Banfill, Phillip Frank Gower

Forster, Alan Mark

MacKenzie, Scott

Pinilla Sanz , Montserrat

Szadurski, Ewan Marek

Torney, Clare

English

Lime mortars are preferred for repair of historic masonry because their greater flexibility enables them to accommodate expansion and contraction in service without damaging the stone but there is little information on properties of mortars made with commercially available limes. Binder hydration rate and workability of mortars using Natural Hydraulic Limes of grades NHL2, NHL3.5 and NHL5 from four manufacturers is reported. Significant differences in the hydration rates between different limes offer the possibility of a better classification system. However, the variation in the workability between different products could pose challenges to users and specifiers of mortars for masonry repair

Heriot Watt Pure

1  34th Cement and Concrete Science Conference     Paper Number 224 14-17 September 2014      University of Sheffield  Natural hydraulic limes for masonry repair: hydration and workability P.F.G. Banfill, A.M. Forster, S. MacKenzie, M. Pinilla Sanz and E.M. Szadurski School of the Built Environment, Heriot-Watt University, Edinburgh  C. Torney Historic Scotland, Edinburgh  ABSTRACT  Lime mortars are preferred for repair of historic masonry because their greater flexibility enables them to accommodate expansion and contraction in service without damaging the stone but there is little information on properties of mortars made with commercially available limes. Binder hydration rate and workability of mortars using Natural Hydraulic Limes of grades NHL2, NHL3.5 and NHL5 from four manufacturers is reported. Significant differences in the hydration rates between different limes offer the possibility of a better classification system. However, the variation in the workability between different products could pose challenges to users and specifiers of mortars for masonry repair.     1.   INTRODUCTION  Lime binders have been used in masonry for centuries. The development of Portland cement in the 19th century, with its superior setting and strength gain, even under water, led to a severe decline in the use of lime. However, when the use of cement mortar for repair and repointing of stone masonry was found to cause severe damage and loss of historically-important fabric, interest in the use of lime binders in repair materials was rekindled. Lime mortars are more flexible and better able to accommodate expansion and contraction in the masonry, while the much harder cement mortars concentrate the stresses into the stone masonry units, which subsequently deteriorate. Additionally, lime binders are perceived as more environmentally friendly than cements [1,2].  Commercially available Natural Hydraulic Limes are classified according to their hydraulicity, conferred by the presence of C2S, and are assigned to grades NHL2, NHL3.5 and NHL5 according to their compressive strength in an arbitrarily defined standard laboratory mortar [3]. However, these grades do not necessarily align with performance in use and specifiers of limes for masonry repair are hindered by a lack of information on the mortars used in practice. The objective of this work, as part of a Knowledge Transfer Partnership between Heriot-Watt University and Historic Scotland, was to compare the properties of alternative natural hydraulic limes from four manufacturers, commercially available in the UK. This paper reports the rate of heat evolution in a conduction calorimeter and the workability of mortars made with two sands.  2. MATERIALS  NHL2, NHL3.5 and NHL5 lime binders were obtained from four UK suppliers – Hanson (www.hanson.com), originating from France, Otterbein (http://www.zkw-otterbein.de), Germany, St Astier (www.stastier.co.uk) France, and Singleton Birch (http://www.lime-mortars.co.uk) Portugal - and typical properties are shown in Table 1. These vary between suppliers but it can be seen that as the strength class increases the C2S content increases and the free Ca(OH)2 decreases. There is essentially no C3S and the aluminate content is around 1-2% in these products. Hanson do not supply an NHL5 lime, so the testing programme used 11 products.  