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84-494: The camp site remained unexplored after the war due to the depth of the gorges where bodies were disposed and the fact that some of them had been filled with concrete by Yugoslavia 's Communist authorities. Additional sites containing the skeletal remains of camp victims were uncovered in the 1980s. Commemoration ceremonies honouring the victims of the camp have been organized by the Serb National Council (SNV),

168-613: A Day of Remembrance of the Jadovno Camp in Croatia. A monument commemorating those who perished was constructed in 1975 and stood for fifteen years before being removed in 1990 prior to the outbreak of ethnic violence during the Croatian War of Independence . A replica of the original monument was constructed and dedicated in 2010, but disappeared within twenty-four hours of its inauguration. Concrete Concrete

252-412: 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

336-532: A 2009 research by the Belgrade Museum of Genocide Victims , between 15,300–15,900 people were killed in the Gospić, Jadovno and Pag camps. Sources generally offer a range of 10,000–68,000 deaths at the camp. Estimates of the number of Jewish deaths range from several hundred to 2,500–2,800. The Jadovno camp site remained unexplored after the war due to the depth of the gorges where bodies were disposed of and

420-433: 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

504-452: 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 ,

588-400: 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

672-434: 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

756-600: A figure of 1,794 individual victims in Jadovno. The results of this survey were not published until 1989. The 1960 edition of the Encyclopedia of Yugoslavia states at least 35,000 were killed in Jadovno, with a possible final death toll of 50,000–60,000. The 1967 Military Encyclopedia of Yugoslavia estimates that 72,000 inmates perished in the camp. The 1971 edition of the Encyclopedia of Yugoslavia also revised

840-452: 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

924-559: 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

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1008-415: 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

1092-461: 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

1176-563: 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. Gospi%C4%87 Gospić ( pronounced [ɡǒːspitɕ] ) is a town in Lika , Croatia . It is the seat of the Lika-Senj County . Gospić is located in the mountainous and sparsely populated region of Lika. It is the administrative center of Lika-Senj County . Gospić

1260-469: 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

1344-751: A new statue on the square, a replica of the Frano Kršinić original. Gospić has a humid continental climate , Dfb by Köppen climate classification, with mean temperatures varying from −0.9 °C (30.4 °F) in January to 18.1 °C (64.6 °F) in July. Being situated higher than 500 metres (1,640 ft) above sea level , the area experiences high diurnal ranges, especially in summer, and frost has been recorded in every month except for July. The record low and high temperatures are −33.5 °C (−28.3 °F) and 38.7 °C (101.7 °F), respectively. Gospić

1428-405: 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

1512-549: A replica of the Tesla statue that had been destroyed in 1992 to be reinstated. The mayor of Gospić at the time, Milan Kolić, refused to give his approval for such a move and instead vowed to erect a statue of wartime Croatian President Franjo Tuđman on the spot where the Tesla statue had once stood. In 2021, under mayor Karlo Starčević, the town renamed a square after Tesla, and the Croatian Ministry of Culture sponsored

1596-522: A secluded area about 20 kilometres (12 mi) from the town of Gospić , the Jadovno camp was formed during the early stages of the persecution of Serbs in the NDH and was placed under the command of the Ustaša Juco Rukavina  [ sr ; hr ] . Intended as an extermination camp , it was established between 11 and 15 April 1941 and was the first of twenty-six concentration camps located in

1680-424: 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

1764-522: A significant population of ethnic Serbs in the Gospić region. Scientist and inventor Nikola Tesla , of Serb descent, was born in the nearby village of Smiljan and grew up in Gospić between 1862 and 1870, when he moved to Karlovac . He again lived in Smiljan between 1873 and 1879, when he briefly returned to Gospić until 1880 when he went to Graz . In the 19th century, Gospić was the headquarters of Military Frontier "Likaner Regiment" N° I. Following

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1848-493: 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

