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109-488: The DMWD had been asked to come up with a device capable of penetrating the 10 ft (3.0 m) high, 7 ft (2.1 m) thick concrete defences that made up part of the Atlantic Wall . It was further specified that the device should be capable of being launched from landing craft since it was highly likely that the beaches in front of the defences would act as a killing ground for anyone attempting to deliver

218-412: A bitumen binder, which is frequently used for road surfaces , and polymer concretes that use polymers as a binder. Concrete is distinct from mortar . Whereas concrete is itself a building material, mortar is a bonding agent that typically holds bricks , tiles and other masonry units together. Grout is another material associated with concrete and cement. It does not contain coarse aggregates and

327-433: A French structural and civil engineer . Concrete components or structures are compressed by tendon cables during, or after, their fabrication in order to strengthen them against tensile forces developing when put in service. Freyssinet patented the technique on 2 October 1928. Concrete is an artificial composite material , comprising a matrix of cementitious binder (typically Portland cement paste or asphalt ) and

436-452: A cementitious material forms a cement paste by the process of hydration. The cement paste glues the aggregate together, fills voids within it, and makes it flow more freely. As stated by Abrams' law , a lower water-to-cement ratio yields a stronger, more durable concrete, whereas more water gives a freer-flowing concrete with a higher slump . The hydration of cement involves many concurrent reactions. The process involves polymerization ,

545-400: A concrete component—and become a part of the binder for the aggregate. Fly ash and slag can enhance some properties of concrete such as fresh properties and durability. Alternatively, other materials can also be used as a concrete binder: the most prevalent substitute is asphalt , which is used as the binder in asphalt concrete . Admixtures are added to modify the cure rate or properties of

654-598: A copy of the plan, declared it useless, and announced that he would rewrite it from scratch. The established deceivers were dubious about Strangeways's announcement and assumed that he would resubmit the existing plan with some modifications. However, he duly submitted a rewritten operation that was met, in Harmer's words, with "astonishment". Strangeways's revised Fortitude plan and an operational implementation, dubbed Quicksilver, invented an entire new field army but crucially without significant fictional forces. The skeleton of

763-517: A decrypted transmission by Hiroshi Ōshima , the Japanese ambassador, to his government recounted a recent conversation with Hitler and confirmed the effectiveness of Fortitude. When asked for Hitler's thoughts on the Allied battle plan, he had said, "I think that diversionary actions will take place in a number of places – against Norway, Denmark, the southern part of western France, and

872-434: A dispersed phase or "filler" of aggregate (typically a rocky material, loose stones, and sand). The binder "glues" the filler together to form a synthetic conglomerate . Many types of concrete are available, determined by the formulations of binders and the types of aggregate used to suit the application of the engineered material. These variables determine strength and density, as well as chemical and thermal resistance of

981-545: A distraction from the later main invasion. Pas-de-Calais offered a number of advantages over the real invasion site, such as by being the shortest crossing of the English Channel and the quickest route into Germany. As a result, Erwin Rommel had taken steps to fortify that area of coastline heavily. Strangeways felt that would help the deception seem realistic in the minds of German high command. A deception of such

1090-521: A focus on creating a more realistic threat. Both Fortitude plans involved the creation of phantom field armies (based in Edinburgh and southern England), which threatened Norway ( Fortitude North ) and Pas de Calais ( Fortitude South ). The operation was intended to divert Axis attention away from Normandy and, after the invasion on 6 June 1944, to delay reinforcement by convincing the Germans that

1199-452: A greater degree of fracture resistance even in seismically active environments. Roman concrete is significantly more resistant to erosion by seawater than modern concrete; it used pyroclastic materials which react with seawater to form Al- tobermorite crystals over time. The use of hot mixing and the presence of lime clasts are thought to give the concrete a self-healing ability, where cracks that form become filled with calcite that prevents

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1308-537: A handful of cordite rockets were attached to the wheels, and the payload was simulated by an equivalent weight of sand . When Shute gave the signal, the rockets were ignited and the Panjandrum catapulted itself forward, out of the landing craft used as a launchpad, and a fair distance up the beach before a number of the rockets on the right wheel failed and the weapon careened off course. Several further attempts were made with more and more rockets, but on every occasion

1417-559: A key event in the history of architecture termed the Roman architectural revolution , freed Roman construction from the restrictions of stone and brick materials. It enabled revolutionary new designs in terms of both structural complexity and dimension. The Colosseum in Rome was built largely of concrete, and the Pantheon has the world's largest unreinforced concrete dome. Concrete, as

1526-415: A large aggregate that is too large for the size of the formwork, or which has too few smaller aggregate grades to serve to fill the gaps between the larger grades, or using too little or too much sand for the same reason, or using too little water, or too much cement, or even using jagged crushed stone instead of smoother round aggregate such as pebbles. Any combination of these factors and others may result in

1635-461: A large type of industrial facility called a concrete plant , or often a batch plant. The usual method of placement is casting in formwork , which holds the mix in shape until it has set enough to hold its shape unaided. Concrete plants come in two main types, ready-mix plants and central mix plants. A ready-mix plant blends all of the solid ingredients, while a central mix does the same but adds water. A central-mix plant offers more precise control of

