Concrete First World
This article is about some aspects of the use of concrete and reinforced concrete defensive structures used in the positional period of the First World War.
Concrete and reinforced concrete slabs and structures were actively used in the fortifications of opponents during the positional period of World War II. Of particular importance was their presence in the designs of machine-gun caponiers and polukaponiry production of both Russian and foreign engineers.
Combined caponier military engineer Berg defended against a single hit 152-mm projectile. The weight of the concrete blocks used in the construction is 5,7 thous. Pounds, the rail is 1,8 thous. Pounds, and oak beams are 600 pounds. The entire system (without iron ties and oak frames) weighed 8,1 thous. Pounds. The half-caponier of the same design weighed 6,15 thousand pounds.
The collapsible reinforced concrete machine gun polukaponir military engineer Selyutin, also protected from getting 6-inch projectile, weighed 4,6 thousand pounds, and collapsible machine-gun caponier from concrete masses military engineer Moiseev - 4,5 thousand pounds.
Of particular importance was the issue of high-quality equipment of firing points for machine guns, which are the basis of the defensive system. The most serious enemy for heavy machine guns was field light artillery. It was from this artillery that the closures for operating machine guns should have been primarily protected. During the shelling of heavy artillery, a machine gun could be covered in a heavy blindage - and here concrete and reinforced concrete also came to the aid of the defenders.
Combat practice formulated the following conclusions in relation to concrete and reinforced concrete slabs.
When in 1916 the Russian artillery bombarded the Austrian positions on the Tsuman-Olyka-Koryto front, then, according to observations of the military engineer Blueberry, the resistance of concrete and reinforced concrete bunkers was as follows.
The dugout with a coating thickness of 0,69 m (ground 0,25 m., Reinforced concrete pieces in the 2 series with a total thickness of 0,33 m, oak boards 0,10 m) 152-mm projectile pierced and destroyed.
Dugout with a coating of 0,82 m thick (0,05 m earth, 0,22 m earth bags, reinforced concrete pieces in 3 series with total 0,33 m thickness, 0,10 m boards, rails with soles up 0,12 m thick) bottom row of reinforced concrete pieces. Boards were pierced, rails ruined and bent.
The dugout with a coating of 0,82 m thick (0,20 m ground, 0,50 m reinforced concrete slabs, reinforced concrete pieces on 0,12 m rails) was hit by a 152-mm projectile.
0,87 m thick coated dugout (0,25 m ground, ferroconcrete pieces in 3 series with total 0,44 m thickness, oak bars, 0,18 m braced with thickness) 107-mm projectile pierced through, while 76-mm projectile destroyed the concrete and displaced bars, but the dugout did not break.
0,88 m thick coated dugout (0,20 m ground, 3 row of reinforced concrete slabs 0,44 m thick, 0,12 m thick rails, second row 0,12 m thick rails) 152-mm projectile, although it produced significant damage, but could not pierce.
0,95 m thick coated dugout (0,20 ground m, two rows of reinforced concrete slabs with total thickness 0,33 m, solid row 0,12 m thick rail, oak bars 0,18 m thick, solid row 0,12 m thick rail) 107-mm projectile damaged by exploding in concrete . The rails of the upper row were partially destroyed, the oak bars were damaged, but the lower row of rails was intact. Blindage is not broken.
A dugout with a coating of 1,26 m thick (0,50 m earth, reinforced concrete things in 2 series 0,22 m thick, three rows of 0,54 m logs) was punched through and destroyed by 152-mm projectile, while 76-mm projectile, although significant destruction, to break through the dugout could not.
The dugout with a coating of 1,58 m thick (1 m earth, reinforced concrete things in 1 row 0,22 m thick, 2 row logs 0,18 m and 0,22 m thick, respectively) 76-mm high-explosive projectile pierced through, but did not destroy, while 107-mm projectile destroyed this dugout.
A dugout with a coating of 1,69 m thick (1 m earth, 2 row of reinforced concrete slabs 0,33 m thick, two rows of logs 0,36 m thick) was punched through with a 107-mm projectile.
Thus, based on the foregoing, dugouts with coatings in 0,95 and 0,88 m turned out to be the most durable. Yet, this is only relative strength - in fact, none of these structures was perfect, since, despite the considerable thickness of the coatings, shells in all dugouts made serious damage. The comparative strength of the two above-mentioned dugouts is explained by the presence of pillows, causing premature rupture of the projectile and softening its effect on the lower layers of structures. The reasons for the insufficient resistance of coatings should be sought both in their structure and in the material from which they are created.