Table 1. Range of properties of Natural Hydraulic Limes Binder NHL2 NHL3.5 NHL5 Bulk density kg/m3 500-600 600-700 700-800 % Free Ca(OH)2 50-60 25-30 20-25 % Unburnt CaCO3 10-15 20-25 20-25 % Insoluble residue 5-10 5-10 5-10 % C2S 15-20 30-40 40-50   Two mortar sands were used – Loanleven, Perthshire, a mainly quartzitic sand, and Cloddach, Morayshire, predominantly granitic. Figure 1 shows that Cloddach’s particle size distribution is slightly finer. Additionally, 2  Cloddach sand has a slightly lower bulk density and higher voids ratio than Loanleven sand.    Figure 1. Particle size distribution of the sands.  3. METHODS  Using the Wexham Developments (Reading, UK) JAF conduction calorimeter, 20g of each of the 11 NHLs was mixed with 14g of DI water by kneading in a sealed polythene bag which was placed carefully around the heat sensor. The calorimeter was sealed and held at constant temperature of 20°C in a water bath for 72 hours. Each experimental run was calibrated in accordance with the manufacturer’s instructions and the data processed using Excel®.  Due to time restrictions, mortars were prepared using only the NHL3.5 limes at a binder/sand ratio 1:2.5 by volume, calculated using the bulk densities of each material. Each mortar was prepared at several water/binder ratios, by successive addition of water to the parent mix, following a strict timetable to ensure comparability of the results. These repeated tests enabled a first assessment of the relationship between workability and water content for each binder to be made. The weighed amounts of lime and sand were placed in the bowl of a mixer complying with BS EN 196-1 and mixed dry by hand for 1 minute. Half of the water was added and mixed at low speed for 2 minutes, followed by the remainder and mixed for 7.5 minutes. When stationary, the bowl was then scraped to move any mortar adhering to the walls back into the body of the material, and mixing restarted for a further 7.5 minutes. The mortar was then tested and returned to the mixing bowl and more water added to achieve the new water content. This was repeated on a strict 20 minute time interval to give 4-5 results.  The workability of each mortar was determined with the Flow test according to BS EN 459-2 and the rheology measured in the Viskomat NT (Schleibinger, Germany) apparatus following the two-point principle [4,5]. The torque T exerted on a stationary paddle during rotation of a cylinder containing the mortar was measured as the speed of rotation N increased to 200 rev/min over 2 minutes and decreased to zero again over 2 minutes. Mortars conform to the Bingham model, with the intercept g corresponding to the yield stress and the slope of the line h corresponding to the plastic viscosity:  T = g + hN.  4. RESULTS AND DISCUSSION 4.1 Heat of hydration  The rate of heat evolution over 72 hours for each of the natural hydraulic limes is shown in Figure 2.      Figure 2. Rate of heat evolution of NHL2s (top), NHL3.5s (middle) and NHL5s (bottom).  All the curves showed relatively high initial values due to the heat of wetting and the initial dissolution of free lime, although the rate of heat evolution is much less than is observed in cement. After this the rate of heat evolution decreases over time but with thermal events which are more pronounced in the NHL3.5 and NHL5 binders. Otterbein 3.5 and 5 showed a peak at about 5 hours, while St Astier 5 peaked at about 8 hours and Singleton Birch 3.5 and 5 peaked at 20-25 hours. The absence of thermal peaks in the NHL2 binders but their presence in the NHL3.5 and 5 binders is consistent with the hydraulicity differences: there is insufficient hydraulic matter in the NHL2s to show any 3  detectable hydration in the conduction calorimeter. The time of the later thermal events is consistent with the slow reaction of dicalcium silicate.  The cumulative heat evolution over 72 hours is shown in Figure 3. The results are not consistent with the grades assigned by BS EN 459-1. The cumulative heat evolved from limes of the same grade covers a range from a 2.5-fold difference (NHL2) through 1.9-fold (NHL3.5) to 1.7-fold (NHL5). Singleton Birch NHL3.5 and 5 are significantly more reactive than the others of the same grade, due to the heat evolution at 20-25 hours. Finally, Otterbein’s cumulative heat evolved decreases from NHL2 to 3.5 to 5. but as expected from the heat evolution rate the cumulative trace rises rapidly at first and then more slowly.     Figure 3. Cumulative heat evolution of NHL2s (top), NHL3.5s (middle) and NHL5s (bottom).  