REPORT ON THE FUTURE OF

QUARRIED STONE

Anthony Cassar

Saviour Scerri

May 2004

REPORT ON THE FUTURE OF QUARRIED STONE. This report is being prepared to assist the Building Industry Consultative Council (BICC) within the Ministry for Resources and Infrastructure in the study of the effects the size of quarried stone in Malta has with respect to various implications and regulations. These include:- Local Health and Safety Regulations, Structural Load Bearing Implications Aesthetic Implications in relation to the size of stone, Economic and social implications deriving from the prospect of changing quarry practices. 1. INTRODUCTION It is said that Malta’s Heritage is built in stone. One resource found in abundance is stone and its use started thousands of years ago. In fact the oldest freestanding structures in the world are found in Malta. At Hagar Qim and Mnajdra there are single blocks of stone, which are over 5m in height. They are so big and heavy that we have no idea how they were transported and placed upright in position. However, it is noted that the Globigerina and Lower Coralline Limestone Formations at the localities where these temples are located are bedded; beds are of the order of 30cm to 80cm thick. Strata could have been easily detached in any desired length and width from exposures on account of the natural bedding planes. Rubble was used in building dry walls to form the numerous terraced fields. Stone was used to make artifacts. There are a number of dwellings dating back centuries where stone was used for all the elements in the structure. Walls, floors and ceilings are all in stone. To avoid transport, as with the temples, stone was cut in the area where the dwelling was to be constructed. The resulting hole produced by the cutting of dimensioned stone was roofed over, again in stone, to form a water reservoir. We therefore find that old buildings in southern Malta including the city of Valletta are in Lower Globigerina Limestone while churches, towers and old village cores in northern Malta are in Upper Coralline or Lower Coralline Limestone. Arches and barrel vaults where used to span large spaces, while a flat slab measuring a “qasba” (6ft 7 ½” or 2020mm) was used for shorter spans. Until a few years ago, the stone was quarried by hand and although machinery was later introduced, very little progress was registered in the way construction was carried out. Although the Maltese Islands are small and consist mainly of Malta and Gozo, different dimensions in the size of building stone are used. . The height of the normal stone in Malta is 260mm (10.25 inches) while that in Gozo is 280mm (11 inches).

2. GEOLOGY OF THE MALTESE ISLANDS. All rocks exposed over the Maltese Islands are of sedimentary origin and have been deposited under water. They consist of five different strata and the sequence is as shown below. Upper Coralline Limestone at top Greensand Blue Clay Globigerina Limestone Lower Coralline Limestone at bottom. Limestone quarrying is practically the only raw material industry in the Maltese Islands. It is the primary building material in construction and thus the extensive expansion of development in the last 30 years has seen an enormous increase in production to cater for this need. The strata predominantly used for the purpose are the Coralline Limestone formations and the Globigerina Limestone. The Attard Member of the Lower Coralline Limestone as well as a bed from the Mtarfa Member, the Tal-Pitkal and Gebel Imbark Members of the Upper Coralline Limestone are quarried for the extraction of aggregate, monumental stones and curbstones. Until a few years ago the Attard Member and the Xlendi Member were quarried commercially for the production of Maltese ‘Marble. Such activity is still going on though on a very small scale. ENTEC UK prepared a Minerals Subject Plan in collaboration with the Planning Authority. According to this study, the volume of permitted reserves at the current rate of production is 34 years for Globigerina Limestone and 38 years for the Coralline Limestone. 3. ENVIRONMENTAL CONSIDERATIONS Quarry Wall Stability The Maltese Islands are traversed by two main fault systems of different ages • NE-SW Faults that dissect the Maltese Islands into a system of horts and grabens • A younger system of faults oriented NW-SE is the Maghlaq Fault Associated with these master faults is a system of conjugate fractures in the form of joints, fissures and minor faults that dissect the local quarry sites at frequency that may range from as high as a fracture every three metres to widely spaced fractures say one every 30m. These fractures are inclined from about 60Degrees to 80Degrees and at times may give rise to rock wedges dipping perilously into the quarry. Such rock wedges may become unstable as the quarrying operations proceed and may result in sudden deadly rock slides. Furthermore it is noted that ramps are usually very narrow and no safety corridor is usually allowed between the excavation and adjacent roads or third party property.

