ICS 93.080.10   
 
Reference number  
DRS  62: 2021  
© RSB 2021  
  
 RWANDA 
STANDARD  DRS  
62  
 
Third  edition  
2021-mm-dd 
Reinforced concrete  box culvert — 
Specification   
 
   
DRS  62: 2021  
©RSB 2021  - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB 2021  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
Requests for permission to reproduce this document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS  62: 2021  
iii                ©RSB 2021 - All rights reserved  
 Contents  Page 
Reinforced concrete box culvert — Specification  ................................ ................................ .................  1 
1 Scope  ................................ ................................ ................................ ................................ .............  1 
2 Normative references  ................................ ................................ ................................ ...................  1 
3 Terms and definitions  ................................ ................................ ................................ ..................  1 
4 Requirements  ................................ ................................ ................................ ................................  3 
4.1 Types of culverts  ................................ ................................ ................................ ..........................  3 
4.2 Materials  ................................ ................................ ................................ ................................ ........  4 
4.3 Structural design  ................................ ................................ ................................ ..........................  6 
4.4 Resistance to proof load ................................ ................................ ................................ ..............  7 
4.5 Resistance to ultimate load  ................................ ................................ ................................ .........  7 
4.6 Manufacture  ................................ ................................ ................................ ................................ .. 7 
5 Workmanship and finish  ................................ ................................ ................................ ............  10 
6 Sampling and compliance  ................................ ................................ ................................ .........  10 
6.1 Gene ral ................................ ................................ ................................ ................................ ........  10 
6.2 Sample for inspection  ................................ ................................ ................................ ................  10 
6.3 Sample for testing  ................................ ................................ ................................ ......................  10 
6.4 Sample  for ultimate load testing  ................................ ................................ ...............................  10 
6.5 Criteria for compliance  ................................ ................................ ................................ ..............  10 
7 Inspection  ................................ ................................ ................................ ................................ .... 11 
8 Rejection  ................................ ................................ ................................ ................................ ..... 11 
9 Physical tests  ................................ ................................ ................................ ..............................  11 
9.1 Straightness test  ................................ ................................ ................................ ........................  11 
9.2 Cover over reinforcement test  ................................ ................................ ................................ .. 11 
9.3 Squareness test at ends of section  ................................ ................................ ..........................  12 
9.4 Compression test  ................................ ................................ ................................ .......................  12 
9.5 Proof load and ultimate load test  ................................ ................................ ..............................  14 
9.6 Water absorption test ................................ ................................ ................................ .................  15 
10 Testing facilities  ................................ ................................ ................................ .........................  15 
11 Cost of testing  ................................ ................................ ................................ ............................  15 
12 Information  to be supplied by the purchaser  ................................ ................................ ..........  15 
13 Information to be supplied by the manufacturer  ................................ ................................ .... 15 
14 Marking  ................................ ................................ ................................ ................................ ........  16 
Annex  A (normative)  B ox culvert load —Test method  ................................ ................................ ........  17 
A.1 Apparatus  ................................ ................................ ................................ ................................ .... 17 
A.2 Positioning of culvert in testing machine  ................................ ................................ ................  18 
A.3 Application and calculation of test load  ................................ ................................ ..................  18 
Annex  B (normative)  Water absorption — Test method  ................................ ................................ .... 19 
B.1 Method of test  ................................ ................................ ................................ .............................  19 
B.2 Calculation  ................................ ................................ ................................ ................................ .. 19 
 DRS  62: 2021  
©RSB 2021  - All rights reserved                  iv 
 Foreword  
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task o f technical committees is to prepare national standards.  Final Draft Rwanda S tandards adopted 
by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and gazettment as 
Rwanda Standards.  
RS 62 was prepared by Technical Comm ittee RSB/TC 009, Building materials and civil engineering . 
In the preparation of this standard, reference was made to the following standard s: 
1)  ASTM C1433M -20, Standard specification for precast reinforced concrete monolithic box sections for 
culverts, storm drains, and sewers (Metric)   
2)  ASTM C822 -20, Standard terminology relating to concrete pipe and related products   
3)  SANS 986:2019 , precast reinforced concrete culverts   
