^{~ '} - __ Process and adjuvant for the manufacture- of cement, mortar and concrete.

BACKGROUND:

The present invention relates to utilization of alkylated lignin products as adjuvants in cement, mortar, and con¬ crete.

The invention especially relates to utilization of alkylated lignin products as s.c. super plasticizers in concrete.

Furthermore, the invention relates to utilization of alkylat¬ ed lignin products as combined plasticizers and air intro¬ ducing substances in concrete.

Plasticizing or super plasticizing adjuvants for concrete, often called water reducing adjuvants as well, are used in concrete, either to reduce the need of water or to enhance the processability or flow.

It is well known that a reduction of the need of water in a concrete mixture without changing its processability will increase the strength of the concrete. Water reducing adju¬ vants are, thus, used when a concrete having especially high strength is to be produced.

If demands on high strength of the concrete are not raised water reducing adjuvants may be used for cement saving pur¬ poses. The strength of concrete normally will increase with an increased admixture of cement. If an increased strength is achieved due to water reduction it is, thus, possible to reduce the cement content without impairing the strength of the concrete.

Whereas it is mostly desirable to reduce the cement content of a concrete from economical considerations, in connection with solid constructions it may be desirable to reduce the cement content because of the generation of heat in the concrete. In the course of the reactions between cement and water, so called hydration, heat is generated. In solid constructions it may be difficult to lead off the heat and

the generated heat may at the worst result in cracking of the concrete. A much used method of reducing the heat genera¬ tion is to reduce the cement content.

In many cases it is especially desirable that the produced concrete is easily processed or has good flow properties.

Concrete for pumping and gunite are examples of concrete where good flow properties are important.

Another example is flow concrete that should be self compress¬ ing, i.e. casting should be possible without compressing the concrete by vibrators or in another manner. It is. thus, possible to use flow concrete in cases where reinforcement bars are closely arranged or where the space to be filled with concrete has a shape preventing access for a vibrator.

In certain cases a combination of good flow properties and a reduced water addition might be desirable. An example to be mentioned is the production of concrete elements in a factory. In that case a moderate cement dosage, high strength and mo¬ derate vibration are desirable. The last mentioned measure has the purposeof reducing bothersome noise in the factory.

Air introducing adjuvants are used to increase the content of finely distributed air in the concrete. It is well-known that concrete with an increased content of finely distribut¬ ed air is more resistant to frost, i.e. it has an improved capability of standing freezing and thawing.

However, it is also well-known that a reduced air content will result in reduced strength of the concrete.

To compensate for the loss of strength, it may be desirable to add a water reducing adjuvant .

To some extent an air introducing adjuvants has also a water reducing e ect. This is due to the fact that the finely

distributed air acts as a lubricant and, thus, improves the flow of the concrete. In most cases, however, it is possible to reduce the demand for water additionally by adding a water reducing adjuvant. Combinations of water reducing and air introducing adjuvants are usually utilized to day.

It is important that the air ^' in the concrete is so stable that the concrete is resistant to mechanical treatment: transport, vibration, etc. Unstable air has often resulted in surprises, the air content of the set concrete being con¬ siderably lower that the air content of the newly mixed concrete. In practical cases, where combinations of air in¬ troducing and water reducing adjuvants are used, the air content often turns out to be unstable.

Lignosulphonates have been used for many years as plasti¬ cizing or water reducing adjuvants for concrete. Said lignosulphonates are, to day, used in concrete in amounts up to approx. 0.2% ^" dry substance, on the basis of cement in the concrete. With higher amounts the lignosulphonates to some extent start to have an ef ect that retards setting. In cases where high strength is necessary at an early stage, e.g. because formwork has to be removed, such admixture, thus-, must not exceed 0.2$.

During later years some so called super plasticizing adju¬ vants have appeared in the market. Such substances are made on a synthetic basis, mainly sulphonated naphtalene- and melamine compounds.

Said super plasticizing adjuvants , when used in the same relative amounts, usually, have no more water reducing effect than the lignosulphonates. An advantage of them, however, is that they do not to any considerable degree re¬ tard setting. Super plasticizing adjuvants can, thus, be added in larger amounts than the lignosulphonates, and that permits the achievement of a considerably larger water re¬ duction in concrete than with the lignosulphonates.

Generally used amounts of super plasticizing adjuvants are approx. 0.5% dry substance, based on the cement content of the concrete. In some cases additions of up to approx. 1.0% may be used.

Lignosulphonates as well as naphtalene- and melamine com¬ positions are used, to day, together with air introducing adjuvants in the production of frost-resistant concrete. Conventionally used air introducing adjuvants are resin derivatives, fatty acids and surface active compositions.