4.2 Workability – flow test  Figure 4 shows the relationship between flow and water/binder ratio for NHL3.5 limes with the two sands. Whilst the measured flow increases with increasing water/binder ratio, there is a complex interaction between the effect of type of binder and type of sand on the water/binder ratio needed for a particular flow. Hanson and Singleton Birch require less water when used with Cloddach sand than with Loanleven, whereas Otterbein and St Astier require more water with Cloddach sand than with Loanleven. As noted above, Cloddach is slightly finer with a lower bulk density and higher voids ratio than Loanleven sand. Table 2 gives the measured bulk density of each of the NHL3.5 limes but the differences do not explain the differences in water/binder ratio.  Figure 4. Effect of water/binder ratio on flow (NHL3.5).  Table 2. Bulk density of NHL3.5 limes Lime Hanson Otterbein St Astier Singleton Birch Bulk density kg/m3 710 610 776 863  4.3 Rheology – two-point test  Figure 5 shows the general form of the flow curve of a lime mortar tested as described above in the Viskomat NT. The hysteresis loop between the up- and down-curves is due to the breakdown of structure formed by the flocculation of particles in water, and the parameters g and h, corresponding to yield stress and plastic viscosity respectively, are obtained by the best fit straight line through the points on the downcurve.                Figure 5. Flow curve for lime mortar in the VIskomat NT.  Figure 6 shows the relationship between yield stress, plastic viscosity and water/binder ratio for NHL3.5 limes with the two sands. In most cases the yield stress follows the expected Speed of rotation - rev/sec Torque - Nmm 0         1  2             3 100         0  Measured upcurve Measured downcurve Bingham line of best fit to downcurve: T=g+hN 4  decreasing trend with increasing water/binder ratio [5] but only two plastic viscosity results show this effect. In part this is because some of the stiffer mortars tended to stick around the impeller and slip against the wall of the container: this tends to make the value unreliable. The same complex interaction between the effect of type of binder and type of sand on the water/binder ratio needed for a particular yield stress is visible.    Figure 6. Effect of water/binder ratio on g (top) and h (bottom).  Figure 7 confirms the well-established relationship between yield stress and the single point tests like slump and flow which test the mortar at a low shear rate [5]. The negative correlation is significant but there is no correlation between plastic viscosity and flow.   Figure 7. Relationship between flow and g.   5. DISCUSSION  The rate of heat evolution of lime binders is considerably less than that of cements, for which the conduction calorimeter was designed, but differences between the limes are clearly visible. The total (cumulative) heat evolved over 72 hours hydration is at variance with the NHL classification assigned in the BS EN 459-1 hydraulicity test and this raises the important question of whether heat evolution would be a more discriminating test of hydraulicity.  Within an overall relationship with water/binder ratio, workability depends in a complex way on the physical properties of the binder and sand. This is particularly important because in practice mortars are proportioned by volume and the different bulk densities of the binder interacts with the voids ratio in the sand. Controlling workability by water content, as done in practice, may mean that specifying mortar by grade of binder may not achieve the expected properties: a binder of low bulk density may produce mortar of high water/binder ratio and poor strength and durability. Clearly data on mortars using NHL2 and 5 binders is needed to complete the story.  6. CONCLUSIONS  These preliminary results confirm that not all natural hydraulic limes show the same performance in mortar, even when they are graded the same by BS EN 459-1. This has significant implications for the use of lime mortar in practice.  REFERENCES  [1] Allen G, Allen J, Elton N, Farey M, Homes S, Livesey P, Radonjic M, 2003. Hydraulic lime mortar for stone, brick and block masonry. Shaftesbury: Donhead. [2] Holmes S, Wingate M, 2002. Building with lime. London: Intermediate Technology Publications. [3] British Standards Institution, 2011. BS EN 459-1:2010 Building lime. Definitions, specifications and conformity criteria. [4] Banfill PFG, 1994. Rheological methods for assessing the flow properties of mortar and related materials. Con. Build. Mat., 8(1), 43-50. [5] Banfill PFG, 2006. Rheology of fresh cement and concrete. Rheology Reviews, 61-130.  

