Masonry mortar – Masonry mortar – building limes building limes

Dr. Sara PavíaDr. Sara PavíaDept. of Civil, Structural and Environmental Dept. of Civil, Structural and Environmental

Engineering. Engineering. Trinity College Dublin.Trinity College Dublin.

Mortar bindersBinder Hardening

mechanismHydraulicity Contraction

coefficientProduction temperature

Clay dehydration Nil

Medium ambient

Gypsum Addition of water (rapid hardening <15 minutes)

Nil Nil 175 C

Lime (non-hydraulic)

Chemical reaction: carbonation

Nil High 900 C

Hydraulic lime Chemical reaction: hydraulic set

Low to high Medium-depends on hydraulicity

1000-1300 C

PortlandCement

Chemical reaction: hydraulic set

High Medium 1500 C

Natural cement

hydraulic set High Medium 1500 C

Types of lime• Air lime (non-hydraulic). Pure lime. Produced by

calcination of pure limestone. Hardens in the air by carbonation-No hydraulic set. CL (calcium lime) 90. CL 80. Ca(OH)2

• Hydraulic limes. Natural (NHLs) or Formulated (PFLs or FLs)–see EN459-1.

• Designation: NHL2/NHL3.5/NHL5. (according to reactivity determined by strength development over time: feebly, moderately, emminently). Calcination of limestones containing SiO2, Al2O3, Iron oxides etc. e.g. clay minerals. • Depending on the amount of hydraulic strength:

– Less sticky to substrate. Harden faster (hydraulic set) and achieve greater strengths. Lower shrinkage. Can partially set underwater. More complicated chemistry.

• FLs /HLs can contain PC. Hydraulicity ranges.• Magnesian (dolomite) and selenic (gypsum)

Other bindersNatural cements- high alumina cement or

Roman cement - Produced from clay

mineral rich septarian nodules

- Special applications- where high early strength

and/or fast setting are required.

- Cast - architectural detail

Mortar Identification• Cohesiveness• Colour• Porosity• Brittleness• Hardness• Condition• Aggregate %

• Several mortar generations may be in place.– Wrong mortar

repairs common in masonry structures.

TECHNOLOGY OF LIME PRODUCTION

Technical Advice Note no.1: Preparation and use of Lime Mortars’, Historic Scotland, Edinburgh, 1995.

Building Limes• Air lime Ca (OH)2

speed up carbonation - air entrainers.

• Hydraulic limesCa (OH)2 +aluminates+silicates

CO2

H2O

hardening

hardening

H2O

CO2

faster setting (earlier resistance to weather); insolubility; additional mechanical strength

Calcite -Ca CO3

Calcite

Hydraulic setHydraulic setCa silicates and aluminates

CarbonationCarbonation

CarbonationCarbonation

• NHL2/NHL3.5/NHL5• Strength

development of NHL mortars by lime strength class.

3:1 mix

Age (days)

stregth MPa

EN 459 parts 1, 2 and 3.CEN – European Committee for Standarisation.

Definitions, specifications.Testing. Conformity evaluation.

natural hydraulic limes (NHL)limes produced by burning of more or less argillaceous or siliceous

limestones with reduction to powder by slaking with or without grinding. All NHL have the property of setting and hardening under water. Atmospheric carbon dioxide contributes to the hardening process.

natural hydraulic limes with additional material (Z)Special products may contain added suitable pozzolanic or hydraulic

materials, up to 20 % by mass, are additionally designated by "Z"

hydraulic limes (HL)limes mainly consisting of calcium hydroxide, calcium silicates and

calcium aluminates produced by mixing of suitable materials. They have the property of setting and hardening under water. Atmospheric carbon dioxide contributes to the hardening process.

