referred to as paving units). The 
surface may have or be free of surface course (material), and may have colour or be colourless.  
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 lates t edition of the referenced document (including any amendments) applies.  
US 310 -1: 2016 , Portland Cement and Ordinary Portland Cement   
US 1681 - 2017, Chemical admixtures for concrete — specification   
DUS 2107 , Test methods for concrete block and brick  
DUS  2108: 2018 , Sand for construction   
DUS 1691; Aggregates for concrete  
US EAS 12:2014, Potable water — Specification  
3 Terms and definitions   
No terms and definitions are listed in this document.  
ISO and IEC maintain terminological databases for use in st andardization at the following addresses:  
— ISO Online browsing platform: available at http://www.iso.org/obp  
4 Classification   
4.1 Varieties   
Concrete paving unit includes common paving unit and interlocking paving unit by the shape of paving units.   
2 © UNBS 2018  – All rights reserved  
 2.2 Codes   
a) The code for common paving unit is N.  
b) The code for interlocking paving unit is S.  
4.3 Specification   
See Table 1 for the specifications of paving units. The specifications of paving units may also be determined 
according to user requirements.  
Table 1 Specifications  (mm) 
Side Length  100,150,200,250,300,400,500  
Thickness  50,60,80,100,120  
4.4 Grade  
4.4.1  Compressive strength grade: C c30, C c35, C c40, C c50, and C c60. 
4.4.2  Rupture strength grade: C f3.5, C f4.0, C f5.0, and C f 6.0. 
4.4.3  Quality grade: the  paving units meeting specified strength grade include premium products (A), first 
grade products (B) and conforming products (C) according to appearance quality, dimensional deviation and 
physical properties.  
4.5 Marks  
Marking shall be performed in the se quence of product code, specifications, strength, quality grade, and the 
standard No.  
Common paving unit has specifications of 250mm×250mm×60mm, and compressive strength grade of C c40; 
marking example for class -C product:  
201862USC 40cC 250x250x60N 
 
4 General provisions  
4.1 Raw m aterials  
4.1.1  Cement shall be slag Portland cement in accordance with US 310 -1  
4.1.2  Fine aggregates shall comply with DUS 2108 . 
4.1.3  Coarse aggregates shall comply with DUS 1691  
4.1.4  Hard industrial waste residues, stone powder and  stone crumbs shall meet the following requirements:  
a) Loss on ignition may not be more than 8%;  
b) Not containing harmful components and other inclusions that affect the performance of concrete.  
4.1.5  Fly-ash shall be in accordance with the provisions of US 31 0-1. 
4.1.6  Admixture shall be in accordance with the provisions of US 1681 . DUS  65: 2018  
© UNBS 2018  – All rights reserved  3 
 4.1.7  Pigment shall be in ac cordance with the relevant standard  
4.1.8  Water shall comply with US EAS 12  
4.2 The surface of paving units shall have necessary anti -skid function to guarantee the safety of 
pedestrians and vehicles.  
4.3 Exposed surface of paving units shall be flat, and are better to have chamfer.  
4.4 Finish coat of paving unit shall have thickness of not less than 5mm, and groove depth of surface 
pattern shall be not more than the thickness of surface course (material).  
5 Technical requirements  
5.1 Appearance quality  
Appearance quality of the paving units shall comply with the provisions in Table 2.  
Table 2  Appearance q uality  mm 
Item Premium 
products  First grade 
produc ts Conforming 
products  
Maximum projected dimension of front tack and defect  ≤ 0 5 10 
Maximum projected dimension of missing edge/corner  ≤ 0 10 20 
Cracks  Maximum projected dimension of non -through crack 
length  ≤ 0 10 20 
 Through -cracks  Not allowed  
Layering  Not allowed  
Color difference, variegated  Not o bvious  
5.2 Dimensional deviation  
Allowable dimensional deviation of paving units shall comply with the provisions in Table 3.  
Table 3  Allowable dimension deviation  mm 
Item Premium products  First grade products  Conforming products  
Length and width  ±2.0 ±2.0 ±2.0 
Thickness  ±2.0 ±3.0 ±4.0 
Thickness difference  ≤2.0 
≤ 2.0  ≤3.0 
≤ 3.0  ≤3.0 
≤ 3.0  
Flatness  ≤1.0 
≤ 1.0  ≤2.0 
≤ 2.0  ≤2.0 
≤ 2.0  
Perpendicularity  ≤1.0 
≤ 1.0  ≤2.0 
≤ 2.0  ≤2.0 
≤ 2.0  
5.3 Mechanical properties  
Compressive strength or rupture strength test shall be performed according to the ratio of side length  and 
thickness of paving units, and mechanical properties shall meet Table 4.   
4 © UNBS 2018  – All rights reserved  
 Table 4   Mechanical p roperties  MPa 
Side length/thickness  <5 ≥5 
Compressive strength 
grade  Average  Minimum value of a 
single brick ≥  Rupture strength 
grade  ≥ 
Average  Minimum valu e of 
a single brick ≥  
Cc30 30.0 25.0 Cf3.5 3.50 3.00 
Cc35 35.0 30.0 Cf4.0 4.00 3.20 
Cc40 40.0 35.0 Cf5.0 5.00 4.20 
Cc50 50.0 42.0 Cf6.0 6.00 5.00 
Cc60 60.0 50.0 - - - 
5.4 Physical properties  
Physical properties of paving units shall meet Table 5.  
Table 5 Physical properties  
Quality grade  Abrasive resistance  Water 
absorption %  
≤ Frost Resistance  
 