1744-493: A letter to the deception planners that asked them to focus on Pas-de-Calais as the main assault and was almost certainly sent at the behest of Strangeways. With those criticisms in hand, Wild produced his final draft for Fortitude. In the revised plan, which was issued on 30 January and approved by the Allied chiefs on 18 February, fifty divisions would be positioned in Southern England to attack Pas de Calais. After

1853-461: A method of deception had been pioneered in Cairo by Dudley Clarke 's 'A' Force earlier in the war. Fortitude made heavy use of Clarke's techniques for inflating the size of an army and used a number of methodologies which had come to be referred to as "special means." They included combinations of physical deception, fake wireless (radio) activity, leaks through diplomatic channels or double agents and

1962-494: A mix which is too harsh, i.e., which does not flow or spread out smoothly, is difficult to get into the formwork, and which is difficult to surface finish. Operation Fortitude Airborne assault British Sector American Sector Normandy landings American Sector Anglo-Canadian Sector Logistics Ground campaign American Sector Anglo-Canadian Sector Breakout Air and Sea operations Supporting operations Aftermath Operation Fortitude

2071-469: A mixture of calcium silicates ( alite , belite ), aluminates and ferrites —compounds, which will react with water. Portland cement and similar materials are made by heating limestone (a source of calcium) with clay or shale (a source of silicon, aluminium and iron) and grinding this product (called clinker ) with a source of sulfate (most commonly gypsum ). Cement kilns are extremely large, complex, and inherently dusty industrial installations. Of

2180-405: A number of manufactured aggregates, including air-cooled blast furnace slag and bottom ash are also permitted. The size distribution of the aggregate determines how much binder is required. Aggregate with a very even size distribution has the biggest gaps whereas adding aggregate with smaller particles tends to fill these gaps. The binder must fill the gaps between the aggregate as well as paste

2289-433: A realistic threat to Calais to which Axis forces would be forced respond in defence. He was concerned the Germans might well be aware of the Allied readiness in southern England and so they would be alert to the risk of an invasion in early June. However, that would realise this gave them several weeks to defeat any bridgehead and return to defend Calais. On 25 January, Montgomery's Chief of Staff, Francis de Guingand , sent

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2398-424: A semi-liquid slurry (paste) that can be shaped, typically by pouring it into a form. The concrete solidifies and hardens through a chemical process called hydration . The water reacts with the cement, which bonds the other components together, creating a robust, stone-like material. Other cementitious materials, such as fly ash and slag cement , are sometimes added—either pre-blended with the cement or directly as

2507-493: A simple, fast way of getting a basic idea of the properties of the finished concrete without having to perform testing in advance. Various governing bodies (such as British Standards ) define nominal mix ratios into a number of grades, usually ranging from lower compressive strength to higher compressive strength. The grades usually indicate the 28-day cure strength. Thorough mixing is essential to produce uniform, high-quality concrete. Separate paste mixing has shown that

2616-496: A size required significant organisation and input from many organisations, including MI5 , MI6 , SHAEF via Ops B, and the armed services. Information from the various deception agencies was organised by and channelled through the London Controlling Section. To help keep the approach well-organised, Strangeways divided the implementation stages into six subplans, codenamed Quicksilver. The FUSAG deception

2725-467: A small empire in the regions of southern Syria and northern Jordan from the 4th century BC. They discovered the advantages of hydraulic lime , with some self-cementing properties, by 700 BC. They built kilns to supply mortar for the construction of rubble masonry houses, concrete floors, and underground waterproof cisterns . They kept the cisterns secret as these enabled the Nabataeans to thrive in

2834-446: A speed of up to 24 km/h. In the event, it travelled in a straight line, but only for 50 metres. The event was recorded on video. Neil A Downie described the science and fabrication of a 'Turbo Panjandrum', a Panjandrum driven by 2 or more high power electric motors with propellers attached to a pair of large bicycle wheels. Turbo Panjandrums made by different teams have been raced against each other. Concrete Concrete

2943-534: A steel drum filled with explosives, suspended between a pair of steel-treaded wooden wheels. The wheels were 1 ft (0.30 m) wide, and 10 ft (3.0 m) in diameter. The weapon would be propelled by sets of cordite rockets attached to each wheel. The designers predicted that, with a full 4,000-pound (1,800 kg) load, Panjandrum would achieve speeds of around 60 mph (100 km/h), with enough momentum to simply crash through any obstacles between its launch point and target. The name "Great Panjandrum"

3052-535: A visit, along with a photographer, to ensure that their location was noted. The landing craft, built from wood and canvas and nicknamed Bigbob's, suffered from being too light. Wind and rain flipped many of them over or ran them to ground during the operation. Instead of extensive physical measures, most of Strangeway's plan relied on radio signals and leaks through double agents. Managing that information flow had to be done with caution since leaking supposed top-secret invasion plans would have been very obvious. Instead,

