smeaton project

The Smeaton Project: Factors Affecting the

Properties of Lime-Based Mortars

JEANNE MARIE TEUTONICO, IAIN McCAIG, COLIN BURNS, JOHN ASHURST

The broad objective of the Smeaton Project is to contribute to the understanding of the characteristics and behavior of lime-based mortars for the repair and conservation of historic buildings. This article presents the first phase results of a joint research program of ICCROM, English Heritage, and Bournemouth University.

Preface

The first phase of the Smeaton Project was intended to be a range- finding exercise, which would 1) assist the project team in refining the methods used for preparation, cure, and testing of samples and 2) establish some trends so as to better define and limit future phases of the research. In general, these objec- tives were achieved.

However, the authors wish to emphasize the very preliminary nature of the findings reported in this paper. They are published primarily to promote dialogue and, perhaps, more widespread collaboration in the future. In no way should the results be considered definitive or conclusive.

The paper should, thus, be read as an exploratory exercise that will be used to focus and refine future work, rather than as a conclusive scientific study. In the first phase, insufficient samples were produced to statistical- ly validate trends. The consistency of results was also affected by both the method of preparation and cure of the samples. Problems with demoulding and cutting of the large samples used in Phase I, for example, meant that certain samples were not available for all test procedures. Based on this experience, both preparation and cure methods have been altered in Phase II, which is now underway.

Similarly, there is controversy about some of the test procedures utilized. In particular, the salt crystallization test that is still widely used to assess durability in the U.K. is no longer recognized by the Canadian Standards Association and is currently under review by ASTM.

There is much discussion regarding this test and freeze-thaw durability tests in general on a European and international level. Again, it was decided to utilize the salt crystallization test largely to assess its suitabil- ity and to establish some basis for comparison of samples. Modifica- tions have been made in the experimental design of Phases II and III based on this experience.

Finally, it was impossible, in this very preliminary stage of research, to consider all variables that might have affected the behavior of the mortars tested or to explain all mechanisms observed. This is the nature of scientific enquiry. It is hoped that some questions may be answered through more detailed laboratory studies later in the project as well as through comparison with long-term results observed on the exposure site and in field testing.

Introduction

Interest (or perhaps renewed interest) in the use of lime based materials -

mortars, grouts, plasters, renders and paints - for use in the repair and maintenance of historic buildings and monuments has been growing steadily in the international conservation community for the past 15 to 20 years. To a large extent, current practices have evolved through trial and error informed by only limited scientific and academic research. Although there is a significant body of experience in the use of lime-based materials in certain parts of the world, it is apparent that practice is not always matching theory and that there are still many partially un- solved problems. 32

THE SMEATON PROJECT 33

The characteristics of mortars may be defined in several ways. In practical terms, the ones that concern us most are:

1. Of the fresh mortar * workability * moisture content * rate of hardening

? shrinkage

2. Of the hardened mortar * appearance * moisture and air content * permeability * mechanical properties

including * adhesion * ability to tolerate

movement

? strength * durability (resistance to dam-

age by frost and salts)

These, together with the chemical properties of the mortar, must clearly be compatible with existing historic materials and appropriate to the context in which they are to be used.

The factors affecting the characteristics and behavior of lime mortars are derived not solely from the mortar constituents but also from the techniques used in processing the ingredients and in preparing and placing the mortars. The properties of materials in contact with the mortar and ambient environmental conditions at the time of placing and hardening of the mortar are also influential.

In summary, there are probably three categories of problems that need to be addressed. These are :

1. Mortar analysis and the components of historic mortars

2. Performance criteria and components of specification mortars

3. Mortar preparation and utilization

The Smeaton Project - a joint research program of ICCROM (the International Centre for the Study of the Preservation and the Restoration of Cultural Property), English Heritage (the Historic Buildings and Monuments Commission for England), and Bournemouth University - was set up in response to the need to address such issues in a systematic way through both laboratory and field research.

The broad objective of the Smeaton Project is to contribute to the understanding of the characteristics and behavior of lime-based mortars by attempting to identify - and where possible quantify - the material and practice parameters that affect their properties.

Specific emphasis has been placed in the first stage of the research on material and practice parameters that will improve the durability and frost-resistance of lime-based mortars in harsh climates. It is hoped that the research will ultimately lead to the production of practical guide- lines for specifying, preparing, and utilizing conservation mortars in a wide variety of regional conditions.

The name of the project refers to John Smeaton, a mathematical instrument maker and engineer, who in 1756, after experimenting with limes and additives for "water building" (mortar capable of hardening under water), decided to lay the courses of stone for the Eddystone lighthouse (20 miles off the coast of Devon, England) in a mixture of pozzolana from Italy and Lias lime from the southwest of England. His report on this work1 was the first of many studies preceding the current project that, in a sense, brought together England and Italy in seeking to identify and quantify pozzolanic additives for optimum performance.

BACKGROUND TO CURRENT PROJECT

The Smeaton Project grew out of experimental work begun by English Heritage in 1986 to identify suitable mortars for use in the conservation of Hadrian's Wall (Fig. 1) in the north of England. Sections of this Roman wall are on high ground and exposed to severe weather conditions.

In the recent past, relatively strong mortars gauged with portland cement had been used for pointing and repair. This mortar was itself sufficiently durable to withstand the extreme exposure to which the Roman wall is subjected but con- tributed to the deterioration of the wall in a number of ways that are typical where cement is used in contact with weaker and more porous materials.

These deleterious effects include:

1. Concentrating cycles of wetting and drying through the stone faces because water cannot escape through the relatively impervious pointing mortar

2. Trapping water, thereby caus- ing leaching of original core mortar and increasing the risk of frost damage

3. Increasing the likelihood of mechanical damage to stone on removal of high-strength mortar in the course of maintenance works

Recognition of these problems led to an attempt to exclude all cement in mortars used on the Roman wall. However, early trials with lime mortars were not completely successful because the mortars had inadequate frost resistance. While their behavior as a sacrificial material was techni- cally satisfactory, such mortars had to be replaced at a frequency that was not economically sustainable for English Heritage.

34 APT BULLETIN

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Mortar Trials at Hadrian's Wall

A testing program was thus initiated to develop more appropriate conservation mortars for the site.

As a first step, a number of joint- ing and core mortars were sampled from areas of the Roman wall known to contain original material. These were found to contain lime, crushed tile, crushed sandstone, sand, and kiln debris. The binder: aggregate ratio ranged from 1:1 to 1:3. Traces of animal fat, probably tallow, were also observed in some of the samples.

The next phase was a program of comparative durability tests on a range of 120 mortar mixes com- menced at Hadrian's Wall in 1986.

This exercise was designed primarily to observe the comparative performance of the binding materials in the mortars and was not intended at that stage to simulate site practice.

The trial mortars were grouped in three categories according to the type of the principal binder material:

Group A: non-hydraulic limes (both putty and dry hydrate)

Group B: hydraulic limes

Group C: portland cements

The mortars were mixed in varying proportions of binder: aggregate with and without pozzolanic and air- entraining additives. Principal pozzolanic additives were ordinary brick dust (essentially crushed facing brick

obtained from a local manufacturer) and HTI Powder (High-Temperature Insulant-refractory brick dust2), both crushed to pass a 300 micron sieve. The sand type and grading was consistent throughout the trial mixes and conformed to relevant British standards for building sands.

