GB1576515A - Sulphur cements and concretes made therefrom - Google Patents

Description

(54) SULPHUR CEMENTS AND CONCRETES MADE THEREFROM (71) I, ALAN HEARD VROOM, a citizen of Canada, of 3015 58th Avenue, S.E., Calgary, Alberta, Canada T2C OB4 do hereby declare the invention for which I pray that a Patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to sulphur cements and concretes produced therefrom.

Sulphur cements have a long history of use in specialized applications. Thus, Canadian Patent No. 71,686 issued to George McKay provided a sulphur-containing composition useful for sealing purposes at a joint, for roofing purposes, for the forming of ornamental figures, and for the coating of the exposed surfaces of iron or steel steps, the composition including sulphur, brick-dust, tin, lead, bismuth, plaster of paris and borax.

However, attempts to make durable, high strength concrete-like materials from sulphur cements have encountered cost, durability, or other difficulties that precluded commercialization. Proposals have been made to increase the strength of sulphur as a bonding agent by the addition of coal, sand or pumice thereto. Moreover pecular characteristics were proposed to be imparted by the addition thereto of bitumens, metallic sulphides, and fibrous materials.

Also United States Patent No. 3,459,717 patented August 5, 1969 by J.B. Signouret, provided a sulphur-based plastic composition of improved fireproofing characteristics by the incorporation, into the molten sulphur, of a diester of dithiophosphoric acid and an ethylenic hydrocarbon. A major problem in the connercialization of sulphur cements has been the progressive embrittlement and subsequent crumbling, under thermal stress, of the sulphur cement. The cause of this embrittlement is believed to be the progressive crystallization of the initially amorphous sulphur. Partial inhibition of the crystallization has been achieved through various organic and inorganic additives.

Thiokol products (Trade Mark of Thiokol Chemical Corporation for olefin polysulphides) have been used to stabilize the amorphous form of sulphur in sulphur cements. Thus, Canadian Patent No. 356,181 issued February 25, 1936 to W.W. Duecker, purports to provide a solution to the problem by dissolving, in the sulphur, certain olefin polysulphides or polymerization products thereof. These cements, however, were not practical on a large scale due to their high cost and disagreeable odour. Dicyclopentadiene has good stabilization properties and more favourable economics, but imparts a nauseating odour to the sulphur cement and has other shortcomings, eg: its vapour, even at low concentrations, is highly toxic (see for example Kinkead et al, "The Mammalian Toxicity of Dicyclopentadiene", Toxicology and applied Pharmacology,20 552-561 (1971) ).Moreover, discyclopentadiene requires refluxing with molten sulphur to avoid excessive loss of material in vapour form.

One object of this invention is to provide a sulphur cement composition which alleviates some of the disadvantages of the compositions of the prior art.

According to the present invention there is provided a sulphur cement pre-mix composition (a) sulphur and (b) up to 10% by weight of the sulphur of a bonding agent adapted to stabilize said sulphur cement against progressive embrittlement and subsequent crumbling under thermal stress, said bonding agent comprising either an olefinic hydrocarbon polymer material derived from petroleum, and having a non-volatile content greater than 50% by weight and a minimum Wijs iodine number of 100 cg/g, such polymer material being capable of reacting with sulphur to form a sulphur-containing polymer, or the sulphur-containing reaction product of an olefinic hydrocarbon polymer material derived from petroleum, and having a non-volatile content greater than 50% by weight and a minimum Wijs iodine number of 100 cg/g with a smaller proportion of sulphur than that present in the sulphur premix composition.

In a first preferred embodiment said bonding agent comprises said head reactive olefinic hydrocarbon polymer material derived from petroleum.

In another preferred embodiment the weight ratio of the sulphur reacted with liquid olefinic hydrocarbon polymer is 2.45:1 or greater. In another embodiment the amount of the bonding agent is present in an amount of 1 to 5% of the total sulphur by weight.

Further the sulphur cement may include an additive to provide fire resistance, eg: 1, 5, 9-cycloclodecatriene, or the reaction product of diphenoxyphosphinic acid with sulphur and with a-methyl styrene.