The assistance de rived from the above source is hereby acknowledged with thanks.  
This third edition cancels and replaces the second edition (RS  62:2014), of which has been technically revised.  
Committee membership  
The following organizations were  represented on the Technical Committee on Building materials and civil 
engineering (RSB/TC 009) in the preparation of this standard.  
B. J Construction Ltd  
Bridge to Prosperity  
City of Kigali  
Green Pact Africa  
MASS Design  
NPD Ltd  
Rwanda Housing Authority (RHA)  
Rwanda Inspectorate , Competition  and Consumer Protection Authority (RICA)  
University of Rwanda/College of Science and Technology (UR -CST)  
Rwanda  Standards Board  (RSB) – Secretariat  
 DRS 62: 2021  
1                ©RSB 2021 - All rights reserved  
 Reinforced concrete  box culvert — Specification   
1 Scope  
This Draft Rwanda Standard specifies the requirements for reinforced concrete box culverts primarily intended 
for conveying water not under pressure, and for carrying highway vehicle loadings.   
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.  
RS EAS 1 2, Potable water — Specification   
RS 142, Design of concrete structure s — Code of practice  
RS 373 , Aggregates for concrete — Specification  
RS EAS 18 -1, Cement ─ Composition, specifications and conformity criteria for common cements   
RS ISO 1920 -1, Testing of concrete — Part 1: Sampling of fresh concrete   
RS ISO 1920 -4, Testing of concrete — Part 4: Strength of hardened concrete   
RS ISO 6935 -2, Specification for the reinforcement of concrete — Part 2: Ribbed bars   
RS ISO 6935 -3, Specification for the reinforcement of concrete — Part 3: Welded fabric    
3 Terms and definitions  
For the purposes of this standard, the following terms and definitions apply.  
3.1 
absorption  
increase in weight of concrete resulting from the penetration of w ater into the concrete  
3.2  
absorption test  
test made to determine the absorption of concrete  
3.3  
admixture  
material other than water, aggregates, cement and fibre reinforcing used as an ingredient of concrete and added 
to the batch immediately before or during its mixture  
3.4  
batch  
material from a single mix or, in the case of a continuous process, the material from a single day's production   
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 3.5  
box culvert  
precast  concrete unit with a clear opening of rectangular shape which may have internal splayed corners  
3.6  
box section  
concrete pipe with a rectangular cross section  
3.7  
box section bottom slab  
lower horizontal portion of a box section in the installed con dition  
3.8  
box section top slab  
upper horizontal portion of a box section in the installed condition  
3.9  
box section wall  
vertical sides of a box section in the installed condition  
3.10  
cage  
assembled unit of steel reinforcement consisting of circ umferential and longitudinal bars or wires  
3.11  
circumferential reinforcement  
reinforcement that is approximately perpendicular to the longitudinal axis of the concrete box culvert  
3.12  
compression test  
test made on a concrete specimen to determine t he compressive strength  
3.13  
compressive strength  
maximum resistance of a concrete specimen to axial compressive loading; or the specified resistance used in 
design calculations  
3.14  
concrete  
mixture of portland  cement, fine aggregate, coarse aggregate, and water. The mixture may also contain 
admixtures, or other cementitious materials, or both  
3.15  
core  
cylinder of concrete obtained from concrete by means of a core drill  DRS 62: 2021  
3                ©RSB 2021 - All rights reserved  
 3.16  
culvert  
pipeline intended to c onvey water under a highway, railroad, canal, or similar facility  
3.17  
cylinder (test)  
cast cylindrical specimen of concrete  
3.18  
joint  
connection of two concrete  box section ends, made either with or without the use of additional parts and/or 
mater ials  
3.19  
reinforcement  
steel in the form of continuous wire, welded wire fabric, or bars embedded in concrete in such a manner that 
the above referenced concrete and steel act together to resist stresses  
3.20  
lot  
assemblage of concrete products, all  being of like size, material, and strength designation, manufactured by the 
same process.  
4 Requirements  
4.1 Types of culverts  
The types of culvert covered by this standard are as follows:  
a) double U: two U -shaped sections arranged to form a rectangle with horizontal joints at the mid -point of each 
wall;  
b) single U: U -shaped section forming the invert slab and walls, with a separate deck slab;  
c) inverted U: U -shaped section forming the deck, sla b and walls, with a separate invert slab;  
d) one-piece: A monolithic hollow rectangular section forming deck, walls and invert; and  
e) sectional: Four separate sections forming walls, deck and invert slab.   
The dimensions of reinforced concrete box culverts ar e illustrated in figure 1.   
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Figure 1 — Section of a monolithic reinforced concrete box culvert  
Key  
TT: is the top slab thickness   
TB: is the bottom slab thickness   
TS: is the wall thickness   
H: is the haunch  
NOTE  The haunch dimension H, is equal to th e wall thickness T S.  
4.2 Materials  
4.2.1  General  
The reinforced concrete shall consist of cementitious materials, mineral aggregates , admixtures if used  and 
water, in which steel has been embedded in such a manner that the steel and concrete act together.  
4.2.2  Cement  
Cements used in the manufacture of the culverts shall comply, in all respects, with RS EAS 18 -1.  
4.2.3  Aggregate  
4.2.3.1  Aggregates shall consist of crushed or uncrushed gravel, stone or rock, or a combination of any of 
these. The aggregates shall be hard, strong, inert and durable and shall be clean and free from clay films and 
DRS 62: 2021  
5                ©RSB 2021 - All rights reserved  
 other adherent coatings. No mica, shale, lamin ated particles or harmful material shall be present in sufficient 
quantity to affect adversely the quality of the concrete. Other requirements shall conform to  RS 373 .  
4.2.3.2  When required by the purchaser, a sample of the aggregate shall be submitted to  him for approval.  
NOTE  Aggregates from all sources should be adequately tested to establish whether or not they are satisfactory.  
4.2.4  Reinforcement  
4.2.4.1  Reinforcement shall consist of reinforcing bars conforming to RS ISO 6935 -2 or welded wire 
reinforc ement conforming to RS ISO 6935 -3 where relevant.  
4.2.4.2  Steel used for reinforcement shall show no loose scale, oil or grease and shall be free from loose 
or heavy rusting.  
4.2.4.3  The reinforcement shall be assembled into units so designed that they m ay readily be placed and 
held in proper positions within the casting mould during the manufacture of the culvert sections.  
4.2.4.4  Arrangement of steel reinforcement in a monolithic reinforced concrete box culvert is illustrated in 
figure 2.  
 