 Wear length 
mm 
≤ Abrasive 
resistance  
≥  
  
 
Premium 
products  28.0 1.9 5.0 After freezing and thawing cycle test, 
appearance quality shall meet Table 2, and 
strength loss may not be more than 20.0%.  
First grade 
products  32.0 1.5 6.5  
 
Conforming 
products  35.0 1.2 8.0  
 
Notes: Only wear length test or abrasive resistance test is needed.  
6 Test m ethod  
6.1 Appearance quality  
6.1.1  Measuring gauges  
Paving unit s shall be measured with calipers (as shown in Fig. 1) or other measuring gauges with accuracy of 
not less than 0.5mm.  DUS  65: 2018  
© UNBS 2018  – All rights reserved  5 
 
 
1-vertical square, 2 -stablizer blade  
Fig. 1 Calipers for paving units 
6.1.2  Measurement m ethod   
6.1.2.1  Front tack and defect   
Measure projected dimensions of length and width of corresponding paving unit side with front tack and defect, 
accurate to 0.5mm (as shown in Fig. 2).  
 
l-projected dimension in length direction; b-projected dimension in width direction  
Fig. 2  Measurement method f or front tack and d efect  
6.1.2.2  Missing edge/corner   
Measure projected dimensions of length, width and thickness of corresponding paving unit side with missing 
edge/corner, accurate to 0.5mm (as shown in Fig. 3).  
 
l-projected dimension in length directio n, b-projected dimension in width direction; d-projected dimension in 
thickness direction   
6 © UNBS 2018  – All rights reserved  
 Fig. 3  Dimension measurement for missing edge/c orner  
6.1.2.3  Crack   
Measure maximum projected length on crack plane, in case the crack extends from one plane to other  planes, 
measure the sum of projected length of extension, accurate to 0.5mm (as shown in Fig. 4).  
 
