The Mortar Batching Course For Brick & Block Laying 2001

1. The Mortar Batching Course For Brick &Block Laying 2001

2. CONTENTS • Introduction • Section 1 – Exposure Grades • Section 2 – Volume Batching • Section 3 – Mortar Testing • Section 4 – Materials In Mortar – AS 3700 • Section 5 – Water And Additives • Section 6 – Cement Chemistry • Section 7 – All about Bricks & Blocks • Section 8 – Brick ties

3. Introduction

4. Why was this course was created? On the 7th of December 1989 an earthquake of substantial measure devastated the city of Newcastle in NSW Australia. Many long-standing structures suffered severe damages along with buildings that were only a few years old. The fact that many buildings were builtrecently demanded a revision of the current Australian Standards for Brick & Block Mortar and for some detailed research into their intricate chemistry. This research was conducted at Newcastle University. At the time of the earthquake there were, and still are numerous publications available on the compositions of Concrete and Cement characteristics, however there was little available that was published on Brick & Block Mortars. Obviously there are now many fine publications available in the market place to accompany the current published Australian Standard AS3700. The problem is that most of the information in these texts is aimed at Engineers, Architects or Chemists. There has not been a document written to communicate to the individuals who mix the cement mortar on site, as to what to do and what not to do according to the Australian Standards and manufacturers recommendations. Therefore …….

5. Batcher’s Certificate Peter Smith : Name Completed: 27/10/00 This course aims to communicate the relevant information available in the previously mentioned publications and deliver them to you within the confines of a 3-hour session. You will take away this manual as an easy on site weatherproof reference book and leave this course with a certificate of completion. In a few days you will also receive a wallet size Mortar Batchers card with your photo id and a member number. Your details will also go onto a data base at the Masonry Contractors of NSW,so that Brick laying companies can contact you for your services and that the MCA can send you out any relevant changes to the Australian standards or industry news that relates directly to your job. So you can smile when we take your photo today, as this course will make you more employable than you already are!

6. Brick & Block Mortar Batchers Certificate Under the Guidelines of AS3700 Standards Australia Awarded to Fred Bloggs Signature – Date Garry Roberts – MCA President Certificate #: 001

7. Current Affairs and News programs from time to time like to run articles on “shoddy workmanship” in the building industry, they show a family or struggling couple who are unhappy with a particular builder and the builder is usually always named. The following videotape is one of these news stories. We will have a ten-minute open discussion at the end of it. Pay attention to the section showing the crumbling mortar at the bottom wall of the garage to the slab and see if you can pick the problem that the current affairs program doesn’t. Ten-Minute Open Forum Was there any other problems that the affairs program didn’t notice?

8. 1. Exposure Grades

9. Questions • What materials are regulated by exposure grade? • How do these exposure grades affect my work place? • Where is the most expensive real estate situated in Australia?

10. Mortar, Bricks, Blocks and Brick Ties are all manufactured to exposure grades. Companies such as Rocla, Austral,Bowal Bricks, Boral Clay Pavers,Boral Concrete Masonry, CSR PGH & ABEY Ties manufacture bricks,blocks and brick ties. The bricks, blocks and ties are all provided to your work site having been specified by the buildings designer based on the proximity of the building to a marine or exposed environment. The manufacturer of Mortar on site is… You!

11. M o r t a r C l a s s i f i c a t i o n s – A S 3 7 0 0 M 1 • Used only in restoration work to match existing construction. • Mild Environments. • Interior environments – Above dampcourse and enclosed within the building. • Above dampcourse in non-marine exterior environment with waterproof coating and • other building elements protecting masonry. • Below dampcourse and protected from water ingress by impermeable membrane. • Remote from the coastline. M 2 • Interior environments subject to non-saline wetting and drying. • Above and below the dampcourse in non-aggressive soils. • Marine environments.(100m to 1 km from a non surf coast and 1km to 10 km of a surf coast). • Freshwater environments. M 3 • Interior environments subject to saline wetting and drying. • Below dampcourse in aggressive soils. • In severe marine environments (up to 100 metres non-surf coast and up to 1 km surf coast. • Within 1 km of industry which produces chemical pollutants. • Especially aggressive environments, e.g.. Subject to attack by corrosive liquids and gases. M 4 Exposure Grading Awareness According to the Australian Standard AS3700 (Table 10.1) In June 1998 the following exposure grades were published in Standard AS3700. ( The easiest way to check your site for an exposure grade is with a street directory.)

