STANDARDS ASSOCIATION OF ZIMBABWE

DRAFT FOR PUBLIC COMMENT

LATEST DATE FOR RECEIPT OF COMMENTS: 2014-09-30

Our ref: MA 050

Draft Number: MA 050 – D976/2

Date: 2014-08-05

TECHNICAL COMMITTEE: MA 050: MODULAR PRECAST CONCRETE PANELS

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DRAFT SAZ STANDARD FOR

EXPANDED POLYSTYRENE – MODULAR PRECAST

COMPOSITE CONCRETE PANELS BUILDING SYSTEM

This draft is now available for public comment. Your views and technical comments on it

would be appreciated. If you have no specific comments to make but find it generally acceptable

it would be helpful if you would notify us accordingly. Suggestions entailing revisions of the

text should indicate the preferred wording using the attached template. The relevant clause

number should be quoted against any comment.

All comments should be sent to the Committee Secretary Mr K N Dzapasi at the address shown

below.

Standards Association of Zimbabwe

P O Box 2259

Harare

E-mail: kdzapasi@saz.org.zw

Website: www.saz.org.zw

THIS IS A DRAFT AND MUST NOT BE REGARDED OR USED AS A ZIMBABWE

STANDARD.

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CONTENTS Page

PREFACE ............................................................................................................ 2

1. SCOPE .......................................................................................................... 4

2. DEFINITIONS ............................................................................................. 4

3. ABBREVIATIONS ...................................................................................... 6

4. GENERAL CONDITIONS .......................................................................... 6

5. QUALITY MONITORING .......................................................................... 7

6. ASSESSMENT ............................................................................................. 9

7. TECHNICAL DESCRIPTION ..................................................................... 10

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PREFACE

This Zimbabwe Standard Specification ZWS 976:2014: Expanded polystyrene – Modular precast

composite concrete panels building system, is based on the Agreement Certificate 2007/331 of

Agreement South Africa published by it, in terms of the powers granted to it by the Minister of

Public Works, Republic of South Africa.

This standard was prepared by Technical Committee MA050: Modular Precast Concrete Panels,

under the general direction of the Building and Civil Engineering Standards Council.

This standard makes reference to the following publication:

ASTM C 150 : Standard specification for Portland cement

ASTM A/060/A1060 M-11: Standard specification for zinc-coated (galvanized) steel welded

wire reinforcement, plain and deformed, for concrete

BS 5075 : Concrete admixtures

Part 1 : Specification for accelerating admixtures,retarding admixtures and

water reducing admixtures

BS EN 12667 : Thermal performance of building materials and products

SANS 1016 : The designs of foundations for Buildings

SANS 307 : Industrial Bitumen

SANS 952 : Polyolefin film for Damp proofing & Waterproofing in Buildings

SANS 1090 : Sands for Plaster and Mortar

SANS 10218: Part 1 : Acoustical Properties of Buildings

ZWS 162 : Structural use of Timber

Part 1 : Limit states design

Part 2 : Allowable stress design

ZWS 170 : Structural use of concrete

ZWS EN 197 : Cement

Part 1 : Composition, specifications and conformity criteria for cement

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ZWS ISO 9001 : Quality Management System

The Zimbabwe Model Building By-Laws, Model Building (amendment) by-Laws,1980 (No.1),

(Amendment) By-Laws, 1981 (No.2).

The following interests were represented on the technical committee entrusted with the

preparation of this standard.

Doku Engineering Consultants .............................................. Dr J C Kuchena

(Chairman)

City of Harare ........................................................................ Mr I T Machingura

Mr L K Chirombo

Hastel Investments (Pvt) Ltd ................................................. Mr A Matope

Greenside Investiments (Pvt) Ltd. ......................................... Mr A Dapida

Institute Architects of Zimbabwe........................................... Mr O Manyara

Ministry of National Housing ................................................ Mr A Paradza

Ministry of Public Works....................................................... Mr Njoma

Prosper Logistics .................................................................... Mr P Muchenje

Mr A Kapuya

Scientific & Industrial Research Development Centre.......... Mr R Mubvunzi

Standards Association of Zimbabwe ..................................... Mr K N Dzapasi

(Committee Secretary)

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ZIMBABWE STANDARD

FOR

EXPANDED POLYSTYRENE - MODULAR PRECAST COMPOSITE

CONCRETE PANELS BUILDING SYSTEMS

1. SCOPE

This Zimbabwe standard contains guidelines on erecting built structures using the:

The Expanded Polystyrene - Modular Precast Composite Concrete Panels

Building Systems that shall:

- be manufactured and erected by the technology provider or licensee under

the control of a professional engineer or approved competent person,

- be constructed in accordance with the technical description and the

technology provider’s detailed specifications and quality management

manual, complying with the conditions outlined in this standard.