It is therefore recommended that for safety reasons quarries should be surveyed for structural stability and mapping of joints fissures and faults to identify any joints of such dip and strike as to potentially render the walls of the excavation unstable. In addition consideration should be given to the width of the corridor between the walls of an excavation and third party property. 4. ENVIRONMENTAL IMPACT of HARDSTONE QUARRIES AND SOFT

STONE QUARRIES It is noted that in major developments and even in the construction of houses, reinforced concrete and hollow concrete blocks are becoming the predominant building material. This amount of concrete required results in an unbalanced use of aggregate with respect to ‘Franka’ stone. This is putting a considerable environmental strain on the environment where hardstone quarries are located. In Malta, hardstone quarries are located in geomorphologically sensitive regions such as the Rabat-Dingli Plateau - Ta’Zuta Quarries, or the hill slopes of the main valley systems - Wied Ghomor and Wied il-Ghasel, or close to the cliffs - Wied Moqbol, Wied il-Bassasa. The locality of Ta’Zuta is fast disappearing and the scar left in the plateau can be seen from Valletta. Dust Generation Dust in the form of limestone fines is associated with both quarrying activities. However, while ‘Franka’ stone quarries are usually located in low-lying regions where dust is mostly confined to the quarry, hardstone quarries are mostly located in exposed regions. For this reason the risk of wind blown dust being swept beyond the hardstone quarry precincts is much higher. To make matters worse crushing machines are usually perched high above the ground with the result that on windy days dust may spread as far away as a kilometer beyond the quarry precincts thus covering the countryside in a white patina. This is harmful as it destroys surrounding vegetation. For this reason it is imperative that crushing machines be protected from the wind and should be placed low in the shelter of the quarry. In addition the storage of mounds of sand out of the shelter of the quarry should not be permitted. Some time such stacks are left exposed for days or even months to the mercy of the winds, which in exposed regions is frequently strong enough to spread the sand around. 5. QUARRYING PRACTICES Coralline Limestone The Coralline limestones are relatively similar in form, the lower being generally less fissured, more compact and crystalline and thus more water-resistant than the upper one. Colour varies from white to grey and from yellow to red and is classified as first quality hardstone (gebel tal-qawwi) and second quality hardstone (tas-sekonda). Both qualities can sometimes be found in the same quarry, the second quality usually being above the first. Although the first quality hardstone is used in building, originally as foundations for important buildings and others facing the sea, its use is nowadays largely restricted to the production of aggregates in concrete. There still exists a small demand however for its use as paving stones, cladding etc. it being marketed under the name of Malta Marble. The second quality hardstone is burnt in kilns to produce lime.

More hardstone quarries are found along the southwest coast of Malta as well as around Mosta and Naxxar while in Gozo they are predominantly located on the southeastern coast in Qala and Nadur. Globigerina Limestone. The rock formation known as Globigerina Limestone formation is composed of three rock units known as Members: • Upper Globigerina Limestone Member (youngest)-Gebla tal-kwiener • Middle Globigerina Limestone Member –Kahla or Turbazz • Lower Globigerina Limestone Member (oldest) Franka and/or Soll The Lower Globigerina Limestone Member is extensively exposed in south and central Malta and is divided into two main units: • A top mostly pure limestone or Franka stone -10m to 35m thick • A lower clayey to marl bed locally known as ‘Soll’ of more or less the same

thickness as the overlying Franka The Franka bed of the Lower Globigerina is the most important building material in the Maltese Islands. Its lower strata known as ‘Franka’ or freestone is massive and very soft when freshly quarried and is easily cut into any shape by means of hand tools. It also possesses very good weathering properties due to the development of an outer patina for protection. However, its properties may be variable in which case the stone weathers quickly. Its most common use is for the construction of single or double skin walls in the form of blocks of various sizes but is sometimes cut in long roofing slabs (xorok), paving slabs (cangatura) or large moulding blocks (vazi). The underlying ‘soll’ bed is usually bedded. It is clayey or marly, grey yellow in colour with frequent rust discolorations. Intense burrowing is often characteristic. This bed unless fissured is impermeable and may retain rainwater which has to be pumped away during quarrying operations. Similar ‘soll’ beds normally a few courses thick are also found within the Franka bed but usually they are few in number. Presently most of the sixty or so quarries of this kind are found in the southern part of Malta namely Imqabba, Luqa, Qrendi, and Siggiewi regions although there was substantial quarrying activity around tal-Balal and Xwieki areas in Naxxar in the past. In Gozo, good limestone used to be quarried at tal-Bardan but today all the stone being extracted comes from the Kercem and San Lawrenz area. QUARRYING TECHNIQUES The techniques used for quarrying the two types of limestone in the building industry are different due to the native and intended use of the two materials. The Coralline limestones are harder and more compact than the soft Globigerina limestone and this has to be broken down into smaller more manageable boulders before being cut or ground whereas the ‘Franka’ is cut directly on site and immediately transported to the construction sites. For this reason both quarry types can be identified on visual inspection, the hardstone quarry faces being rough and irregular, uneven, and heavily fissured as opposed to the smooth wall-like characteristics of the free stone type.