Natural hydraulic limes for masonry repair: hydration and workability

    Heriot-Watt University Research Gateway                                                          Heriot-Watt UniversityNatural hydraulic limes for masonry repair: hydration and workabilityBanfill, Phillip Frank Gower; Forster, Alan Mark; MacKenzie, Scott; Pinilla Sanz , Montserrat;Szadurski, Ewan Marek; Torney, ClarePublication date:2014Link to publication in Heriot-Watt Research GatewayCitation for published version (APA):Banfill, P. F. G., Forster, A. M., MacKenzie, S., Pinilla Sanz , M., Szadurski, E. M., & Torney, C. (2014). Naturalhydraulic limes for masonry repair: hydration and workability. 451-454. Paper presented at 34th Annual Cementand Concrete Science Conference, Sheffield, United Kingdom.General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.1  34th Cement and Concrete Science Conference         Paper Number 224 14-17 September 2014           University of Sheffield  Natural hydraulic limes for masonry repair: hydration and workability P.F.G. Banfill, A.M. Forster, S. MacKenzie, M. Pinilla Sanz and E.M. Szadurski School of the Built Environment, Heriot-Watt University, Edinburgh  C. Torney Historic Scotland, Edinburgh  ABSTRACT  Lime mortars are preferred for repair of historic masonry because their greater flexibility enables them to accommodate expansion and contraction in service without damaging the stone but there is little information on properties of mortars made with commercially available limes. Binder hydration rate and workability of mortars using Natural Hydraulic Limes of grades NHL2, NHL3.5 and NHL5 from four manufacturers is reported. Significant differences in the hydration rates between different limes offer the  possibility  of  a  better  classification  system.  However,  the  variation  in  the  workability  between different products could pose challenges to users and specifiers of mortars for masonry repair.     1.   INTRODUCTION  Lime  binders  have  been  used  in  masonry  for centuries. The development of Portland cement in the 19th century, with its superior setting and strength gain, even under water, led to a severe decline in the use of lime. However, when the use of cement mortar for repair and repointing of  stone  masonry  was  found to cause severe damage and loss of historically-important fabric, interest  in  the  use  of  lime  binders  in  repair materials was rekindled. Lime mortars are more flexible  and  better  able  to  accommodate expansion and contraction in the masonry, while the  much  harder  cement  mortars  concentrate the  stresses  into  the  stone  masonry  units, which  subsequently  deteriorate.  Additionally, lime  binders  are  perceived  as  more environmentally friendly than cements [1,2].  Commercially available Natural Hydraulic Limes are  classified  according  to  their  hydraulicity, conferred  by  the  presence  of  C2S,  and  are assigned  to  grades  NHL2,  NHL3.5  and  NHL5 according  to  their  compressive  strength  in  an arbitrarily  defined  standard  laboratory  mortar [3]. However, these grades do not necessarily align with performance in use and specifiers of limes for masonry repair are hindered by a lack of information on the mortars used in practice. The  objective  of  this  work,  as  part  of  a Knowledge  Transfer  Partnership  between Heriot-Watt  University  and  Historic  Scotland, was  to  compare  the  properties  of  alternative natural hydraulic limes from four manufacturers, commercially  available  in  the  UK.  This  paper reports  the  rate  of  heat  evolution  in  a conduction  calorimeter  and  the  workability  of mortars made with two sands.  2. MATERIALS  NHL2,  NHL3.5  and  NHL5  lime  binders  were obtained  from  four  UK  suppliers  –  Hanson (www.hanson.com),  originating  from  France, Otterbein  (http://www.zkw-otterbein.de), Germany, St Astier (www.stastier.co.uk) France, and  Singleton  Birch  (http://www.lime-mortars.co.uk) Portugal - and typical properties are  shown  in  Table  1.  These  vary  between suppliers but it can be seen that as the strength class increases the C2S content increases and the  free  Ca(OH)2  decreases.  There  is essentially no C3S and the aluminate content is around 1-2% in these products. Hanson do not supply an NHL5 lime, so the testing programme used 11 products.  Table 1. Range of properties of Natural Hydraulic Limes Binder  NHL2  NHL3.5  NHL5 Bulk density kg/m3 500-600  600-700  700-800 % Free Ca(OH)2  50-60  25-30  20-25 % Unburnt CaCO3  10-15  20-25  20-25 % Insoluble residue 5-10  5-10  5-10 % C2S  15-20  30-40  40-50   Two  mortar  sands  were  used  –  Loanleven, Perthshire,  a  mainly  quartzitic  sand,  and Cloddach,  Morayshire,  predominantly  granitic. Figure  1  shows  that  Cloddach’s  particle  size distribution  is  slightly  finer.  