Speaking about the manufacture of concrete and reinforced concrete floors, it should be noted that the strength of cement concrete depends primarily on the quality of the material.
The latter had the following requirements.
From slowly hardening cements for combat concrete structures, it was recommended to use the so-called Portland cement. Cement must be dry. It was only in exceptional cases that wetted cement could be used, but under the condition that the lumps, crushed into powder, were calcined on the iron sheets to red heat. Even under this condition, the cement lost half its ability to quickly grab. Before use, the cement had to be tested. The normal setting of the cement should meet the following conditions: the beginning is not earlier than 20 minutes, the end is not earlier than an hour and not later than 12 hours.
Of the concrete used at the end of the war to build shelters, concrete occupied a special place on the so-called fused cement, which differs from Portland cement in that it had the ability to harden quickly, whereas the start time of the setting came much later. If Portland cement is predominantly silicate cement, then the melted cement belonged to alumina cements: its action depended on the cementing properties of calcium aluminates.
The composition of the combat concrete was supposed to include the so-called small unit. The best aggregate is coarse quartz sand mixed with fine sand. The sand must be dry and free from harmful organic matter. Allowable clay or silt content - 7% by volume. It was allowed to use a small aggregate of seeding from the crushing of hard stones, such as cobblestones.
The large aggregate was to consist of crushed stone without vegetable or other organic matter. The largest gravel size is 1 inch. The best large aggregate was considered to be gravel, which had the greatest crush resistance.
For reinforcement, it was recommended to use iron of circular cross-section, and best of all, mild steel.
The main disadvantage of cement concrete was considered a long time of its hardening. In some cases, asphalt concrete was allowed to be used instead of cement concrete, the strength of which was expressed in the resistance of one square centimeter 250-kg.
For internal interlayers (pillows), less durable concrete was suitable for gravel, fine sand, asphalt powder and asphalt resin.
For shelter machine gun was considered sufficient to protect him from the 76-mm projectile. To do this, the 1 series of rails was poured with asphalt concrete with a total thickness of 107 mm, a 80-mm row of stones made of weak asphalt concrete (cushion), a number of reinforced concrete stones of cement or durable asphalt concrete (100 mm), a series of ribbed stones (air gap - 100 mm) and cobble (for premature projectile rupture) 150-mm thickness. The gaps between the cobblestones were poured with reinforced concrete (that is, containing organic and metal particles), and if not possible - strong asphalt concrete (so that the surface of the coating was flat and smooth).
Cobblestone, filled with concrete, performed an important function - it was a layer causing premature rupture of the projectile. If the width of the slit in 25 centimeters is added to the total thickness of the coating, the machine-gun firing point could be active in the usual conditions of general combat.
What happened to the concrete shelter during the shelling of it with projectiles of larger caliber?
Monolithic shelters proved to be the most resistant to the resistance of heavy artillery shells. While concrete stone shelters (i.e. stones interconnected with cement) were destroyed, monolithic shelters resisted 155 and 240-mm projectiles, and sometimes even 270- and 280-mm caliber shells. Heavy shells often chipped off pieces of concrete, sometimes producing cracks in the latter, but in general the shelters remained unharmed. The most serious results were obtained when the projectile hit the wall at a right angle or when the arch was broken through, but this did not always lead to the destruction of the shelter. Iron reinforcement was subjected to strong bending, but remained in the mass of concrete.
Projectiles that fell nearby acted on small monolithic shelters primarily with their shock waves — they often tilted their shelters, sometimes to 45 °. There were cases that the shelters completely overturned. Filled with earth, with loopholes looking up, they became unsuitable for combat purposes. Extremely dangerous were the shells bursting under the shelters. Experience has shown that deepening a shelter of less than a meter is unacceptable.
The following was established.
The 155-mm shell destroyed concrete stone shelters, but rarely destroyed monolithic shelters. But the fire of these guns opened shelters, making them more noticeable, leading to their cracking - and thus facilitating the task of heavier artillery.
220-mm projectile sometimes pierced monolithic shelters, but did not destroy them entirely. Shells often penetrated inside, along with debris, and were torn there.
270 and 280-mm shells largely destroyed monolithic shelters, punching arches and walls, tipped shelters or deepened them into the ground. Sometimes, but very rarely, they destroyed the asylum entirely.
Concrete was a powerful help for the defender - as witnessed by the positional operations of the First World War.