This invention also provides a sulphur cement composition comprising (a) sulphur, which has been melted to contain dispersed therein (b) up to 10% by weight of the sulphur, of a bonding agent adapted to stabilize said sulphur cement against progressive embrittlement and subsequent crumbling under thermal stress, said bonding agent comprising either an olefinic hydrocarbon polymer material derived from petroleum, and having a non-volatile content greater than 50 % by weight and a minimum Wijs iodine number of 100 cg/g such polymer material being capable of reacting with sulphur to form a sulphur-containing polymer, or the sulphur-containing reaction product of an olefinic hydrocarbon polymer material derived from petroleum, and having a non-volatile content greater than 50% by weight and a minimum Wijs iodine number of 100 cg/g with a smaller proportion of sulphur than is required in the final sulphur cement.

The invention also provides a sulphur concrete comprising a sulphur cement pre-mix composition and a sulphur cement composition of the invention along with a natural or manufactured aggregate.

In a variant thereof, the ratio of sulphur cement to aggregate is 20-64 : 80 - 36.

The bonding agent for said sulphur cement may comprise said sulphur containing reaction product of an olefinic hydrocarbon polymer derived from petroleum, and having a nonvolatile content greater than 50%byweight and a minimum Wijs iodine number of 100 Cg/g with a smaller proportion of sulphur than is required in the sulphur cement premix composition.

By other variations, the sulphur cements used in the sulphur concretes may include an additive to provide fire resistance, eg: 1,5,9-cyclododecatriene, or the reaction product of diphenoxyphosphinic acid with sulphur and with a-methyl styrene.

The present invention in one of its aspects provides a sulphur cement which can be used for the manufacture of sulphur concrete having numerous applications in the construction field.

It is substantially free from the disadvantages of the products described previously and has positive advantages, as will be described hereinafter.

The sulphur cement according to one aspect of this invention as described above employs, as an essential stabilizer, the chemical stabilizer derived from petroleum. The proportions of the chemical stabilizer may be varied depending upon the end use of the cement.

The chemical stabilizer used in the compositions of aspects of this invention is any of the olefinic hydrocarbon polymers derived from petroleum having a non-volatile content greater than 50 % by weight and a minimum Wijsiodine number of 100 cg/g capable of reacting with sulphur to form a sulphur-containing polymer. The chemical stabilizer is used in amounts up to 10% by weight of the total sulphur, and more especially in the proportion of 1 - 5 % of the total sulphur by weight. The amount of such chemical stabilizer required depends upon the end use of the cement and the properties desired.

The chemical stabilizer can be incorporated into the final cement mix by several reaction routes within the ambit of this invention. Preferably, the chemical is prereacted at approximately 140"C for 30 minutes with a smaller proportion of sulphur than is required in the final mix. The resulting concentrate can then be either stored for future use or dissolved in the residual sulphur (liquefied) required for the final mix at the mixing temperature.

While any chemical stabilizer having the above properties may be used, typical such chemical stabilizers are those known by the following Trade Marks: RP220, a product of Exxon Chemical Co.; RP020, a product of Exxon Chemical Co.; CTLA, a product of Enjay Chemical Co.; and Escopol a product of Esso Chemical AB (Sweden); all identifying a heat reactive olefinic liquid hydrocarbon obtained by partial polymerization of olefins.

In order to provide a sulphur-containing cement of aspects of this invention having a workable consistency, it is desirable to add a finely divided, viscosity increasing material, for example, fly ash, gypsum, dolomite, pulverize limestone, a mixture of pyrites and pyrrhotites, or rock dust of a size up to minus 100 mesh (US), but preferably of a size of minus 200 mesh (US). Fly ash from the burning of hydrocarbon fossil fuels and generally in the form of tiny hollow spheres called cenospheres and consisting of major amounts of silicon oxide and aluminum oxide, with smaller quantities of ferric oxide, calcium oxide, magnesium oxide, sodium oxide, potassium oxide and carbon, is particularly effective in this regard due to its small particle size, shape and surface texture.It has been found to impart an extra measure of durability to the final cement, independent of its source, and serves the dual function of viscosity increaser and sulphur cement stabilizer. Depending upon the degree of fineness of the fly ash and the consistency desired, an amount up to one and one-half times the total weight of the sulphur may be beneficially added.

A notable feature of the sulphur cement of this invention is that such sulphur cement does not require high purity sulphur and can be made with off-grade sulphur containing hydrocarbon impurities, blow dirt, and other "contaminants". The presence of hydrogen sulphide (H2 S) in the sulphur has been determined to be detrimental, but the simple process of remelting the sulphur usually reduces the concentration of this contaminant to harmless levels.