12. The ABEY Tie company have provided the following graphic to give you an idea of how these exposure grades look in a more diagrammatic form. M4 M3 M2 M2

13. Mortar ExposureGrades

14. Brick Tie Exposure Grades AS3700

15. Brick & Block Exposure Grades Note : Concrete blocks will comply to exposure grade after they have coated with a suitable waterproof coating. Some non exposure grade bricks will also comply if treated with an impermeable surface coating.

16. And you have probably guessed the whole point already, the most expensive real estate in Australia is right on the coast line in the most severe marine environment that a structure can be exposed to! It is the affect of salt particles on mortar brick joints, bricks and ties that has the most detrimental result on these materials. Yet the question must be asked that if we chose just a 500 km section of the coastline say encompassing Newcastle, Sydney and Wollongong and visited every Surf Club and took note of how old there are? What they were built out of and where they are located we would discover that: (a) many have been built out of bricks and blocks (b) many structures are in excess of 30 years of age and (c) that a lot of these clubs are practically located on the sands of some beaches. So this throws up yet another lot of questions. Questions such as what has changed in the last 30 years that has made our end product today not as durable as work completed many years ago? Especially when we know technology has been working to improve Cements, Limes,Brick Ties, Bricks, Blocks and Sand. We will address some of the reasons and probabilities later on in the course.

17. 2. Volume Batching

18. Correct Volume Mixing By far one of the most contentious and debated issue of mixing mortar is correct volume mixing. The standard AS3700 advocates volume mixing by equal measuring buckets or box only. We all know that the most common use of mixing into an onsite barrel type portable mixer is by shovel. Shovel mixing is the easiest way to attain erratic volume levels and hence colour and strength variance in a mortar mix. If you are going to still mix with a shovel after today and this course has not convinced you to volume batch by bucket, then at least consider this advice. If you are using a standard 3.5 cubic foot mixer always make sure that you put at least the volume of 20 kgs of Cement into the mixer first! Ideally it should be a GP cement, you can still overdose the mix with sand but you have less chance if you place a half 40 kg bag or a full 20 kg bag of cement into the mixer first. Some mixes being tested in the market place are as high as 19 to 1 after testing. Many houses that should be lived in by now are having to be pulled down, rebuilt or repaired all because correct batching did not occur. Note: Shovel mixing is not the industry recommendation of best work-place practice.

19. The difference between weight and volume is what engineers and technical type people call the difference between “specific gravity” and “mass density”, but as we are not incredibly technical type people we will leave those terms alone. So here is a way of describing weight against volume batching. Fact - A bucket of completely dry sand weighs slightly more than a bucket of wet sand! Reason - There are no water particles in the bucket of dry sand so that there is extra room for more sand particles which are heavier than water particles. Scientists figure that why sand sits on the bottom of the ocean. We will get into moisture content in sand later on in water to cement ratio. Fact - A 25 kg bag of hydrated lime is larger in size than a 40 kg bag of cement. Reason - the particle size of the lime is larger than the particle size of the cement. Because of this, just with the sand and water the extra dimensions in the bag of lime are taken up with air particles, cement, has a denser smaller particle so there is less room for air a bag of cement.

20. More Questions What’s wrong with batching with a shovel? I’ve batched with shovels for years! The answer is on the following slide in 2,000 words!

21. 2 Pictures are worth 2,000 words Effects of bulking on shovels of cement (left) and sand (right) Note: Photos reproduced courtesy of the Clay Brick & Paver Institute publication “Construction Guidelines for Clay Masonry”

22. M3 + + = 6 1 1 Cement Sand Lime Mortar Remember volume mixing has nothing to do with weight Volumenot weights!  Let us go over old ground already and examine the required volume batches for the mortar grade M2, M3 and M4.