1932-411: A skull for which I believe to belong to an adult person between age 30 and 50, killed approximately two months before. The opening of the pit is 8x5m in size, and it seems to have no bottom. A rock I threw in did not stop, but fell so deeply that I could not hear it hit the bottom. The rim of the pit and its sides were covered with lime that seemed to be used several days before. Despite that the whole area

2016-467: 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

2100-484: 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

2184-405: 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 ,

2268-578: Is also quite a rainy city, with a slight summer minimum, but it experiences plentiful precipitation all year long, with the maximum being in autumn. During winter, Gospić can get strong blizzards, with on average 5.1 days a year when more than 50 cm (20 in) falls, and 16.1 days when more than 30 cm (12 in) falls. Its record snow cover was 285 cm (112.2 in), and it was measured in February 1916. Directly elected minority councils and representatives are tasked with consulting tasks for

2352-473: 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

2436-402: Is full of the terrible smell of decomposing corpses. It seems that around 500 victims were thrown into this pit. The Italian team discovered additional Velebit killing pits - Jamina pit, near Tribnje] (“hundreds of victims”, including women and children), Jama na Pločama, near Stupačinovo (2.000 Serb victims), Duliba jama (200 victims), etc. Dr. Vittori notes that due to very difficult terrain and

2520-945: Is located near the Lika River in the middle of a karst field ( Ličko Polje ). The first organised inhabitation of the area was recorded in 1263 as Kaseg or Kasezi . The name Gospić is first mentioned in 1604, which likely originates from the Croatian word for "lady" ( gospa ) or another archaic form, gospava . During the Ottoman wars in Europe , Gospić was for a time ruled by the Ottoman Empire as part of Sanjak of Lika initially in Rumeli Eyalet (1528–1580), later in Bosnia Eyalet (1580–1686). Today's town

2604-559: 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

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2688-566: 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

2772-399: 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

2856-868: The Kingdom of Yugoslavia . Poorly equipped and trained, the Royal Yugoslav Army was quickly defeated. After the invasion, the extreme Croat nationalist and fascist Ante Pavelić , who had been in exile in Benito Mussolini 's Italy , was appointed Poglavnik ("leader") of an Ustaše -led Croatian state – the Independent State of Croatia (often called the NDH, from the Croatian : Nezavisna Država Hrvatska ). The NDH combined most of modern Croatia , all of modern Bosnia and Herzegovina and parts of modern Serbia into an "Italian-German quasi-protectorate". NDH authorities, led by

2940-562: The Ustaše militia , then implemented genocidal policies against the Serb , Jewish and Romani populations living in the new state. Aiming to exterminate the entire Serb population of the NDH, the Ustaše sought to murder one-third of Serbs, convert one-third to Roman Catholicism , and force the rest from the country. A series of massacres were committed by the Ustaše, and the degree of cruelty with which

3024-640: The Velebit mountains and on the island of Pag , all part of the Jadovno system of Ustaše camps and killing pits. This description of the Plana pit, located above the village of Buđak, on Velebit, is from the report filed by Dr. Finderle Viktor: In the area around the pit I found pieces of chains, padlocks of various sizes and shapes, railway employee badges, ribbons from trousers of Yugoslav customs officers, toothbrushes, pocket mirrors, combs, and very interestingly, emptied and torn wallets. On one spot I found pieces of

3108-751: The compromise of 1867 , it became part of the Kingdom of Croatia-Slavonia . In the late 19th century and early 20th century, Gospić was part of the Lika-Krbava County . During the Genocide of Serbs in the Independent State of Croatia in WWII , the district of Gospić experienced the first large-scale massacres which occurred in the Lika region, as some 3,000 Serb civilians were killed between late July and early August 1941. A concentration camp

3192-480: 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

3276-529: The Jewish community in Croatia, and local anti-fascists since 2009, and 24 June has since been designated as a "Day of Remembrance of the Jadovno Camp" in Croatia. A monument commemorating those killed in the camp was constructed in 1975 and stood for fifteen years before being removed in 1990. A replica of the original monument was constructed and dedicated in 2010, but disappeared within twenty-four hours of its inauguration. On 6 April 1941, Axis forces invaded