NOTE. Any person required to check on details of construction shall refer to the

documentation listed in the Preface.

The Expanded Polystyrene - Modular Precast Composite Concrete Panels

Building System is a combination of innovative and conventional construction. A

change to any one aspect could result in one or more of the other aspects no

longer complying with the requirements of this standard and/or the Model

Building By-laws performance criteria.

2. DEFINITIONS

For the purposes of this Zimbabwe Standard, the following definitions shall

apply:

2.1 Licensee. Any person or company appointed or trained by the technology holder

and registered with relevant authorities.

2.2 Professional Engineer. A registered engineer who under the Model By-Laws is

approved to sign off engineering drawings.

2.3 Technology Provider. Contractor or licensee who erects structures using the

technology.

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2.4 Modular. Pertaining to a module or a modulus, composed of standardized units or

sections for easy construction or flexible arrangement constructed with

standardized units or dimensions allowing flexibility and variety in use.

2.5 Standard. Conforming to or constituting a standard of measurement or value, or

of the usual or regularized or accepted kind.

2.6 Polystyrene (PS). A synthetic aromatic polymer made from the monomer styrene,

a liquid petrochemical. Polystyrene can be rigid or foamed.

2.7 Expanded polystyrene (EPS).A rigid and tough, closed-cell foam. It is usually

white and made of pre-expanded polystyrene beads.

Thermal conductivity of EPS shall be measured according to EN 12667.

Water vapor diffusion resistance (µ) of EPS shall be between 30 and 70.

2.8 Sandwich-structured composite. A special class of composite materials that is

fabricated by attaching two thin but stiff skins to a lightweight but thick core. The

core material is normally low strength material, but its ,higher thickness provides

the sandwich composite with high bending stiffness with overall low density.

Open and closed-cell structured foams like polyvinylchloride, polyurethane,

polyethylene or polystyrene foams, balsa wood, syntactic foams, and

honeycombs are commonly used core materials. Open- and closed-cell metal

foam can also be used as core materials.

3. ABBREVIATIONS

For the purposes of this draft Zimbabwe standard the following abbreviations

shall be used:

ASTM American Society for Testing and Materials

MPCP Modular Precast Concrete Panels

MPCCP Modular Precast Composite Concrete Panels

EPS Expanded Polystyrene

ISO International Organization for Standardization

TC Technical Committee

SANS South African National Standard

SAZ Standards Association of Zimbabwe

ZWS Zimbabwe National Standard

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4. GENERAL CONDITIONS

4.1 This standard shall cover single and or multi-storey attached and detached

dwellings and related out buildings that:

a) are the responsibility of a professional engineer or approved competent

person who will prepare a rational design that:

- will ensure the structural integrity of the entire building adheres to

construction details within this standard guideline

b) and for which the structural engineer or professional engineer or competent

person monitors those aspects of the works that are covered by the rational

design, to verify that the design is being correctly interpreted and that the

construction techniques being used are appropriate to the stability of the

subject.

4.2 Reappraisal

- shall be requested by the technology provider or licensee before making

changes to the building system.

- shall be required by the relevant authorities if there are changes to the

Zimbabwe Model Building By-Laws.

The built structure may be condemned and/or demolished if the technology

provider or a registered licensee fails to comply with the Zimbabwe Model

Building By-laws.

5. QUALITY MONITORING

The technology provider shall be required to abide by relevant quality

management scheme, which requires:

a) that the technology provider continues to implement and manage the quality

system expected by the Zimbabwe Model Building By-Laws and relevant ISO

standards.

b) the co-operation of the technology provider in facilitating post-certification

quality monitoring by relevant authorities as required by the Zimbabwe Model

Building By-Laws.

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TABLE 1 - PERFORMANCE

Aspects of performance Requirements

1. Behaviour in fire - External walls shall be type FR (non-

combustible)

- All walls shall have a 6 min fire resistance

rating.