Lower Coralline Limestone The sites chosen for quarrying Coralline limestone are ‘xaghri’ (barren land) and usually on sloping terrain. Here very little or no topsoil exists and sometimes clearance of a surface chalky material called ‘rina’ is removed before the actual quarrying commences. A panel of earth called ‘traversa’ is laid out in the bedrock and ‘furnelli’ or holes are drilled into the rock. They are filled with gunpowder and compacted to approximately half their height after which a blasting chord is placed. The remaining top half is filled with clay and again compacted. These ‘furnelli’ and smaller ‘maskli’ are placed in various distances away from each other and when blasted break the rock into smaller boulders of various sizes. They are then either crushed on site for aggregate or cut as blocks or slabs. If the hardstone is of the second quality they are taken to a kiln and burnt to produce lime. Globigerina Limestone In the case of the Globigerina limestone, preliminary operations consist of the removal of the topsoil, which is either put aside to be reused or carried away for relocation. The upper beds of broken rock which are weathered layers known as ‘Tisfija’ are removed by means of a mechanical shovel exposing the good stone, which is leveled. A vertical circular saw proceeds along metal rails to cut the surface at regular intervals in the longitudinal and transverse directions according to the length and width desired (photo No 1). The horizontal blade is then brought up to a free edge of the panel and cuts a horizontal groove just short of the vertical one (photo No 2). The stones are broken off, put up vertically standing on end, rolled away and prepared for transportation. The quarry always has a deeper end on one side to allow water to run off the working surface into a lower level when it rains. Layers of ‘soll’ or clay-impregnated stone may be encountered at various depths. This is poor quality stone and is removed so as to proceed to the next layer. The depth of quarries usually goes as far down as possible and only stops if the quality is found to be unsuitable for construction or else the level of the water table is met in which cases it is abandoned. Globigerina limestone used to be exported to Constantinople, the Black Sea, Egypt and Libya. The Royal Palace in Athens, the natural history museum in Tripoli and the Protestant Church in Naples have been built with this stone. Entec UK recommends that the stone should no longer be exported, although ones we are part of the EU, it may not be possible to stop its export. If stone is to be exported it should, if possible, be in the form of mouldings so that at least there would be an added value to it. Of course such stone would have to conform to EU standards. The deadline for the CE marking of building products in stone was March 2004. The CE mark comes together with a certificate of conformity covering the declaration of conformity by the manufacturer. Such a declaration presumes a series of tests carried out to ascertain petrographical, physical and application characteristics in addition to denomination and the use of standard technology.

6. SHORT HISTORY OF QUARRYING. Although Globigerina limestone is soft and easy to work, people involved in the construction trade have no easy job. The stone has first to be quarried, then placed vertically standing on a short face, rolled by hand to a storage place, loaded, transported to the construction site, unloaded and manually handled to be laid in place. Although great improvements were registered as equipment was introduced through the years, the sequence in the methods employed remained the same. As the quarry is made deeper, a ramp is formed so that loaded lorries could go up to road level. This ramp is usually very steep, sometimes unstable and accidents often happened. Cranes were sometimes used instead of ramps. Here the stone blocks are lifted from the quarry and placed on lorries at road level. The ramp was not required and this space was also quarried. Although the lorries were not required to go up such ramps, they were often overloaded with blocks posing danger just the same. Ramps were often preferred because lorries could be loaded quicker and the capital and running cost of the crane avoided. Machinery started being used in quarries in the early fifties. The first machine to be introduced was referred to as “Siscol” and worked with compressed air. It used to cut a 10-cm width trench about 1.2m deep. The diesel-operated generator was then introduced in 1956 and this “Siscol” was no longer used. Then came the conveyor belt and the machines that cut vertically and horizontally and which run on rails. The rails are moved manually and so the work became semi-mechanised. The blocks are loaded on lorries by means of a conveyor belt and when the conveyor is out of action, a tractor is used to load the blocks on the lorries. Five workmen are normally required to operate a quarry and these are usually members of the same family. Until a few years ago, they obtained their experience through practice, as there was no course that they could follow. One recurring problem is the change from imperial units to metric units and the accuracy used in measurement. Workmen in both quarries and most construction sites have not yet adapted to the metric system and still use feet and inches. Measurement is made by means of an angled ruler called “skwerra” and the smallest unit of measurement is half an inch or 12mm, so the best accuracy obtained cannot be better than 6mm. The blocks are supposed to have a height of 260mm (10.25 inches equivalent to a Maltese term ‘xiber’). The width of the longitudinal vertical cuts is made according to the width of stone block required and usually varies between 150mm (6”), 178mm (7”), or 230mm (9”) but this can be any width desired. Similar cuts are then made at right angles to these and their spacing would be equivalent to the length of the blocks which is usually 556mm (22”) but can be any length. A lot of dust (xahx) (about 6%) is generated when these cuts are made (photo No 3) and on windy days the workman operating this machine become covered in it. One can only imagine what these workmen look like if it then rains.