Two 150 mm and two 50 mm cubes were prepared of each sample in the spring of 1986. After an initial curing period of two weeks, the larger mortar cubes were placed on exposure racks (Fig. 2) in two loca- tions near the Roman wall. The two smaller sets of cubes were stored in a ventilated frost-free environment and were subjected to the British Research Establishment (BRE) salt crystallisation test3 in spring, 1987.


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The samples exposed on site were visually assessed for signs of break- down after each winter period, utilizing a simple A - E code to describe the degree of deterioration. The letter A described mortars which showed no deterioration; E indicated total disintegration. The letters B, C, D and various letter combinations were used to designate levels of deterioration in between these two extremes. In 1988 selected mortars were used in the consolidation of small trial sections of the wall. The purpose of these trials can be summarized as follows:

1. To evaluate the practical issues involved in the preparation of lime mortars both on site and at a remote depot

2. To evaluate such issues as workability and ease of handling in the use of lime mortars on site and to record any problems encountered

3. To provide realistic and varied test sites for the long-term moni- toring of performance of the trial mortars

A joint inspection of the exposed cubes and of the trial sections of wall in 1989 posed many questions but also indicated trends, some of them surprising given assumptions about lime mortars and some standard conservation practice at the time. Similar trends were observed in a report produced after a five-year exposure period,4 which compared field results to those observed in the laboratory tests. These trends include:

1. In the mortars based on non- hydraulic lime, the best performerss were the mixtures of lime:sand:brick dust in proportions 1:3:1 (Fig. 3, samples A2B, A2D).

In all cases, the standard brick dust performed significantly better and more consistently than the HTI Powder (refractory brick dust).

2. The worst performer was the mixture of lime and sand, to which a 1/10 part of white cement had been added (Fig. 3, Sample A3D).

In fact, all of the lime:cement mixtures performed poorly until at least 1/2 part of cement had been

added to the standard 1:3 mix. This trend was a bit disturbing,

given the widespread tendency in the UK to add small amounts of cement to lime mortars in conservation work. However, the observation did seem to be consistent with laboratory results that had been achieved in an earlier Swedish study published by Ingmar Holmstrom in 1977.6

3. In the mortars based on hydraulic lime, results were extremely inconsistent, depending very much on the type of hydraulic lime utilized in the mix (Fig. 4).

Those made with a buff hydraulic lime (Samples B1 A-D) performed reasonably well; those mixed with a white hydraulic lime (Samples B1 E- H) showed severe deterioration. In the case of the buff hydraulic lime, performance was markedly improved by the addition of one part standard brick dust (Samples B3 A-D). And again, the standard brick dust was more successful in improving the durability of these mortars than equivalent parts of the refractory brick dust (Samples B2 A-D).

Clearly, there was a need to try to

quantify some of these empirical observations and to determine the effect of various factors on performance. The overall framework of the Smeaton Project was, in fact, designed in response to the questions raised by that site inspection and the frustration inherent in trying to specify materials based on the observed results.

THE SMEATON PROJECT

The Smeaton Project is to be carried out in phases that will test a variety of material and practical parameters over a five-year period. A general outline and schedule for the project is given in Appendix A.

Scope of Work

Given the questions raised at Hadrian's Wall and in the subsequent

36 APT BULLETIN

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Mortar Reference Numbers

Group Al: based on lime: sand

Group A2: based on lime: sand plus brick dust or HTI powder

Group A3: based on lime: sand plus ordi-

nary portland cement or white cement

Group Bi: based on hydraulic lime: sand

Group B2: based on hydraulic lime: sand

plus HTI powder Group B3: based on hydraulic lime: sand

plus brick dust

Mortar Constituents AGG Aggregate (sand) PLQ Lime putty from Quicklime PLH Lime putty from Hydrated

Lime LH Hydrated Lime (powder) HL Hydrated hydraulic Lime

(buff) HLW Hydrated hydraulic Lime -

White OPC Ordinary Portland Cement WOPC White Portland Cement

HTI High Temperature Insulant

refractory brick dust BD Brick Dust

Exposure Sites on Hadrian's Wall Hexham Housesteads

Fig. 4. Results, Hadrian's Wall trials, hydraulic limes.


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literature search, it was decided to focus the initial phases of the research on the effects of set additives, specifically brick dust and cements, on the performance of lime:sand mortars.

The first phase, completed in August, 1992, had two main objec- tives:

1. To confirm trends observed in the field and in the literature regarding brick dusts and cements so as to develop parameters and limit variables in future phases

In terms of brick dusts, an attempt was made to understand the effects of such factors as optimum particle size, firing temperature, and proportion of dust in the mix.

In terms of cement, it was hoped to confirm the trends shown at Hadrian's Wall and in the Swedish experiments indicating that small additions of cement to lime:sand mortars actually reduce the performance of the mortar.

2. To develop appropriate methods for the preparation and testing of samples to obtain useful results regarding the established variables. Since most mortar test procedures have been developed for cement- based mortars, this was an important area of investigation

Phase I

Materials and preparation of samples. A series of 34 mortars were tested in Phase I (Appendix B). All were based on a coarse stuff of one part lime putty to three parts sand by volume, modified by the addition of brick dusts and/or cements.7 In general, the mix types fell into three categories:

Group A: based on lime:sand coarse stuff plus various amounts of four different brick dusts in particle sizes from 75 to 300 microns.

Group B: based on lime:sand coarse stuff plus varying amounts of

either white ordinary portland cement or sulphate resisting cement.

Group C: based on lime:sand coarse stuff plus brick dust and white ordinary portland cement.

All test mixes were prepared by English Heritage. Initially, lime putty, obtained by slaking lump lime, and sand were blended with excess water in a "Rollpanit" roller pan mixer. The resultant coarse stuff was then stored for a period of two months in humid conditions.

At the time of sample preparation, the seasoned coarse stuff was reworked using a small "Mixal" mixer and by hand. Brick dusts and cements were added in the form of a slurry at this stage.

Where necessary, further measured amounts of water were then added to the mixes before moulding to achieve a consistency suitable for bedding as judged by English Heritage master craftsmen.

The prepared mixes were then hand compacted into wooden moulds to create large rectangular mortar blocks (600 x 100 x 100 mm) (Fig. 5). These blocks were removed from their moulds after one week and then placed in an environ- mentally controlled room at 25" C and 90% RH for 120 days.

After this curing period, the blocks were cut to size for the various tests which were carried out by the Weathering Sciences Section of the Building Research Establishment under contract to English Heritage.

Test procedures. The following tests were performed:

1. On the fresh mortar:

Moisture content. Samples of each wet mix were placed in a small plastic bag and weighed. The sample bags were then slit open and placed in a drying oven at 60'C until constant mass was achieved. The differ- ence in weight was used to determine the moisture content of the mix, expressed as a percentage of the mass of the oven-dry sample.