Il 1. Concrete shelters and observation post fortress Osovets. 1915
Il 2. Concrete machine-gun point. Drawing
Concrete and reinforced concrete slabs and structures were actively used in the fortifications of opponents during the positional period of World War II. Of particular importance was their presence in the designs of machine-gun caponiers and polukaponiry production of both Russian and foreign engineers.
Combined caponier military engineer Berg defended against a single hit 152-mm projectile. The weight of the concrete blocks used in the construction is 5,7 thous. Pounds, the rail is 1,8 thous. Pounds, and oak beams are 600 pounds. The entire system (without iron ties and oak frames) weighed 8,1 thous. Pounds. The half-caponier of the same design weighed 6,15 thousand pounds.
The collapsible reinforced concrete machine gun polukaponir military engineer Selyutin, also protected from getting 6-inch projectile, weighed 4,6 thousand pounds, and collapsible machine-gun caponier from concrete masses military engineer Moiseev - 4,5 thousand pounds.
Of particular importance was the issue of high-quality equipment of firing points for machine guns, which are the basis of the defensive system. The most serious enemy for heavy machine guns was field light artillery. It was from this artillery that the closures for operating machine guns should have been primarily protected. During the shelling of heavy artillery, a machine gun could be covered in a heavy blindage - and here concrete and reinforced concrete also came to the aid of the defenders.
Combat practice formulated the following conclusions in relation to concrete and reinforced concrete slabs.
When in 1916 the Russian artillery bombarded the Austrian positions on the Tsuman-Olyka-Koryto front, then, according to observations of the military engineer Blueberry, the resistance of concrete and reinforced concrete bunkers was as follows.
The dugout with a coating thickness of 0,69 m (ground 0,25 m., Reinforced concrete pieces in the 2 series with a total thickness of 0,33 m, oak boards 0,10 m) 152-mm projectile pierced and destroyed.
Dugout with a coating of 0,82 m thick (0,05 m earth, 0,22 m earth bags, reinforced concrete pieces in 3 series with total 0,33 m thickness, 0,10 m boards, rails with soles up 0,12 m thick) bottom row of reinforced concrete pieces. Boards were pierced, rails ruined and bent.
The dugout with a coating of 0,82 m thick (0,20 m ground, 0,50 m reinforced concrete slabs, reinforced concrete pieces on 0,12 m rails) was hit by a 152-mm projectile.
0,87 m thick coated dugout (0,25 m ground, ferroconcrete pieces in 3 series with total 0,44 m thickness, oak bars, 0,18 m braced with thickness) 107-mm projectile pierced through, while 76-mm projectile destroyed the concrete and displaced bars, but the dugout did not break.
0,88 m thick coated dugout (0,20 m ground, 3 row of reinforced concrete slabs 0,44 m thick, 0,12 m thick rails, second row 0,12 m thick rails) 152-mm projectile, although it produced significant damage, but could not pierce.
0,95 m thick coated dugout (0,20 ground m, two rows of reinforced concrete slabs with total thickness 0,33 m, solid row 0,12 m thick rail, oak bars 0,18 m thick, solid row 0,12 m thick rail) 107-mm projectile damaged by exploding in concrete . The rails of the upper row were partially destroyed, the oak bars were damaged, but the lower row of rails was intact. Blindage is not broken.
A dugout with a coating of 1,26 m thick (0,50 m earth, reinforced concrete things in 2 series 0,22 m thick, three rows of 0,54 m logs) was punched through and destroyed by 152-mm projectile, while 76-mm projectile, although significant destruction, to break through the dugout could not.
The dugout with a coating of 1,58 m thick (1 m earth, reinforced concrete things in 1 row 0,22 m thick, 2 row logs 0,18 m and 0,22 m thick, respectively) 76-mm high-explosive projectile pierced through, but did not destroy, while 107-mm projectile destroyed this dugout.
A dugout with a coating of 1,69 m thick (1 m earth, 2 row of reinforced concrete slabs 0,33 m thick, two rows of logs 0,36 m thick) was punched through with a 107-mm projectile.
Thus, based on the foregoing, dugouts with coatings in 0,95 and 0,88 m turned out to be the most durable. Yet, this is only relative strength - in fact, none of these structures was perfect, since, despite the considerable thickness of the coatings, shells in all dugouts made serious damage. The comparative strength of the two above-mentioned dugouts is explained by the presence of pillows, causing premature rupture of the projectile and softening its effect on the lower layers of structures. The reasons for the insufficient resistance of coatings should be sought both in their structure and in the material from which they are created.