Especially in combination with the super plasticizing naphtalene compounds it is known to be difficult to achieve satisfactory air introduction and stable air.

DESCRIPTION OF THE INVENTION

The present invention relates to the utilization of alkylated lignin products in cement, mortar,and concrete.

Lignin products here comprise products derived from so called sulphite, sulphate and alkali waste liquor.

It is characteristic of all these kinds of waste liquor that their main components are materials containing lignin , but that they, additionally, contain carbohydrates, low-molecular organic compounds, and inorganic salts. The waste liquor is obtained from the production of cellulose from lignin - cellulose containing material by known methods.

A sulphite process is characterized by the fact that a. liquor containing sulphite and a base that may be Ca, Na, Mg, or NH^ is used in sulphite cooking. The waste liquor after cooking will then contain Ca-, Na-, Mg-, or NH,-lignosulphon¬ ates respectively.

The lignosulphonate proportion of the sulphite waste liquor can be increased by complete or partial removal of the carbo-

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hydrates. Carbohydrates may e.g. be prefermented and, thus, form the basis of an ethanol production.

Other methods of enriching the lignosulphonate portion in sulphite waste liquor are e.g. various methods of fractionat- ion, e.g. ultra fractionation.

By precipitation, Ca-lignosulphonates may in a known man¬ ner form the raw material for the production of Na-, Mg-, NH ₃ ~, Fe- and other metal lignosulphonates.

In alkali processes aqueous solutions of NaOH are used as cooking liquids, whereas the cooking liquids in sulphate processes contain Na«S in addition. In alkali- and sulphate processes the waste liquor is often burned for recovery of energy and chemicals. In some cases, however, these waste liquors are used as raw materials for the production of alkali- and sulphate lignin . respectively.

It is possible to fractionate alkali- and sulphate waste liquor in a number of known manners - e.g. by precipitation with acids or ultra filtration.

The concept of waste liquor in this context, as mentioned, also includes so called oxylignin waste liquors. This may e. g. be a waste liquor from the production of vanillin by oxy- dation and alkali processing of the sulphite waste liquor. It may also e.g. be a waste liquor from oxygen bleaching of lignocellulose material.

According to the invention lignosulphonates, alkali-, and sulphate-, and oxylignin, modified in a number of ways that are well-known to those skilled in the art of lignin process- ing, may be used as raw materials.

As known to organic chemists, alk lation can be carried out with a number of alkylation agents in aqueous as well as or¬ ganic solvents. ^*

_S uitable alkylation agents in an aqueous environment may e. g. be dimethyl- or diethyl sulphate.

The dry substance concentration of the lignin products during alkylation may be between 5 and 60%, preferably between 30 and 55%. The pH during alkylation should be higher than 7, preferably between 8 and 12. The amount of alkylat¬ ion agent will depend on the selected agent. If dimethyl- sulphate is selected, 1-50%, based on waste liquor dry sub¬ stance, and preferably 20 to 30% are used. The temperature during alkylation may be between 0 and 200°C, preferably between 10 and 100°C.

Alkylation causes the properties of the lignin products to change substantially when used in concrete. On one hand, alkylated waste liquor products are made considerably less retarding to setting. On the other hand, these products are made more air introducing.

By adding suitable dampers to the alkylated waste liquor products it was possible to obtain lignin products having a water reducing effect at the same time as they do not act much retarding on the setting and are not much air introduc¬ ing. Said products, thus, advantageously may be used as super plasticizing substances in concrete. Suitable dampers may e.g. be tributylphosphate, n-butylcarbonate, aliphatic alcohols or fatty acid esters.

By using the alkylated waste liquor products alone, products are obtained that have an air introducing as well as water reducing effect. When used in amounts that are of interest to achieve a full water reducing effect, said products may in certain cases have a too strong air introducing effect. In these cases the air content of the concrete may e.g. be adjusted by an addition of small amounts of dampers.

The alkylated lignin products were found to introduce air that was very stable in the concrete. In mixtures with

dampers alkylated lignin products also resulted in consider¬ ably more stable air than achievable by combinations of air introducing and plasticizing/super plasticizing substances conventionally used to day.

Alkylation of lignin products is previously known. In US-PS 4 184 845 alkylation is e.g. used in combination with other processes to reduce the natural color of the lignin products. The properties of alkylated lignin products in concrete, how¬ ever, were known. It was previously known that the properties of lignin products in concrete could be improved by alkoxy- lation, as described in the US Specifications Nos. 3 398 005, and 3 398 006. Alkoxylation agents, however, are very explosive and, thus, difficult to handle. In most cases, alkylation will, thus, be preferable to alkoxylation.