The way quarrying is carried out leads to great variations in the three dimensions of the blocks. The rails are usually poorly maintained and they are often out of alignment with the result that the blocks end up with non-square edges. The length of 556mm does not tally with that stipulated in Legal Notice 47. 1976 of 533.4mm (21”). The said Notice also states that the length of the blocks to be used in building cannot be larger than 508mm (20”). Even here the Notice is clearly implying that the work in both quarries and construction sites is measured in inches. The said Notice also makes allowance for damage sustained by the blocks and that the said blocks are cut to the correct size at the construction sites, adding further waste and dust. This stone dust is removed manually from over the underlying rock and gathered in heaps to be used in construction as part of the mortar. ‘Xahx’ contains a lot of fine particles and some may be smaller than 10µm which particles are called PM10. It has been found that such dust may give rise to respiratory problems. Horizontal cuts are made shorter than the width of the blocks so that the blocks do not fall down on the cutting saw. To be completely removed the block has to be stepped on or pushed down. All blocks end up with a small jagged lip (spika) about 25mm wide running the whole length of the block which is to be removed before the blocks are laid. The loose blocks are placed vertical resting on a short end ready to be loaded on lorries. This is done either by conveyor belts or by crane when the ramp is missing. When loading by conveyor, the blocks are rolled over and tightly packed on lorries. When fully loaded, ‘xahx’ is placed in a heap on top of the blocks and the truck is driven up the ramp to deliver the blocks and the ‘xahx’ to construction sites. The loads were not usually covered and dust used to blow all the way from the quarry to the construction site. Laws stating that transported material was to be covered were only introduced a few years ago. A machine now in use is a conveyor incorporating a planer (il-magna tal-ingara) to remove the ‘spika’ and smoothen the faces of the blocks as they are loaded on to lorries. This facilitates the work, produces better-finished blocks but again creates more dust and the dimensions are again reduced further. The system used in loading and transport leads to a lot of damage to the blocks. Those blocks used in facades are finished with exact square edges and a length that measures between 450mm and 485mm (18” and 19”) as even more damage is sustained when the blocks are tipped off from lorries onto the ground at construction sites. An attempt has been made to reduce this damage by transporting blocks on timber pellets. This did register an improvement but blocks continued to suffer damage as no packing is used between the blocks. Until the late forties, quarrying used to be done manually and used to employ a number of tradesmen. The top soil used to be removed with the help of mules and then the rock surface would be divided into blocks each measuring about 7 ‘qasab’ (14m) x 4 ‘qasab’ (8m) and the perimeter of each block was trenched using hand tools. The width of the trench was about 180mm at the top and narrowed as one went deeper. A hole was then cut at the centre of the block to the same depth as the trench. At the bottom of this hole, horizontal cuts were made along the whole perimeter and wedges were hammered inside these cuts until the block detached itself from the rock.

This block with the hole in the middle would then be cut into smaller blocks, again by means of wedges to the required sizes. The blocks used to be rough and had to be cut smoothly again with the use of hand tools. No lorries were available and the blocks used to be loaded on mule drawn carts up the ramp and transported to the construction site. To avoid the labour involved in cutting the blocks to smaller and more manageable sizes, the blocks were quite large and heavy. Although it was hard work, the workmen involved in carrying the blocks seemed to get used to it, although it is known that quite a number suffered back problems in later years. The work in the quarry is carried out in the open and being in a hole, the heat in summer becomes unbearable. Work often starts at sunrise and stops early in the afternoon. Workmen sweat and the stone dust clings to their skin. Things get worse on windy days as the dust blows in their eyes so they often cover their head and their mouth. When it rains, matters get even worse. The dust turns to mud and becomes slippery and dangerous. Lorries in the quarry sometimes get stranded, as it would be too dangerous for them to try going up the ramp. In such a case, gravel would have to be thrown along the whole length of the ramp to provide grip for the tyres. Globigerina is very porous and absorbs a lot of water, making the blocks much heavier to handle and carry. Although machinery has improved both output and conditions of work, working in a quarry is still considered hard work. In 1980, consultations were held with the government to improve the conditions of work of men working in quarries. Between 1969 and 1977 the number of hard and soft stone quarries went down from 85 to 70 and the number of full time workmen from 664 to 465. Inspite of this, and the fact that there was a building boom and great demand for properties, demand continued to be met as quarrying methods became partly mechanised. Improvements were not only made in machinery but also hauling. The first lorry to be used could only carry about 50 blocks (vjegg) and could not tip. So the blocks had to be unloaded by hand. Lorries in the 1980’s could carry 550 blocks or 11 ‘vjeggi’. 7. STONE BLOCK SIZES When the stone blocks started being cut by machine, the typical size was a thickness of 230mm (9”), height 260mm (10 1/4”) and length of 750mm (2’6”). These sizes seem to correspond to the size of one’s hand (xiber) while eight ‘xiber’ (2020mm) is the ‘qasba’ which is the length often used by tradesmen even though the official metric unit of measurement was introduced several years ago. It is most unfortunate that there are no standards in acceptable measurements and finish of stone blocks in both quarries and construction sites. This confusion of using three different systems should be stopped and tradesmen are to become familiar with the metric system. Some tradesmen, although very capable in their work are unable to read a scale, or use a measuring tape and hence continue to rely on the ‘skwerra’. The Egyptians, Greeks and Romans used large blocks in their constructions but as years went by and slavery became abolished the loads to be manually lifted became smaller and smaller. In more recent years laws were also locally introduced. For example, Section 98 of the Code of Police Laws, Act 55. 1975.3. states that “No person shall cut, or cause or allow to be cut, from any quarry any ‘franka’ stone of any dimension exceeding those, or any of those which the Minister responsible for