Figure 2 — Steel reinforcement in a monolithic reinforced concrete box culvert  
4.2.5  Water  
The water used in the mixing of the concrete shall conform to RS EAS 12 .  
4.2.6  Admixtures  
The admixtures used shall not have any harmful effect on the properties of the concrete  and s hall comply with 
their respective standard requirements . Admixtures containing  calcium chloride or rust -inhibiting admixtures 
shall not be used.  
4.2.7  Spacers  
Bar spacers shall be used to ensure correct cover and they shall be of adequate strength to resist lo ads imposed 
during manufacture. They shall be of concrete mortar (which may be fibre reinforced) to a specification 
compatible with the culvert concrete or, when used against vertical formwork only, they may be of plastic with 
 
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 perforations of not less than  25 % of their area.  
4.2.8  Concrete  
4.2.8.1  General  
The concrete shall be fully compacted and shall have:  
a) minimum cement content of 350 kg/m3;  
b) maximum free water/cement ratio of 0.5;  
c) lowest grade of C25/30 ;  
d) total chloride content expressed as a percentage of chloride ion by weight of cement not exceeding 0.1 %;  
e) a total water -soluble sulphate content expressed as SO 3 not exceeding 4 %; and  
f) air content of ( 5 ± 1.5) % when air entrainment is specified and nom inal maximum aggregate size is 20.  
NOTE  Other limits apply to higher grade concrete and to sulphate -resisting concrete.   
4.2.8.2  Control of alkali silica reaction  
In order to control the possibility of alkali silica reaction, either of the following conditions shall be met:  
a) alkali content of the concrete shall not exceed 3.0 kg/m3; and  
b) aggregates, both coarse and fine, shall be of a non -reactive nature.  
4.3 Structural design  
4.3.1  Box culverts shall be designed  to resist the combination of vertical load acting on the roof and floor and 
horizontal load acting on the walls. This load combination is known as proof load (kN/m of length) and it shall 
be considered at  maximum and minimum fill heights . Intermediate dep ths need not to be considered.  
4.3.2  Design and detailing of sections to resist moments and shear forces shall be in accordance with RS 
142.  
4.3.3  It is recommended that the minimum fill height  should be not less than 200 mm or one -fifteenth of the 
internal width of the box culvert for fill height  greater than or equal to 600 mm.   
4.3.4  Other requirements for structural arrangements are as follows:  
a) top slab : cover over reinforcement shall be 25 mm for fill heights  greater than or equal to 600 mm, 50 mm 
for fil l heights  lower than 600 mm;  
b) slab thickness : for fill heights greater than 600 mm, 1/12 times inside span plus 25 mm up to 2 m span, 
1/12 inside span above 2 m span;   
c) side wall thickness : 1/12 times inside span plus 25 mm up to 2 m span;  
d) haunch dimension s: vertical and horizontal dimensions both equal to wall thickness; and  
e) Circumferential  wire spacing : 100 mm.  DRS 62: 2021  
7                ©RSB 2021 - All rights reserved  
 4.4 Resistance to proof load  
A box culvert shall sustain the simultaneous application of the proof loads given in table 4, appropriate to the 
class  of culvert required, without the development of cracks of 0.3 mm width such that the feeler gauge can 
enter to a depth of 2 mm or more over a continuous length of at least 300 mm.    
4.5 Resistance to ultimate load  
4.5.1  The ultimate load tests shall be conducted as in 8.5.1 with at least 1.25 times the proof loads and applied 
in the same manner.  
4.5.2  When so required (see annex A), an ultimate load test shall be carried out. When a box culvert is tested, 
it shall sustain a load of at least 1.25 times t he proof load without failure.  
4.6 Manufacture  
4.6.1  Mixture  
4.6.1.1  The aggregates shall be sized, graded, proportioned, and mixed with such proportions of 
cementitious materials of such quality that the box culvert will conform to the test and design requiremen ts of 
this specification. All concrete shall have a water -cementitious materials ratio not exceeding 0.53 by weight.  
4.6.1.2  Cementitious materials shall be added to the mix in a proportion not less than 350  kg/m3 unless 
mix designs with lower cementitiou s materials  content demonstrate that the quality and performance of the  box 
culvert meet the requirements of this specification.  
4.6.2  Form  
The forms used in manufacture shall be sufficiently rigid and accurate to maintain the box section dimensions 
within the  permissible variations. All casting surfaces shall be of smooth nonporous material .  
4.6.3  Curing  
4.6.3.1  Exposed surfaces shall be protected from low humidity until the concrete has reached sufficient 
maturity for lifting and storage.   
4.6.3.2  The box sectio ns shall be cured for a sufficient length of time so that the concrete will develop the 
specified compressive strength in 28 days or less.  
4.6.4  Reinforcement cages  
Reinforcement shall be cut and/or bent , assembled into cages and fixed by tack welding or by us ing soft 
annealed iron or stainless steel tying wire.  
4.6.5  Cover over the reinforcement  
4.6.5.1  Nominal cover shall be provided to the steel as indicated in RS 142 where design to this standard 
is specifically requested .   
4.6.5.2  The concrete cover over rein forcement to the concrete surface on any culvert face shall not be less 
than 25 mm for at least 95 % of the reinforcing bars. In addition, under no circumstances shall any single bar 
have a cover over reinforcement to the concrete surface on any culvert fa ce of less than 20 mm.  
4.6.6  Lifting arrangements  of precast reinforced concrete box culverts    
Precast reinforced concrete  box culverts shall be provided with lifting points such that they may be safely lifted  
©RSB 2021  - All rights reserved                  8 
 by crane.  
4.6.7  Transport and Storage  of precast reinf orced concrete box culverts  
4.6.7.1  Units shall not be transported from the precast yard within seven days  after casting and the curing 
has been completed in accordance with Clause 4.6.3. Units shall be supported on timber bearers which  are 
fitted with rubber strips on top. Rubber strips shall also be placed between units, both laterally and longitudinally. 
All tie down straps and chains shall have rubber protection strips over box culvert edges. The legs of all box 
culverts shall be ade quately braced to prevent whipping and bending.  
4.6.7.2  Precast reinforced concrete box culverts shall be stored in ambient temperature on a level surface and 
in a manner preventing damage to the members. Do not place any load on box culverts until design  strength is 
reached and curing is completed.  
4.6.8  Geometry  
4.6.8.1  Nominal sizes  
Box culverts shall be described by their nominal internal size expressed by their manufacturing dimensions in 
millimetres in the sequence of width and height of opening.  
4.6.8.2  Joints  
All faces of box culvert sections which are to adjoin when the culvert is assembled shall be of such form that 
the culvert can be laid to form a continuous conduit with a smooth and uniform interior surface.   
4.6.9  Permissible deviations  
4.6.9.1  Dimensions  
4.6.9.1.1  Internal di mensions  
The internal dimension shall not vary more than 1 % from the design dimensions. The haunch dimensions shall 
not vary more than 6 mm from the design dimensions.  
4.6.9.1.2  Internal cross -sectional dimensions  
4.6.8.1.2.1  The nominal internal cross -sectional  dimensions of box culverts shall be one the combination 
given in table 1, as required. The actual dimensions shall not differ from the stated dimensions by  more than:  
a) spans or heights of up to and including 1 200 mm : 5 mm;  
b) spans or heights that exceed 1 200 mm : 10 mm; and  
c) length of unit : 12 mm   
4.6.8.1.2.2  The slab and wall thickness shall not be less than that shown in the design by more than 5 % 
or 5 mm, whichever is greater. A thickness more than that required in the design shall not be a cause fo r 
rejection.  
4.6.8.1.2.3  The actual internal cross -sectional area of a culvert shall be not less than 95 % of the nominal 
internal cross -sectional area given in table 1.   
4.6.8.1.2.4  The cross -sectional area of haunches and similar features may be includ ed in the stated internal 
cross -sectional area. However, the stated area shall not exceed the actual cross -sectional area available for 
flow of water by more than 5 %.  DRS 62: 2021  
9                ©RSB 2021 - All rights reserved  
  
