US2942321A - Means for making and heat curing concrete structures - Google Patents

Description

June 28, 1960 a. s. PINTER ETAL 2,942,321

MEANS FOR MAKING AND HEAT CURING CONCRETE STRUCTURES 2 She i s-sheaf; 1

Filed Aug. 23, 1956 INVENTORS: GEORGE SUPINTER and INNIS OROURKE JR.

AGENT June 28, 1960 5, PINTER ETAL MEANS FOR MAKING AND HEAT CURING CONCRETE STRUCTURES Filed Aug. 23, 1956 2 Sheets-Sheet 2 GEORGE S. PINTER 0nd INNIS OROURKE JR.

INVENTORS AGENT Sttes 4 Claims. c1. 2s--12'1 Our present invention relates to a means for making concrete structures, especially elongated channel slabs with diaphragms'.

An object of our invention is to provide a novel and improved mold for producing channel slabs of the character referred to.

Another object of this invention is to provide an advantageous means for curing a channel slab or similar concrete structure. i

A feature of our invention resides in the provision of a, mold including one or more hollow, dome-shaped inserts resting on a support with their concavity facing downwardly, these inserts serving to form channels or recesses in a concrete slab subsequently poured over them. preferably, especially in the-case of long. structures or of multiple molds, these insertsare movable- (at least within certain limits) on their support so as to allow for relative sliding motion when the usual prestressing elements are released against the hardened concrete.

According to another feature of this invention, we expedite the curing of the poured concrete bylive steam which is admitted directly to the hollow underside of the inserts and also passes underneath the support and around the slab to the upper surface thereof, being guided in its travel by a suitable enclosure, such as a tarpaulin, covering the slab. The steam condenses on the concrete and counteracts the partial dehydration occurring as the result of the heating action which tends to drive off the water particularly in the upper portion of the slab; this prevents case-hardening and insures thorough and uniform curing of the concrete.

A suitable support for the hollow inserts consists of a pair of parallel soflit plates defining a gap of adjustable width through which the steam designed to heat the interior of the inserts may pass; these soffit plates form part of the mold and may each have hinged to it a re- 1 ate i Fig. 2 is a longitudinal sectional view ofone of, the inserts forming part of the mold of Fig. 1;

Fig. 3 is a sectional view taken on the line 3-3 of Fig. l and showing the mold after the concrete has been poured;

Fig. 4 is a cross-sectional view, drawn to a larger scale, of the moldand the slab of Fig. 3; i

Fig. 5 is a perspective view of a' finished slab from the mold of the preceding figures; and

Fig. 6 is a fragmentary longitudinal sectional view of a slightly modified mold embodying the invention.

The mold shown in Figs. l,v 3 and-.4 comprises a pair of sofiit plates 10a, 10b" made from prestressed concrete, the respective p'restressing elements being indicated at 11aran'd11b- These soffit plates are adjustably supported on wooden cross-beams lza and 12b between which there is disposed a perforated steam pipe 13 aligned with the gap 14 separating the two plates. One or more wedge pieces 15 may be inserted in the gap 14 to maintain the spacing between the plates 10a and 10b.

Hingedly securedto each soflit plate 10a, 10b is "a respective side wall 16a,'16b also extending along the full length of the mold. End plates 17 (only one shown) and one or more partitions 18 divide the mold into lon'gi ' tudin'ally adjoining sections 19, 19 for the simultaneous pouring of a corresponding number of slabs 20, 2'0 (Figl 3). The sidewalls 16a, 16b are formed with slotsto receive pins 21a, 21b (Fig-4) fromthe end plates 17 and from the partitions 18,-sui table fastening means suchas wedges serving to keep these end plates and "partitions locked to the side walls during the hardening of the slabs. Each partition 18 is of hollow constructionand its interior is accessible when'the side walls 16a, 165 are swung out wardly upon removal of these wedges, as illustrated in dot-dash lines in Fig. 4, so that the prestressing rods or cables 22a and 22b, extending the length of the molds, can be severed between slabs by the use of a suitable cutting tool, such as a blow torch.

Each mold section 19, 19 further comprises a pair of longitudinally spaced, dome-shaped inserts 23 designed to form within the slab 20 or 20 two recesses 24 separated by a diaphragm 25. These inserts are given a draft suflicient to enable ready removal from the hardened slab;

they are also formed with expansion joints 26 allowing spective side plate adapted to be swung outwardly when the finished slab is to be removed. We have found, in

accordance with a further feature of the present invention, that such soflit plates can conveniently be in the form of solid slabs of prestressed concrete, presenting smooth upper and lower surfaces to receive the poured concrete and to enable unhindered passage of the steam. Moreover, such plates are heavy enough to rest by their own weight on an array of supporting timbersor the like so that no special anchorage is required therefor when the slab is to be lifted ofi its mold. Slabs of different widths may be readily produced by changing the spacing between these plates.

