Masonry mortar – building limes Dr. Sara Pavía Dept. of Civil, Structural and Environmental Engineering. Trinity College Dublin.

Mortar binders BinderHardening mechanism HydraulicityContraction coefficient Production temperature ClaydehydrationNil Mediumambient GypsumAddition of water (rapid hardening <15 minutes) Nil 175 C Lime (non- hydraulic) Chemical reaction: carbonation NilHigh 900 C Hydraulic limeChemical reaction: hydraulic set Low to highMedium- depends on hydraulicity C Portland Cement Chemical reaction: hydraulic set HighMedium 1500 C Natural cement hydraulic setHighMedium 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 EN Designation: NHL2/NHL3.5/NHL5. (according to reactivity determined by strength development over time: feebly, moderately, emminently). Calcination of limestones containing SiO 2, Al 2 O 3, 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 binders Natural 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 limes Ca (OH) 2 +aluminates+silicates CO 2 H2OH2O hardening H2OH2O CO 2 faster setting (earlier resistance to weather); insolubility; additional mechanical strength Calcite -Ca CO 3 Calcite Hydraulic set Ca silicates and aluminates Carbonation Carbonation

NHL2/NHL3.5/NHL5 Strength development of NHL mortars by lime strength class.

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 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 lime 4.1 Classification Air 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 limes Designation Notation Calcium lime 90 CL 90 Calcium lime 80 CL 80 Calcium lime 70 CL 70 Dolomitic limes 85 DL 85 Dolomitic limes 80 DL 80 Hydraulic lime 2 HL 2 Hydraulic lime 3,5 HL 3,5 Hydraulic lime 5 HL 5 Natural hydraulic lime 2 NHL 2 Natural hydraulic lime 3,5 NHL 3,5 Natural hydraulic lime 5 NHL 5 In 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 1 Calcium lime 90 in the form of quick lime is identified by EN CL 90-Q EXAMPLE 2 Calcium lime 80 in the form of hydrated lime (slaked) is identified by EN CL 80-S EXAMPLE 4 Hydraulic lime 5 is identified by EN HL 5

Table 3 – Compressive strength of hydraulic lime and natural hydraulic lime 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 days28 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 F 04 EN OC - 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 Mortar Company BP 14 Servon F 04 EN Thin 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 %