Foundation cast in situ with a concrete casing

Abstract

 The finding relates to a modular prefabricated foundation to be cast in place with a concrete casting, wherein each module or base element comprises at least two parallel elements (11) made of concrete, called outer slabs, a plurality of iron reinforcement stirrups (12) arranged in parallel and at suitable distances from one another on planes orthogonal to the longitudinal axis of the outer slabs, and each having the opposed sides buried in their concrete, a plurality of reinforcement rods (13) buried longitudinally and for the entire length of the outer slabs, and means for the application of belts, ropes, chains or the like for handling and laying the foundation on a lean concrete bed (20) arranged in the excavation beforehand.

Description

[0001] The present finding relates to the building sector and in particular, it relates to a modular prefabricated foundation to be cast in place with a concrete casting.

[0002] As known, continuous foundations are currently realised using wooden or iron formworks that are collected from a store, carried to the yard, and laid using poles, nails, Trieste nails, etc. After the foundation has been formed, the formworks must be removed, cleaned and carried to the store or installed again. This requires considerable labour, long times, very large excavations to allow the laying of the formworks and of the formwork-holding nails. Moreover, the workers directly work into the excavation, so in case of building of retaining walls, basement walls, or continuous foundations in deep ditches, they are exposed for a long time to the danger of being buried.

[0003] Object of the present finding is that of proposing a modular prefabricated foundation which should allow the realisation of continuous foundations made of reinforced concrete with a considerable saving in terms of means, labour, scraps, and with a smaller number of processing operations compared to the current methods.

[0004] Another object of the finding is that of providing a modular prefabricated foundation which should allow the workers to operate safely, limiting the use of machines and obtaining a finished element having such quality as cannot be reached with current formworks, while at the same time ensuring a reduction of the costs both directly ascribable to the finished product and relating to the general costs incurred by any company when they have to create a continuous foundation.

[0005] These and other objects and advantages of the finding are achieved with a modular prefabricated foundation to be cast in place with a concrete casting, wherein each module or base element of the foundation comprises at least two parallel concrete elements, called outer slabs, a plurality of iron reinforcement stirrups arranged in parallel and at suitable distance from one another on planes orthogonal to the longitudinal axis of the outer slabs and each having the opposed sides buried in their concrete, a plurality or reinforcement rods buried longitudinally and for the entire length of the outer slabs, and means for applying belts, ropes, chains or the like for handling and laying the foundation on a lean concrete bed arranged in advance into the excavation.

[0006] Further details of the finding will appear more clearly from the following description, made with reference to the attached indicative and non-limiting drawings, wherein:

Fig. 1 shows a perspective view of an element of the prefabricated foundation under discussion;

Fig. 2 shows the cross section of the foundation;

Fig. 3 shows a section of the foundation according to the line III-III in Fig. 2;

Fig. 4 shows a section of the foundation according to the line IV-IV in Fig. 2;

Fig. 5 shows the handling of the prefabricated foundation element;

Fig. 6 shows the prefabricated foundation laid on lean concrete;

Fig. 7 shows a cross section of the foundation provided with a side water collection and drainage channel; and

Fig. 8 shows a cross section of a variant of embodiment of the foundation.

[0007] The modular prefabricated foundation under discussion, of which a base module is described and illustrated, essentially comprises two parallel elements 11 made of concrete, called outer slabs, a plurality of iron reinforcement stirrups 12, each having a rectangular shape, arranged in parallel and at suitable distances from one another on planes orthogonal to the longitudinal axis of the outer slab, with the smaller sides 12' buried in concrete, a plurality of reinforcement rods 13 longitudinally buried in the outer slabs for their entire length and arranged at the tops of the reinforcement stirrups 12, and at least four anchoring elements 14, such as slots, bushes and the like, made of iron or steel, fastened in pairs to the internal sides of the outer slabs for handling and laying the prefabricated foundation by belts, ropes or chains provided with catch.

[0008] The concrete outer slabs 11 have the main function of guaranteeing the necessary bar cover for the bearing reinforcement consisting of stirrups 12 and containing the concrete cast. In particular, outer slabs 11 protrude from top and bottom of the reinforcement stirrups 12 so as to guarantee a suitable bar cover to the concrete that will be cast in the formwork.

[0009] Moreover, the outer slabs are sized to stand the stresses exerted on the article, based on the exposure class relating to the environmental conditions of use of the foundation, from which the minimum covering to be ensured to the structural reinforcements, in compliance with the regulations in force, and the diameter of the reinforcement rods 13 buried therein, derive.