3360-634: The NDH during the war. Most inmates at Ustaše camps – including Jadovno – were Croatian Serbs . Other victims included Jews and anti-Ustaše Croats. Notable Jadovno inmates included the Croatian Jewish mayor of Koprivnica , Ivica Hiršl , and the Croatian Jewish Communist Aleksandar Savić . Immediately, the Ustaše trucked several hundred detainees to a site intended almost exclusively for extermination near Gospić . Located on Mount Velebit ,

3444-508: 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

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3528-564: The Serb population was persecuted shocked even the Germans. The Cyrillic script was banned, Orthodox Christian church schools were closed, and Serbs were ordered to wear identifying armbands. Similar measures were enacted against Jews, who were required to wear a yellow armband with a black-on-yellow Star of David for identification. These armbands bore the word "Jew" in two languages: German (" Jude ") and Croatian (" Židov "). Located in

3612-516: The Ustaše in the camps on Pag. The number of deaths at the camp is difficult to establish as many inmates often went unregistered as they were taken directly to the edge of ravines and murdered. The highest recorded estimate of Jadovno deaths was made in 1942 by a former inmate of the Gospić prison, who claimed that 120,000 people were killed. In 1964, a survey of World War II victims by the War Victim Census Commission showed

3696-407: The Ustaše transferred several hundred Jewish families from Zagreb to Jadovno. Afterwards, the camp was visited by Ustaše commander Vjekoslav Luburić , who opened his visit by cutting the throat of a two-year-old Jewish child. Luburić then forced a camp guard to murder and squash the skull of a second child with his foot. The last group of inmates at Jadovno were killed with machine guns . The camp

3780-643: 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

3864-519: The area finally devolved to the Croatian government with the success of Operation Storm in August 1995. Gospić is the third smallest seat of a county government in Croatia. Its status as the county capital helped to spur some development in it, but the town as well as the entire region have suffered a constant decrease in population over the last several decades. Gospić is also the site of one of

3948-476: The camp was the Šaran pit, located 1 kilometre (0.62 mi) away, while the pit where inmates were executed and dumped was 5 kilometres (3.1 mi) from the camp. Here, inmates were bound together in a line and the first few victims were murdered with rifle butts or other objects. Afterwards, an entire row of inmates were pushed into the ravine. In some cases, inmates were also killed by gunfire, as well as with knives and blunt objects. Once inmates were thrown into

4032-526: 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

4116-399: 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

4200-461: 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

4284-483: 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

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4368-562: 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 ,

4452-438: The fact that some of these had been filled with concrete by Yugoslavia 's Communist authorities. Additional sites containing the skeletal remains of camp victims were uncovered in the 1980s. Commemoration ceremonies honouring the victims of the camp have been organized by the Serb National Council (SNV), representatives of the Jewish community in Croatia, and local anti-fascists since 2009. 24 June has since been designated as

4536-431: 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

4620-554: 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

4704-459: The local or regional authorities in which they are advocating for minority rights and interests, integration into public life and participation in the management of local affairs. At the 2023 Croatian national minorities councils and representatives elections Serbs of Croatia fulfilled legal requirements to elect 15 members minority council of the Town of Gospić with only 13 members being elected in

4788-521: The locals not assisting out of fear of Ustashe retaliation, they were unable to locate other suspected killing pits. Beyond that, the Italian medical teams investigated the Slana and Metajna concentration camps on Pag island, part of the same system of Ustaše camps, where they dug up 791 corpses in mass graves, with nearly half being women and children, and estimated that eight to nine thousand were killed by

4872-406: 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

4956-531: 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

5040-419: 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

5124-478: 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

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5208-441: 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