The resulting cement of this invention is substantially resistant to the corrosive influences of salts, most acids, and solvents. Hot oxidizing acids at high concentrations and strong concentrated bases do attack the cement, however. The cement is essentially impervious to moisture penetration. It provides good thermal insulation, is used hot with no water, and develops high strength within hours of cooling. Thus, sulphur concrete pouring can take place in winter without the usual freezing problems of conventional portland cement concretes, which require the presence of water for setting.

A wise range of aggregates can be used with the sulphur cement of this invention as described above, to make strong, durable concretes of another aspect of this invention.

Among the conventional aggregates useful herein for preparing the concrete of another aspect of this invention are sand, crushed cinders, brick dust, foundry sand, crushed quartzite gravel, crushed limestone, siliceous tailing said, expanded shale, expanded clay, crushed barite, crushed brick, crushed portland cement concrete, and crushed granite. Preferably, the aggregate particles are of angular shape and of rough surface texture as can be obtained by crushing. With a sufficiently fluid mix, or through use of heated molds, the mold surfaces are reproduced precisely. Where sulphur is readily available, the cement and the concrete of aspects of this invention can be produced at competitive costs.The compatibility of the sulphur cement with aggregates of wide ranging densities permits the design of concretes having very wide ranges of densities ranging, for example, as low as 10 Ibs. per cubic foot, to ranges between 100 lbs. per cubic foot and 230 lbs. per cubic foot, or even as high as 500 lbs.

per cubic foot. The sulphur concrete of an aspect of this invention can be reinforced in conventional fashion by the use of steel, asbestos or glass fibre, or other reinforcing materials.

The sulphur concretes of this invention tend to be self-extinguishing with ash contents approaching two-thirds the weight of sulphur and can be made fire resistant, and/or to inhibit the formation of SO2 when heated, by the addition of suitable additives, e.g., 1,5,9cyclododecatriene or the reaction product of diphenoxyphosphinic acid with sulphur and a-methyl styrene, in the manner taught by United States Patent No. 3,459,717.

The sulphur concretes of this invention derived from the sulphur cements of this invention are not refractory materials and will soften and melt if heated above 1200C., although the rate of melting is slow due to the low thermal conductivity imparted to the concrete by the sulphur.

The principles developed for the grading of aggregates used in conventional concretes are essentially unchanged for sulphur concretes of aspects of this invention except for the much greater tolerance of fines and silt of the sulphur concretes. 80% of the ultimate concrete strength is developed in one day; virtually 100%of the ultimate strength is realized after four days.

These sulphur concretes may be used as a construction material for a wide variety of precast and poured-in-place applications such as, for example, sidewalks, steps, parking curbs, highway median barriers, sewer pipe, septic tanks, pilings, footings, foundations, pavements, industrial tanks, ponds, swimming pools, etc. The hot sulphur concrete mix may also be pumped and sprayed for waterproof and erosion proof coatings on earth-fill dikes, highway and railway embankments and as linings for irrigation canals, farm ponds, etc.

The examples given below are intended only to illustrate aspects of the present invention.

Samples 1 - 7. Prereaction of the Hydrocarbon Stabilizers The hydrocarbon stabilizer (at 25"C) was added to molten sulphur (at 1400C) with vigorous stirring. Heat was applied only to maintain a reaction temperature of 140 to 1500C.

At this temperature reaction times were in the order of 15 to 40 minutes. The progress of the reaction could be monitored by the degree of homogeneity of the mix, by careful observation of the temperature of the reaction mixture, or by observation of the increasing viscosity of the mixture. At sulphur-stabilizer ratios of less than 4:1 by weight, control of the addition rate was required to prevent the exothermicity of the reactions raising temperatures above 155"C., at which point hydrogen sulphide (H2S) was evolved with consequent foaming and degradation of the product.

When reactions were conducted under the above-prescribed conditions, the product was a sulphur-containing polymer which, on cooling, possessed glass-like properties which were retained indefinitely.

The properties of the olefinic hydrocarbon polymers used for illustrative purposes herein are given in Table 1. Reaction conditions for the preparation of seven sulphur-containing polymers are contained in Table 2.