23. Which brings us to our next section.

24. 3. Testing Mortar

25. How is the mortar that I mix tested? The properties that mortars are tested for in in-situ masonry when required are: (i)             Tests for either Compressive (durability) or Flexural Strength (bond) (ii)             Tests for its Cement and Lime Content

26. The Bond Wrench Test The Bond wrench (or flexural strength) test is the primary testing apparatus for the testing of mortars. By testing bond strength, results can be measured on the probability of a structure moving from forces such as earthquakes. (Pass around bond wrench tester.) Diagram courtesy of Clay Brick & Paver Institute publication”Construction Guidelines for Clay Masonry”

27. The Stack Bond Beam Test The stack bond beam test is a compressive strength (or Mortar Durability) test. It is conducted by making a beam of bricks stuck together by perpendicular mortar joints. A force is the applied to the bricks until a the mortar joint breaks. The force of the break is then measured. The stack bond beam test is rarely carried out and therefore little information or visual images are available. It is the bond wrench test which has greater accuracy and measurability and is therefore become the primary measure of the industry. Also the bond wrench test can be carried out on completed work see below photo, where as the stack bond beam can only be done at the time of mortar mixing with a controlled sample. LOAD

28. Testing Mortar for Lime and Cement Content Testing of Mortar for Lime and Cement Content falls under the standard of AS2701 “Methods of testing Mortar for Masonry Construction”. The standard can only best be understood by laboratory chemists. Determination for Lime and cement content and consequently calcium oxide crystals is devised by a complicated process of breaking down the chemical content of the mortar by reacting the samples with various chemicals and solutions (e.g. hydrochloric acid) then drying them and reacting them with the mortar and weighing their remaining contents. The testing for these properties would take a lab technician the best part of an 8 hour shift to determine a cement and lime content. It should go without saying that if correct lime and cement contents are used from the beginning that there will never be a need for a mortar to be tested. Anything less than an 80% result of the prescriptive mortar is a fail!

29. The Difference between Concrete and Mortars for Bricks and Blocks Mortars and Concretes have basically the same primary ingredients cement ,water and aggregates. In the case of Concrete there are fine and course aggregates. Blue metal or stone is your coarse aggregate and concrete sand is your fine aggregates. There should also be a grading as fine aggregates within concrete sand but not as complex as the grading that we require for mortar which we will discuss in our sand topic in the materials section. The main difference between Mortar for Bricks and Blocks against a Concrete is that the mortar must form a solid rock like finish but also act as a GLUE between bricks and blocks. The amount that your mortar works like a glue is tested in the bond wrench test. The amount of mortar durability and how your finished mortar hardens like a concrete is judged under the mortars exposure grade.We will show the uses of lime in mortar later on in materials and chemistry. Cement experts have constantly agreed that wherever there is a strong bond between mortar and brick/block that there is a high presence of calcium hydroxide crystals. The greatest sources of calcium hydroxide is in GP Cement & Builders Lime. Quote: we cannot yet dismiss the possibility that calcium hydroxide crystals contribute to the strength of Portland Cement.(Chemistry of Cement & Concrete Frederick M Lea 3rd edition)

30. Time for a ten minute break

31. 4. Materials In Mortar – AS 3700 100

32. Materials Under AS3700 (10.4.2) 10.4.2.1 Cement and Building Lime Cement and Building Lime shall comply with the following Australian Standards: • Portland (Type GP) and Blended (Type GB) Cements…………………….….………………………………..AS3972 • Limes for Building……………………………………………….AS1672.1 • Masonry Cement…………………………………………………AS1316

33. What ever happened to Type “A”Cement? In 1991 standard terminology of cements were changed to reflect a more common usage in wider world markets. The old Type A,B,C ,D and so on standards were primarily based on the chemical constitution of the cement products. The new standards introduced in 1991 now require Cements used in Australia to be more performance based other thantheir individual chemical ingredients. So in answer to the above question ,what happened to Type A ? The following Table reveals the answer: Changes To Cement Types - 1991 Please Note: Type HE, LH and SR are classified as Special Purpose Cements under the Standard AS 3972 for cement. It should be noted that exposure grades in AS 3700 only deal with Type GP and GB Cements.