public works may from time to time establish. Provided that the said Minister may deem fit to impose, to cut ‘franka’ stone of different dimensions” One therefore had to write to the minister requesting permission to cut stone blocks to one’s required size which permit was usually granted. On May 1, 1976 a Building Stone order was introduced as Legal Notice 47. This legal notice specified the sizes of blocks that could be cut in quarries and those that could be used in construction. This stated the following:- • The thickness of any wall of any room exposed to the rain shall be 38cm (1’3”)

consisting of two faces of equal thickness of ‘franka’ stone, separated by a cavity as prescribed by law

• No person may use in the building of any wall any ‘franka’ stone the dimensions of which, or any dimensions of which, exceed the following: a) 50.80cm (20”) in length, 26.03cm (10 ¼”) in height and 15.24cm (6”) in

thickness in the case of stone used in Malta and b) 50.80cm (20”) in length, 27.94cm (11”) in height and 15.24cm (6”) in

thickness in the case of stone used in Gozo or Comino. • Franka stone cut from any quarry shall in no case exceed the dimensions or any

of the dimensions shown hereunder:- a) 53.34cm (21”) in length, 27.30cm (10 ¼”) in height and 16.51cm (6 ½”) in

thickness in the case of stone cut in Malta and b) 53.34cm (21”) in length, 29.21cm (11 1/2”) in height and 16.51cm (6 ½”) in

thickness in the case of stone cut in Gozo or Comino These changes were only introduced to reduce the handling weight of the blocks and although this was for the better, the arising disadvantages were overlooked. The main advantage in the reduction in length and thickness was the reduction in weight to be handled and the economic advantage that resulted to the owners of the quarries. As with every thing else, several disadvantages resulted as well. It was argued that the reduction in thickness from 230mm (9”) to 152.4mm (6”) reduced the bearing strength of walls by about a third and rooms of certain height had to be made with two skins for stability purposes. The practice of having one side of flight of stairs encased in walls and that of encasing electrical conduits and water pipes in walls rendered 6” walls weak. Party walls between properties had to be in 2 skins so that there would be enough support for the slabs and provision for sound insulation and privacy. It was found difficult to lay the thinner blocks than the thicker 230mm ones. Buildings ended up with more joints and as more blocks were used workmen had to go up ladders more often. For these reasons, these laws were only enforced for a short period and blocks 230mm wide continued to be cut. However, the length of 533.4mm continued to be observed. The quarry owner got more blocks but the workmen found that they had to bend lower in order to roll the blocks within the quarry or construction sites. (photo No 4) Other laws were published in the Gov. Gazette of 11 April 1980. The length of a truck load (vjegg) was reduced to15m from 30m and this in effect doubled the cost of stone. Most of the alleged disadvantages that resulted from the reduction in thickness and length of stone blocks as stipulated in LN 47. 1976 are mainly due to the quarrying and construction practices employed at the time and still employed without any improvement, at present. The art of construction is now being taught to tradesmen apprentices at the Malta College of Arts And Science (MCAST) and masons are also supposed to sit for an exam as directed by the Masons Licensing Board.(Code of

Police Laws Ch. 10 Part V). However, although it has always been a requisite that a stone mason had to have a license issued by this Board in order to be employed on construction works, such condition has never been enforced. Moreover the knowledge required for a person to qualify for such a license is no longer adequate for present standard expectations. 8. DIRECTIVES ON THE MANUAL HANDLING OF LOADS The purpose of Community Directive No 90/269/EEC is the prevention of musculo-skeletal disorders by regulating the manual handling of loads. It lays down three key stages in the prevention of risks related to the manual handling of loads:- • Avoidance of handling • Risk assessment where handling cannot be avoided • Where it cannot be avoided to be made as safe as possible. No specific regulations seem to exist in any of the Member States on the manual handling of loads and there does not seem to be any agreement as to what constitutes too heavy a load. However, there is an explicit obligation on the employer to carryout a risk assessment as a basis for preventive action of injury. The load limit that may be safely handled is not the only issue as there are other considerations that have to be taken. These relate to manipulation difficulties, over frequent handling and room and working environment available. The definition of what constitutes a heavy load is therefore very difficult to evaluate and hence varies significantly between countries as illustrated in the following table:- For men aged between 19 - 45 Country Repeated Handling (kg) Occassional Handling (kg) Portugal 20 30 Italy 30 30 France 55 105 Finland 20 ILO directive 1967 30 55 They are less for females and men outside the above age bracket. These can be used as reference values or limits above which handling may be prohibited. These values are therefore only indicative and all circumstances likely to influence the risk and handling must be taken into account. The ILO directive discriminates in recommending different weights that may be handled by gender and age. Research has shown that physical capacities differ more between individuals of either sex than between men and women taken as groups. It therefore seems more likely that if limits would be imposed, they would be defined (like other occupational health parameters) in a way that eliminates all forms of gender based discrimination. Moreover, within any limits recommended, there would be the obligation on the employer to adapt the work to the individual. This means that all factors, which may constitute a health risk, must be taken into account in the expected performance of any manual work.