3161-484: Is exothermic , which means ambient temperature plays a significant role in how long it takes concrete to set. Often, additives (such as pozzolans or superplasticizers ) are included in the mixture to improve the physical properties of the wet mix, delay or accelerate the curing time, or otherwise change the finished material. Most concrete is poured with reinforcing materials (such as steel rebar ) embedded to provide tensile strength , yielding reinforced concrete . In

3270-405: Is a composite material composed of aggregate bonded together with a fluid cement that cures to a solid over time. Concrete is the second-most-used substance in the world after water , and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminium combined. When aggregate is mixed with dry Portland cement and water ,

3379-473: Is flat and had been covered with cement". "The floors were cement, in some places hard, but, by long exposure, broken, and now crumbling under the feet." "But throughout the wall was solid, and consisting of large stones imbedded in mortar, almost as hard as rock." Small-scale production of concrete-like materials was pioneered by the Nabatean traders who occupied and controlled a series of oases and developed

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3488-559: Is then blended with aggregates and any remaining batch water and final mixing is completed in conventional concrete mixing equipment. Workability is the ability of a fresh (plastic) concrete mix to fill the form/mold properly with the desired work (pouring, pumping, spreading, tamping, vibration) and without reducing the concrete's quality. Workability depends on water content, aggregate (shape and size distribution), cementitious content and age (level of hydration ) and can be modified by adding chemical admixtures, like superplasticizer. Raising

3597-465: Is thought that the Germans were not actually monitoring the radio traffic that was being simulated. Overall, Fortitude was successful for several reasons: One author says that on 5 June before he gave the Go message for Overlord, Eisenhower received a message that was couriered from Bletchley Park and had been sent by Hitler to Rommel with battle orders that the invasion of Normandy was imminent but that it

3706-566: Is usually either pourable or thixotropic , and is used to fill gaps between masonry components or coarse aggregate which has already been put in place. Some methods of concrete manufacture and repair involve pumping grout into the gaps to make up a solid mass in situ . The word concrete comes from the Latin word " concretus " (meaning compact or condensed), the perfect passive participle of " concrescere ", from " con -" (together) and " crescere " (to grow). Concrete floors were found in

3815-399: Is usually reinforced with materials that are strong in tension, typically steel rebar . The mix design depends on the type of structure being built, how the concrete is mixed and delivered, and how it is placed to form the structure. Portland cement is the most common type of cement in general usage. It is a basic ingredient of concrete, mortar , and many plasters . It consists of

3924-655: The London Controlling Section in late 1943. Early revisions in January 1944 suggested a fictional buildup of troops in southern England with the hope of drawing German attention to the Calais region. Colonel David Strangeways , head of Montgomery's R Force deception staff, was unimpressed with the approach. He was widely critical of the original plan and eventually rewrote the Fortitude deception with

4033-708: The Moray Firth , and the British media co-operated by broadcasting fake information, such as football scores or wedding announcements, to nonexistent troops. Fortitude North was so successful that by late spring 1944, Hitler had positioned 13 army divisions in Norway. In the early spring of 1944, British commandos attacked targets in Norway to simulate preparations for invasion. They destroyed industrial targets, such as shipping and power infrastructure and military outposts. That coincided with an increase in naval activity in

4142-480: The construction industry , whose demand is ever growing with greater impacts on raw material extraction, waste generation and landfill practices. Concrete production is the process of mixing together the various ingredients—water, aggregate, cement, and any additives—to produce concrete. Concrete production is time-sensitive. Once the ingredients are mixed, workers must put the concrete in place before it hardens. In modern usage, most concrete production takes place in

4251-474: The Allied Channel crossing, and Fortitude North, staged out of Scotland, introduced a threat to occupied Norway . Planning for Bodyguard overall came under the auspices of the London Controlling Section (LCS), a secret body that was set up to manage Allied deception strategy during the war. However, the execution of individual plans fell to the various theatre commanders. In the case of Fortitude, it

4360-541: The Allies to maintain and to build upon their foothold in Normandy. Having served its purpose, on 28 September 1944, it was agreed to end the Fortitude deception and to move any remaining operational deceptions in the field to the overall charge of Ops (B). The Allies were able to judge how well Fortitude worked because of Ultra , the signals intelligence that was obtained by breaking German codes and ciphers. On 1 June,

4469-541: The DMWD received notification that the weapon was only required to be consistently able to travel in the general direction of the enemy. With some degree of confidence, a final trial was scheduled to be performed in January 1944, in front of a number of Navy officials and scientists, as well as an official photographer. The day of the test was described in detail by Brian Johnson , for the 1977 BBC documentary The Secret War : At first all went well. Panjandrum rolled into

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4578-519: The European front, with Operation Fortitude representing the main effort to misdirect the Oberkommando der Wehrmacht (German High Command) to believe in specific mainland invasion objectives. The problem facing the Allies was that France was the most logical choice for an invasion into mainland Europe. Therefore, the Allied high command had only a small geographical area across which to mislead