Table 1 — Nominal internal cross -sectional dimensions of culvert  
Height. H 
mm     Nominal internal cross — Sectional area m2    
   Span. S mm    
450   600  750  900  1 200  1 500  1 800  2 400  3 000  3 600  
300  0.12  0.18  0.23  0.27  0.36  0.45  0.54  0.72  0.90  1.08  
450  0.20  0.27  0.34  0.41  0.54  0.68  0.81  1.08  1.35  1.62  
600  -  0.36  0.45  0.54  0.72  0.90  1.08  1.80  1.80  2.76  
900  -  -  -  0.81  1.08  1.35  1.62  2.16  2.37  3.24  
1 200   -  -  -  -  1.44  1.80  2.16  2.86  3.60  4.32  
1 500   -  -  -  -  -  2.25  2.70  3.60  4.50  5.40  
1 600  -  -  -  -  -  -  3.24  4.32  5.40  6.48  
2 400   -  -  -  -  -  -  -  5.76  7.20  8.64  
3 000   -  -  -  -  -  -  -  -  9.00  10.8  
4.6.9.1.3  Flatness  
The maximum deviation from a 1 500 -mm straight edge placed in any position on an internal surface shall not 
exceed 6 mm.  
4.6.9.1.4  Squareness  
The side of the opening shall not vary in its distance from the perpendicular to the top or bottom so that the 
difference between the greatest and shortest dimensions exceeds:  
a) 6 mm for heights up to 1 200 mm;  
b) 9 mm for heights from 1 200 mm - 1 800 mm; and   
c) 12 mm for heights over 1 800 mm  
The ends of the culvert shall be square within the greater of 5 mm or 0.5 % of the length of the culvert.  
4.6.9.1.5  Twist  
Any corner shall not be more than 12 mm from the plane conta ining the other three corners.  
4.6.9.1.6  Straightness  
When the inner surfaces of the culvert are measured in accordance with 8.1 they shall not at any point deviate 
from straightness by the lesser of 12 mm and 5 mm per metre length of the culvert    
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 5 Workmanship and finish  
The interior and exterior surfaces of the sections shall be substantially free from roughness voids , honey 
combing , chipped edges laitance and other imperfections which would impair the serviceability of the culvert.  
The sections shall be free fro m cracks other than craze cracks i.e cracks occurring superficially and usually of 
irregular pattern and shall be free from defects resulting from faulty materials or faulty methods of manufacture.  
6 Sampling and compliance  
6.1 General  
Samples of concrete sha ll be taken at a rate of one per 20 m3 or one per 20 batches whichever is the lesser. 
Other requirements for sampling fresh concrete shall be in compliance with RS ISO 1920 -1. Cubes from these 
samples shall be prepared and tested for compressive strength i n accordance with RS ISO 1920 -4.  
A prescribed sampling procedure shall be followed to determine whether a lot complies with the standard and 
the samples so taken shall be deemed to represent the lot. Samples shall be  taken in accordance with the 
procedure s given in 6.2 and 6.3.  
6.2 Sample for inspection  
From the lot take at random the number of specimens shown in column 2 of table 2 relative to the appropriate 
lot size shown in column 1.  
Table 2 — Sample sizes for inspection and testing and permissible numb er of defectives  
Lot size  
(L)  Inspection  Testing  
Sample size  Permissible 
number of 
defective  Sample size  Permissible 
number of 
defective  
10 ≤ L ≤ 20  All  0  3  0  
21 ≤ L ≤ 100  20  0  3  0  
101 ≤ L ≤ 300  30  1  5  0  
301 ≤ L ≤ 500  45  1  7  0  
6.3 Sample for testing  
From the lot take at random the number of specimens shown in column 4 of table 2 relative to the appropriate 
lot size shown in column 1.  
6.4 Sample for ultimate load testing  
The ultimate load test shall be conducted  on one sample from a lot of 500 unless otherwise dictated by the 
manufacturer's quality system.   
6.5 Criteria for compliance  
6.5.1  Acceptance   
6.5.1.1  Acceptability of the box sections produced in accordance with 4.3  shall be determined by the results DRS 62: 2021  
11                ©RSB 2021 - All rights reserved  
 of the conc rete compressive strength tests described in 8.2 by the material requirements described in clause 4 
and by inspection of the finished box sections.  
6.5.1.2  Box sections shall be considered ready for acceptance when they conform to the requirements of 
this specification.  
6.5.1.3   The lot shall comply with the following relevant requirements:  
a) on inspection of the sample drawn in accordance with 6.2 with regard to the properties given in 4.6. the 
number of defectives found does not exceed the relevant permissible number of defectives given in 
column 3 of table 2;  
b) on testing of the sample drawn in  accordance with 6.3 for compliance with the requirements given in 
4.3.  
c) no defective is found (see column 5 of table 2); and  
d) sample subjected to the ultimate load does not collapse.  
7 Inspection  
The quality of materials , the process of manufacture and th e finished box sections shall be subject to inspection 
by the purchaser.  
8 Rejection  
8.1 Box sections shall be subject to rejection on account of failure to conform to any of the specification 