Table 1 RP220 RP020 CTLA Escopol Flash Point (COC) minimum 150 138 150 125 Gravity (API) maximum 4 4.0 9.6 3 Iodine Number (100 cg/g minimum) 200 160 255 135 Non-volatile Matter (% by weight) 80 70 83 75 (3 hrs. @ 105"C) minimum Density (15.6"C.) gm/cc 1.05 1.04 1.00 1.03 Viscosity (cst/1000C) maximum 25 26 28 25* *cst/50 C.

Table 2 Reaction Conditions for the Preparation of Sulphur-containing Polymers Stabilizer Weight (Kg) Reaction Reaction Product Sample (STB) STB S Temp.( C) Time (Min) Colour 1 CTLA 12.5 37.5 140 30 dark brown 2 CTLA 8.3 41.7 140 40 dark brown 3 Escopol 10.0 40.0 150 15 light brown 4 Escopol 14.5 35.5 140 20 light brown 5 RP220 8.3 41.7 150 15 dark brown 6 RP220 12.5 37.5 140 20 dark brown 7 RP020 12.5 37.5 140 15 dark brown Examples 1 to 9 - Sulphur Cements and Concretes Derived Therefrom A first series of sulphur cements, Examples 1 through 9, were prepared by addition of: the required sulphur (less than contained in the prereacted material), the prereacted material, and lastly, fly ash to achieve the desired consistency of the sulphur cement. Then the aggregate was added to provide the sulphur concrete.

The components were mixed at 1300C. in a heated 1/3 cubic foot concrete mixer for 15 minutes before pouring into molds. Compaction was obtained through vibration or tapping of the molds. For simplicity of representation, all the examples are chosen using RP220 as the hydrocarbon stabilizer.

Examples 10 to 13 A second series of sulphur cements and sulphur concretes was prepared in a manner analogous to that of Examples 1 to 9 with the exception that raw stabilizer (i.e. not prereacted with sulphur) was added directly to the mix at the previous point of prereacted material addition. In order to allow complete reaction, the mixing time was increased to 20 minutes.

Examples 14 to 22 A third comparative series of sulphur cements and sulphur concretes were prepared in a manner analogous to that of Examples 1 to 9 but with the omission of the hydrocarbon stabilizer. Sulphur concretes prepared according to these mix designs would be limited to reasonably isothermal applications, such as underground or underwater structures subjected to very mild thermal cycling and hence do not have the durability of the cements according to the invention.

The results are summarized and tabulated below in Table 3.

Table 3 Sulphur concretes - Composition and Properties Chemical Stabi- Compres Exam- Aggre- lizer Density sive* ple gate Sulphur Fly Ash RP220 (g/cc) Strength 1 Crushed quartzite 71.7 20.4 7.4 0.50 2.38 7,160 gravel 2 Crushed limestone 73.5 26 - 0.50 2.41 5,290 3 Siliceous tailings 63.5 34.8 - 1.7 2.21 5,290 sand 4 Expanded shale 38.6 37.6 23.2 0.59 1.73 4,610 5 Expanded clay 38.4 32.0 29.2 0.38 1.77 8,350 6 Crushed harite 78.7 15.0 5.9 0.38 3.18 7,520 7 Crushed brick 54.5 27.3 17.5 0.68 2.17 8,530 8 Crushed portland 64.1 24.1 11.2 0.60 2.23 5,690 cement concrete 9 Crushed granite 65.9 20.0 12.6 0.50 2.39 7,760 10 Crushed quartzite 64.4 19.6 15.5 0.49 2.38 8,710 gravel 11 Siliceous tailings 60.9 30.8 7.5 0.77 2.23 6,530 sand 12 Expanded shale 50.0 26.6 22.7 0.66 1.70 4,740 13 Crushed barite 79.1 13.2 7.4 0.33 3.28 7,650 14 Crushed quartzite 65.6 18.8 15.6 - 2.40 9,270 gravel 15 Crushed limestone 60.8 21.8 17.4 - 2.32 7,730 16 Crushed granite 66.2 21.2 12.6 - 2.37 8,250 17 Crushed barite 79.6 12.8 7.6 - 3.25 7,570 18 Siliceous tailings 61.2 34.8 4.0 - 2.20 6,420 sand 19 Expanded shale 35.8 35.8 28.4 - 1.68 4,860 20 Expanded clay 41.0 34.0 25.0 - 1.79 9,320 21 Crushed brick 55.0 27.4 17.6 - 2.18 10,130 22 Crusbed portiand 64.8 23.0 12.2 - 2.24 7,840 cement concrete * Mean of three (3) tests in P.S.I.