4687-572: The French Mediterranean coast". He added that he expected the Allies would then attack in force across the Strait of Dover . The deception was also assisted by very high German assessments of Allied capabilities. In an appreciation of 8 May von Rundstedt said: Observed tonnage of landing shipping could be taken as sufficient for 12 or 13 divisions (less heavy equipment and rear elements) for fairly short sea routes. In all (estimating

4796-515: The German defences. Montgomery, commanding the Allied landing forces, knew that the crucial aspect of any invasion was the ability to enlarge a beachhead into a full front. He also had only 37 divisions at his command, compared to around 60 German formations. That meant that any deception would have to convince the German high command that the Allies were not committing their full forces into Normandy, but holding many of those formations in reserve. After

4905-496: The Panjandrum lost control before reaching the end of the beach. After tinkering with the project for a further three weeks, the Department returned to the beach. Panjandrum was now equipped with over seventy cordite rockets and a stabilising third wheel. When launched, it hurtled towards the coast, skimming the beach before turning back out to sea. A number of the 20 lb (9.1 kg) rockets detached and whipped wildly above

5014-508: The Romans knew it, was a new and revolutionary material. Laid in the shape of arches , vaults and domes , it quickly hardened into a rigid mass, free from many of the internal thrusts and strains that troubled the builders of similar structures in stone or brick. Modern tests show that opus caementicium had as much compressive strength as modern Portland-cement concrete (c. 200 kg/cm  [20 MPa; 2,800 psi]). However, due to

5123-525: The South-West of England indicated few troop sightings, but in reality, many units were housed there in preparation for D-Day. Reports from the South-East depicted largely-notional Quicksilver forces. That approach aimed to convince German intelligence services of an order of battle for the Allied forces that placed the centre of gravity of the invasion force opposite Pas-de-Calais. Fortitude North

5232-643: The absence of reinforcement, its tensile strength was far lower than modern reinforced concrete , and its mode of application also differed: Modern structural concrete differs from Roman concrete in two important details. First, its mix consistency is fluid and homogeneous, allowing it to be poured into forms rather than requiring hand-layering together with the placement of aggregate, which, in Roman practice, often consisted of rubble . Second, integral reinforcing steel gives modern concrete assemblies great strength in tension, whereas Roman concrete could depend only upon

5341-640: The aim of landing in France toward the end of July. In order to explain Patton's appearance in Normandy, news was transmitted of a rumour that Patton had refused to transfer any of his units to Montgomery's 21st Army Group, and as a result had been demoted and given the lesser command of the Third United States Army . His replacement at FUSAG was Lieutenant General Lesley J. McNair , but after touring Southeast England, he visited Normandy where he

5450-423: The approaching roar he looked up from his viewfinder to see Panjandrum, shedding live rockets in all directions, heading straight for him. As he ran for his life, he glimpsed the assembled admirals and generals diving for cover behind the pebble ridge into barbed-wire entanglements. Panjandrum was now heading back to the sea but crashed on to the sand where it disintegrated in violent explosions, rockets tearing across

5559-475: The beach at great speed. Given the results of the trial, it is perhaps not surprising that the project was scrapped almost immediately over safety concerns. However, it has since been suggested that the entire project was a hoax devised as part of Operation Fortitude , to convince the Germans that plans were being developed to attack the heavily fortified defences surrounding the Pas-de-Calais rather than

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5668-536: The bulk of Allied forces in England and therefore the main Allied threat. To add credence to the importance of FUSAG, Bradley was replaced by Lieutenant General George Patton , whom the Germans held in high regard and who was known to be a competitor to Montgomery. The Fortitude South story would be that FUSAG was being prepared to invade Pas-de-Calais some weeks after an initial diversionary invasion. That would allow Operation Neptune 's landings to be passed off as

5777-587: The capacity of the other English ports not so far covered by visual and photo recce) probable employment of at least 20 and probably more divisions in first wave must be expected. To these must be added strong air-landing forces. During the course of Fortitude, the almost-complete lack of German aerial reconnaissance, together with the absence of uncontrolled German agents in Britain, came to make physical deception almost irrelevant. The unreliability of "diplomatic leaks" resulted in their discontinuance. Most deception in

5886-526: The concrete at the time of batching/mixing. (See § Production below.) The common types of admixtures are as follows: Inorganic materials that have pozzolanic or latent hydraulic properties, these very fine-grained materials are added to the concrete mix to improve the properties of concrete (mineral admixtures), or as a replacement for Portland cement (blended cements). Products which incorporate limestone , fly ash , blast furnace slag , and other useful materials with pozzolanic properties into

5995-399: The concrete can cause the initially placed material to begin to set before the next batch is added on top. This creates a horizontal plane of weakness called a cold joint between the two batches. Once the mix is where it should be, the curing process must be controlled to ensure that the concrete attains the desired attributes. During concrete preparation, various technical details may affect

6104-461: The concrete quality. Central mix plants must be close to the work site where the concrete will be used, since hydration begins at the plant. A concrete plant consists of large hoppers for storage of various ingredients like cement, storage for bulk ingredients like aggregate and water, mechanisms for the addition of various additives and amendments, machinery to accurately weigh, move, and mix some or all of those ingredients, and facilities to dispense