Stiffening rate. This was determined at intervals of 15 minutes, two hours, five hours and 24 hours after placing using a Stanhope-Seta penetrometer (Fig. 6). The penetrometer measures in 0.1 mm units how far a weighted cone penetrates the mortar.

2. On the hardened mortar:

Compressive strength. Two 100 mm cubes were cut from each prism and tested on a standard 200 kN compressive test machine. Before testing, the samples were immersed

38 APT BULLETIN

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in water at 20?C for at least 24 hours. The load rate was 0.03 N/mm2/s.

Water vapor permeability. This was measured using a modified ver- sion of BS 3177:1959. Samples measuring 25 x 100 x 100 mm were

placed in aluminium trays containing approximately 70 grammes of calcium chloride. The edges of the samples were sealed to the sides of the tray with hot wax, leaving only the 100 mm2 face free to transfer water vapor. The samples in their trays were then weighed and placed in a relative humidity cabinet maintained at 75% RH. The increase in weight was measured and plotted against time until no further increase in weight was observed.

Depth of carbonation. This was established by spraying the freshly cut surface of the sample with phe- nolphthalein (a standard pH indica- tor). The sample turns purple when the alkalinity of the sample remains greater than pH 9 to 9.5 leaving the carbonated areas colorless.

Sodium sulphate crystallization test. This is the standard test used by the BRE to approximate freeze-thaw cycles and provide an indication of the durability of a stone or mortar. Four 50 mm mortar cubes of each sample were subjected to 15 cycles of:

1. soaking in a 21.5% sodium sulphate solution for two hours

2. drying in an oven for 16 to 20 hours at 105" C.

The weight loss after the 15 cycles was used to rank the different mortars. Fig. 7 shows the results of 15

cycles of the salt crystallization test on one of the samples.

In addition to these laboratory tests, 33 cubes were placed on a rack on the BRE exposure site. Before exposure, samples were dried in an oven at 600 C to constant weight and the physical dimensions measured. It is intended to measure and weigh the samples at intervals of six months (Fig. 8).

Discussion of results

Moisture content: Mortars had a relatively consistent water content, in a range from 15 to 19% (Table 1). Above all, this result is an indication that the skill of the craftsman is an important factor in any conservation operation.

There are no obvious trends, other than a general reduction in the amount of water added to the lime:sand:brick dust mixes as the brick dust size is reduced. This may be due to the fact that the larger brick dust particles tend to function as porous particulates (which absorb

Table 1. Moisture Content Sorted by increasing content

Sample Moisture Sample Moisture No. Content No. Content

a4/1 15.11 a17/1 17.02 a8/1 15.25 a9/1 17.07 bl/1 15.34 all/1 17.11 b5/1 15.62 a7/1 17.11 a6/1 15.74 c4/1 17.18 a10/1 16.21 a13/1 17.27 a14/1 16.22 a21/1 17.38 a3/1 16.47 b7/1 17.40 a18/1 16.55 b3/1 17.42 al5/1 16.61 a25/1 17.54 a16/1 16.72 a23/1 17.61 a5/1 16.74 b4/1 17.62 cl/1 16.74 a2/1 17.80 b2/1 16.81 a22/1 18.27 a24/1 16.81 al/1 18.42 c2/1 16.89 a19/1 18.84 a12/1 16.91 a20/1 19.30

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water in mixing), a factor which will be discussed further in this paper.

Stiffening rate. It is difficult to discern subtle trends regarding stiffening rate, due to the limited number of samples tested in this first phase

and the wide number of variables. However, certain general trends can be observed

Regarding the lime:sand:brick dust mortars, there were wide varia- tions in the depth of penetration of

the mortars after 15 minutes, probably due to the variation in water content and working.

The mortars made with one of the lower-fired brick dusts did tend to harden slightly more rapidly than the other lime:sand:brick dust mortars.

In all of these mortars, however, the shape of the curve is relatively similar and probably representative of the numerous factors which lead to stiffening in lime-based mortars (Fig. 9). Initially, the mortar simply tends to revert to the stiffness it pos- sessed before re-working on site. Subsequent stiffening is caused by loss of water and, eventually, by carbonation.

By comparison, all mortars from groups B and C (containing cement or cement and brick dust) hardened after two hours . It is interesting to note, however, that this initial speed in stiffening bore no relationship to the eventual strength and durability achieved after 120 days of cure.

Carbonation depth. This test was not expected to establish trends, but simply to provide some idea of the values which could be expected under

260 -

240 -

220 -

200 -

180 - 160- A 12 140 A- 11

D120 A7

E 100 C 80 A8

40 A 10 20 -

0.00 10.00 20.00 Hours

Table 2. Carbonation Depth Sorted on increasing depth Sample Carbonation Sample Carbonation No. Depth (mm) No. Depth (mm)

b7/1 0- 1 a15/1 10.0 b5/1 5.0 c2/1 11.0 a5/1 6.0 cl/1 11.0 b4/1 6.0 all/1 11.0 a7/1 7.0 a18/1 11.0 a8/1 7.0 a17/1 11.0 bl/1 7.0 b2/1 12.0 a10/1 8.0 c4/1 12.0 a9/1 8.0 a6/1 12.0 al/1 8.0 a16/1 13.0 a4/1 8.0 a20/1 10 - 17 a12/1 8- 12 a22/1 14.0 a24/1 10.0 a23/1 15.0 a3/1 10.0 a19/1 15.0 a2/1 10.0 b3/1 15.0 a13/1 10.0 a21/1 17.0 a14/1 10.0

Fig. 9. Stiffening rate curve: Samples A7-12.

40 APT BULLETIN

the established curing conditions. As seen in Table 2, carbonation depth varied from 0 to 17.00 mm.

Compressive strength. Here, the tests (Table 3) confirmed the trends seen at Hadrian's Wall and in the Swedish experiments reported on by I. Holmstrom in 1977.8

In general, the lime mortars containing a higher proportion of brick dust were stronger than those containing a lower proportion.

For three of the brick dusts, strength appears to increase with reduction in particle size. This trend is more apparent for the higher brick dust to coarse stuff ratio (Fig. 10: samples A6, A18, A24).

As seen at Hadrian's Wall, the compressive strengths of the mortars with small quantities of white ordinary portland cement or sulphate resisting cement (Fig. 10: samples B3, B4, B7) were generally lower than those of lime mortars with brick dust. This was the case until a ratio of 1:12 (cement:coarse stuff) or approximately 1/4:1:3 (cement:lime: sand) was reached.

The lime:cement:brick dust mortars (C group) were all stronger than the mortars of 1:12 cement:coarse stuff.

Water vapor permeability (WVP). As would have been expected, the WVP of the lime mortars with white ordinary portland cement or sulphate- resisting cement seem to decrease with increasing cement content.

The mortars with the highest white ordinary portland cement or sulphate-resisting cement content (samples B1 and B5) had lower WVP than all the lime mortars with brick dust additives (Table 4).

Among the lime:brick dust mortars, there is some indication that WVP decreases with increasing proportion of brick dust.

For three of the brick dusts, this trend seems to be more marked with decreasing particle size (Fig. 11). This may again be an indication that the larger-size brick dusts act more as porous particulates in the mix than as pozzolanic components, a factor which will be discussed later in this paper.