Alkylated lignin products according to the invention can be added to cement, mortar, and concrete in amounts up to 2.0%, based on cement, preferably from 0.1 to 0.8%. The addition may be made to the cement when mortar or concrete are mixed, or to the finished mortar or concrete mixture. Alkylated lignin products according to the invention may al¬ so be added to so called pozzulans, e.g. flue dust and silica, which are then admixed with cement, mortar, and con¬ crete. The products may also be added in mixtures with other additives.

EXAMPLE 1

The following example illustrates how the setting retardation effect of lignin products may be reduced by alkylation.

A Ca-ligninsulphonate "BORREBOND NORMAL", a fractionated Na-ligninsulphonate "ULTRAZINE NAS", and an oxylignin pro¬ duct "VANISPERSE CB", which are all commercially available products from BORREGAARD IND. LTD, Sarpsborg, Norway, were alkylated. A lab product from sulphate waste liquor, frac¬ tionated by precipitation and subsequently sulphonated.

here called "SL 45", was also alkylated. "Borrebond Normal", and 'Borresperse NA" were alkylated in a 50% solution; "Ultra- zine NAS" and "Vanisperse CB" in a 40% solution; and "SL 45" in a 30% solution.

The alkylation was carried out in a 5-necked round flask provided with inter alia a mixer and a reflux cooler. The solutions were heated to 60°C. Whereas the pH was main¬ tained at 10 by addition of 45% NaOH, dimethylsulphate, 30% based on waste liquor dry substance, was bled into the sol¬ utions in the course of one hour.

The solutions were left standing at least another hour at 60°C before they were spray dried.

The setting retarding effect of the lignin product was tested in cement slurries. Standard Portland cement from Norcem, Norway was used. The stated amount of thelignin product was dissolved in 75.0 g of water and 300 g cement were added. As a blind test 300 g of cement and 90.0 g of water were used. The mixture was kneaded for 2 minutes with a spoon and sub¬ sequently placed in containers.

The containers were placed in a calorimeter and the develop¬ ment of temperature was monitored by the aid of thermoele¬ ments and a printer. The initial setting time is noted as the time lapsed for the temperature to raise above 40°C.

From the results in Table 1 it will be seen that alkylation in all cases resulted in a reduced effect of setting retard¬ ation.

Table 1

Degree of alkylation

Product Initial setting time

Dosing on cement 0.2 0.4 0.6 % "Borrebond Normal" 6 h 18 min 8 h 46 min 16 h 30 mi "Alkylated Borrebond

Normal" 95 5 II 03 II 5 II 42 6 II 37

"Borresperse NA" 0 6 II 20 It 8 II 55 " 16 II 38

"Alkylated Borre¬ sperse NA" 95 5 II 05 II 5 II 40 6 II 27

"Ultrazine NAS" 0 6 II 30 II 9 II 46 ^■ 21 II 00

"Alkylated Ultrazine NAS" 95 5 II 08 II 5 It 58 6 II 46

"Vanisperse CB" 0 7 II 58 II 22 II 03 ' 53 It 05

"Alkylated Vanisperse CB" 89 6 II 00 II 8 II 14 ' 16 II 38

"SL 45" 0 6 II 36 II 9 II 10 ' * 23 II 16

"Alkylated SL 45" 92 6 02 8 II 05 ' ' 11 II 12

4 h 33 min

EXAMPLE 2

In this example it will be illustrated how alkylation increas¬ es the air introducing capability of the final product in concrete and how the air introduction can be adjusted by addition of dampers.

The concrete was mixed in a 60 1 free fall mixer. A fixed mixing time was used.

The concrete had the following composition:

6.0 kg cement, 15.0 kg sand,and 19.0 kg shingle. Cement, sand, and shingle were dry mixed for 15 sec.Then water con- taining the stated amounts of adjuvants was added, and mixing continued for further 2 min. The amount of water was selected so as to give the concrete mix a consistency corre¬ sponding to a sink value of approx. 10 cm. The consis¬ tency was measured according to Norwegian Standard 427A,

Part 2, Page 5.1.4. The air content of the concrete was measured by a ACME-air meter and according to Norwegian Standard 427A, Part 2, Page 5.3.4.

From the results shown in Table 2 it will be seen that alky¬ lated "Borresperse NA" had a considerably higher air introd¬ ucing effect than "Borresperse NA".

From the results in Table 3 it will appear that the air in¬ troduction by alkylated "Borresperse NA" stay be reduced by adding suitable dampers.