requirements.  
8.2 Individual box sections shall be allowed to b e rejected because of any of the following:  
 Fractures or cracks passing through the wall, except for a single end crack that does not exceed the 
depth of the joint,  
 Defects that indicate mixing and moulding  not in compliance with 4.6.1, or honeycombed or o pen texture 
that would adversely affect the function of the box sections, and  
 Damaged ends, where such damage would prevent making a satisfactory joint.  
 Any continuous crack having a surface width of 0.3 mm or more and extending for a length of 300 mm 
or more, regardless of position in the wall of the box culvert, for box culvert not installed or under load.  
9 Physical tests  
9.1 Straightness test  
Take a straight -edge of length at least equal to that of the culvert under test and so lay it on an inner face of th e 
culvert that the straight -edge is parallel to the longitudinal axis of the culvert. Measure to  the nearest 2  mm. any 
deviation of the culvert surface from the straight -edge. Repeat the test on each of the other inner faces of the 
culvert and check the re sults for compliance with 4.6.8.1.6.  
9.2 Cover over reinforcement test   
Using a calibrated electronic cover meter measure the concrete cover over reinforcement. Conduct at least 
twenty spot tests per face of the culvert. Check for compliance with 4.6.5.  
The exposure of the ends of spacers which have been used to position the reinforcement during the placement 
of concrete shall not be a cause of rejection.   
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 9.3 Squareness test at ends of section  
When tested by means of a try -square. The ends of the culvert shall be square within 3 mm.  
9.4 Compression test  
9.4.1  Type of test specimen  
Compression tests for determining concrete compressive strength shall be allowed to be made on either  
standard rodded concrete cylinders or concrete cylinders compacted and cured in like manner as the box 
sections or on cores drilled from the box section .  
9.4.2  Compression testing of cylinders  
Cylinders shall be obtained and tested for compressive strength.  
9.4.2.1  Apparatus  
9.4.2.1.1  Moulds  
Moulds for specimens or fastenings thereto in contact with the concrete shall be made of steel cast iron or other 
non-absorbent material nonreactive with concrete containing portland or other hydraulic cements. Moulds shall 
hold their di mensions and shape under all conditions of use and shall be watertight during use as judged by 
their ability to hold water poured into them. A suitable sealant such as heavy grease modeling clay or 
microcrystalline wax shall be used where necessary to prev ent leakage through the joints. Positive means shall 
be provided to hold base plates firmly to the moulds. Reusable molds shall be lightly coated with mineral oil or 
a suitable nonreactive form release material before use .  
9.4.2.1.2  Tamping rod  
A round smooth stra ight steel rod with a diameter conforming to the requirements in Table 3 shall be used. The 
length of the tamping rod shall be at least 100 mm greater than the depth of the mold in which rodding is being 
performed but not greater than 600 mm in overall len gth. A rod of 400 mm - 600 mm should be suitable. The 
rod shall have the tamping end or both ends rounded to a hemispherical tip of the same diameter as the rod.  
Table 3 — Tampering rod length  
Diameter of cylinder  Rod length  
< 150 mm  10 ± 2 mm  
≥ 150 mm  16 ± 2 mm  
9.4.2.1.3  Vibrators  
8.4.2.1.3.1  Internal vibrators shall be used . The vibrator frequency shall be at least 9 000 vibrations per 
minute (150 Hz) while the vibrator is operating in the concrete. The diameter of a round vibrator shall be no 
more than one -fourth the diameter of the cylinder mould or one -fourth the width of  the beam mould.  
8.4.2.1.3.2  Other shaped vibrators shall have a perimeter equivalent to the circumference of an appropriate 
round vibrator. The combined length of the vibrator shaft and vibrating element shall exceed the depth of the 
section being vibrated by at least 75 mm. The vibrator frequency shall be checked periodically with a vibrating -
reed tachometer or other suitable device.  
9.4.2.1.4  Mallet  
A mallet with a rubber or rawhide head weighing 0.6 kg ± 0.2 kg shall be used.  DRS 62: 2021  
13                ©RSB 2021 - All rights reserved  
 9.4.2.1.5  Scoop  
A scoop shall be use d to place concrete in a cylinder mould.    
9.4.2.2  Testing requirements  
9.4.2.2.1  Cylindrical specimens  
8.4.2.2.1.1  Compressive or splitting tensile  strength specimens shall be cylinders cast and allowed to set 
in an upright position. The number and size of cylinders cast  shall be as directed by the specifier of the tests. In 
addition, the  length shall be twice the diameter and the cylinder diameter shall be at least 3 times the nominal 