[0010] The reinforcement stirrups 12 are the connecting element between the two outer slabs 11, thereby ensuring the article's stiffness and dimensional stability, and at the same time, the foundation bearing reinforcement. The diameter and step of stirrups 12 depend on the load weighing on the foundation, the size of the foundation, and the carrying capacity of the ground where the structure is laid. Moreover, the brackets can exhibit visual references useful during the laying in order to ensure a quick alignment of the foundation elements and an accurate insertion of any jutting rods for elevation walls resting on the foundation.

[0011] The diameter and number of longitudinal reinforcement rods 13 is determined on the basis of the carrying capacity of the ground on which the foundation lays, of the stirrup diameter and of the geometry of the masonry resting on the foundation itself. In order to ensure continuity between adjacent elements of the prefabricated foundation, the longitudinal rods of each element are longer than the element itself, so as to ensure the necessary superimposition length, as required by the technical regulations in force, with the longitudinal rods of the nearby elements. For convenience and safety reasons, the portion of rod 13' in excess of the outer slab length is bent at an angle of 100° towards the inside of the foundation. To this purpose, the longitudinal rods have such diameter as to allow - once the adjacent elements have been laid - an easy straightening and superimposition of the same.

[0012] Feet 15 can be buried in the concrete of outer slabs 11 in order to guarantee - during the realisation of the foundation - a suitable and even bar cover to the stirrups and the reinforcement rods.

[0013] The foundation under discussion can also be provided with tie rods of iron or steel 16 that, attached in the plane of stirrups 12, during the handling, transport and laying steps strengthen the articles that due to their weight, size and geometry are not very steady, since the stiffness of the stirrups is not sufficient to ensure the stability of the foundation yet to be laid.

[0014] The same article strengthening function can be carried out - in replacement or in combination with the tie rods - also by steel wires 17 laid on planes perpendicular to stirrups 12.

[0015] As shown in Fig. 7, along one of the two outer slabs 11 it is possible to obtain a side channel 18 for water collection and drainage, for collecting the meteoric waters that accumulate at the base of the foundation, thereby avoiding the ascent of humidity along the walls.

[0016] Between the two side outer slabs 11 it is also possible to provide for a base horizontal outer slab 19 - Fig. 8 - that allows the realisation of a foundation in especially difficult conditions, such as high stratums, ascending water in the excavation area, without being forced to expensive branching that could also cause the collapse of neighbouring grounds.

[0017] The operations to be carried out at the yard to create a foundation starting from the prefabricated element under discussion are:

• realising the excavation in ditch or in any case, at the fixed height;
• laying of a lean concrete bed layer 20, on which the prefabricated element will be laid, as required by the technical regulations in force for all types of foundations;
• laying of the prefabricated elements along the alignments traced beforehand, optionally using an adjustment axis 21;
• inserting any additional longitudinal reinforcements if required by the static computations;
• filling the outer slabs with a concrete casting having suitable resistance; and
• laying underground again, after ensuring the necessary concrete curing.

[0018] The prefabricated foundation under discussion is suitable for several applications, among which for example the creation of continuous foundations for bearing walls, boundary walls, reinforced concrete walls, the quick realisation of panel-holding foundation girders, tearing of foundations for retaining walls of any kind.

[0019] In the practice, the prefabricated foundation proposed herein allows the creation of continuous foundations without using formworks and without creating and inserting the reinforcement cage, since the outer slabs of the prefabricated element acts as disposable formwork which at the same time ensures the necessary bar cover. The reinforcement cage, suitably sized on the basis of the ground and of the loads, is buried in the outer slabs, thereby ensuring dimensional stability to the article.