Additionally, 2  Cloddach sand has a slightly lower bulk density and higher voids ratio than Loanleven sand.    Figure 1. Particle size distribution of the sands.  3. METHODS  Using  the  Wexham  Developments  (Reading, UK) JAF conduction calorimeter, 20g of each of the 11 NHLs was mixed with 14g of DI water by kneading in a sealed polythene bag which was placed  carefully  around  the  heat  sensor.  The calorimeter  was  sealed  and  held  at  constant temperature  of  20°C  in  a  water  bath  for  72 hours. Each experimental run was calibrated in accordance with the manufacturer’s instructions and the data processed using Excel®.  Due to time restrictions, mortars were prepared using  only  the  NHL3.5  limes at a binder/sand ratio 1:2.5 by volume, calculated using the bulk densities  of  each  material.  Each  mortar  was prepared  at  several  water/binder  ratios,  by successive addition of water to the parent mix, following  a  strict  timetable  to  ensure comparability  of  the  results.  These  repeated tests  enabled  a  first  assessment  of  the relationship  between  workability  and  water content  for  each  binder  to  be  made.  The weighed amounts of lime and sand were placed in the bowl of a mixer complying with BS EN 196-1 and mixed dry by hand for 1 minute. Half of the water was added and mixed at low speed for  2  minutes,  followed  by  the  remainder  and mixed  for  7.5  minutes.  When  stationary,  the bowl  was  then  scraped  to  move  any  mortar adhering to the walls back into the body of the material, and mixing restarted for a further 7.5 minutes.  The  mortar  was  then  tested  and returned  to  the  mixing  bowl  and  more  water added to achieve the new water content. This was repeated on a strict 20 minute time interval to give 4-5 results.  The workability of each mortar was determined with  the  Flow  test  according  to  BS  EN  459-2 and the rheology measured in the Viskomat NT (Schleibinger,  Germany)  apparatus  following the  two-point  principle  [4,5].  The  torque  T exerted on a stationary paddle during rotation of a cylinder containing the mortar was measured as  the  speed  of  rotation  N  increased  to  200 rev/min over 2 minutes and decreased to zero again over 2 minutes. Mortars conform to the Bingham  model,  with  the  intercept  g corresponding to the yield stress and the slope of  the  line  h  corresponding  to  the  plastic viscosity:  T = g + hN.  4. RESULTS AND DISCUSSION 4.1 Heat of hydration  The  rate  of  heat  evolution  over  72  hours  for each of the natural hydraulic limes is shown in Figure 2.      Figure 2. Rate of heat evolution of NHL2s (top), NHL3.5s (middle) and NHL5s (bottom).  All  the  curves  showed  relatively  high  initial values due to the heat of wetting and the initial dissolution  of  free  lime,  although  the  rate  of heat evolution is much less than is observed in cement.  After  this  the  rate  of  heat  evolution decreases  over  time  but  with  thermal  events which are more pronounced in the NHL3.5 and NHL5  binders.  Otterbein  3.5  and  5  showed  a peak at about 5 hours, while St Astier 5 peaked at about 8 hours and Singleton Birch 3.5 and 5 peaked at 20-25 hours. The absence of thermal peaks in the NHL2 binders but their presence in the NHL3.5 and 5 binders is consistent with the hydraulicity  differences:  there  is  insufficient hydraulic  matter  in  the  NHL2s  to  show  any 3  detectable  hydration  in  the  conduction calorimeter. The time of the later thermal events is consistent with the slow reaction of dicalcium silicate.  The cumulative heat evolution over 72 hours is shown  in  Figure  3.  The  results  are  not consistent with the grades assigned by BS EN 459-1. The cumulative heat evolved from limes of the same grade covers a range from a 2.5-fold  difference  (NHL2)  through  1.9-fold (NHL3.5)  to  1.7-fold  (NHL5).  Singleton  Birch NHL3.5  and  5  are  significantly  more  reactive than the others of the same grade, due to the heat  evolution  at  20-25  hours.  Finally, Otterbein’s cumulative heat evolved decreases from NHL2 to 3.5 to 5. but as expected from the heat  evolution  rate  the  cumulative  trace  rises rapidly at first and then more slowly.     Figure  3.  Cumulative  heat  evolution  of  NHL2s  (top), NHL3.5s (middle) and NHL5s (bottom).  4.2 Workability – flow test  Figure  4  shows  the  relationship  between  flow and water/binder ratio for NHL3.5 limes with the two sands. Whilst the measured flow increases with  increasing  water/binder  ratio,  there  is  a complex interaction between the effect of type of binder and type of sand on the water/binder ratio needed for a particular flow. Hanson and Singleton  Birch  require  less  water  when  used with  Cloddach  sand  than  with  Loanleven, whereas  Otterbein  and  St Astier  require  more water with Cloddach sand than with Loanleven. As noted above, Cloddach is slightly finer with a lower bulk density and higher voids ratio than Loanleven  sand.  