maximum size of the coarse aggregate. When the nominal maximum size of the coarse aggre gate exceeds 50 
mm. the concrete sample shall be treated by wet sieving through a 50 mm sieve as described. For acceptance 
testing for specified compressive strength cylinders shall be 150 mm by 300 mm or 100 mm by 200 mm.  
8.4.2.2.1.2  Cylindrical specimen s of sizes other than 150 mm by 300 mm may be used provided all other 
requirements of moulds  are met. If the concrete is of a consistency too stiff for compaction by rodding or internal 
vibration Cylinders shall be exposed to the same curing conditions as the manufactured box sections and shall 
remain with the sections until tested.  
8.4.2.2.1.3  Prepare not less than three test cylinders from each concrete mix used within a group (one 
day’s production) of box sections.  
9.4.2.2.2  Acceptability on the basis of cylinde r test results  
When the average compressive strength of all cylinders tested is equal to or greater than the design concrete 
strength not more than 10 % of the cylinders tested have a compressive strength less than the design concrete 
strength and no cyli nder tested has a compressive strength less than 80 % of the design concrete strength the 
lot shall be accepted.  
9.4.3  Compression testing of cores  
Cores shall be obtained and tested for compressive strength. Three cores shall be cut  from a section selected 
at random from each group of 15 box sections or fraction thereof of a single size from each continuous 
production run.  
9.4.3.1  Acceptability by core tests  
8.4.3.1.1  The compressive strength of the concrete in each group of box sections i s acceptable when 
concrete compressive strength defined as the average of three cores taken at random from the subject group 
is equal to or greater than 85 % of the required strength of the concrete with no one core less than 75 % of the 
required strength.   
8.4.3.1.2  If the compressive strength of the three cores does not meet the stated requirements the sections 
from which the cores were taken shall be rejected. Two box sections from the remainder of the group shall be 
selected at random and one core shall  be taken from each. If both cores have strength equal to or greater than 
85 % of the required strength of the concrete the remainder of the group is acceptable. If the compressive 
strength of either of the two cores tested is less than 85 % of the require d strength of the concrete the remainder 
of the group of box section shall be rejected or at the option of the manufacturer each box section of the entire 
group shall be cored and accepted individually and any of these box sections that have cores with les s than 
85 % of the required strength of the concrete shall be rejected.  
9.4.3.2   Plugging core holes  
The core holes shall be plugged and sealed by the manufacturer in a manner such that the box section will meet 
all of the test requirements of this specification . Box sections so sealed shall be considered as satisfactory for 
use.   
©RSB 2021  - All rights reserved                  14 
 9.4.3.3  Test equipment  
Every manufacturer furnishing box sections under this specification shall furnish all facilities and personnel 
necessary to carry out the tests required .  
9.4.4  Transportation  of specimens to laboratory  
8.4.4.1  Prior to transporting cure and protect specimens as specimens shall not be transported until at least 
8 h after final set. During transporting protect the specimens with suitable cushioning material to prevent damage 
from jarring. During cold weather protect the specimens from freezing with suitable insulation material.  
8.4.4.2  Prevent moisture loss during transportation by wrapping the specimens in plastic wet burlap by 
surrounding them with wet sand or tight fitting p lastic caps on plastic moulds. Transportation time shall not 
exceed 4 h.  
9.5 Proof load and ultimate load test   
9.5.1  Proof load test  
8.5.1.1  From each 20 or part of 20 culvert lengths of each size ordered the purchaser may select one 
length for proof load testin g by the method given in Annex A.  
8.5.1.2  When so tested the culvert length shall sustain a proof load as set out in Table 4 without developing 
a clearly visible crack and on removal of the load minor cracks caused by the load shall close.  
8.5.1.3  Additi onal vertical proof loads may be used to designate additional proof loads but in all cases the 
horizontal load should be 30 kN/m .  
NOTE 1  A clearly visible crack is one into which the point of crack -measuring gauge conforming to the details given in 
Annex B may be inserted at close intervals over a length of at least 300 mm to a depth of 1.5 mm.  
NOTE 2  Cracks smaller than a clearly visible, crack are considered minor crack.  
Table 4 — Proof loads for commonly available culverts  
Span. S   Proof loads kN /m    
 Vertical. Pv   Horizontal. pH  
  