6213-483: The crack from spreading. The widespread use of concrete in many Roman structures ensured that many survive to the present day. The Baths of Caracalla in Rome are just one example. Many Roman aqueducts and bridges, such as the magnificent Pont du Gard in southern France, have masonry cladding on a concrete core, as does the dome of the Pantheon . After the Roman Empire, the use of burned lime and pozzolana

6322-428: The deceivers used tactics developed by Clarke in Cairo. Agents were allowed to report minutiae such as insignia on soldiers' uniforms and unit markings on vehicles to allow the Germans to build up a picture. The observations in the south-central areas largely gave accurate information about the real invasion forces since Clarke had stressed that using as much real information as possible led to better outcomes. Reports from

6431-562: The desert. Some of these structures survive to this day. In the Ancient Egyptian and later Roman eras, builders discovered that adding volcanic ash to lime allowed the mix to set underwater. They discovered the pozzolanic reaction . The Romans used concrete extensively from 300 BC to AD 476. During the Roman Empire, Roman concrete (or opus caementicium ) was made from quicklime , pozzolana and an aggregate of pumice . Its widespread use in many Roman structures ,

6540-407: The device by hand. Sub-Lieutenant Nevil Shute calculated that over 1 long ton (1,000 kg) of explosives would be needed in order to create a tank-sized breach in such a wall. The delivery method for such a quantity of explosives posed a significant problem, and one of the concepts discussed ultimately resulted in the construction of the prototype "Great Panjandrum". The proposed device comprised

6649-469: The enemy to do something, not just to think something, and so his criticism focused on that. He pointed out that convincing the Germans of so many fictional divisions would be difficult, and even more so would be convincing them of Montgomery's ability to manage two entire invasions at the same time. Wild's plan outlined ten divisions for the Calais assault, six of them being fictional and the remainder being

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6758-598: The established deception organization". Harmer writes that Strangeways displayed the same arrogance as his commanding officer. Montgomery was famously opinionated and held a low opinion of the London establishment of the "old boys'" of Ops (B) and the LCS. More importantly, however, he had worked under Dudley Clarke in Cairo during the beginning of the war and had extensive experience of deception operations. In North Africa, he had learned Clarke's maxim that deception relied on getting

6867-566: The face of a known manpower shortage. Secondly, the new plan reduced the threat to Pas-de-Calais which might give the German command confidence to move the Fifteenth Army to reinforce Normandy. As before, in late June, Strangeways rewrote the operation to ensure that the focus remained on Calais. In his version, the Normandy beachhead was struggling to succeed and so Eisenhower had taken elements of FUSAG to reinforce its efforts. FUSAG would then be rebuilt with newly-arrived US formations with

6976-431: The finished product. Construction aggregates consist of large chunks of material in a concrete mix, generally a coarse gravel or crushed rocks such as limestone , or granite , along with finer materials such as sand . Cement paste, most commonly made of Portland cement , is the most prevalent kind of concrete binder. For cementitious binders, water is mixed with the dry cement powder and aggregate, which produces

7085-474: The heads of the gathered audience or exploded underwater. Despite these failures, Shute and his team persevered, removing the third wheel and attaching steel cables to the remaining two wheels as a basic form of steering. Panjandrum proved to be too powerful however, snapping the cables and whipping them back across the beach when they were used. More weeks were spent testing every conceivable variable from thicker cables to heavier rocket-clamps without success before

7194-481: The impression that an invasion was aimed at the Pas-de-Calais slightly later in the year (July, instead of June). Once the real invasion had landed, six fictional divisions would then keep the threat to Calais alive. Colonel David Strangeways , head of Montgomery's R Force , raised concerns about the entire plan. Strangeways argued that the plan aimed to cover the Allies' real intentions, instead of creating

7303-554: The interlinking of the silicates and aluminate components as well as their bonding to sand and gravel particles to form a solid mass. One illustrative conversion is the hydration of tricalcium silicate: The hydration (curing) of cement is irreversible. Fine and coarse aggregates make up the bulk of a concrete mixture. Sand , natural gravel, and crushed stone are used mainly for this purpose. Recycled aggregates (from construction, demolition, and excavation waste) are increasingly used as partial replacements for natural aggregates, while

7412-439: The landings had been purely a diversionary attack. Fortitude was one of the major elements of Operation Bodyguard , the overall Allied deception stratagem for the Normandy landings. Bodyguard's main objectives were to ensure that the Germans would not increase troop presence in Normandy and to do so by promoting the appearance that the Allies would attack in other locations. It consisted of a wide range of deceptions ranging across

7521-470: The landings, there would then need to be some way to delay the movement of German reserves to the Normandy beachhead to prevent a potentially disastrous counterattack. Operation Fortitude focused on creating invasion threats from the United Kingdom into various parts of Western Europe. The plan was eventually split into two parts, North and South. Fortitude South focused on creating confusion about