l-projected dimension of crack  
Fig. 4  Measurement for Crack Length  
6.1.2.4  Layer  
Perform visual inspection for the side of paving units.  
6.1.2.5  Color diff erence and mixed color   
Pave paving units into square of not less than 1m2 on flat ground, and perform visual observation and 
inspection in the distance of 1.5m under natural day  lighting or the fluorescent lamp with power of not less 
than 40W.  
6.2 Specifi cations   
6.2.1  Measuring gauges   
Use the measuring gauges specified in 6.1.1.  
6.2.2  Measurement m ethod   
6.2.2.1  Length, width, thickness, and thickness difference   
In the measurement for the length and width of rectangular paving units, measure correspondi ng parallel side 
of the front of paving unit at 10mm from corner (as shown in Fig. 5), measure two lengths and two widths; for 
interlocking paving units, the supplier shall provide the length and width in marked dimension for paving units. 
For thickness, m easure the middle of width of paving units 10mm from the edge. The different between two 
measured thicknesses is thickness difference (as shown in Fig. 5). Measured value shall be accurate to 
0.5mm.  DUS  65: 2018  
© UNBS 2018  – All rights reserved  7 
 
 
1-length; 2 -width; 3 -thickness  
Fig. 5  Measurement for L ength, Width and Thickness  
6.2.2.2  Flatness  
Put Vertical Square of calipers for paving units in any edge of the front of a paving unit, slide intermediate 
measuring ruler of the calipers to measure maximum unevenness on the surface of the paving unit. Accu rate 
to 0.5mm (as shown in Fig. 6).  
 
Fig. 6  Flatness Measurement  
6.2.2.3  Perpendicularity  
Put the body of calipers for paving units in close contact with the front of a paving unit, jack a stabilizer blade 
at the edge of unit bottom, and read the deviatio n of corresponding edge of the front of the paving unit as 
perpendicularity deviation, measure each edge for two times and record maximum value, accurate to 0.5mm 
(as shown in Fig. 7).  
 
1-perpendicularity; 2 -paving unit   
8 © UNBS 2018  – All rights reserved  
 Fig. 7  Perpendicularity m easurement  
6.3 Mechanical properties  
Compressive strength test shall be performed as per Appendix A to the Standard. Rupture strength test shall 
be performed as per Appendix B to the Standard.  
6.4 Physical properties  
6.4.1  Abrasive resistance  
Wear length test shall be performed as per DUS 2107 . Abrasive resistance test shall be performed as per 
DUS 2107 . 
6.4.2   Water absorption  
6.4.2.1  Test equipment  
a) Balance: weighing capacity of 10kg, sensitivity of 5g;  
b) Drying oven: enabling temperature control at 105°C±5°C.  
6.4.2.2  Test pieces  
Prepare 5 test pieces from the entire paving units. For mass of more than 5kg, cut (4.5±0.5)  kg part of paving 
unit from an entire paving unit.  
6.4.2.3  Test procedures  
Dry the test pieces in 105°C±5°C drying oven, take out and weigh the test p ieces in the interval of 4h, and 
take the weight with weighing difference of less than 0.1% as dry mass of the test pieces ( m0). 
Cool the test pieces to room temperature, and erect the test pieces in water tank in side direction, fill clean 
water with temp erature of 20°C±10°C; immerse the test pieces in water and keep water surface about 20mm 
above the test pieces.  
Immerse the test pieces in water for , and then take the test pieces out of water, wipe off surface water with 
dried wet towel, weigh the test p ieces respectively till weighing difference is less than 0.1%, and take the 
weight as test pieces mass upon water absorption for 24h ( m1). 
6.4.2.4  Result calculation and assessment  
Water absorption shall be calculated by formula (1):  
1.... .......... .......... .......... .......... x100......mmmw
00 1
 