  
  
  
  
30   Culvert class   
75S  100 S  150 S  175 S  200 S  
450  -  -  -  -  90  
      
600  -  -  -  -  120   
750  -  -  -  31.25  -  
900  -  -  -  157.50  -  
1 200  -  -  180  -  -  
1 500  -  150  -  -  -  
1 800  135  -  -  -  -  
2 100  157.5  -  -  -  -  DRS 62: 2021  
15                ©RSB 2021 - All rights reserved  
 2 400  180  -  -  -  -  
300  225  -  -  -  -  
3 600  270  -    -  -  
NOTE  S is the nominal span in meter     
9.5.2  Ultimate load test  
Where so specified by the purchaser up to 1 % or 1 length whichever is the greater of the total number of culvert 
lengths in the order shall be subjected to an ultimate load test by the method described in Annex A. When so 
tested each culvert length shall sustain a load of not less than the appropriate load set out in Table 4 before 
increased deformation occurs without any increase in load.  
9.6 Water absorption test  
Where so specified by the purchaser the water absorption of the concrete in the culverts shall  be determined 
using the test pieces cut from culvert lengths that have been subjected to and have complied with the cracking 
or ultimate load tests (see Annex B).  
10 Testing facilities  
Unless otherwise agreed between the purchaser and the manufacturer the manufacturer shall supply all facilities 
for measuring inspecting and testing the culverts in accordance with this specification.  
11 Cost of testing  
The cost of the ultimate load test an d the water absorption test shall be borne by the purchaser. The cost of all 
other testing shall be borne by the manufacturer.  
12 Information to be supplied by the purchaser  
The purchaser shall supply the following information to the manufacturer:  
a) the type  of culvert required;  
b) the preferred internal dimensions for the culvert;  
c) the length of culvert sections if the recommended length is not desired;  
d) whether the ultimate load test is required and. if the test is required. the number of culvert lengths to b e 
so tested; and  
e) whether the water absorption test is required and. if the test is required the number of test pieces 
required and the number of culvert lengths from which the test pieces are to be obtained.  
13 Information to be supplied by the manufacturer   
When requested by the purchaser, the manufacturer shall supply the following information:  
a) drawings showing the proposed internal dimensions of the culverts and the proposed thickness of the 
sections; and  
b) the approximate weights of the individual culver t lengths or sections.   
©RSB 2021  - All rights reserved                  16 
 14 Marking  
Each culvert (or each component of a culvert) shall bear the following information legibly impressed (during 
moulding) or indelibly marked in another manner on the inner face of a leg and in such a position that it cannot 
be covered by a joint. The following information shall be supplied:  
a) manufacturer’s name, trade name or trade mark and location of the factory;  
b) nominal internal cross -sectional dimensions;   
c) class of the culvert;  
d) date of manufacture;  
e) any additional proje ct-specific requirements; and   
f) box section span, rise and the minimum design earth cover.  
 