[0020] It should be noted that thanks to its particular geometry, the foundation has a low weight, such as to allow handling and laying using simply cranes, telescopic arms or crane arms directly mounted on lorry.
From the above description it is clear that using this article considerably easies and quickens the processing steps required to create a foundation compared to the conventional methods. In brief, the advantages of the foundation proposed herein compared to the current art, as regards continuous foundations cast in place, are:

• total elimination of wooden and iron formworks;
• elimination of all machining operations to be carried out on the formworks, that is, transport to the yard, laying, removal (dismantling of the formworks), cleaning and return to the store or other place;
• elimination of the hardware, nails required to fix the formworks, wooden Trieste nails, iron crop ends for fixing in gravelly grounds, and subsequent scrap;
• reduction of the yard labour for the formwork formation, dismantling and handling;
• elimination of the formwork storage area at the yard;
• possibility of realising a foundation having certain and very accurate dimensional characteristics, guaranteeing a bar cover matching exactly that of the design, and avoiding concrete wastes that currently occur due to the deformation of the wooden formworks or casting directly into the excavations;
• a suitable detachment of the rods and of the stirrups from the lean concrete bed, so as to allow an easy laying of any additional rods, both longitudinal and transversal;
• elimination of the works relating to the formation and laying of the reinforcement cages;
• the possibility of realising a quick and accurate alignment of the prefabricated elements and of the jutting rods for the upper walls, thanks to the visual reference signals obtained by painting the centre line of the stirrups of the cage inside the article;
• the possibility of making a narrower excavation compared to that currently required to cast the same foundation, since the latter requires technical areas for laying formworks and formwork fixing nails;
• the solidity of the outer slabs of the article under discussion which, thanks to the constraint of the reinforcement stirrups, can retain the ground thrusts in case of collapse of the excavation walls, avoiding continual cleaning and maintenance of the formworks;
• the drastic reduction of the foundation laying times compared to the conventional laying methods, which is very advantageous for all works that expose the workers to the danger of being buried (retaining walls, basement walls, continuous foundation in deep ditches), since it reduces the exposure to such dangers and allows the creation of the foundation without the need to making the workers work directly into the excavation in a ditch to create conventional formworks: the prefabricated element, handled by a crane or a telescopic arm, thanks to its light weight is directly laid on the lean concrete bed into the excavation and can immediately receive the concrete casting;
• the realisation of foundations of very accurate and constant dimensions, an important aspect from the technological point of view (sure performance) both from the accounting and quotation point of view (certainty of the material actually used without any waste of damaged formworks, excess concrete and iron scrap).

Claims

1. Modular prefabricated foundation to be cast in place with a concrete casting, characterised in that each module or base element comprises at least two parallel elements (11) made of concrete, called outer slabs, a plurality of iron reinforcement stirrups (12) arranged in parallel and at suitable distances from one another on planes orthogonal to the longitudinal axis of the outer slabs, and each having the opposed sides buried in their concrete, a plurality of reinforcement rods (13) buried longitudinally and for the entire length of the outer slabs, and means for the application of belts, ropes, chains or the like for handling and laying the foundation on a lean concrete bed (20) arranged in the excavation beforehand.

2. Modular prefabricated foundation according to claim 1, wherein the outer slabs (11) protrude from top and bottom of the reinforcement stirrups (12) so as to guarantee a suitable bar cover to the concrete casting that will be cast.

3. Modular prefabricated foundation according to claim 2, wherein the longitudinal reinforcement rods (13) are arranged at the tops of the reinforcement stirrups (12) and are longer than the outer slabs, so as to guarantee the necessary superimposition length with the longitudinal rods of the adjacent elements or modules, the iron portion in excess of the length of the outer slabs being normally bent towards the inside of the foundation.

4. Modular prefabricated foundation according to any one of the previous claims, wherein the reinforcement stirrups (12) also exhibit visual references intended to ensure a quick alignment of the elements or modules of the foundation and an accurate insertion of any jutting rods for the elevation walls resting on the foundation.

5. Modular prefabricated foundation according to any one of the previous claims, wherein two feet (15) are buried in the concrete of the outer slabs (11) to ensure - during the realisation of the foundation - a suitable and even bar cover to the reinforcement rods and stirrups.

6. Modular prefabricated foundation according to any one of the previous claims, further comprising a plurality of iron or steel tie rods (16) extending between the elements of the outer slab in the plane of the stirrups (12) for further formwork stiffening.

7. Modular prefabricated foundation according to any one of the previous claims, further comprising a plurality of steel wires (17) laid in planes perpendicular to the stirrups (12) for further foundation stiffening.

8. Modular prefabricated foundation according to any one of the previous claims, wherein between the two outer slabs (11) there is provided a third base horizontal outer slab (19) intended to lay on the lean concrete bed.

9. Modular prefabricated foundation according to any one of the previous claims, characterised in that along one of the two outer slabs (11), a side channel (18) is obtained for collecting and draining the meteoric waters accumulating at the base of the foundation.

Drawing