Sodium sulphate crystallization test. There is some indication that this test may be too aggressive to dis- cover very subtle differences between the durability of different mortar mixes. A large variation in weight loss made it difficult to identify trends conclusively in the lime:sand:

brick dust mortars (Appendix C). However, there does seem to be an indication that the lower-fired brick dusts (Samples A1-A12) performed better than those fired at higher tem- peratures. This corroborates information from a much earlier study on lime:pozzolan mortars carried out by the BRE in 1940.9

In general, though, this test again confirmed the trends seen at Hadrian's Wall regarding lime:sand mortars containing small additions of cement. All of the lime mortars with cement:coarse stuff ratios between 1:12 and 1:60 (1/4 to 1/20 part of cement in a 1:3 lime:sand mix) failed by the end of the 15th cycle (Table 5). The addition of brick dust to the lime mortar:cement mixture does not seem to have produced much improvement in the result of this test.

These results are most clear in the bar graph (Fig. 12) where it can be observed that:

1. All of the lime:sand:brick dust mortars (Group A) survived all cycles.

2. The B mortars containing small quantities of cement (B2, B3, B4, B7) all failed by the end of the 15th cycle.

3. The C mortars containing lime:sand:brick dust:cement also failed or suffered significant weight loss.

Conclusions: Phase I

The work carried out in Phase I of the Smeaton Project has allowed us to confirm various trends observed in the field and to refine the variables to be tested and the testing procedures for Phase II. In general, the preliminary conclusions can be summarized as follows:

i. ThTe addition of brick dust does significantly alter the properties of lime mortars. This is more pronounced in lime: sand: brick dust mixtures of at least 1:3:1.

9.00 -

8.00 -

7.00

S6.00o

Ss.00oo

4.00-

3.00

2.00

1.00

0.00

Sample No.

Fig. 10. Results: Compressive strength tests.


Table 3. Compressive Strength 100mm Cubes

Sorted on Descending Strength Sample Cube 1 Cube 2 Mean Sample Mean No. N/mm2 No. N/mm2

al/1 0.65 0.65 0.65 bl\1 8.10 a2/1 0.90 0.90 0.90 b5/1 8.08 a3/1 0.65 0.605 .65 c2/1 3.45 a4/1 1.85 1.85 1.85 cl/1 3.13 a5/1 0.90 0.90 0.90 a24/1 2.43 a6/1 2.40 2.10 2.25 c4/1 2.30 a7/1 0.95 0.90 0.93 a6/1 2.25 a8/1 1.50 1.40 1.45 a18/1 2.18 a9/1 0.95 0.75 0.85 a4/1 1.85 a10/1 1.35 1.50 1.43 a16/1 1.83 all/i 0.85 0.90 0.88 b2/1 1.73 a12/1 1.10 1.15 1.13 a14/1 1.60 a13/1 0.90 1.00 0.95 a8/1 1.45 a14/1 1.45 1.75 1.60 a10/1 1.43 al5/1 0.70 0.75 0.73 a17/1 1.13 a16/1 2.00 1.65 1.83 a12/1 1.13 a17/1 1.40 0.85 1.13 a22/1 1.00 a18/1 1.95 2.40 2.18 a13/1 0.95 a19/1 0.55 0.60 0.58 a7/1 0.93 a20/1 0.65 0.60 0.63 a23/1 0.90 a21/1 0.80 0.85 0.83 a2/1 0.90 a22/1 1.10 0.90 1.00 a5/1 0.90 a23/1 0.85 0.95 0.90 all/1 0.88 a24/1 2.10 2.75 2.43 a9/1 0.85 bl/1 8.25 7.95 8.10 a21/1 0.83 b2/1 1.75 1.70 1.73 al5/1 0.73 b3/1 0.45 0.45 0.45 a3/1 0.65 b4/1 0.30 0.30 0.30 al/1 0.65 b5/1 7.80 8.35 8.08 a20/1 0.63 b7/1 0.55 0.60 0.58 b7/1 0.58 cl/i 3.05 3.20 3.13 a19/1 0.58 c2/1 3.30 3.60 3.45 b3/1 0.45 c4/1 2.40 2.20 2.30 b4/1 0.30

1.0

0.9

- 0.8 \

0.7

0.6

300o 150s 751 Hastings

1.0

0.9

E 0.8-

0.7

0.6 .

300 150L 75p Waingroves

1.0

0.9

0.8

S0.7

0.6

3001 1501 75p Kirton

1.0

0.9

0.8

0.7

0.6 \

300L 150•

75cr HTI

Parts Coarse stuff: Brick Dust

S9:1

-.. ...4:1

Fig. 11. Results: Water vapor permeability plotted against type and proportion of brick dust.

2. Low-fired brick dusts seem to have the most positive effect on the strength and durability of lime:sand: brick dust mixtures. This trend is more pronounced if the brick dust is a more significant portion of the mix. At this point in the research, however, it is not possible to say whether this result is due strictly to firing temperature or is also related to clay type.

3. The addition of small quantities of cement to lime:sand mortars has a negative effect on the strength and durability of the mortars. In general, mortar mixes composed of

lime: sand: brick dust show better strength and durability than lime: sand:cement mortars until the amount of cement in the mix is equal to 1/2 the volume of lime (in a 1:3 lime:sand mix).

It seems from these results and from trends perceived by other researchers both in Europe1l and North Americall that the addition of brick dust to lime:sand mortars may improve their performance in two ways.

In the lower size particle range (< 75 microns or < 38 microns according to some researchers), the

42 APT BULLETIN

Table 4. Water Vapor Permeability Sorted by increasing permeability

Sample Water Vapor Sample Water Vapor No. Permeability No. Permeability

g/100mm2/day g/100mm2/day

b5/1 0.39 a3/1 0.71 bl/1 0.47 a5/1 0.71 a18/1 0.54 al/1 0.72 a6/1 0.57 c4/1 0.72 a24/1 0.59 all/1 0.74 a14/1 0.62 a7/1 0.74 a10/1 0.63 a22/1 0.77 c2/1 0.64 a2/1 0.78 a4/1 0.65 a13/1 0.80 a17/1 0.66 b7/1 0.80 a16/1 0.67 a21/1 0.82 a8/1 0.67 a19/1 0.87 a12/1 0.67 a15/1 0.90 cl/1 0.68 b3/1 0.93 b2/1 0.69 a20/1 0.96 a23/1 0.69 b4/1 0.98 a9/1 0.71

brick dust acts as pozzolan, which reacts with the lime to speed setting and create a higher strength hydraulic mortar.

In the higher particle size range (> 300 microns), the brick dust tends to act more as a porous particulate or air-entraining additive. The air content of the aggregate aids carbonation and improves resistance to frost and salt crystallization.

In the former case, it seems that a firing temperature below 950'C pro- duces the best quality brick dust for addition to lime mortars.

In the latter case, the porosity of the brick dust may be more significant than firing temperature.12

Phase II

These hypotheses are being tested in Phase II of the Smeaton Project in a limited series of mixes utilizing low- fired brick dusts with particles in the extremes of the particle size range. A non-pozzolanic porous particulate is also being tested to attempt to distin- guish between the two phenomena

which seem to have improved performance in Phase I.