7630-545: The less-defended Normandy coastline. On the occasion of the 65th anniversary of the Normandy Landings a replica was constructed and set off on the original beach in Devon. The wheel, commissioned by the local Appledore Book Festival, was 6 ft (1.8 m) high and 3 ft (0.9 m) wide and loaded with fireworks fitted by Skyburst of Bristol, instead of explosives; it was expected to travel 500 metres at

7739-406: The making of mortar. In an English translation from 1397, it reads "lyme ... is a stone brent; by medlynge thereof with sonde and water sement is made". From the 14th century, the quality of mortar was again excellent, but only from the 17th century was pozzolana commonly added. The Canal du Midi was built using concrete in 1670. Perhaps the greatest step forward in the modern use of concrete

7848-531: The material. Mineral admixtures use recycled materials as concrete ingredients. Conspicuous materials include fly ash , a by-product of coal-fired power plants ; ground granulated blast furnace slag , a by-product of steelmaking ; and silica fume , a by-product of industrial electric arc furnaces . Structures employing Portland cement concrete usually include steel reinforcement because this type of concrete can be formulated with high compressive strength , but always has lower tensile strength . Therefore, it

7957-419: The mix, are being tested and used. These developments are ever growing in relevance to minimize the impacts caused by cement use, notorious for being one of the largest producers (at about 5 to 10%) of global greenhouse gas emissions . The use of alternative materials also is capable of lowering costs, improving concrete properties, and recycling wastes, the latest being relevant for circular economy aspects of

8066-478: The mixed concrete, often to a concrete mixer truck. Modern concrete is usually prepared as a viscous fluid, so that it may be poured into forms. The forms are containers that define the desired shape. Concrete formwork can be prepared in several ways, such as slip forming and steel plate construction . Alternatively, concrete can be mixed into dryer, non-fluid forms and used in factory settings to manufacture precast concrete products. Interruption in pouring

8175-441: The mixing of cement and water into a paste before combining these materials with aggregates can increase the compressive strength of the resulting concrete. The paste is generally mixed in a high-speed , shear-type mixer at a w/c (water to cement ratio) of 0.30 to 0.45 by mass. The cement paste premix may include admixtures such as accelerators or retarders, superplasticizers , pigments , or silica fume . The premixed paste

8284-440: The mixture forms a fluid slurry that is easily poured and molded into shape. The cement reacts with the water through a process called concrete hydration that hardens it over several hours to form a hard matrix that binds the materials together into a durable stone-like material that has many uses. This time allows concrete to not only be cast in forms, but also to have a variety of tooled processes performed. The hydration process

8393-492: The new force already existed in the form of the First United States Army Group (FUSAG), commanded by Omar Bradley . It had been formed for administrative purposes but never used, but the Germans had discovered its existence through radio intercepts. Strangeways proposed activating the unit, with a series of fictional and real formations. The order of battle for the army would be intended to represent

8502-603: The northern seas and in political pressure on neutral Sweden. Similar to the operation in the south, Fortitude North had a subsidiary plan used to implement the extensive radio deceptions. Codenamed Operation Skye, it began on 22 March 1944, was overseen by Colonel R. M. McLeod, and became fully operational by 6 April. Skye was split into four sections, relating to different divisions of the Fourth Army On 20 July, Ops (B) took over control of Fortitude South from R Force. The previous month, it had begun work to follow up

8611-437: The operation. The new story centered on the idea that Eisenhower had decided to defeat the Germans through the existing beachhead. As a result, elements of FUSAG had been detached and sent to reinforce Normandy, and a second smaller Second American Army Group (SUSAG) would be formed to threaten the Pas-de-Calais. The plan again met criticism from Strangeways. Firstly, he opposed the creation of so many fictional US formations in

8720-428: The past, lime -based cement binders, such as lime putty, were often used but sometimes with other hydraulic cements , (water resistant) such as a calcium aluminate cement or with Portland cement to form Portland cement concrete (named for its visual resemblance to Portland stone ). Many other non-cementitious types of concrete exist with other methods of binding aggregate together, including asphalt concrete with

8829-419: The plan's implementation, he refused to undertake most of the physical deception. A power struggle ensued throughout February and early March between Ops(B) and Strangeways as to who had authority to implement each part of the deception plan. Montgomery put his full support behind his head of deception and so Strangeways prevailed. Finally, in a 23 February meeting between R Force and Ops(B), Strangeways tore up

8938-506: The properties or increase the performance envelope of the mix. Design-mix concrete can have very broad specifications that cannot be met with more basic nominal mixes, but the involvement of the engineer often increases the cost of the concrete mix. Concrete mixes are primarily divided into nominal mix, standard mix and design mix. Nominal mix ratios are given in volume of Cement : Sand : Aggregate {\displaystyle {\text{Cement : Sand : Aggregate}}} . Nominal mixes are

9047-468: The quality and nature of the product. Design mix ratios are decided by an engineer after analyzing the properties of the specific ingredients being used. Instead of using a 'nominal mix' of 1 part cement, 2 parts sand, and 4 parts aggregate (the second example from above), a civil engineer will custom-design a concrete mix to exactly meet the requirements of the site and conditions, setting material ratios and often designing an admixture package to fine-tune