- Expected to meet Zimbabwe Model Building

By-laws, 1981, Chapter II Part 1 to 7.

- See Section 8, Chapter II tables 5 and 6.

2. Structural

performance

- The concrete in use shall comply with the

requirements specified in ZWS 164, ZWS 166

and ZWS 170 respectively.

- Combination of loads and forces shall be as

stated in ZWS 160.

- Provision of stable foundation shall be as

required by Chapter 4 of the Model Building

By-laws.

- The requirements for materials and building-

units shall be as required by Chapter 5 Section

5, subsection 1 and Section 7 of the Model

Building By-laws.

3. Water Penetration

and rising damp

- The constructed structure shall meet the

requirements as stated in the Model Building

By-laws, Chapter 5, Section 7, Subsection 2

(d).

4. Acoustic

Performance

- The acoustical properties of the built structure

shall be deemed to meet the requirements laid

out in SANS 10218: Part 1.

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6. ASSESSMENT

6.1 Scope of Assessment. This assessment applies to those innovative aspects of the

EPS-MPCCP building system described in Clause 7 of this standard. It also

applies to those conventional aspects of the building system are influenced by the

innovative aspects. The innovative aspects referred to are:

i) the manufacture of the wall panels using EPS suitably reinforced and

finished with structural plaster;

ii) the anchorage of wall panels to foundations;

iii) the erection of wall panels; and

iv) the monolithic construction method

The EPS-MPCP Building system as described in the standard is suitable for the

construction of buildings of the types specified (Clause 4.1). The performance in

use of buildings erected with this system will be such that they shall satisfy:

- the relevant performance requirements for safety and health prescribed by

the relevant authorities,

- where stated in Table 1, the requirements of the Zimbabwe Model Buildings

By-laws,

- Zimbabwe Model Building By-Laws performance criteria and requirements

for durability and habitability.

6.2 Compliance with the Building Regulations and Zimbabwe Model Building By-

Laws. The innovative aspects of the EPS-MPCCP Building System relate to the

National Building Regulations, and Model Building By Laws,1981, Chapter 5, as

set out in Table 1. Any regulation not specifically referred to is considered to be

outside the scope of this standard and must be applied by the local authority in the

normal manner.

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7. TECHNICAL DESCRIPTION

7.1 General Description. The EPS-MPCCP, dwellings are single or multi-storey

buildings that are constructed under the control of a structural or professional

engineer or competent person who:

a) prepares a rational design that:

- ensures the structural integrity of the entire building

- adheres to the conditions of this standard and the technology provider’s

detailed specifications and quality management documentation

b) monitors those aspects of the works that are covered by the rational design, to

verify that the design is being correctly interpreted and that the construction

techniques that are being used are appropriate.

The EPS-MPCCP, Building System utilizes factory produced wall panels and

conventional timber roof construction. The wall panel consists of a core of 80 mm

thickness (Thickness varies according to design calculations e,g. 40, 60 mm)

expanded polystyrene (EPS) with a density of 16kg/m3. The panels have a

corrugated profile and are 1,2m wide x 2,4m high, as minimum dimension.

Galvanized weldmesh to both sides of the EPS, is electro-welded to galvanized

wire ties passing through the EPS core (see Figure 2).

If specified by an engineer a reinforced concrete ring beam can be cast at eaves

level to all external eaves and gable walls. External corner and T-wall junctions

are reinforced with U-shaped reinforcing Y6 bars “starter bar” at 300 mm centres,

spaced alternately on either side of the walls (see Figure 4).

All Corners and Internal wall junctions are reinforced with L-shaped strips of

weldmesh wire tied to the wall panel weldmesh (see Figure 5). Wall panels are

finished with 35 mm thick spray applied (Gunite) structural plaster at the valley

deepest point (15MPa) to both sides of EPS core and 20 mm at the galvanized

weldmesh. (cement and fine aggregates comply with relevant Zimbabwe

specifications), ZWS EN 197: Part 1 defines 5 classes of common cement with

Portland cement as a main constituent, CEM I is Portland, Type I - For use when

the special properties specified for any other type are not required. The definition

according to ASTM-C150.

Foundations and surface beds are engineer designed where soil conditions are

problematic. Roof construction is conventional timber trusses or lightweight steel

trusses with lightweight or heavyweight roof coverings cladding. Insulated

ceilings are recommended for installation. Windows, doors and services are

conventional.