Speaking about the manufacture of concrete and reinforced concrete floors, it should be noted that the strength of cement concrete depends primarily on the quality of the material.
The latter had the following requirements.
From slowly hardening cements for combat concrete structures, it was recommended to use the so-called Portland cement. Cement must be dry. It was only in exceptional cases that wetted cement could be used, but under the condition that the lumps, crushed into powder, were calcined on the iron sheets to red heat. Even under this condition, the cement lost half its ability to quickly grab. Before use, the cement had to be tested. The normal setting of the cement should meet the following conditions: the beginning is not earlier than 20 minutes, the end is not earlier than an hour and not later than 12 hours.
Of the concrete used at the end of the war to build shelters, concrete occupied a special place on the so-called fused cement, which differs from Portland cement in that it had the ability to harden quickly, whereas the start time of the setting came much later. If Portland cement is predominantly silicate cement, then the melted cement belonged to alumina cements: its action depended on the cementing properties of calcium aluminates.
The composition of the combat concrete was supposed to include the so-called small unit. The best aggregate is coarse quartz sand mixed with fine sand. The sand must be dry and free from harmful organic matter. Allowable clay or silt content - 7% by volume. It was allowed to use a small aggregate of seeding from the crushing of hard stones, such as cobblestones.
The large aggregate was to consist of crushed stone without vegetable or other organic matter. The largest gravel size is 1 inch. The best large aggregate was considered to be gravel, which had the greatest crush resistance.
For reinforcement, it was recommended to use iron of circular cross-section, and best of all, mild steel.
The main disadvantage of cement concrete was considered a long time of its hardening. In some cases, asphalt concrete was allowed to be used instead of cement concrete, the strength of which was expressed in the resistance of one square centimeter 250-kg.
For internal interlayers (pillows), less durable concrete was suitable for gravel, fine sand, asphalt powder and asphalt resin.
For shelter machine gun was considered sufficient to protect him from the 76-mm projectile. To do this, the 1 series of rails was poured with asphalt concrete with a total thickness of 107 mm, a 80-mm row of stones made of weak asphalt concrete (cushion), a number of reinforced concrete stones of cement or durable asphalt concrete (100 mm), a series of ribbed stones (air gap - 100 mm) and cobble (for premature projectile rupture) 150-mm thickness. The gaps between the cobblestones were poured with reinforced concrete (that is, containing organic and metal particles), and if not possible - strong asphalt concrete (so that the surface of the coating was flat and smooth).
Cobblestone, filled with concrete, performed an important function - it was a layer causing premature rupture of the projectile. If the width of the slit in 25 centimeters is added to the total thickness of the coating, the machine-gun firing point could be active in the usual conditions of general combat.
What happened to the concrete shelter during the shelling of it with projectiles of larger caliber?
Monolithic shelters proved to be the most resistant to the resistance of heavy artillery shells. While concrete stone shelters (i.e. stones interconnected with cement) were destroyed, monolithic shelters resisted 155 and 240-mm projectiles, and sometimes even 270- and 280-mm caliber shells. Heavy shells often chipped off pieces of concrete, sometimes producing cracks in the latter, but in general the shelters remained unharmed. The most serious results were obtained when the projectile hit the wall at a right angle or when the arch was broken through, but this did not always lead to the destruction of the shelter. Iron reinforcement was subjected to strong bending, but remained in the mass of concrete.
Projectiles that fell nearby acted on small monolithic shelters primarily with their shock waves — they often tilted their shelters, sometimes to 45 °. There were cases that the shelters completely overturned. Filled with earth, with loopholes looking up, they became unsuitable for combat purposes. Extremely dangerous were the shells bursting under the shelters. Experience has shown that deepening a shelter of less than a meter is unacceptable.
The following was established.
The 155-mm shell destroyed concrete stone shelters, but rarely destroyed monolithic shelters. But the fire of these guns opened shelters, making them more noticeable, leading to their cracking - and thus facilitating the task of heavier artillery.
220-mm projectile sometimes pierced monolithic shelters, but did not destroy them entirely. Shells often penetrated inside, along with debris, and were torn there.
270 and 280-mm shells largely destroyed monolithic shelters, punching arches and walls, tipped shelters or deepened them into the ground. Sometimes, but very rarely, they destroyed the asylum entirely.
Concrete was a powerful help for the defender - as witnessed by the positional operations of the First World War.
Il 1. Concrete shelters and observation post fortress Osovets. 1915
Il 2. Concrete machine-gun point. Drawing
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