The above seem to be more directed to handling operations within factories and although all manual handling of loads may give rise to injury, the risks associated with the manual handling of stones in the construction industry should be considered on its own. One fact is that no women are involved in such trade. There never have been and it is most unlikely that there would ever be. So what is being suggested is good prevention practice to reduce risk to human health and injury. The local Occupational Health and Safety Authority has published Legal Notice 379 of 2003 “Protection of Workers in the Mineral Extracting Industries through drilling and working in surface and underground mineral extracting industries.” This does not make any reference to manual handling of loads but stipulates that work involving a special risk should only be entrusted to competent workers and carried out under the instructions given by the employer. It also puts a duty on the employer to maintain the work environment in such a way that workers can perform the work assigned to them without endangering their health or the health and safety of other workers. RISKS FROM HANDLING HEAVY BUILDING BLOCKS. It is an established fact that handling of such blocks can give rise to serious injuries. Damage is usually gradual and progressive over a substantial period of time. The heavier the load, the higher the risk of injury. The main hazards are • Heavy loads and poor posture. Excessive stress may result on tendons and

muscles as handling involves bending, twisting and other difficult postures. • Slips, trips and falls usually caused by dropped blocks • Sharp edges leading to cuts and abrasions to the skin which can also result from

contact with cement mortar. The Construction Advisory Committee (UK) has concluded that there is a high risk of injury in the single-handed, repetitive manual handling of blocks heavier than 20kg. Where it is not practicable to avoid specifying blocks heavier than 20kg, provision should be made for mechanical handling or handling and laying by two people. It is emphasised that this is not the recommended solution as team lifting has inherent risks. Although most risks associated with handling blocks may be avoided or reduced by wearing protective equipment, the risk from lifting weights can only be reduced if manual handling is avoided or weights reduced to the absolute practicable minimum. The bottom line seems the Duty of Care that must be fulfilled by all the parties involved in construction to comply with Occupational Safety and Health Regulations. Although most of the responsibility rests with the employer, stonemasons and their assistants have a legal responsibility to ensure their own safety and health.

9. LOCAL CONSTRUCTION PRACTICES Although work in quarries has long been semi mechanised, the manual work involved is still strenuous and the quality standard of workmanship is far from satisfactory. Mechanised loading on to lorries that can carry a large number of blocks resulted in less manual handling and greater efficiency but no attention has ever been given to protect the blocks from damage while loading, transporting and delivery to construction sites. Once on site, blocks are often tipped down on the ground. (photo No 5) They are then lifted to higher levels by crane, Blocks are bundled together by metal chains and kept from sliding by friction (photo No 6).This method improved since blocks started being delivered on timber pellets. But again, very little progress has been achieved in construction. The mason still works on narrow timber planks that have no room where blocks can be lifted and placed by crane (photo No 7). Stones still continue to be manually handled and lifted up ladders, sometimes of dubious strength. (photos Nos. 8 and 9) Site linear measurements used are still the ‘qasba’ and areas in ‘qasab kwadri’ and ‘tumoli’. It is only in contract documents that the official metric units are used. Most contractors still prefer measured work to be in “qasab kwadri” rather than metric units. On construction works, most stone masons still use the right angled ruler “skwerra” for measurement purposes. This is still in imperial units mainly inches. Most stone masons have not yet become familiar with metric units or with the use of measuring tapes. Horizontal levels are kept by following a stretched string between two end blocks leveled by using a spirit level (photo No 10). The accuracy reached is questionable. Once a row of blocks is laid, overlying blocks are kept crudely plumb by using the same spirit level instead of a vertically aligned guide (photo No 11). Mortar used is usually very weak, and only used sparingly at the ends of individual blocks in horizontal layers (photo No 12). Vertical joints are, in most instances left without mortar (photo No 13). The resulting walls are very often out of plumb and there is practically no tying-in effect between the individual blocks. Stability results from the thickness of the blocks used and the number of crosswalls involved in most constructions. The carrying capacity of the stone is therefore very much underutilised. The blocks used in construction are either the hollow concrete blocks or the ‘franka’ stone. The hollow concrete blocks come in “standard” 450mm length and 255mm height. Again, widths, are referred to in imperial units - 4 1/2”, 6”, 7”, 9” single and 9” double blocks, these being measured as110mm, 145mm, 172mm and 220mm respectively. When measured in mm, the dimensions of the blocks do not correspond exactly with the imperial units to which they refer. It is very often that variations are noted in dimensions. Although the word standard is given, lengths of hollow concrete blocks varying between 450mm and 460mm have been measured and heights varying between 250 and 260mm have also been noted. Variations in “standard” lengths, heights and thickness of ‘franka’ stone are also often found..