Based on the experience of Phase I, the preparation of samples was altered to afford better control and to more closely simulate field practice. Specifically, groups of smaller moulds have been used to create the samples for each test to avoid the

problems and inconsistencies created by cutting large prisms in Phase I. Compaction has been more regular and more carefully controlled. In addition, certain tests have been performed on samples which were formed between pairs of saturated bricks.13

The tests for moisture content, stiffening rate, compressive strength and water vapor permeability all gave useful information and are being repeated in Phase II.

Additional tests have been made on the fresh mortar for consistency using a flow table and on the hardened mortar for porosity since recent research has indicated important cor- relations between porosity/porosime- try and the strength and durability of mortars.14

The salt crystallization test has been altered to be less aggressive, in an attempt to reveal more subtle differences between samples.15

Data has now been collected for most of the samples tested in Phase II. Complete test results are expected by July, 1994.

In all cases, laboratory results for durability will be correlated in the long term with results observed on samples placed on the exposure racks.

80.00

70.00

60.00

50.00

0

o of

S40o.oo00

• 30.00

20o.oo00-

10.00a-

0.00

Sample No

Fig. 12. Results: Salt crystallization tests.


Table 5. Salt Crystallization Test Sorted by increasing weight loss

Sample Mean Sample Mean No. % Weight Loss No. % Weight Loss b5/1 9.47 a22/1 33.21 bl/1 15.43 a12/1 33.38 a9/1 16.42 a16/1 34.14 a4/1 17.37 a14/1 34.80 a6/1 18.02 a23/1 35.28 a7/1 19.45 a19/1 37.22 a5/1 20.63 a21/1 39.80 a3/1 21.13 a20/1 41.85 al/1 23.32 a18/1 47.47 a10/1 23.47 c2/1 74.99 a2/1 25.29 b3/1 f9 all/1 26.21 c4/1 f12 a15/1 26.76 b7/1 f12 a24/1 29.32 b2/1 f13 a8/1 30.07 cl/1 f14 a13/1 30.69 b4/1 f15 a17/1 32.24

Future Phases

Future phases of the project will attempt to provide a more in-depth understanding and more conclusive statistical data regarding the material parameters which affect the behavior of pozzolanic additives in lime mortars, especially as regards particle size, mix ratio, and clay type (in the case of brick dusts).

The project will also begin to investigate hydraulic limes and to compare the behavior of hydraulic lime mortars with those previously studied. This is an important area of concern, especially in view of emerging standardization in the European marketplace. Trials will attempt to characterize and evaluate the performance of various hydraulic limes.

Of equal concern, however, are practice parameters, which are, perhaps, more difficult to quantify but of great importance in the performance of mortars.

Final phases of the project will attempt to quantify performance variables of fresh and hardened lime- based mortars in respect of issues such as:

1. Preparation of lime putty

Ways in which lime putty is prepared, such as

* lime putty from slaking * hydrated lime run to putty

by soaking

The effects of storage or "seasoning"

2. Blending and preparation of mortar

Form in which lime is used: * dry mixed hydrated

lime/sand * lime putty/sand * granular quicklime slaked

with sand

Method of blending binder and aggregates: * hand mixing * mechanical mixing/milling * minimum water vs. excess

water

Storage of mortar vs. immedi- ate use

Method of 'knocking up' or reworking: * hand processes (optimum

duration and technique)

* mechanical milling (optimum duration and roller/paddle settings)

Method and timing of introduction of additives

3. Utilization of mortar

Workability/consistency of the mortar when used

Compaction of mortar: * degree of compaction * influence of aggregate type/

shape * method and timing of com-

paction \(duration and limiting factors)

Finishing: * closed texture vs. open

texture.

4. Setting and hardening of mortar

Effects of low and high suction backgrounds (to what extent can effects be regulated by pre- treatment of surfaces or by mortar formulation) Environmental conditions: * effects of drying rates * methods of control

Other treatments: * periodic re-wetting (duration

and limiting factors) Since on-site correlation of labora-

tory work is essential, it is intended that the project will conclude with field testing of selected mortar mixes.

A number of sites will be chosen, representing different conservation problems, exposures and environmental conditions. Performance will be monitored at established intervals.

PRACTICE IMPLICATIONS

At this preliminary stage in the research, it is premature to make sweeping statements regarding the implications of the Smeaton Project Phase I results on field practice. Definitive conclusions can be drawn only after repeated tests on a greater

44 APT BULLETIN

number of samples and after field trials.

At this point, it is possible to provide only general indications based on observed trends in the hopes that more specific recommendations can be made in the future. These can be summarized as follows:

Cement-Gauging of Lime Mortars

Results indicate that the addition of small quantities of cement to lime:sand mortars has a negative effect on strength and durability.

In practice, this means that cement-gauged mortars with less cement than a 1:3:12 (cement:lime: sand) mix should be avoided. However, it must be remembered that though stronger mixes (such as 1:2:9 and 1:1:6) do improve durability, they may be unacceptable in terms of hardness, water vapor permeability, etc. Similarly, pure lime mortars may not have adequate durability in very harsh climates. As always, deci- sions must be made based on the nature and condition of the masonry and on the environmental conditions which it must withstand, as well as an informed understanding of the original material and technology.

Brick Dust Gauging of Lime Mortars

Results indicate that the addition of brick dust to lime:sand mortars does improve strength and durability, especially if the brick dust is a more significant component of the mix.

In terms of firing temperature, low-fired brick dusts (fired below 950oC) seem to have the most positive effect. These performed better and more consistently than HTI powder (refractory brick dust) in the trials. At this point in the research, however, it is not possible to say whether this result is due strictly to firing temperature or is also related to clay type.

As for particle size, both large and small particles seem to play a part in the improvement of strength and durability, though these mechanisms are not yet well understood.

It is, thus, difficult to be extremely precise regarding practice. If brick dust gauging is considered desirable to enhance the durability of a lime mortar, best results will probably be achieved with a low-fired brick dust in a range of particle sizes from 38- 600 microns. A mix ratio of 1:3:1 proved most successful in the trials, though this will obviously have implications in terms of mortar color and texture.

It is hoped that the results of Phase II may permit more specific recommendations regarding particle size, mix ratio, and clay type.

EUROPEAN AND INTERNATIONAL CONTEXT

Before concluding, it is of interest to place the Smeaton Project in the context of other European efforts to promote technical research on building limes, lime-based mortars, renders and plasters and the manufacturing, processing and construction crafts practices associated with them.

In this regard, it is probably most important to mention the "Euro- lime" project, a family of aligned and overlapping research programs under the umbrella of the EUREKA EURO- CARE research protocols. Countries involved to date include the United Kingdom, Germany, Sweden, and the Netherlands, with expertise also drawn from ICCROM.

Detailed information on EURO- CARE can be obtained from its sec-

retariat.16 Briefly, EUROCARE is the arm of the EUREKA system which deals with the conservation and maintenance of the built environment. "Eurolime" is one of the projects being developed under the EUROCARE umbrella.