34. Packing, Marking & Delivery of Bagged Cement – AS 3972 Packing and delivery – Bagged cement shall be delivered in sound packages undamaged by moisture or other defects. Marking – Where the unit package size is less than 100 kg, each package shall be legibly marked with the following: • Name of manufacturer. • Type of cement. • Nominal proportion of slag, fly ash or silica fume in the case of blended cement. Occupational Health & Safety As this course is a mortar standards awareness course (not an OH&S course) the manufacturers of cements, sands, brick ties, bricks and blocks can all provide material safety data sheets on requests. All safety warnings on bags of cement, lime and sand should be observed

35. TypeofCement Setting Time (AS 2350.4) Soundness (AS 2350.5) SO3 content (AS 2350.2) Compressive strength (AS 2350.11) min. MPa at Peek Temperature Rise (AS 2350.7) Expansion (AS 2350.14) max. microstrain at Shrinkage (AS 2350.13) max. microstrain Properties and Characteristics for Portland and Blended CementsAS 3972 – 1997 Min. Minutes Max. H Max. Mm Max. % 3 days 7 days 28 days Max. ºC 16 weeks exposure 28 days GeneralPurpose Type GP Type GB 45 45 10 10 5 5 3.5 3.5 - - 25 15 40 40 - - - - - - SpecialPurpose Type HE Type LH Type SR¹ Type SR² 45 45 45 45 10 10 10 10 5 5 5 5 3.5 3.5 3.5 3.5 20 - - - 30 10 15 20 - 30 30 30 - 23 - - - - 900 - - - - 750 NOTES: • The use of Type SR cement may not ensure sulfate resistance in cement applications. In addition, other significant factors, including water content, compaction, and curing should be considered. • The use of Type SL cement may not ensure low drying shrinkage in cement applications. In addition, other significant factors, including aggregate type, water content, and admixtures, should be considered.

36. What are the Differences between a GP and a GB Cement? Table 10.1 of AS 3700 (which we have already seen twice) shows a difference in ratio of sand to cements, depending on whether you use a GP or a GB Cement. This section dealswith the difference in performance, character and propertiesof Type GP and Type GB Cements. Cementitious Materials,Minerals and Additions Portland Cement is the name of a process of manufacturing of cement. It’s invention dates back to it’s invention by a man named John Aspen in England in 1824. There have been many technological advances since it’s inception but the initial chemical reaction that was discovered in 1824 is still the same. John Aspen used materials to create a cement powder that when mixed with water looked similar to the colour of stone quarried in an area named Portland in England and so the name was born Portland Cement. !991 with an amendment to the standard the AS3700 The old Type A or as we now know it by General Purpose Cement was allowed the addition of no more than 5% of Mineral additions . These additions can be ground Limestone. Blast Furnace Slag, Fly Ash or Silica Fume.

37. Type GB or Builders Cements Blended Cements are generally sold in the marketplace as “Builder’s Cements or Blends. AS3972 Classifies cements which have a greater percentage than 5% of Flyash, Granulated Iron Blast furnace Slag or Silica Fume to be classified as Blended or Type GB Cements. Because Blended cements contain large amounts of unprocessed cementitious materials they are cheaper to manufacture and are usually sold at a cheaper price in the market-place. Fly ash is a fine powder many times finer than a Portland cement particle. It is a bi product of electric Power Stations powered by coal .Fly ash is mainly aluminosilicates with various other elements . Fly ash will absorb water. Fly ash shall comply with Australian Standard AS 3582.1 Ground Blast Furnace Slag is a bi product of the steel manufacturing industry. Slag is very angular In its particle shape. Slag is primarily a material containing silicates and aluminosilicates of calcium produced simultaneously with iron in a blast surface. Slag will not absorb water. Ground Furnace Blast Slag Shall comply with the Australian Standard AS 3582.2 Silica Fume is a bi product of silica alloy metal production and is very rarely if ever used in Brick and Block Laying Mortars. Silica fume is much finer than Fly ash. Silica fume is primarily Silica. Silica fume shall comply with the Australian Standard AS 3582.3 GB Cements, Builder’s cements or Blends have the characteristic of having slower initial setting times. This Makes blended cements attractive for use with the brick layer as he will not have to worry about his mud going hard on hot days and losing money through loss of wasted material. GB cements are usually sold in the market-place at a cheaper price than General Purpose Cements.