The above and other objects, features and advantages of our invention will become more fully apparent from the following detailed description given with reference to the accompanying drawing in which:

Fig. 1 is a top plan view of part of a multiple mold serving for the simultaneous production of a plurality of prestressed channel slabs each with an intermediate diaphragm;

longitudinal shrinkage of the concrete during hardening. Each expansion joint comprises a layer of cork 27 held between internal flanges 28, 29 of the two relatively movable shell portions together constituting insert 23.

In operation, exposed portions of the gap 14 between soffit plates 10a, 10b are covered by fiat strips 30 whereupon the concrete is poured upon the suitably lubricated .sofiit plates within the mold. Tension is imparted to the prestressing elements 22a, 22b in a manner well known per se. Next a tarpaulin 31 is placed over the poured concrete and steam is admitted into pipe 13, escaping through the perforations thereof. Part of the steam rises 'by way of gap 14 to heat the metal of the inserts 23;

another part passes between the beams 12a, 12b and continues under the tarpaulin 31 toward the top face of slabs 20, 20' to heat and, at the same time, to humidity the outer surface thereof. When the concrete has been sufiiciently cured, the side walls 16a, 16b are swung out, the prestressing elements 11a, 11b are severed'at partitions 18 and the slabs are ready to be lifted out of the mold by means of cranes (not shown) engaging wire loops 32 which had been imbedded in the concrete during the molding operation; this has also been illustrated in dot-dash lines in Fig. 4. The loops 32 may be subsequently cut or burned away.

In order to facilitate the removal of the inserts 23 from the slab 20 when the latter is lifted, We may providev each insert with a series of lugs 33a, 33b from which anchor cables 34 extend through passages in soffit plates 10a, 10b with sufiicient slack to allow some longitudinal displacement of the inserts relative to these plates. Another arrangement serving the same end has been illustrated in Fig. 6 where a helix'35, known as a Richmond anchor screw, has b'eenimbedded in the slab prior to its hardening and serves as a socket for a screw-threaded bolt 36 which, in the hardened condition of the concrete, can be rotated to pushthe insert 23 out of the slightly raised slab; it will be understood that a number of such bolts may be provided at various locations to exert symmetrical pressure upon the insert.

In addition, we prefer to provide a separate framework 37 (Fig. 4) to help sustain the weight of the concrete. This framework, positioned within each insert 23, is so dimensioned as to touch the top of the dome whereby deformations of the, insert will be avoided.

The invention is, of course, not limited to the specific embodiments described and illustrated but may be realized in various modifications and adaptations without departing from the spirit and scope of the appended claims.

We claim:

1. A mold for, making a concrete slab having a bottom recess, comprisinga pair of elongated, substantially parallel sofiit plates forming a narrow longitudinal gap therebetween, side walls rising from said sofiit plates and defining a mold cavity therewith, atleast one domeshaped, elongated insert resting on said sofiit plates above said gap with its concavity facing downwardly, perforated conduit means extending longitudinally underneath said gap in alignment therewith for admitting a heating fluid therethrough into said insert, and covering means within said mold cavity bridging said sofiit plates and closing said gap externally of said insert.

2. A mold according to' claim 1 wherein said insert has at least limited horizontal mobility on said soffit plates.

3. A mold for making a concrete slab having a bottom recess, comprising a pair of elongated, substantially parallel soffit plates forming a narrow longitudinal gap therebetween, side walls rising from said soflit plates and defining a mold cavity therewith, at least one dome-shaped, elongated insert resting on said sofiit plates above said gap with its concavity facing downwardly, perforated conduit means extending underneath said gap for admitting a heating fluid therethrough into said insert, covering means within said mold cavity bridging said sofiit plates and closing said gap externally of said insert, and hood means open toward said conduit means and surrounding said side walls and said insert for guiding part of said fluid along the exterior of said mold cavity.

4. A mold according to claim 3 wherein said side walls are respectively hinged to said soffit plates.

References Cited in the file of this patent UNITED STATES PATENTS 1,188,759 Guay June 27, 1916 1,925,733 Pandolfi Sept. 5, 1933 1,948,093 Baird et al Feb. 20, 1934 1,951,344 Caldwell Q Mar. 20, 1934 2,114,048 Davis Apr. 12, 1938 2,170,936 Baron Aug. 29, 1939 2,250,020 Henderson July 22, 1941 2,306,548 Leemhuis Dec. 29,1942 2,414,011 Billner Jan. 7, 1947 2,437,003 Ruegg Mar. 2, 1948 2,495,100 Henderson Jan. 17, 1950 2,533,479 Leggat Dec. 12, 1950 2,671,941 Fabian Mar. 16, 1954 2,807,071 Francis et al. Sept. 24, 1957 2,823,442 Miller et al. Feb. 18, 1958 FOREIGN PATENTS 749,124 7 Great Britain May 16, 1956

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