Work being considered in this preliminary period of Eurolime develop-

ment includes:

1. Mapping national lime types in use in the building industry.

2. Cataloguing common national building practices with lime, in order to see how practice parameters may affect performance.

3. The effects of pozzolans (trass, pozzolana, pulverized fuel ash, brick dust, etc.) on the qualities of lime mortars.

Though the Smeaton project remains a tri-lateral collaboration between English Heritage, Bournemouth University and ICCROM, links have been established with Eurolime which may lead to future joint endeavors in areas of common concern.

Through ICCROM, it is also hoped to link the Smeaton research to non-European contexts and to diverse field situations. Such projects will allow us to test research results in the field and to broaden the research design to account for a variety of environmental conditions and local usage.

CONCLUSIONS

The repair of mortars, plasters and renders requires an understanding of the historical materials which are to be conserved and repaired, together with sufficient knowledge of the materials which are now available to prepare a sensible specification for such work. Good conservation practice dictates maximum compatibility and minimum intervention so that new material can co-exist with the old in a sympathetic, supportive and, if necessary, sacrificial capacity.

However, there are some important points to be remembered:

1. The materials in use today are not always the same as those used by the builders whose work is to be conserved and repaired - even if they are called by the same name.


2. Materials are not always being used in the same way. Although analysis can indicate the ingredients of a mortar, it does not tell how the mortar was made or used. In places where traditional skills have been lost, such practices must often be rediscovered through trial and error. Field experience suggests that the

techniques employed in the preparation and utilization of mortars may be of equal significance to their com- position in determining their performance. Thus, laboratory research which is not correlated with field experience is of limited usefulness.

3. The performance requirements of a repair mortar may be significantly different from those of the

original mortar. For example, the walls of a ruined building remain wetter and colder for longer than those of a roofed and occupied building. In such a situation, the repair mortar might well need to possess greater resistance to damage by frost and salts than the original.

The Smeaton Project is a collabo- rative international effort seeking to address some of these issues. The research team is an interdisciplinary one including scientists, architects, conservators and artisans, all of whom have a specific area of knowledge and expertise to contribute.

The program includes both laboratory and field research, in an effort both to develop practical solutions and to improve test methods.

It is hoped that the information gained through this research will provide a more informed basis for the selection, manufacture and utilization of suitable conservation mortars in a wide variety of regional conditions.

More generally, it is hoped that this endeavor will lead to construc- tive dialogue and, perhaps, to more widespread collaboration in the future.

JEANNE MARIE TEUTONICO is an architectural conservator who worked for ten years on the staff of the Architectural Conservation Program at ICCROM (The International Centre for the Study of the Preservation and the Restoration of Cultural Property) in Rome, Italy. She is currently in private practice in London, England, and con- sults for organizations including English Heritage, UNESCO, and the University of Pennsylvania. IAIN McCAIG trained in architecture and spent a formative period in the Greater London Council's Historic Buildings Division before joining English Heritage, where he has spent over ten years on technical advice, research and training in its Architectural Conservation Branch.

COLIN BURNS is a master mason and trainer at English Heritage's Building Conservation Training Centre at Fort Brockhurst, Gosport, in the United Kingdom and is a member of the organi- zation's Architectural Conservation Branch, Science and Conservation Services Division.

JOHN ASHURST is an architect who worked for more than 25 years for English Heritage and its predecessors on the care of ancient monuments in the United Kingdom. Co-author of English Heritage's Practical Building Conserva- tion series, he is currently Director of Historic Building and Site Services, a research and consultancy unit in the Department of Conservation Sciences at Bournemouth University.

Notes 1. J. Smeaton, A Narrative of the Building and a Description of the Construction of the Eddystone Lighthouse ... (London, 1791).

2. HTI powder came into widespread use in the United Kingdom in the early 1970s. It was originally used in limestone conservation, meeting the requirements for a low-sulphate reactive brick dust of appropriate color.

3. K. Ross, D. Hart and R. Butlin, "Durability Tests for Natural Building Stone" in Fifth International Conference on Durability of Building Materials and Components, Brighton, UK, 7-9 November 1990 , ed. by J.M. Baker, P.J.

Dixon, A.J. Majmundar and H. Davies (London: E. & EN. Spon, 1991), 97-111.

4. J. Ashurst, Hadrian's Wall Project 1985 - 1991 with Notes on Developments in Canada (Internal report, English Heritage, 1991). 5. "Best" performance was determined by evaluating both field trials and the results of the salt crystallization test. Though some of the mortars containing 1/2 part white or portland cement in a 1:3 mixture of lime:sand also performed well in the field trials (Samples A3C, A3F, A3K, A3N), they were less consistent in the laboratory tests.

6. I. Holmstrom, "Suitable Materials for Use in Repair of Historic Structures," presented at Conference on Structural Conservation of Historic Buildings, ICCROM, Rome, Italy, 13-19 September 1977, manuscript, ICCROM Library. 7. The materials used in the trials were the following: Lime putty: The raw material for this lime is a limestone from the Pennines in the northwest of England, which is 96.5% calcium carbonate. The lime putty was produced from lump lime slaked in excess water by Chards Ltd., Bristol. The putty as supplied was kept in sealed plastic containers for a further 6 months by English Heritage. Sand: Warmwell sand from Warmwell, Dorset, was obtained from the English Heritage depot at Lulworth Castle, Dorset.

Brick dusts: These were obtained from Butterley Brick Ltd., Kirton, Newark, Nottinghamshire. The three types provided were:

Works Firing Temp. Raw Material

Kirton 10000C Keuper Marl

Wain- 1050"C Middle Coal groves Measures Shale

Hastings 950'C Brick Earth

HTI powder: This was provided by Steetley Refractories Ltd., Dudley, West Midlands. Firing Temperature was between 1120 and 1350oC.

Cements: White Ordinary Portland Cement conforming to BS 12: 1971. Sulphate Resisting Cement conforming to BS 4027.

8. Holmstrom, "Suitable Materials."

9. F.M. Lea, Investigations on Pozzolana I, Pozzolana and Lime- Pozzolana Mixes, Building Research

46 APT BULLETIN

Technical Paper 27 (Garston: Building Research Station, Department of Scientific and Industrial Research, 1940).

10. T. Perander and T. Raman, Ancient and Modern Mortars in the Restoration of Historical Buildings, Research Note No. 450 (Espoo: Technical Research Centre of Finland, Concrete and Silicate Laboratory, May 1985).

11. G. Litvan and P.J. Sereda, Particulate Admixture for Enhanced Freeze-Thaw Resistance of Concrete (Ottawa: National Research Council of Canada, 1978).

G.G. Litvan, Further Study of Particulate Admixtures for Enhanced Freeze-Thaw Resistance of Concrete (Ottawa: National Research Council of Canada, 1985).

12. Litvan and Sereda, Particulate Admixture. Litvan, Further Study.

13. W.H. Harrison, "Durability Tests on Building Mortars, Effects of Sand Grading," Magazine of Concrete Research 38:135 (1986): 95-107.

W.H. Harrison and M.E. Gaze, "Lab- Scale Tests on Building Mortars for Durability and Related Properties," Masonry International 3:1 (1989): 35- 41.