Wherein;   
W represents water absorption, % ; 
m1 represents test pieces mass upon water absorption for 24h, g;  
m0 represents dry mass of the test pieces, g.  
Results shall be expressed by mean value of 5 test pieces, and calculation results shall be accurat e to 0.1%.  DUS  65: 2018  
© UNBS 2018  – All rights reserved  9 
 6.4.3   Frost resistance  
6.4.3.1  Test equipment  
a) Freezing box (chamber): the temperature in refrigerator after test pieces are put i n shall be kept in the 
range of ; 
b) Water tank: water temperature after test pieces are put in shall be kept in the ra nge of 20°C±10°C.  
6.4.3.2  Test pieces  
Prepare 10 test pieces, with 5 for freeze - thaw test, and 5 as comparison test pieces.  
6.4.3.3  Test procedures  
Perform appearance inspection for the test pieces, make marks for defects and cracks, and record defect 
conditions. Put the test pieces in 20°C±10°C for 24h. Keep water surface about 20mm above the test pieces 
in immersion.  
Take the test pieces out of water, wipe off surface water with dried wet towel, and then put the test pieces in 
the re frigerator (room) pre -cooled to , and keep test pieces in the spacing of not less than 20mm.  Calculate 
freezing time when temperature returns to -15°C, and the time from test pieces loading to the temperature of -
15°C shall be not more than 2h. Freezing time at -15°C depends on  test piece thickness: not less than 3h for 
the test pieces with thickness of less than 60mm, and not less than 4h for the test pieces with thickness of not 
less than 60mm. Then, take out and put the test pieces in 20°C±10°C water for thawing for 2h. The p rocess 
refers to a freezing and thawing cycle. Perform 25 freezing and thawing cycles by the method.  
After 25 freezing and thawing cycles, take out the test pieces out of water, wipe off surface water with dried 
wet towel, inspect and record surface peelin g, layering, crack and crack extension conditions of the test 
pieces. Then perform strength test as per Appendix A or B to the Standard.  
6.4.3.4  Result calculation  
Strength loss rate after freezing and thawing test shall be calculated by formula (2):  
(2)......... .......... .......... .......... .......... .......... x100RRRΔRD
 