Table  2  gives  the  measured bulk density of each of the NHL3.5 limes but the differences  do  not  explain  the  differences  in water/binder ratio.  Figure 4. Effect of water/binder ratio on flow (NHL3.5).  Table 2. Bulk density of NHL3.5 limes Lime  Hanson  Otterbein  St Astier Singleton Birch Bulk density kg/m3 710  610  776  863  4.3 Rheology – two-point test  Figure  5  shows  the  general  form  of  the  flow curve  of  a  lime  mortar  tested  as  described above in the Viskomat NT. The hysteresis loop between the up- and down-curves is due to the breakdown  of  structure  formed  by  the flocculation  of  particles  in  water,  and  the parameters  g  and  h,  corresponding  to  yield stress  and  plastic  viscosity  respectively,  are obtained by the best fit straight line through the points on the downcurve.                Figure 5. Flow curve for lime mortar in the VIskomat NT.  Figure 6 shows the relationship between yield stress,  plastic  viscosity  and  water/binder  ratio for NHL3.5 limes with the two sands. In most cases  the  yield  stress  follows  the  expected Speed of rotation - rev/sec Torque - Nmm 0          1    2              3 100         0   Measured upcurve Measured downcurve Bingham line of best fit to downcurve: T=g+hN 4  decreasing  trend  with  increasing  water/binder ratio  [5]  but  only  two  plastic  viscosity  results show this effect. In part this is because some of the  stiffer  mortars  tended  to  stick  around  the impeller  and  slip  against  the  wall  of  the container:  this  tends  to  make  the  value unreliable.  The  same  complex  interaction between the effect of type of binder and type of sand  on  the  water/binder  ratio  needed  for  a particular yield stress is visible.    Figure  6.  Effect  of  water/binder  ratio  on  g  (top)  and  h (bottom).  Figure  7  confirms  the  well-established relationship between yield stress and the single point  tests  like  slump  and flow which test the mortar  at  a  low  shear  rate  [5].  The  negative correlation  is  significant  but  there  is  no correlation between plastic viscosity and flow.   Figure 7. Relationship between flow and g.   5. DISCUSSION  The  rate  of  heat  evolution  of  lime  binders  is considerably  less  than  that  of  cements,  for which the conduction calorimeter was designed, but  differences  between  the  limes  are  clearly visible. The total (cumulative) heat evolved over 72 hours hydration is at variance with the NHL classification  assigned  in  the  BS  EN  459-1 hydraulicity  test  and  this  raises  the  important question of whether heat evolution would be a more discriminating test of hydraulicity.  Within an overall relationship with water/binder ratio, workability depends in a complex way on the physical properties of the binder and sand. This  is  particularly  important  because  in practice  mortars  are  proportioned  by  volume and  the  different  bulk  densities  of  the  binder interacts  with  the  voids  ratio  in  the  sand. Controlling  workability  by  water  content,  as done  in  practice,  may  mean  that  specifying mortar by grade of binder may not achieve the expected  properties:  a  binder  of  low  bulk density  may  produce  mortar  of  high water/binder  ratio  and  poor  strength  and durability. Clearly data on mortars using NHL2 and 5 binders is needed to complete the story.  6. CONCLUSIONS  These  preliminary  results  confirm  that  not  all natural  hydraulic  limes  show  the  same performance  in  mortar,  even  when  they  are graded  the  same  by  BS  EN  459-1.  This  has significant  implications  for  the  use  of  lime mortar in practice.  REFERENCES  [1] Allen G, Allen J, Elton N, Farey M, Homes S, Livesey  P,  Radonjic  M,  2003.  Hydraulic  lime mortar  for  stone,  brick  and  block  masonry. Shaftesbury: Donhead. [2] Holmes S, Wingate M, 2002. Building with lime.  London:  Intermediate  Technology Publications. [3]  British  Standards  Institution,  2011.  BS  EN 459-1:2010  Building  lime.  Definitions, specifications and conformity criteria. [4] Banfill PFG, 1994. Rheological methods for assessing  the  flow  properties  of  mortar  and related materials. Con. Build. Mat., 8(1), 43-50. [5] Banfill PFG, 2006. Rheology of fresh cement and concrete. Rheology Reviews, 61-130.  

Building with lime.

Hydraulic lime mortar for stone, brick and block masonry.

Rheological methods for assessing the flow properties of mortar and related materials.

Rheology of fresh cement and concrete. Rheology Reviews,

Natural hydraulic limes for masonry repair: hydration and workability

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