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7.2 Manufacture. Wall panels (see Figure 2) are fabricated from the following

elements:

i) corrugated EPS core;

ii) wire transverse ties passing through the EPS core;

iii) weldmesh is electro-welded to the transverse wires on both sides of the

EPS core.

The EPS core has a density of 16 kg/m3 and is fluted vertically to form

corrugations both sides of the core. The core dimensions are:

1 200 x 2 400 x 80 mm thick.

Dimension Variations:

- Width is set at 1200 mm minimum, varying according to design

- Height 3 m or as required

- Thickness of core 60 mm or 40 mm due to thermal calculations

Galvanized transverse wire ties pass through the EPS core thickness at 200 mm

vertically and 200 mm horizontally protruding on both sides of the core (Figure

5). Galvanized weldmesh 150 mm x 80 mm is electro-welded to both sides of the

EPS core. The verticals of the weldmesh coinciding with the flutes of the EPS

core and are 6 mm proud of ridges. The transverse and weldmesh wires are 3 mm

diameter galvanized steel, that meet the requirements of ASTM A1060/A1060 M-

11e1.

7.3 Erection

7.3.1 Foundations and surface bed (see Figures 1 and 3). A competent person classifies

the site in accordance with the site class classification set out in Table 3 of the

South African Institute of Engineering Geologists (SAIEG) publication

Guidelines for urban engineering geological investigations.

In abnormal or problematic ground conditions, foundations are designed by a

professional engineer in accordance with the requirements of SANS 10161 and

constructed in accordance with this design. Zimbabwe Model Building By-Laws,

Chapter 5 & Chapter 4 – provision of stable foundation.

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Typically three types of foundation design can be used depending on ground

conditions:

a) cast in situ surface bed with thickened edge beam (see Figure 3a);

b) conventional concrete strip footing and foundation walls (see Figure 3b);

c) ring-beam (see Figure 3c).

A damp-proof membrane in accordance with SANS 952 or one covered by a valid

SAZ and or Agreement certificate, is laid on the compacted fill under the surface

bed and taken under the external walls.

The surface bed 85 mm thick is cast in-situ concrete with a minimum compressive

strength of 15 MPa at 28 d when screeded and 25 MPa when power floated.

Weldmesh, when specified, reinforcing is incorporated in the surface bed. Cement

used is either CEM 1 or CEM 11A and meets the requirements of SANS

EN50197-1. (Type I - For use when the special properties specified for any other

type are not required. Type II A - Air-entraining cement for the same uses as Type

II, where air-entrainment is desired. Refer to ASTM-C150)

Cast into the surface bed are 6 mm diameter U-shaped steel anchor bars or drilled

anchor bars of various lengths as specified at 300 mm centres which form

holding-down anchors for internal and external walls (see Figure 1). The 6 mmφ

starter bars, are cast or drilled into the concrete both sides of openings in all walls.

8.3.2 Wall panels. The surface bed immediately below all wall panels are coated with a

0,5 mm thick coating of a bituminous paint complying with SANS 317 or other

waterproofing methods e.g. DPC. Wall panel erection is commenced with two

external wall panels levelled, plumbed and propped and wire tied to the anchor

bars.

The wall panels are butted together with the weldmesh reinforcement over

lapping and securely wire tied together. No voids should occur between the joints

of the EPS cores, SANS 952. T-junctions between internal and external walls are

reinforced with U-shaped reinforcing Y6 bars with 500 mm legs at 300 mm

centres passing through the external core with the legs to either side of the internal

wall core (Figure 4).

External walls are similarly reinforced with twin U-shaped reinforcing bars at

250 mm centres. All wall junctions and corners are reinforced with L-shaped

strips of weldmesh wire tied to the wall panel weldmesh (Figure 5). The dividing

wall between garage and dwelling must be taken up to the underside of the roof

cladding. Refer to Model Building By-Laws and ZWS 160 and ZWS 164.

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8.3.4 Ring beam (see Figure 1). If required a reinforced concrete ring-beam (to

engineer’s specifications) is shuttered and cast at eaves level to all eaves and

gable walls. Two galvanized wire ties, 3mm diameter, cast into the ring-beam

looping round the lower reinforcing bars and projecting above the Ring- beam

forming roof truss anchors.