9156-418: The real American V Corps and British I Corps. However, the corps would be part of the actual Normandy invasion and so it would be difficult to imply Calais as the main assault after D-Day. Strangeways's final concerns related to the effort required for physical deception, as the plan called for large numbers of troop movements and dummy craft. Strangeways's objections were strong, and having responsibility for

9265-497: The real invasion had landed, the story would change to suggest to the Germans that several assault divisions remained in England that were ready to conduct a cross-Channel attack once the Normandy beachhead had drawn German defences away from Calais. The plan still retained some of its initial form, most notably since the first part of the story still aimed to suggest an invasion date of mid-July. At that point, Winston Churchill judged 'Mespot' to be an unsuitable name and so 'Fortitude'

9374-650: The royal palace of Tiryns , Greece, which dates roughly to 1400 to 1200 BC. Lime mortars were used in Greece, such as in Crete and Cyprus, in 800 BC. The Assyrian Jerwan Aqueduct (688 BC) made use of waterproof concrete . Concrete was used for construction in many ancient structures. Mayan concrete at the ruins of Uxmal (AD 850–925) is referenced in Incidents of Travel in the Yucatán by John L. Stephens . "The roof

9483-489: The sea and began to head for the shore, the Brass Hats watching through binoculars from the top of a pebble ridge [...] Then a clamp gave: first one, then two more rockets broke free: Panjandrum began to lurch ominously. It hit a line of small craters in the sand and began to turn to starboard , careering towards Klemantaski, who, viewing events through a telescopic lens, misjudged the distance and continued filming. Hearing

9592-427: The secrecy surrounding the project broke down, as the beach chosen as a test site was also a popular destination for holidaymakers; from the first test on 7 September 1943 onwards, every trial was witnessed by large citizen audiences despite the DMWD's warnings concerning the safety of the weapon. Since nothing remotely resembling the Panjandrum had ever been constructed before, the trials began with trepidation—only

9701-409: The south was carried out by means of false wireless traffic and through German double agents. However, those methods had significantly less impact for Fortitude North. In his 2000 book, Fortitude: The D-Day Deception Campaign , Roger Fleetwood-Hesketh , a member of Ops (B), concluded that "no evidence has so far been found to show that wireless deception or visual misdirection made any contribution". It

9810-411: The strength of the concrete bonding to resist tension. The long-term durability of Roman concrete structures has been found to be due to its use of pyroclastic (volcanic) rock and ash, whereby the crystallization of strätlingite (a specific and complex calcium aluminosilicate hydrate) and the coalescence of this and similar calcium–aluminium-silicate–hydrate cementing binders helped give the concrete

9919-497: The surface of concrete for a decorative "exposed aggregate" finish, popular among landscape designers. Admixtures are materials in the form of powder or fluids that are added to the concrete to give it certain characteristics not obtainable with plain concrete mixes. Admixtures are defined as additions "made as the concrete mix is being prepared". The most common admixtures are retarders and accelerators. In normal use, admixture dosages are less than 5% by mass of cement and are added to

10028-535: The surfaces of the aggregate together, and is typically the most expensive component. Thus, variation in sizes of the aggregate reduces the cost of concrete. The aggregate is nearly always stronger than the binder, so its use does not negatively affect the strength of the concrete. Redistribution of aggregates after compaction often creates non-homogeneity due to the influence of vibration. This can lead to strength gradients. Decorative stones such as quartzite , small river stones or crushed glass are sometimes added to

10137-401: The time since the invasion fleet had sailed on 4 June but was then postponed for 24 hours, and even with Colossus, Fish decrypts could take days or weeks. He thinks that Flowers may have embellished or misremembered the story in later life. Hitler’s views on the real invasion are widely attributed to the message from the Japanese ambassador to Berlin, Ōshima, after a 27 May meeting. Anyway, during

10246-652: The usage of notable officers in fake formations. One of the main deception channels for the Allies was the use of double agents. B1A, the Counter-Intelligence Division of MI5 , had done a good job in intercepting numerous German agents in Britain. Many of them were recruited as double agents under the Double Cross System . For Fortitude, the intelligence agencies made particular use of three agents: Detailed planning ostensibly sat with Noel Wild and his Ops (B) staff. In practice, it

10355-655: The various ingredients used to produce a given quantity of concrete, the cement is the most energetically expensive. Even complex and efficient kilns require 3.3 to 3.6 gigajoules of energy to produce a ton of clinker and then grind it into cement . Many kilns can be fueled with difficult-to-dispose-of wastes, the most common being used tires. The extremely high temperatures and long periods of time at those temperatures allows cement kilns to efficiently and completely burn even difficult-to-use fuels. The five major compounds of calcium silicates and aluminates comprising Portland cement range from 5 to 50% in weight. Combining water with

10464-439: The water content or adding chemical admixtures increases concrete workability. Excessive water leads to increased bleeding or segregation of aggregates (when the cement and aggregates start to separate), with the resulting concrete having reduced quality. Changes in gradation can also affect workability of the concrete, although a wide range of gradation can be used for various applications. An undesirable gradation can mean using