New standard for Building Lime 2009- approved 2010

• Air Lime, calcium lime- CL• Lime with Hydraulic Properties

– Natural Hydraulic Lime - NHL• No additions allowed• NHL – z class disappears• Introduction of NHL 1 class (grey limes)

– Formulated Lime -FL• Must declare cement, but Up to 10% of contents• can be undeclared.• Can contain cement, clinker, pozzolana,• blastfurnace slag, gypsum, silica fume, etc.• Designer products for specific applications

- Hydraulic Lime -HL• No need to declare contents• Could contain almost anything

EN 459-Part 1: Building lime —Definitions, specifications and conformity criteria

4 Types of building lime4.1 ClassificationAir limes shall be classified according to their (CaO + MgO) content and hydraulic limes according to their compressive strength given in Table 1 (see annex A).Table 1 – Types of building limesDesignation NotationCalcium lime 90 CL 90Calcium lime 80 CL 80Calcium lime 70 CL 70Dolomitic limes 85 DL 85Dolomitic limes 80 DL 80Hydraulic lime 2 HL 2Hydraulic lime 3,5 HL 3,5Hydraulic lime 5 HL 5Natural hydraulic lime 2 NHL 2Natural hydraulic lime 3,5 NHL 3,5Natural hydraulic lime 5 NHL 5In addition, air limes are classified according to their conditions of delivery, quicklime (Q) or hydrated lime (S).

Building Limes• Produced in various forms:

– Lime putties- slaked with an excess of water. CL80, CL90. Ca(OH)2

– Quicklime-powder, non slaked. (CaO) (CL80, CL90)

– Hydrated lime=slaked. dry powder (dry hydrate)- slaked with an estequiometric amount of water (NHLs and HLs).

EXAMPLE 1Calcium lime 90 in the form of quick lime is

identified byEN 459-1 CL 90-QEXAMPLE 2Calcium lime 80 in the form of hydrated lime

(slaked) is identified byEN 459-1 CL 80-SEXAMPLE 4Hydraulic lime 5 is identified byEN 459-1 HL 5

Table 3 – Compressive strength of hydraulic lime and natural

hydraulic lime4.4.1 Standard

strength requirements for hydraulic lime

The standard strengths of the types of hydraulic lime and natural hydraulic lime are the compressive strengths determined in accordance with EN 459-2:2001 after 28 days and shall have the values given in Table 3.

Compressive strength MPa

Type of building lime

7 days 28 days

HL 2 and NHL 2 - ≥ 2 to ≤7

HL 3,5 and NHL3,5 - ≥ 3.5 to ≤10

HL 5 and NHL 5 ≥2 ≥ 5 to ≤15*

* a HL 5 and NHL 5 with a bulk density lower than 0,90 kg/dm³ is allowed to have a strength up to 20 MPa.

CE marking• When a construction material complies with the

Construction Products Directive (89/106/EEC) (CPD) it is awarded the CE marking.

• The CE marking represents an added value for a product because:– it ensures high quality and compliance with legal

requirements, – It provides safety for the end users of the construction

sector and,• As a result, it is increasingly being requested by European

end-users. • To obtain the CE marking for construction products also

reports an economic benefit for the producer because it increases the market.

e.g. rendering mortars

Mortar Company BP 14 Servon 77253 - F04

EN 998-1OC - One coat rendering mortar • Reaction to fire: Euroclass A1• Adhesion: 0,3 N/mm² - FP: C( cohesion)• Water absorption: W2• Compressive strength: CS2• Water vapor diffusion : DV (based on TV)• Thermal conductivity : DV (based on TV)• Durability :based on adhesion and water permeability after cycling on substrates

e.g. bedding masonry mortars

01234

Mortar Company BP 14 Servon 77253 - F04

EN 998-2Thin layer mortar for bedding and pointing masonry • Reaction to fire: Euroclass (A1)• Adhesion: (DV)• Water absorption: W2• Compressive strength: M 10• Water vapor diffusion: =20 (based on density)• Thermal conductivity: DV (based on density)• Durability (after freeze-thaw): DV or NPD• Choride content : 0,07 %