Claims (18)

WHAT I CLAIM IS:

1. A sulphur cement pre-mix composition comprising (a) sulphur and (b) up to 10% by weight of the sulphur of a bonding agent adapted to stabilize said sulphur cement against progressive embrittlement and subsequent crumbling under thermal stress, said bonding agent comprising either an olefinic hydrocarbon polymer material derived from petroleum, and having a non-volatile content greater than 50% by weight and a minimum Wijs iodine number of 100 cg/g, such polymer material being capable of reacting with sulphur to form a sulphur-containing polymer, or the sulphur-containing reaction product of an olefinic hydrocarbon polymer material derived from petroleum, and having a non-volatile content greater than 50% by weight and a minimum Wijs iodine number of 100 cg/g with a smaller proportion of sulphur than that present in the sulphur cement premix composition.

2. The sulphur cement pre-mix composition of claim 1, wherein said bonding agent comprises said heat reactive olefinic hydrocarbon polymer material derived from petroleum.

3. The sulphur cement pre-mix composition of claims 1 ot 2 wherein said bonding agent is present in an amount of 1 to 5% by weight of the total amount of sulphur.

4. The sulphur cement pre-mix composition of claim 1 wherein said bonding agent comprises said sulphur containing reaction product of an olefinic hydrocarbon polymer material derived from petroleum, and having a non-volatile content greater than 50% by weight and a minimum Wijs iodine number of 100 cg/g with a smaller proportion of sulphur than is required in the sulphur cement pre-mix composition.

5. The sulphur cement pre-mix composition of claim 4, wherein the weight ratio of sulphur reacted with liquid olefinic hydrocarbon polymer is 2.45:1 or greater.

6. A sulphur cement composition comprising (a) sulphur, which has been melted to contain dispersed therein (b) up to 10% by weight of the sulphur, of a bonding agent adapted to stabilize said sulphur cement against progressive embrittlement and subsequent crumbling under thermal stress, said bonding agent comprising either an olefinic hydrocarbon polymer material derived from petroleum, and having a non-volatile content greater than 50 % by weight and a minimum Wijs iodine number of 100 cg/g, such polymer material being capable of reacting with sulphur to form a sulphur-containing polymer, or the sulphur-containing reaction product of an olefinic hydrocarbon polymer material derived from petroleum, and having a non-volatile content greater than 50%by weight and a minimum Wijs iodine number of 100 cg/g with a smaller proportion of sulphur than that present in the sulphur cement composition.

7. The sulphur cement of claim 6 wherein said bonding agent comprises said heat reactive olefinic hydrocarbon polymer material derived from petroleum.

8. The sulphur cement of claim 6 wherein said bonding agent is present in an amount of 1 to 5% by weight of the total amount of sulphur.

9. The sulphur cement of claim 6 wherein said bonding agent comprises said sulphur containing reaction product of an olefinic hydrocarbon polymer material derived from petroleum, and having a non-volatile content greater than 50% by weight and a minimum Wijs iodine number of 100 cg/g with a smaller proportion of sulphur than that present in the sulphur cement premix composition.

10. The sulphur cement of claim 6 wherein the weight ratio of sulphur to reactive olefinic hydrocarbon polymer is 2.45:1 or greater.

11. A sulphur concrete comprising (A) the sulphur cement pre-mix composition of any one of claims 1 - 5 inclusive, or the sulphur cement composition of any of claims 6 - 10 inclusive and (B) natural or manufactured aggregate.

12. The sulphur concrete of claim 11 wherein the ratio of sulphur cement (A) to aggregate (B) is 20-64:80-36.

13. The sulphur concrete of claims 11 or 12 including an additive to provide fire resistance.

14. The sulphur concrete of claim 13, wherein said additive comprises the reaction product of diphenoxyphosphinic acid with sulphur and with a-methyl styrene.

15. The sulphur concrete of claim 13, wherein said additive comprises 1,5,9cyclododecatriene.

16. The prereacted sulphur containing material for use in the sulphur cements and concretes substantially as described herein with reference to samples 1 - 7.

17. The sulphur cement substantially as described herein with reference to Examples 2 and 3.

18. The sulphur concrete substantially as described herein with reference to Examples 2 and 3.