14. G. Chiari, M.L. Santarelli and G. Torraca, "Caratterizzazione delle malte antiche mediante l'analisi di campioni non frazionati," Materiali e Strutture 2:1 (1992): 111-137.

15. A simple freeze-thaw test was also attempted in Phase II but proved too aggressive to yield useful results. A revised test design is currently under study for Phase III.

16. Further information on Eurocare can be obtained from Svein Haagenrud, c/o Norwegian Institute for Air Research, P.O. Box 64, N-2001, Lillestrom, Norway.

Selected Bibliography

Lime and Cement Technology Blanks, R.E, and Kennedy, H.L. The

Technology of Cement and Concrete. New York: John Wiley and Sons, 1955.

Boynton, R.D. Chemistry and Technology of Lime and Limestone. New York: Wiley Interscience, 1966.

Building Research Establishment. Bricks and Mortar. Overseas Building Note 173. Overseas Division, Building Research Establishment. London: HMSO, 1977.

Building Research Establishment. Building Mortar. BRE Digest 362. London: HMSO, 1991.

Davison, J.I. Quality Control in Preparing Masonry Mortar. Building Practice Note No. 5. Ottawa: National Research Council of Canada, Division of Building Research, 1977.

Lea, EM., and Desch, C.H. The Chemistry of Cement and Concrete. London: Edward Arnold Ltd., 1956.

Spalding, Frederick P. Hydraulic Cement: Its Properties, Testing, and Use. London: Chapman and Hall, 1898.

Wingate, M. Small-Scale Lime Burning. London: Intermediate Technology Publications, 1985.

Studies of Lime and Lime: Cement Mortars

Cowper, A.D. Lime and Lime Mortars. Building Research Special Report 9. London: HMSO, 1927.

Davison, J.I. Curing of Cement-Lime Mortars. Research Paper 430. Ottawa: National Research Council of Canada, Division of Building Research, 1970. Also ASTM Special Publication 472, 1970, 193-208.

Davison, J.I. Mortar Technology. Research Paper 692. Ottawa: National Research Council of Canada, Division of Building Research, 1976.

Davison, J.I. "Volume Change Due to Freezing in Plastic Masonry Mortar," Masonry: Materials, Properties, and Performance, ASTM STP 778, J.G. Borchelt, ed., American Society For Testing and Materials, 1982: 27-37.

Harrison, W.H. "Durability Tests on Building Mortars, Effect of Sand Grading," Magazine of Concrete Research 38:135 (1986): 95-107.

Harrison, W.H., and Gaze, M.E. "Lab- Scale Tests on Building Mortars for Durability and Related Properties," Masonry International 3:1 (1989): 35- 41.

Holmstrom, I. "Suitable Materials for Use in Repair of Historic Structures." presented at Conference on Structural Conservation of Historic Buildings, ICCROM, Rome, Italy, 13-19 September 1977, manuscript, ICCROM Library.

Hummel, A., and Wesche, A. Tests on Masonry Mortars. Technical Translation 887. Ottawa: National Research Council of Canada, 1960.

Jacob, J., and Weiss, N.R. "Laboratory Measurement of Water Vapor Transmission Rates of Masonry Mortars and Paints," Bulletin of the Association for Preservation Technology 21:3/4 (1989): 62-70.

Malinowski, R. "Ancient Mortars and Concretes, Durability Aspects," Mortars, Cements and Grouts Used in the Conservation of Historic Buildings, Rome, 3-6 November 1981, 341-349. Rome: ICCROM, 1982.

Perander, T. and Raman, T. Ancient and Modern Mortars in the Restoration of Historical Buildings. Research note 450. Espoo: Technical Research Centre of Finland, 1985.

Peroni, S.,and others. "Lime-based Mortars for the Repair of Ancient Masonry and Possible Substitutes," Mortars, Cements and Grouts Used in the Conservation of Historic Buildings, Rome, 3-6 November 1981, 63-99. Rome: ICCROM, 1982.

Ritchie, T. and Davison, J.I. "Moisture Content and Freeze-Thaw Cycles of Masonry Materials," Journal of Materials, 3:3 (1968): 658-671.

Ross, K., D. Hart and R. Butlin. "Durability Tests for Natural Building Stone." Fifth International Conference on Durability of Building Materials and Components, J.M. Baker, P.J. Nixon, A.J. Majmundar and H. Davies, eds., Brighton, 7-9 November, 1990, 97-111. London: E. & EN. Spon, 1991.

Rossi-Doria, P.R. "Mortars for Restoration: Basic Requirements and Quality Control," Materials and Structures 19:114, 445-448.

Van Jessen, C. "Lime, Lime Mortars and Lime Colours," Building Conservation 88 Symposium, 204-213. Helsinki: Finnish National Commission for UNESCO, 1989.


Pozzolans, Brick and Brick Dusts

Allen, W.J. "Locating Reactive Natural Pozzolana," Lime and Other Alternative Cements, N. Hill, S. Holmes and D. Mather, eds., 64-72. London: Intermediate Technology Publications, 1992.

Baradan, B. "Lime Stabilized Lignite Fly Ash." Lime and Other Alternative Cements, N. Hill, S. Holmes and D. Mather, eds., 210-217. London: Intermediate Technology Publications, 1992.

Lea, F.M. Investigations on Pozzolana. Building Research Technical Paper 27. Garston: Building Research Station, Department of Scientific and Industrial Research, 1940.

Lea, F.M. "The Testing of Pozzolanic Cements," Cement Technology (1973): 21-25.

Livingston, R.A. "Geochemical Methods Applied to the Reproduction of Handmolded Brick," Proceedings of the 8th International Brick/Block Masonry Conference, J. de Courcy, ed. New York: Elsevier, 1988.

Luxan, M.P., et. al. "Rapid Evaluation of Pozzolanic Activity of Natural Products by Conductivity Measurement," Cement and Concrete Research 19 (1989): 63-68.

Mielentz, R.C., L.P. Wittle and O.J. Glantz. "The Effect of Calcination on Natural Pozzolanas." American Society for Testing Materials SP-99, 1950.

Popovic, K., V. Ukraincik and A. Djurekovic. "Improvement of Mortar and Concrete Durability by the Use of Condensed Silica Fume," Durability of Building Materials 2 (1984): 171- 186.

Price, W.H. "Pozzolans - A Review," ACI Journal (May 1975): 225-232.

Smith, R.G. "Rice Husk Ash Cement," Lime and Other Alternative Cements, N. Hill, S. Holmes and D. Mather, eds., 89-105. London: Intermediate Technology Publications, 1992.

Surana, M.S. and Joshi, S.N. "Condumetric Technique for Estimating the Activity of Pozzolanic Materials," The Indian Concrete Journal (February 1990): 89-92.

Additives, Admixtures, Porous Particulates

Dolch, W.L. "Air Entraining Admixtures," Concrete Admixtures Handbook, V.S. Ramachandran, ed., 369-392. New Jersey: Noyes Publishers, 1984.

Litvan, G.G. Further Study of Particulate Admixtures for Enhanced Frost Resistance of Concrete. Ottawa: National Research Council of Canada, 1985.