 DRS 62: 2021  
17                ©RSB 2021 - All rights reserved  
 Annex  A 
(normative)  
 
Box culvert load —Test method  
A.1 Apparatus  
A.1.1  Testing machine  
A machine capable of applying the loads specified in 8.5  to a length of culvert without undue deformation or 
yielding of the machine. The machine shall be mounted over a sand bed as specified below.  
A.1.2  Bearing block  
An unyielding bearing block of a length at least as long as the culvert under test and 152 mm wide  having a 
rubber packing piece 152 mm wide and 25 mm thick between the bearer and the culvert. The rubber packing 
shall have a hardness of 70 
  2 BS Hardness Degrees.  
A.1.3  Sand bed  
A sand bed of sufficient area to accommodate the length of the culvert under t est orientated as required below. 
The sand shall not be less than 76 mm deep and the base of the bed shall be level.  
A.1.4  Crack -measuring gauge  
A crack -measuring gauge 0.25 mm thick and 10 mm wide tapering at one end over a length of 22 mm to a width 
of 1.6 mm  as shown in Figure A.1.  
  
 
©RSB 2021  - All rights reserved                  18 
 Figure A.1 — Crack -measuring gauge  
A.2 Positioning of culvert in testing machine  
One piece type culvert lengths shall be placed on the sand bed under the testing machine. Other types of culvert 
shall be assembled  on the sand bed so that the component sections are in the relationship intended in use and 
the culvert length is under the testing machine. Mortar not more than 6.0 mm thick or bituminous felt may be 
used in the longitudinal joints between the sections to  reduce any damage to the concrete surfaces during the 
application of the test load. The orientation of the culvert length shall be such that the line of application of the 
load will be on the centre line for the full length of the culvert.  
A.3 Application an d calculation of test load   
The test load shall be applied vertically along the centre line for the full length of the culvert through the bearing 
block as shown in Figure A.3. The rate of loading shall be uniform and the total load shall be applied in fi ve 
minutes. The test load shall be maintained no longer than is necessary to observe and record the load and 
examine the culvert. The load per unit length shall be calculated by dividing the total recorded load by the length 
of the culvert .  
  
Figure A.2 — Positioning of culvert for testing  
 
 
 
 
 
 
DRS 62: 2021  
19                ©RSB 2021 - All rights reserved  
 Annex  B 
(normative)  
 
Water absorption — Test method  
B.1 Method of test  
B.1.1  From the culvert lengths selected for testing in accordance with 8.6 test pieces having the full thickness 
of the culvert shall be taken.  
B.1.2  Each test piece shall be as nearly square as possible and shall have an area of between 103 cm2 and 
105 cm² measured on one surface. Edges may be broken cut or ground but two faces of the specimen shall be 
the original inner and outer surfaces of the culve rt and shall be free from cracks other than craze cracks. The 
specimen shall not be taken within 152 mm of the end of the culvert.  
B.1.3  The specimen shall be dried in a well-ventilated  drying oven at a temperature not exceeding 100 °C for 
a period of fou r days. The drying shall be continued until two successive weighing  at intervals of not less than 
2 h and not more than 24 h show an increment of loss not greater than 0.1 % of the original weight of the 
specimen.  
B.1.4  The dried specimen shall be placed in a suitable receptacle and covered with distilled or rain water (tap 
water may be used if it is known that its use will not affect the results) raised to boiling point and boiled for five 
hours. At the end of this time,  the specimen shall be allowed to c ool in water to normal room temperature.  
B.1.5  When cool the specimen shall be allowed to drain for not more than one minute and the superficial 
water then removed by means of absorbent paper or cloth; the specimen shall then be weighed immediately.  
B.1.6 If the specimen contains reinforcing wire. The wet specimen shall then be broken up and the wire 
recovered and weighed.  
B.1.7  The balance used shall be sensitive to 0.5 g when loaded with 1 kg.  
B.2 Calculation  
The absorption shall not exceed 8 %.  
Percent age absorption = 𝐵−𝐴
𝐴×100 
where   
A is the weight of specimen dried to a constant weight; and   
B is the weight in air of specimen as saturated with water after boiling.  
  
©RSB 2021  - All rights reserved                  20 
 Bibliography  
[1] RS 62: 2014, Precast reinforced box culvert — Specification  
[2] ASTM C76 − 12a, Standard Specification for Reinforced Concrete Culvert. Storm Drain. and Sewer 
Pipe  
[3] ASTM C31/C31M – 12, Standard Practice for Making and Curing Concrete Test Specimens in the  
Field   
[4] C1577 − 13b, Standard Specification for Precast Reinforc ed Concrete Monolithic Box Sections for 
Culverts. Storm Drains. and Sewers Designed According to AASHTO LRFD   
[5] OPSS 1821, Material specification for precast reinforced concrete box culverts and box sew  
 DRS  62: 2021  
 
Price based on  19 pages  
©RSB 2021 - All right s reserved