38. Lime • Basic Mortar Facts • Mortar consists of cement,lime and sand. • Mortar acts as the bonding agent between the masonry units as well as accommodating variations variations in their dimensions. The mortar must also have adequate workability during laying,and adequate strength and durability in service. 7 GOOD REASONS FOR USING LIME • Workability - imparts plasticity to mortar • Water Retention - stops early stiffening of mortar. • Bond Strength - lime mortar squeezes into irregularities in the brick face giving a close continuous bond. • Compressive Strength – Lime mortars gain strength in time. • Autogenous Healing – “re-knitting” of hairline cracks- recarbonating to plug openings. • Weather Resistance - Tight bonding of lime mortar resists wearing from wind and rain. • AS3700 requires Lime in most of it’s prescriptive mix designs. WARNING: POWDERED HYDRATED LIME IS VERY DANGEROUS KEEP AWAY FROM SKIN, EYES AND LUNGS

39. Sand AS3700 10.4.22 States that Sand shall be free from materials deleterious to the mortar and to embedded items and be chosen to produce mortar that meets the requirements of the Australian Standard AS3700 What the hell is a “ Deleterious Material?” The “Deleterious Materials that the standard refers to is primarily Clay & Silt. AS3700 has no recommendation on amount of clay and silt particles in sand. Amendments in the near future may specify levels. The general industry opinion currently is that anything above 10% will give you problems. Sands used in Australia are usually from either of following sources. Depositional Sands or Dune Sands. Depositional sands are generally found in the basins or valleys of mountainous regions they are sand particles that have their edges rounded off as they are washed down hill and mix with clay particles. Dunes sands are sands that have accumulated in large piles due to the oceans currents or have stockpiled in arid, desert like terrain. Dune sands also contain clays although generally not as much as a depositional sand and the two clays are usually very different in physical and chemical composition All mortar sands need fine particles along with large particles. The washing of sands to attain clean product also washes the fine particles out of the sand so it is necessary for some quarries to keep a percentage of clay within their sands so as to also keep in the fine sand particles. Clay Bricks are made of Clay, Concrete Blocks are made from 100% washed sand, it stands to reason that when laying each different material replicated sands should be used to make their mortar.

40. % passing 100 90 80 70 60 50 40 30 20 10 0 75um 150um 300um 600um 1.18mm 2.36mm 4.75mm A typical sand grading envelope for mortar (Information courtesy of the Clay Brick and Paver Institute)

41. A quick way to check your Sand for Clay Content on Site Get a jar or a bottle (preferably with parallel sides) fill it to about three quarters of the volume with the sand you are using. Then fill the rest of the jar up with water. Screw the lid back on the jar tight and shake the jar vigorously. Leave the jar to settle on a flat surface for about 45 minutes. This is known as a basic settlement test. The sand and Clay will separate. The sand being the larger denser particle will settle to the bottom. The clay being the lighter weight less denser particle will float for a longer period and eventually settle in a band of clay on the top. Measuring how much clay you have in relation to sand in the jar will give you a basic indication of the percentage of clay in the sand. If you want to accelerate the settlement of the sand you can add two teaspoons of salt to the water ,this will help settle the clay particles quicker. This is a guideline test only and can not be used as an accurate science. (Demonstrate coffee jar shake test.) (show prepared samples of kiln dried washed sand compared to on site bricklaying sand)

