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Z21 Mortars (Checklist) G#1648 N#1562

By 20 September 2014September 7th, 2021Checklist, Code, Encyclopaedia, New Build

Z21 Mortars Checklist

GBE > Encyclopaedia > Code > Checklist > New Build > Z > G#1648 N#1562

Z21 Mortars Checklist
Index: 

Problems:

  • Ordinary Portland Cement (OPC)
    • 8% of world man made CO2 production is due to Cement Production
    • 1.8% of UK man made CO2 production is due to Cement Production

Bad Habits:

  • Everybody uses OPC without a second thought
  • Everybody specifies OPC without a second thought
  • Structural Engineers standard Specifications list and permit use of OPC, GGBS and blended OPC and GGBS but do not require use of GGBS or blended GGBS as a replacement for OPC.
  • Brick and blockwork can easily use Cement:Lime or Lime based mortar
  • Earth or Turf are also used as a replacement for mortar in wall construction, by people in the know

Solutions:

  • Lime mortar in preference to OPC mortar in brickwork or blockwork
  • Ground Granulated Blast Furnace (GGBS) Cement in preference to OPC mortar (If height and speed not an issue)
  • Blended GGBS and OPC mortar in preference to OPC mortar (If height and speed are an issue)
  • Concrete mixing plants often have 2 cement silos one for OPC the other for GGBS
  • They will blend OPC and GGBS to permitted limits that the mortar will set and harden like OPC mortar
  • GGBS is cheaper than OPC
  • GGBS is creamy coloured grey OPC is cold grey in colour, this affects the colour of the mortar
  • BREEAM can drive the use of GGBS and blended cements
  • Carbon Counting will drive the use of GGBS and blended cements
  • Substitution needs to be managed proactively to ensure less OPC is used.

Misunderstandings:

  • The cement sector may recommend stronger cement mortar
  • Stronger is not always best:
    • uses more high energy consuming and high CO2 generating materials than necessary
    • stronger mortar in facing brickwork, blockwork or stonework puts the brick, block or stone at risk of frost damage
    • always use a weaker mix in vulnerable materials
    • stronger mortar prevents reclaiming of bricks and blocks

Use:

  • Lime mortar in preference to OPC mortar
  • Blended GGBS and OPC cement mortar in preference to OPC mortar
  • Cement made from other than limestone

Consider:

  • Cement substitution to reduce OPC cement content
  • Preferred alternatives to Ordinary Portland Cement (OPC):
    • Lime mortars
    • Portland Blast Furnace Cement (PBF)
    • Portland Pulverised Fuel Ash Cement (PFA)
    • Ground Granulated Blast Furnace Slag cement (GGBS)
  • OPC replacement by GGBS or PFA cements
  • Lime based mortar and reclaim of blocks for reuse, which requires tough blocks

Avoid:

  • Use of cement mortar: cement production generates high levels of CO2
    • See E10
  • Chasing brickwork and blockwork to run buried conduits, a very dirty job making the building a no-go area whilst in progress
  • Filling conduit chases using cement based mortar/render

Minimise:

  • Use of OPC mortar

Substitute:

  • GGBS for OPC to the maximum % permitted by Codes of Practice

Health:

  • OPC and lime is alkali and bad for skin and eyes
  • OPC is very fine avoid breathing into lungs
  • Wear protective clothing and gloves and goggles when using Lime

Wellbeing:

Biodiversity:

  • Use of turf or earth in place of cement or lime mortar in hedge bank walling provides a way for nature to inhabit walls
  • Using no mortar in place of cement or lime mortar in dry stone walling provides a way for nature to inhabit the interstices in walls

Safety:

  • Wear protective clothing, gloves and goggles when using Lime

Precautionary principle:

Resource Efficiency Issues:

  • Design For Demount ability:
  • Thick blockwork walls used with external insulated render could be laid in lime mortar to encourage the possibility to reuse them at the end of the buildings life
  • Site walls made of solid brickwork could be laid in lime mortar to encourage reuse of bricks

Reduce:

  • Mortar use by using thin joint blockwork

Reclaim:

  • Reclaimed Bricks originally laid in lime mortar

Reuse:

  • Reuse reclaimed bricks using lime mortar to allow further reuse

Recycle:

  • Lime mortar can be recycled
  • Cement mortared brick and blockwork, crushed as hardcore, brown roof gravels, pavement sub-base, permeable pavement or piling mat

Recover:

Waste Issues:

  • Cement mortar once gone off is likely to be inert
  • Lime mortar is not inert until completely hydrated which can take a long time if bulky

Hazardous waste & Deleterious Substances

  • Lime mortar is potentially hazardous until gone off and then inert, but landfill heat could reactivate its capacity to react with water and rehydrate

Waste statistics:

Waste minimization:

  • Buckets of mortar delivered to sight can lead to waste if great care is not taking in ordering sufficient and not excess to requirements.
  • Using set-retarders in the mortar mix might help to avoid waste
  • Set retarders introduce more chemicals, see if they can be avoided

End of Life options:

  • Use lime mortar to enable reclamation of bricks and blocks

Appropriateness:

  • GGBS cements work well with recycled glass aggregates
  • ASR Alkali Silica Reaction can occur between recycled glass aggregates and OPC cement

Competence:

Effectiveness:

  • Drive down carbon by replacing significant percentages of OPC from any mix

Yardstick:

Maintenance issue:

  • Lime mortar pointing is easier to do than cement mortar pointing
  • Do not replace live mortar with cement mortar pointing
  • Mortar should always be weaker than the stones or bricks in the wall

Industry/Sector Initiatives:

  • We detect the OPC manufacturers have finally understood that the GGBS manufacturers are not their enemy but potential collaborative partners in driving down Carbon in concrete, mortar and screed

Information sources:

  • The Whole House Book (Pat Borer and Cindy Harris) page 115

© GBE GBC GBL NGS ASWS Brian Murphy aka BrianSpecMan **
19th November 2018 – 7th September 2021

Z21 Mortars Checklist
Images:

Book_BDA_Illustrated_Guide_to_Brickwork_Design.png

Fig. 1 BDA Introduction to Brickwork Design

21MasonryExtWalls_Page_1.png

Fig. 2 (21) Masonry External Walls

21TimberExtWalls_Page_1.png

Fig. 3 (21) Timber External Walls
Often have brick outer leaf

© GBE GBC GBL NGS ASWS Brian Murphy aka BrianSpecMan **
19th September 2014 – 7th September 2021

Z21 Mortars Checklist
See Also:

GBE Checklist

CAWS Abbreviations

  • E
  • E10
  • E41
  • F10
  • F30
  • M10
  • M20
  • M21
  • Z21 (this page)
CAWS Work section titles

GBE Jargon Buster

CAWS Abbreviations

  • E10
  • F10
  • F30
  • M10
  • M20
  • Z21
CAWS Work section titles
  • Mixing/Casting/Curing Insitu Concrete (E10)
  • Brick/Block Walling (F10)
  • Hedge bank Walling (F23)
  • Accessories/Sundry items for brick/block/stone walling (F30)
  • Cement:Sand/Concrete screeds toppings (M10)
  • Plastered/Rendered/Roughcast coatings (M20)
  • Mortar (Z21)

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GBE Materials

  • Lime
  • GGBS Cement in Silos
  • Blended GGBS & OPC Cement in 25 kg bags

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  • Internal walls
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  • Robust Specification Clause
  • Robust Specification Work Section

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© GBE GBC GBL NGS ASWS Brian Murphy aka BrianSpecMan **
19th September 2014 – 7th September 2021

Z21 Mortars (Checklist) G#1648 N#1562 End.

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