8.3.5 Window and door frame installation (see Figure 6). Openings are cut into wall

panels to accommodate window and door frames. Anchor straps must be

embedded in pockets of mortar, formed by the removal of the EPS core at

appropriate places in the wall. Such pockets must extend through the full

thickness of the core to make the mortar integral with the weldmesh reinforced

wall surface layers and encase the full length of the anchor strap.

Reinforcing bars 3 mmφ, are wire tied to the starter bars to both sides of window

and door openings. The reinforcing bars are on external and internal faces of

external walls and extend from floor level into the ring beam. All window and

door openings have additional weldmesh strip reinforcement placed at 45° on the

corners of the openings. This is done to all windows regardless of the a ring beam.

8.3.6 Structural plaster. Cement must be CEM 1 or CEM 11A and meet the

requirements of SANS EN 50197-1 and sand the requirements of SANS 1090.

Should suitable sand not be available, sands must be blended as determined by a

competent laboratory. Structural plaster, 40 mm thick, is spray applied in three

layers to the EPS core, ensuring the required compaction and that honeycombing

does not occur. The first and second layers are left in rough condition to facilitate

adhesion of the next layer.

Vertical guides, to control the plaster thickness, are secured to the EPS core at

suitable centres, though not easy to implement. After the final layer is applied, the

plaster is struck off against the guides to a reasonably smooth and level finish.

After removal of the guides, the voids are filled with plaster. The structural plaster

is cured by wetting for five days. The structural plaster must have a minimum

compressive strength of 15 MPa at 28 d. (SANS 1090)

8.3.6.1 Plaster mix. 4 parts: Washed River Sand to 1 part: cement with 60 g of

polypropylene fibre per bag of cement. (one loose handful/Atcha cup). Mix well

and add water accordingly. First Spray coat can be more slushy or wetter than

your standard mix to make it easier to work with. From there on its a regular mix,

spray up to the wire and allow to dry then second coat allow to dry and then final

plaster layer.

For the structural plaster, the average thickness of structural plaster required can

be calculated as 25 mm on both sides of the wall. This is an average between the

deepest point 35 mm (at the valley of the mini-columns of the panel) and the

plaster thickness above the mesh which is 20 mm.

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This will give you structural plaster, with a minimum compressive strength of

14 MPa at 28 days. This is spray or hand applied in two layers with the first layer

of 15 mm and second layer of 20 mm, to the galvanised weld-mesh to both sides

of the EPS core, to ensure good compaction and no honeycombing.

Adequate setting time of two days for internal wall and one day for external wall

is allowed between layers to ensure proper adhesion.

The plaster is cured by wetting, once a day for at least five days. Plaster thickness

must consistently be maintained. This can be achieved by, for example, use of a

gut line or plaster spacers (metal or plastic).

8.3.7 Installation of services. For services that run in walls the EPS can be chased

using a heat source or cut with a pointed instrument. Flexible pipes are placed

under the weldmesh. Rigid pipes are placed after the weldmesh has been cut. The

weldmesh is restored by fixing strips of weldmesh over pipe positions. There may

be no services in the dividing wall between garage and dwelling and division

separating walls.

8.3.8 Attachment of fittings. Light and medium weight fittings are secured to walls

using expansion bolts. Heavy weight fittings such as fire extinguishers hoses can

be mounted on wall panels.

8.3.9 Finishes. Exterior walls are painted with two coats of an exterior grade pure

acrylic emulsion paint. Internal walls to tenant requirement.

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FIGURE 1 – TYPICAL EXTERNAL WALL SECTION

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FIGURE 2 – WALL PANEL DETEILS

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FIGURE 3 – TYPICAL FOUNDATIONS DETAILS

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(d) Foundation

NOTE.

Foundations are subject to engineering approval.

Foundation design may vary dependent on soil conditions.

Soil needs to be compacted and leveled before pouring slab.

An additional layer of EPS is recommended for extra insulation.

FIGURE 3 – CONCLUDED

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FIGURE 4 – DIAGRAMATIC EXTERNAL WALL JUNCTION

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FIGURE 5 – TYPICAL INTERNAL WALLS JUNCTION DETAILS

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FIGURE 6 – WINDOW AND DOOR DETAILS

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FIGURE 7 – DETAIL – WALL/FOUNDATION FLASHING