42. 20 cm 5 cm 20 15 10 5 S 0 28cm 18 cm 21.5 cm W 11.5 cm (Demonstrate water level in kin dried washed compared to on site undried sand for brick laying.) Diagram – Sand Moisture Tester

43. 5. Water And Additives

44. Water To Cement Ratios If you have volume mixing of lime and sand and cement figured out by now,welcome to the water section. Water to Cement ratio is by weight! We have already seen the requirements for water under the standard AS3700. The criteria is that if you can drink the water you can use it to mix with cement. Yet AS3700 although prescriptive on mix designs has no recommendation for water volume or content. There is a good reason for that so many variances. For example if this was a course on making good concrete we would be learning that in concrete you never exceed a .5 water cement ratio. A stronger concrete is attained with a ratio of .35. How this is worked out? One litre of water weighs 1 kilogram, therefore in concrete for every 10 kgs of cement you add no more than 5 litres of water. This would be a .5 water to cement ratio. For a .35 ratio you would add only 3.5 litres of water to every 10 kgs of cement. When mixing mortar however it is not unusual to double the water cement ratio. Being that for every 10 kgs of cement you could add 20 litres of water. So why is this so? In our section on bricks and blocks the brick manufacturers have supplied data on initial rates of absorption or suction. Concrete blocks and clay bricks can both absorb a lot of water depending on the materials they were made with and the heat of the day. A dry block with a high porosity can soak all the water out of a mortar and void the cement content in the mortar. It should be stated that your water should be measured up until you have the correct consistency of mud and then maintained with the same amounts providing the weather conditions remain constant.

45. Reasons for variations in water to cement ratio • On hot days water will evaporate from the mix • Warm Bricks and Blocks soak up more water than cold

46. 1.0 0.8 0.6 0.4 0.2 0.0 Water Releasers Bond Strength (MPa) 5% 10% 15% Fireclay Dose (by Volume) Typical effect on bond strength by using clay as a plasticiser

47. 1.0 0.8 0.6 Bond Strength (MPa) 0.4 0.2 0.0 Recommended by Manufacturer Overdosed 40 Times None Air Entrainers Air Entrainer Dose Typical effect of overdosing entrainer.

48. Fracture Surfaces of Mortars Augmented with AEA; • control (no AEA), • Recommended AEA dosage, • 10X overdosed and • 50X AEA overdosed. Secondary electron images, bar length = 100μm. A foamed structure as a result of the high levels of entrained air. Inspection of the above figure revealed that the entrained air bubbles effectively become hollow ‘aggregate-like’ particles within the cementitious fines. Therefore, the decrease in bond strength was due to the reduced capacity of the paste to form a continuous and coherent bond layer along the mortar/brick interface. This is in turn is likely to be due to the reduced flow of the paste as a result of the lower water/solids ratio and the consumption of the paste to form hollow ‘aggregate-like’ particles. note

49. 6. Basic Cement Chemistry 100

50. Basic Cement Chemistry One of the first things we learn in chemistry in school is that some substances are either acid or alkaline. We are trying to keep this course as untechnical as possible, so let us just remember that Portland Cement is an alkali with an alkalinity level of around 12.5. Cements in Australia Cements manufactured in Australia use limestone as their primary source of calcium. In other countries Limestone is also used yet some plants produce cement made from the crushing of sea shells. Cements in Australia are produced by either of two processes, Wet or Dry. We will not go into the details of the processes as Australian Standard AS 3792 guarantees their performance regardless of their process. It is important however to summarise what actually goes into cement so we can have a basic understanding of the chemistry of mortars. Portland Cement Summarised (the “untechnical explanation) Quarry Limestone rock, crush it burn it at high temperature in a kiln adding aluminium. This produces a Dark grey rock called clinker. Clinker is then stored for a few months before it is ground back into powder with the addition of Gypsum.It is gypsum that gives cement it’s guarantee of setting time.