The following table illustrates weights of concrete blocks and stone (dry and wet) in kilograms for the above dimensions. Hollow Concrete Blocks 450 mm x 250mm x thickness shown Weight(kg) 41/2” 14.5 6” 21.5 7” 28.0 9” single 32.0 9” double 38.5 Franka Stone 560mm long (22”), 260mm high and thickness shown-Weight (kg) Dry 6” 40.5 7” 47.5 9” 61.0 Saturated 6” 45.0 7” 53.0 9” 68.5 Weight of Franka stone if cut to the same dimensions as the hollow concrete blocks Franka Stone 450mm long, 250mm high and thickness shown Weight (kg) Dry 6” 29.8 7” 35.5 9” 45.3 Saturated 6” 33.5 7” 39.7 9” 50.7 It has been established that ‘franka’ stone is porous and absorbs a lot of moisture rendering the stone heavier by about 12%. It is also weaker in the wet state than in the dry state. When cut it is moist but not saturated and it makes sense if it is allowed to dry under cover within the quarry before it is delivered to construction sites. 10. RECOMMENDATIONS. The present ILO and the EU Directives do not make any legal obligation on any country to adopt any particular limit in handling weights manually. They express concern to the risks involved and several recommendations are made to reduce the risk of injury. Employers are to take all necessary precautions to make the work environment as safe as practically possible and to reduce the weights to be manually handled to the absolute minimum. Studies have shown that there is risk of injury when weights in excess of 20kg are repetitively handled. In taking everything into consideration, including the different dimensions between both the hollow concrete blocks and the ‘franka’ stone, the working tolerances accepted in quarrying activities and the construction practices followed, a number of improvements are recommended.

• It is of the utmost importance to instill a health and safety culture amongst the

workers especially those involved in stonework construction. • It is most important that all blocks used in construction have identical dimensions

of length and height. It makes more sense to reduce the length of the stone blocks to that of the hollow concrete blocks, that is 450mm. This would reduce the weight of stone blocks of 560mm by about 26.5%. This reduction to 450mm is to be compared with that of LN 47.1976 of 508mm. If all building blocks used in construction, whether in stone or hollow concrete blocks have the same dimensions it would be possible to pre plan buildings according to standard dimensions.

• Exact dimensions would eliminate the need for walls to be planed (invjati) in situ and the dust that results (photos 14 and 15).

• Works are presently carried out without specifications and variations in dimensions are made good by mortar.

• The way blocks are handled and transported leads to damage and waste. • Hollow concrete block factories have to exercise more caution to ensure that their

products conform to exact standard dimensions. • It is impossible to cut stone to exact dimensions when rails are manually set and

often poorly maintained and out of alignment. So rows of stone end up with different widths and distorted dimensions. At present this is overcome by a planing machine, which removes the saw marks and ‘spika’. More dust and waste is thus generated (photo No 3).

• It is important that equipment be properly maintained, that the blocks are carefully cut to exact standard dimensions, carefully handled and laid on timber pellets with packing between the blocks, to dry under cover. They should then be covered in plastic and transported to the construction site. Once on site the pellets should be lifted to the required height by crane and properly stored if they are not to be used immediately.

• Timber planks normally used do not allow for unloading blocks on to the scaffold. Tubular tower scaffolds should be used and blocks lifted by crane directly on to the scaffolds. (photo No 16). This would reduce manual handling considerably.

• There would not be need for further handling in cutting the stones before they are laid in place. Dust generation on site is also reduced.

• Internal walls within the same property need not be thicker than 150mm. The practice of encasing one side of stairs within walls can be eliminated with the use of reinforcement. The practice of chasing walls horizontally along joints in order to place water pipes and electrical conduits can also be changed. Such chasing should only be allowed vertically or not at all (figure 15). In this way no loss in strength of the wall results.

• The strength of such walls can be increased by the use of better quality mortar and better construction techniques. This would raise the normal permitted bearing capacity of 1N/mm2 appreciably. Even with 1N/mm2 a height of 3 floors of residential buildings is allowed on walls of 150mm thickness assuming slabs of 4m span resting on them.

• Proper house keeping should be exercised in both quarries and construction sites and finished work should be protected from damage.

• A new 8” (200mm) width of wall should be introduced. This would weigh about 41kg and corresponds quite close to the weight of a double 9” hollow block of 38.5kg. This could be used in boundary walls between properties and for mouldings.