Wherein;   
ΔR represents strength loss rate after freezing and thawing cycle, %;  
R represents mean value of strength test results for the test pieces before freezing and thawing test by 6.3, 
MPa;  
RD represents mean value of strength test results for the test pieces a fter freezing and thawing test by 6.3, 
MPa.  
Test result calculation shall be accurate to 0.1%.  
7 Inspection r ules 
7.1 Inspection classification  
7.1.1  Delivery inspection items: appearance quality, dimensional deviation, strength, and water absorption.   
10 © UNBS 2018  – All rights reserved  
 7.1.2 Type test items: overall inspection for all the technical requirements for products specified in the 
Standard.  
In case of any following situation, type inspection should be carried out:  
a) Trial production, shaping and identification for new products or old  products produced in the transfer;  
b) In the event of major changes in production, such as varieties, raw materials, concrete mix ratio or 
process, and in the event of equipment overhaul;  
c) Half a year during normal production;  
d) When the results of delivery ins pection have relatively large difference with the results of the last type 
inspection;  
e) The product production is recovered after long -term suspension;  
f) When type inspection requirements are put forward by the General Administration of Quality 
Supervision, I nspection and Quarantine of the People’s Republic of China.  
7.2 Batch  
Each batch of paving units shall be in the same category, specifications and grade, and 20,000 pieces shall 
be taken as a batch; those not more than 20,000 pieces shall also be taken as a batch; for those more than 
20,000 pieces, batch shall be determined by both parties.  
7.3 Sampling  
7.3.1  For the test pieces for appearance quality inspection, sampling method shall be determined in 
advance, 50 paving units shall be taken from each batch of products by random sampling method to ensure 
representativeness of test pieces sampled.  
7.3.2  For the test pieces for specification inspection, 10 paving units shall be taken by random sampling 
method from the test pieces passing appearance quality insp ection.  
7.3.3  For the test pieces for physical and mechanical property inspection, 30 paving units (5 for standby) 
shall be taken by random sampling method from the test pieces passing appearance quality and dimension 
inspection.  
The age of test pieces for  physical and mechanical property test shall be not less than 28d.  
7.4 Judgment rules  
7.4.1  Appearance quality  
In 50 test pieces, judgment shall be performed according to total nonconforming test pieces ( K1) and total 
nonconforming test pieces in secondary  sampling inspection (including nonconforming test pieces in the first 
inspection) ( K2). 
Acceptance may be performed if K1≤3; acceptance may be rejected if K1≥7; secondary sampling inspection 
may be performed as per 7.3.1 if 4≤ K1≤6. 
Acceptance may be performed if K2≤8; acceptance may be rejected if K 2≥9. DUS  65: 2018  
© UNBS 2018  – All rights reserved  11 
 7.4.2  Dimensional deviation  
In 10 test pieces, judgment shall be perform ed by total nonconforming test pieces ( K1) and total 
nonconforming test pieces in secondary sampling inspection (including nonconforming test pieces in the first 
inspection) ( K2). 
Acceptance may be performed if K1≤1; acceptance may be rejected if K1≥3; sec ondary sampling inspection 
may be performed as per 7.3.2 if K1=2. 
Acceptance may be performed if K2=2; acceptance may be rejected if K2≥3. 
7.4.3  Physical and mechanical properties  
Corresponding grade shall be judged for an item if physical and mechanical p roperties meet the provisions for 
a certain grade upon inspection.  
In case of dispute on two abrasive resistance results, the test results by DUS 2107  shall be taken as final 
results.  
7.4.4  Conclusions  
Corresponding grade shall be judged if inspection resu lts for all the items meet the provisions for a certain 
grade; the product shall be judged as nonconforming product in case of an item fails to meet the provisions for 
conforming product grade.  
8 Signs and operation i nstruction  
8.1 Marking   
At least 0.5% p aving units shall have visible marks in the products to be delivered.  
The product quality certificate must be provided when the product is delivered out of the factory. Product 
certificate shall mainly cover producer name, product logo, trademark, batch No ., and certificate No., and shall 
be signed by inspectors or inspection unit.  
8.2 Operation instruction   
To facilitate use, suppliers shall provide Operation Instruction for paving units to describe on -site construction 
method, requirements, and reference quantity for use.  
9 Packaging, transportation and s torage   
9.1 Packing   
When loaded with a hoisting bracket, it shall be fastened firmly. Brackets must not be hoisted in bulk.  
9.2 Transportation   
Products shall be loaded and unloaded gently, and may not be  thrown. Products shall be free of collision in 
transportation.   
12 © UNBS 2018  – All rights reserved  
 9.3 Storage   
Storage site for paving units shall be flat and solid. It shall be stacked separately according to the varieties, 
specifications and quality grades. Stacking height of bulk paving  units shall be not more than 1.5m. A 
paragraph.  DUS  65: 2018  
© UNBS 2018  – All rights reserved  13 
 Annex  A 
(normative)  
 
Method for compressive strength t est  
A.1 Test e quipment  
A.1.1  Testing machine  
Testing machine may be pressure testing machine or universal testing machine. Relative error of indication  of 
testing machine shall be not more than ±1%. Anticipated breaking load of test pieces shall be not less than 
20% full scale of testing machine, and may not be more than 80% full scale.  
A.1.2 Pressure plate  
Flat and smooth steel pressure plate with thick ness of not less than 30mm and hardness of more than HB200 
shall be adopted, and the length and width of pressure plate shall be selected by Table A1 according to 
nominal thickness of paving units.  
Table A1  Dimension of pressure p late mm 
Nominal thickness of test pieces  Pressure plate  
 Length  Width  
≤60 
≤ 60 120 60 
80 160 80 
100 200 100 
≥120  240 120 
It is unnecessary to use pressure plate in case test piece thickness is not less than 0.9x effective side length 
in service plane; in case test piece thickness is not less than 100mm, and 200mmX100mm p ressure plate is 
larger than compression face of the test pieces, 160mmX80mm pressure plate may be adopted.  
A.2 Test pieces  
A.2.1 5 test pieces shall be taken.  
A.2.2 Two compression faces of a test piece shall be parallel with each other, and shall be flat . Otherwise, 
corresponding compression face shall be leveled by grinding or plastering with clean cement mortar, and the 
thickness of troweling course shall be not more than 5mm.  
A.3 Test s teps 
A.3.1 Remove bonded slag and burr from test piece surface, and  immerse the test pieces in the water at 
room temperature for 24h.   
14 © UNBS 2018  – All rights reserved  
 A.3.2 Put the test pieces out of water, and wipe off surface water with dried wet towel, put the test pieces in 
the center of pressure plate under testing machine, and then put pressure pla te in symmetrical position of 
surface center of the test pieces (as shown in Fig. A1).  
 