10573-469: Was Smeaton's Tower , built by British engineer John Smeaton in Devon , England, between 1756 and 1759. This third Eddystone Lighthouse pioneered the use of hydraulic lime in concrete, using pebbles and powdered brick as aggregate. A method for producing Portland cement was developed in England and patented by Joseph Aspdin in 1824. Aspdin chose the name for its similarity to Portland stone , which

10682-422: Was Supreme Headquarters Allied Expeditionary Force (SHAEF), under General Dwight D. Eisenhower and specifically 21st Army Group , the invasion force, under the command of General Bernard Montgomery . A special section, Ops (B) , was established at SHAEF to handle Fortitude, and Montgomery formed R Force under his command to handle the tactical elements of deception. The idea of creating fake formations as

10791-501: Was a military deception operation by the Allied nations as part of Operation Bodyguard , an overall deception strategy during the buildup to the 1944 Normandy landings . Fortitude was divided into two subplans, North and South, and had the aim of misleading the German High Command as to the location of the invasion. Fortitude had evolved from plans submitted by Noel Wild , the head of Ops (B) , and John Bevan , from

10900-511: Was a collaboration between Wild and the heads of the London Controlling Section and B1a. Work began in December 1943 under the codename Mespot. Wild's first version of the Fortitude plan was socialised in early January 1943 with SHAEF, political leaders and the staff officers of the 21st Army Group. That iteration aimed to take advantage of the likelihood that the Germans would notice invasion preparations in southern England. Wild wanted to create

11009-475: Was a feint to draw troops away from the real invasion five days later against the Channel Ports, and Rommel was not to move any troops. That would mean that the Allies would have five days without determined opposition. It was sent in a Fish radio message and decrypted by Colossus, according to an account by Tommy Flowers. Another author doubts whether Hitler would have sent messages about the invasion at

11118-489: Was accidentally killed on 24 July in an Allied air raid and was subsequently replaced by General John L. DeWitt . Through the evolved plan, the Allies maintained the pretense of FUSAG and other forces threatening Pas-de-Calais for some considerable time after D-Day, possibly even as late as September 1944. That was vital to the success of the Allied plan by forcing the Germans to keep most of their reserves bottled up in wait for an attack on Calais that never came. That allowed

11227-476: Was adopted from an alternative list on 18 February. I rewrote it entirely. It was too complicated, and the people who made it had not never done it before. Now they did their best – but it didn't suit the operation that Monty was considering.... You see so much depended on the success of that deception plan. Strangeways was still unimpressed with the Fortitude outline, and, according to Ops(B)'s Christopher Harmer, in mid-February, he set out to ride "roughshod over

11336-404: Was chosen by Shute as a reference to Samuel Foote 's famous extempore nonsense paragraph (though Foote's term was actually "the grand Panjandrum"), and in particular to its closing line "till the gunpowder ran out at the heels of their boots". The prototype was secretly constructed at Leytonstone and transported by night to the testing grounds at Westward Ho! , Devon . However, once there,

11445-429: Was decided to continue to use the same force during Fortitude. Unlike its southern counterpart, the deception relied primarily on fake radio traffic since it was judged unlikely that German reconnaissance planes could reach Scotland without being intercepted. False information about the arrival of troops in the area was reported by the double agents Mutt and Jeff , who had surrendered following after their 1941 landing in

11554-551: Was designed to mislead the Germans into expecting an invasion of Norway . By threatening any weakened Norwegian defence, the Allies hoped to prevent or to delay reinforcement of France after the Normandy invasion. The plan involved simulating a buildup of forces in northern England and political contact with Sweden. During a similar operation in 1943, Operation Tindall , a fictional field army ( British Fourth Army ) had been created, headquartered in Edinburgh Castle . It

11663-602: Was greatly reduced. Low kiln temperatures in the burning of lime, lack of pozzolana, and poor mixing all contributed to a decline in the quality of concrete and mortar. From the 11th century, the increased use of stone in church and castle construction led to an increased demand for mortar. Quality began to improve in the 12th century through better grinding and sieving. Medieval lime mortars and concretes were non-hydraulic and were used for binding masonry, "hearting" (binding rubble masonry cores) and foundations. Bartholomaeus Anglicus in his De proprietatibus rerum (1240) describes

11772-547: Was not implemented primarily with dummy tanks, aeroplanes, or other vehicles. At that stage of the war, the Germans were unable to fly reconnaissance planes over England and so Strangeways felt that such effort would have been wasted. However, temporary buildings were constructed and dummy landing craft were stationed at likely embarkation point in the East and the South-East of England. As the FUSAG commander, Patton paid many of them

11881-622: Was quarried on the Isle of Portland in Dorset , England. His son William continued developments into the 1840s, earning him recognition for the development of "modern" Portland cement. Reinforced concrete was invented in 1849 by Joseph Monier . and the first reinforced concrete house was built by François Coignet in 1853. The first concrete reinforced bridge was designed and built by Joseph Monier in 1875. Prestressed concrete and post-tensioned concrete were pioneered by Eugène Freyssinet ,

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