• 9” (220mm) walls should only be used in mouldings.

• Lintols should be precast concrete, handled and placed in position by two

persons. 11. CONCLUSION

The EU does not set standards on stone but sets standards on methods of test, methods of declaration of performance values and methods of its conformity assessment. Stones have therefore to be CE certified. The EU has a law that is known as the Construction Product Directive. It has no rules on the size of stone but both the EU and the ILO have issued directives that should be followed as the size of stone may affect the health and safety of workers. The present weight of stone blocks is too heavy to be handled by a single person without risk of injury, which injury can be gradually occurring. This weight can be reduced by standardising the length of blocks used to match the same length of 450mm as that of hollow concrete blocks. A new thickness of wall (200mm) should also be introduced and this would have practically the same weight, when dry, as a 220mm (9”) double hollow concrete block of about 40kg. The thicker 220mm stone block should only be used for mouldings. The present mineral reserves, at the current rate of production, is 34 years for Globigerina Limestone and 38 years for Coralline Limestone. However, most large-scale projects and more new buildings are being built with concrete and hollow concrete blocks. Demand for concrete aggregate is increasing while that for ‘franka’ stone is diminishing. Less manual handling is involved in concrete construction and the weight of concrete blocks is less than that of stone blocks as used at present. Works are also carried out faster when in concrete and with hollow concrete blocks than with good quality stone. Quality construction in local stone requires more handling, more work and attention not to damage edges and blemish finished work. However the resulting negative impact of hardstone quarries is more pronounced than that of soft stone ones. This is mainly because of their location, stored aggregate and blown dust.

Work practices in quarries, haulage and construction sites are to be drastically improved. People working in such trades should be made more aware of proper health and safety practices that need to be followed. The EU has health and safety requirements for building sites and quarrying activities that should be followed. Limits in allowable variations in dimensions of both stone and hollow concrete blocks should be imposed and a more in depth study of ways to improve quarrying and constructions practices should also be carried out. At present, results are only dependent on speed in doing things rather than to achieve quality work and maximum strength and stability.

Appendix 1 Photo No.1 Quarrying Globigerina Limestone – Vertical saw machine running on

rails. Rails are manually set. Dimensional variations result. Photo No 2 Horizontal saw machine running on rails.

Conveyor belt used to load blocks on to lorries. Photo No 3 Dust generated by “conveyor – planing” machine Photo No 4 Poor back posture in rolling blocks within quarry and construction sites Photo No 5 Blocks tipped from lorry resulting in damaged blocks and wastage. Note poor housekeeping of site Photo No 6 Blocks lifted in groups – held by friction. Short block on the right is in danger of slipping. If it does all blocks would fall. Photo No 7 Blocks being cut on site – no protective wear used.

Wooden planks too narrow to allow blocks to be lifted and deposited by crane. No vertical guides used to ensure wall verticality.

Photo No 8 Blocks still manually lifted, carried on shoulders and up ladders in poor working environment. Photo No 9 Blocks carried on shoulder in limited working space. Photo No 10 Blocks being laid. Horizontality ensured only by spirit level. Photo No 11 Verticality measured by spirit level for each course. Photo No 12 Shows the little amount of mortar used in horizontal joints. No mortar

is used in vertical joints. Resulting wall stability doubtful. Photo No 13 Wall practically completed. Note absence of mortar in both horizontal

and vertical joints. Photo No14 Stone being cut on site. Workman covered in cloud of dust. Photo No 15 Working without any protective wear. Excessive dust generated may

lead to respiratory problems. Photo No 16 Proper tubular scaffolding. Blocks may be lifted by crane reducing

need for manual handling. (Scaffolding should have protective railings)

Photo No 17 Shows that it is possible to pass electrical conduits without chasing and

damaging wall. Photos have been kindly provided by Mr. Charles Sciberras A & CE.

Appendix II Local Legislation 1. Building Stone Order LN 47. 1976 2. Building Price Control Act Ch. 288. 1980 3. License to act as mason. Code of Police Laws Ch. 10 Part V References 1. Development Planning Act. Act 1. 1992 2. Fertile Soil Preservation Act – Act XX1X. 1973 3. Ministry of Social Policy (2002) Occupational Fatal 4. Occupational Health and Safety Authority Act – Act XXVIII. 2000 5. Occupational Health and Safety Authority Act –(CAP.424). L.N. 379. 2003 6. B.S.I (1976) Code of Practice for Stone Masonry BS 5390:1976 7. Community Directive 90/269/EEC. 1990 -Manual Handling of Loads 8. Health and safety executive, UK (2002) Construction Industry Advisory

Committee (CONIAC)– Information Sheet No 37 on Handling Heavy Building Blocks

9. ILO Directive 1967 10. Sciberras Charles (2002) Quality Management in Local Stonework Construction

BE & A Dissertation. Malta.