5292-440: 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

5376-501: The number to 72,000, which became the most commonly cited estimate in the 1960s and the 1970s. Rev Atanasije Jevtić stated in 1983 that 80,000 inmates were killed. Historian Jozo Tomasevich said this claim was "exaggerated" and not based on any documentation or detailed investigation. Historian estimates in the late 1980s and the 1990s mostly ranged from 15,000 to 48,000 victims. A 2007 research study by historian Đuro Zatezalo  [ hr ; sr ] , using 17 archives, estimated that

5460-428: 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

5544-506: 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

5628-468: 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

5712-406: The ravine, hand grenades were hurtled inside in order to kill off the victims. Dogs would also be thrown in to feed on the wounded and the dead. The pits in the vicinity of the camp were filled with the bodies of Jewish and later Serb inmates. However, killings were not confined to these two groups, and the bodies of some Croats and Roma were disposed of in this fashion as well. By the end of June,

5796-676: The regional branches of the Croatian State Archives , the Državni arhiv Gospić , at Kaniška 17. It was founded 30 September 1999 and officially opened 1 September 2000 in a renovated building and now houses historical documents of relevance to the Lika-Senj region which were formerly housed in the Regional Archive at Karlovac. In 2013, Croatian Prime Minister Zoran Milanović urged the town's authorities to allow for

5880-650: 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

5964-411: 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

6048-497: 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

6132-535: 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

6216-512: The total number of deaths at the camp was 40,123 (38,010 Serbs, 1,998 Jews, 88 Croats and 27 others) and listed the names of 10,502 identified victims, of whom 9,663 were Serbs, 762 Jews, 55 Croats and 22 others. 1,029 children were identified (1,014 Serb and 15 Jewish), as was 55 Serbian Orthodox priests according to Zatezalo's data. As it operated over a period of 122 days, this would suggest that an average of 329 people were killed there every day. Paul Mojzes cites Zatezalos's data. According to

6300-458: The town contained gorges – some up to 91.5 metres (300 ft) deep – that were used as dumping grounds. The Jadovno camp itself was surrounded by such abysses ( Serbo-Croatian : jame ) which were difficult to gain access to and characteristic of the karstic mountain range. The camp itself acted as a "way station" en route to these pits. Here, prisoners had to work the entire day with almost no food until exhaustion. The nearest pit to

6384-655: 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

6468-562: The war, while the rebel Serb forces of the Republic of Serbian Krajina occupied positions directly to the east and often bombarded the town from there. In late 1991, the town was the site of the Gospić massacre , where between 100-120 predominantly Serb civilians were killed by Croatian military units. In February 1992, a statue of Nikola Tesla in downtown Gospić was destroyed in an explosion. The perpetrators were never apprehended. Control of

6552-439: 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

6636-524: 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

6720-659: Was built around two Ottoman forts (the towers of Aga Senković and of Aga Alić). The Turkish incursion was repelled by the end of the 17th century and Gospić became an administrative centre of the Lika region within the Military Frontier , a section of the Habsburg monarchy organized as defense against the Ottomans. Before 1850, there are references to the town as Gospich in German. Since this time, there's been

6804-564: Was closed on 21 August 1941, and the remaining Croat inmates were transferred to other NDH-controlled camps, while the remaining Serbs and Jews were murdered. Work on the replacement Jasenovac concentration camp started in the same month. The area in which the Jadovno camp was located was later handed over to the Italians and became part of Italian Zones II and III. In September 1941, two Italian army medical teams were sent to investigate reports of mass graves contaminating drinking water across

6888-486: Was established in Gospić in which (together with other camps that belonged to the same complex) the Ustaše might have killed between 24,000-42,000 people, most of them being Serbs and Jews , but some of the prisoners were also Croatian . In the 1990s, during the course of the Croatian War of Independence , Gospić suffered greatly during the Battle of Gospić . The town was held by Croatian government forces throughout

6972-602: 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

7056-622: 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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