1-pressure plate; 2 -test pieces; 3 -pressure plate under testing machine; 4 -troweling course  
Fig. A1  Test pieces Position  
A.3.3 Start testing machine, apply load unifor mly and continuously at the speed of 0.4~0.6MPa/s till the test 
pieces is broken, and record breaking load ( P). 
A.4 Result calculation and a ssessment  
Compressive strength shall be calculated by formula (A1):  
A1 ........ .......... .......... .......... .......... .......... .......... ..........APRC
 
Wherein;  
Rc represents c ompressive strength, MPa;  
P represents breaking load, N;  
A represents the area of pressure plate on the test pieces, or compression area of the test pieces, mm2. 
Results shall be expressed by mean value of compressive strength of 5 test pieces and minimum value of a 
single block, and calculation shall be accurate to 0.1MPa . DUS  65: 2018  
© UNBS 2018  – All rights reserved  15 
 Annex  B 
(informative)  
 
Method for rupture strength t est  
B.1 Test e quipment  
B.1.1  Testing machine  
Testing machine may be breaking testi ng machine, universal testing machine or the pressure testing machine 
with breaking test stand. The requirements for relative error of indication and scale of testing machine are the 
same with 1.1 of Appendix A to the Standard.  
B.1.2 Support and pressurization rod  
Two support rods and pressurization rod of the support shall have diameter of 40mm, be made of steel, and 1 
support rod therein shall enable rolling and free levelness adjustment.  
B.2 Test pieces  
5 test pieces shall be prepa red. 
B.3 Test s teps 
B.3.1 Remove bonded slag and burr from test piece surface, and immerse the test pieces in water at room 
temperature for 24h.  
B.3.2 Take the test pieces out of water, wipe off surface water with dried wet towel, and put the test pieces o n 
the support in length direction with exposed surface upward (as shown in Fig. B1). Breaking offset distance 
shall be 4x test piece thickness. Plyw ood cushion with thickness of 3 -5mm shall be lined between 
pressurization rod of the support and test pieces . 
 
1-support; 2 -test pieces; 3 -pressurization rod; 4-plywood cushion   
16 © UNBS 2018  – All rights reserved  
 Fig. B1  Test pieces Position  
B.3.3 Start testing machine, apply load continuously and uniformly at the speed of 0.04~0.06MPa/s till the 
test pieces is broken. Record breaking load ( P). 
B.3.4 Result Calculation and Assessment  
Rupture strength shall be calculated by formula (B1);  
(B1)..... .......... .......... .......... .......... .......... .......... .......... ..........
2bh3PlRt2
 
Wherein ;  
Rf represents rupture strength, MPa;  
P represents breaking load, N;  
l represents the distance between centers of supports, mm;  
b represents test piece width, mm;  
h represents test piece thickness, mm.  
Results shall be expressed by mean value of rupture strength of 5 test pieces and minimum value of single 
block, and calculation shall be accurate to 0.01MPa  DUS  65: 2018  
© UNBS 2018  – All rights reserved  17 
 Bibliography  
[1] JC/T 446 -2000 , Precast concrete paving units  
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© UNBS 2018 – All rights reserved  19 
 Certification marking  
Products that conform to Uganda standards may be marked with Uganda National Bureau of Standards 
(UNBS) Certification Mark shown in the figure below.  
The use of the UNBS Certification Mark is go verned 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 N ational Bureau of Standards. UNBS marked products are 
continually checked by UNBS for conformity to that standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
 US nnnn -n: yyyy    
 
ICS nn.nnn.nn  
Price based on nn pages  
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