Litvan, G. and Sereda, P.J. Particulate Admixture for Enhanced Concrete. Ottawa: National Research Council of Canada, 1978.

Santiago, C.C., and Mendonca de Oliveira, M. "Organic Additives in Brazilian Lime Mortars." Lime and Other Alternative Cements, N. Hill, S. Holmes and D. Mather, eds., 203- 210. London: Intermediate Technology Publications, 1992.

Sickels, L. B. "Organics Vs. Synthetics: Their Use as Additives in Mortars," Mortars, Cements and Grouts Used in the Conservation of Historic Buildings, Rome, 3-6 November 1981, 25-52. Rome: ICCROM, 1982.

Copyright, ICCROM, English Heritage and Bournemouth University.

Appendix A General Project Schedule

February 1990 - September 1990 * Literature search * Assembly of existing test standards * Assessment of field trials to date * Experimental design: Phase I

(Brick dusts and cements)

September 1990 - March 1991 * Acquisition of materials * Preparation of samples

March 1991- January 1992 * Curing of samples * Laboratory testing: Phase I, first

series

January 1992 - July 1992 * Curing of samples * Testing: Phase I, second series * Interpretation, write-up of results

August 1992 - December 1992 * Presentation results: Phase I * Experimental design: Phase II

(Porous particulates) * Preparation of Phase II samples:

Groups 1 and 2 * Curing of samples

1993 * Publication no. 1, Phase I * Preparation of Phase II samples:

Group 3 * Laboratory testing, Phase II

1994 * Laboratory testing, Phase II * Interpretation, write-up of results,

Phase II * Experimental design, Phase III * Preparation of samples, Phase III

1995 * Laboratory testing: Phase III * Evaluation of results to date * Publication no. 2

48 APT BULLETIN

Appendix B

Test Mixes

Group A Based on Coarse stuff (CS) of 1 part lime putty:3 parts sand and various types of brick dust (BD).

Sample Parts CS Parts BD Type Brick Dust

Firing Temperature Al 9 1 BD1 300p A2 4 1 BD1 300p A3 9 1 BD1 150p Hastings A4 4 1 BD1 150p (950oC) A5 9 1 BD1 75p A6 4 1 BD1 75p

A7 9 1 BD2 300p A8 4 1 BD2 300p A9 9 1 BD2 150p Kirton A10 4 1 BD2 150p (1000"C) All 9 1 BD2 75p A12 4 1 BD2 75p

A13 9 1 BD3 300p A14 4 1 BD3 300p A15 9 1 BD3 150p Waingroves A16 4 1 BD3 150p (1050C) A17 9 1 BD3 75p A18 4 1 BD3 75p

A19 9 1 BD4 300p A20 4 1 BD4 300p HTI A21 9 1 BD4 150p (1120- 1350"C) A22 4 1 BD4 150p A23 9 1 BD4 75p A24 4 1 BD4 75p A25 4

Group B Based on Coarse stuff (CS) of 1 part lime putty:3 parts sand with the addition of either white portland cement (WOPC) or sulphate-resisting cement (SRC).

Parts CS : Parts WOPC B1 6 1 B2 12 1 B3 30 1 B4 60 1

Parts CS Parts SRC B5 6 1 B7 30 1 B8 60 1

Group C Based on Coarse stuff (CS) of 1 part lime putty:3 parts sand with the addition of both white portland cement and brick dust.

Parts CS Parts BD Parts WOPC C1 9 4 BD1 150p 1 C2 9 4 BD2 150p 1 C4 9 4 BD4 150p 1


Appendix C Salt Crystallization Test

Sample % Weight Mean % Loss Weight Loss

al/la 15.94 al/lb 34.91 al/lc 15.97 23.32 al/ld 26.46

a2/la 28.01 a2/lb 22.08 a2/lc 31.08 25.29 a2/ld 19.97

a3/la 15.08 a3/lb 25.87 a3/lc 28.18 21.13 a3/ld 15.40

a4/la 16.31 a4/lb 24.80 a4/lc 18.18 17.37 a4/ld 10.18

a5/la 13.98 a5/lb 29.00 a5/lc 24.55 20.63 a5/ld 14.98

a6/la 25.48 a6/lb 23.77 a6/lc 9.34 18.02 a6/ld 13.49

a7/la 22.42 a7/lb 15.99 a7/lc 17.98 19.45 a7/ld 21.41

a8/la 23.50 a8/lb 27.58 a8/lc 28.49 30.07 a8/ld 40.70

a9/la 14.27 a9/lb 20.90 a9/lc 11.40 16.42 a9/ld 19.10

alO/la 24.20 alO/lb 21.51 alO/lc 28.62 23.47 alO/ld 19.57

all/la 15.60 all/lb 14.61 all/1c 32.97 26.21 all/ld 41.65

a12/1a 30.80 a12/1b 27.73 a12/lc 50.65 33.38 a12/1d 24.35


a13/1a 20.61 a13/1b 34.76 a13/lc 27.18 30.69 a13/1d 40.23

a14/1a 33.39 a14/1b 37.07 a14/lc 39.34 34.80 a14/1d 29.38

al5/1a 32.68 a15/1b 16.78 a15/lc 20.11 26.76 a15/1d 37.47

a16/1a 32.95 a16/1b 37.53 a16/lc 26.02 34.14 a16/1d 40.08

a17/1a 36.24 a17/1b 30.23 a17/lc 28.71 32.24 a17/1d 33.77

a18/1a 45.40 a18/1b 47.60 a18/lc 45.50 47.45 a18/1d 51.31

a19/1a 51.95 a19/1b 19.80 a19/lc 25.27 37.22 a19/1d 51.85

a20/la 50.53 a20/lb 32.41 a20/lc 54.89 41.85 a20/ld 29.59

a21/la 23.73 a21/lb 56.60 a21/lc 57.40 39.80 a21/ld 21.47

a22/1a 28.08 a22/lb 36.79 a22/lc 25.27 33.21 a22/ld 42.68

a23/la 23.56 a23/lb 49.31 a23/lc 41.09 35.28 a23/ld 27.15

a24/la 34.52 a24/lb 25.47 a24/lc 30.63 29.32 a24/1d 26.67


bl/la 24.70 bl/lb 13.13 bl/lc 10.45 15.43 bl/ld 13.45

b2/la 100.00 b2/1b 100.00 b2/lc 72.91 f13 b2/ld 100.00

b3/la 100.00 b3/lb 100.00 b3/lc 100.00 f9 b3/ld 100.00

b4/la 69.74 b4/lb 100.00 b4/lc 68.28 f15 b4/ld 100.00 b5/la 18.26 b5/lb 12.69 b5/lc 2.00 9.47 b5/ld 4.92 b7/la 61.29 b7/lb 100.00 b7/lc 100.00 f12 b7/ld 100.00

cl/la 100.00 cl/lb 100.00 cl/lc 100.00 f14 cl/ld 100.00

c2/la 100.00 c2/lb 55.71 c2/lc 74.60 74.99 c2/ld 69.63

c4/la 100.00 c4/lb 100.00 c4/lc 100.00 f12 c4/ld 100.00

smeaton project

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