Table 2

Adjuvant / % air in the dosage based on cement concrete blind test 2.0

"Borresperse NA"

0.2% 2.8

0.4% 4.0 Alkylated"Borresperse NA"

0.1% 3.7

0.2% ^' 6.2

0.4% 10.4

Table 3

Adjuvant/dosage % air in the concrete

0.4% alkylated "Borresperse NA" 10.4

+ 0.12% tributylphosphate ⁺ 6.2

+ 0.25 4.8

+ 0.5 4.1

+ 0.25 % fatty acid ester ^4- 3.8

+ 0.50 % 2.8

based on alkylated "Borresperse NA" dry substance.

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EXAMPLE 3

In this example it will be illustrated how a mixture of alkylated sulphite waste liquor and dampers, here referred to as"Borrecem SP", may be used as a super plasticizing- water reducing substance in concrete.

The sinking measure is at first maintained approximately constant, while the reduction of the water demand is utiliz¬ ed to achieve a concrete with increased strength. The same concrete mixture and mixing conditions as in Example 2 are used, but the addition of water was selected so as to main¬ tain the sink value of approx. 15 cm.

Consistency and air were measured as in Example 2. Initial and finished setting was measured in cemented glue, consist¬ ing of adjuvants, water, cement and sand as described in DIN 1164. The compressive strength of the concrete was mea¬ sured according to Norwegian Standard 427A, Part 2, Page 1 and Pager 5.4. The w/c ratio is the ratio between water and cement in the concrete.

From the results in Table 4 it is seen that "Borrecem SP" is considerably less retarding as to setting than "Borresperse NA", and that "Borrecem SP" yields corresponding increases in compressive strength as commercial super plasticizing products.

An admixture of 0.4 % "Borrecem SP" according to Table 4 results in a reduction of the w/c ratio of approx. 10% and an increase of the 18-days compressive strength of approx. 18%.

If an increase of the compressive strength alternatively was not desirable, it would be possible to save cement. According to calculations an admixture of 0.4 % "Borrecem SP" could result in a reduction of the amount of cement of approx. 12%. In the shown example this would mean that the amount of ce-

ment could be reduced from approx. 325 kg cement/m to

_ _ aapppprrooxx.. 228855 kkgg cceemmeenntt//mm wwiitthhoouutt rreesstulting in a reduced compressive strength of the concrete.

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Table 4

Adjuvant. / w/c % Setting time Compressive strencϊth N/mm ² dosage ratio air Initial Finished 3 days 7 days 28 days

Blind test 0.67 1.6 4 h 10 min. 5 h 10 min. 24.1 26.4 33.0

"Borresperse " 1 (damper added)

0.2% 0.62 2.0 5 II 05 II 5 " 40 " 28.6 32.6 37.9

0.4" 0.58 2.2 7 II 30 ■1 8 " 30 " 31.0 35.2 39.8

0.6" 0.58 3.2 9 II 10 II 10 " 20 " 32.9 38.2 43.1

"Borrecem SP"

0.2% 0.62 2.0 4 II 30 II 5 " 00 " 26.6 31.0 36.5

0.4" 0.58 2.3 5 II 00 II 5 .i 45 « 31.7 34.3 39.2

0.6" 0.57 2.2 5 II 40 It 6 " 30 " 32.2 36.6 43.3

Kommercial sulphonated melamine formaldehyde product

0.4% 0.60 1.4 4 II 10 II 4 .. ₄ 5 .. 30.4 35.3 39.6

0.6" 0.58 1.1 4 II 30 II 5 " 05 " 32.6 37.4 41.0

Commercial sulphonated naphtalene formaldehyde product

0.4% 0.58 2.0 4 II 20 II 5 " 00 " 31.4 34.4 39.8

0.6" 0.57 1.8 4 II 50 5 " 40 " 34.5 37.1 42.0

EXAMPLE 4

In this example it will be illustrated how"Borrecem SP", a mixture of alkylated sulphite waste liquor, and dampers may be used as an agent to yield concrete mixes having im¬ proved flow

The water addition to the concrete was kept constant, i.e. the tests were made with a constant w/c ratio. The 0 concrete mixtures consisted of 6.0 kg cement, 23.0 kg sand, and 19.0 kg shingle. The adjuvants were dissolved in 4.6 kg water and added to the mixer at the end. The mixing con¬ ditions were as in Example 2. The consistency was measured according to Norwegian Standard 427A, Part 2, Page 5.1.4. 5

Table 5 shows the consistency of the concrete mixture af¬ ter 10, 30, 60, and 90 min. as measured after finished mixing. It appears that "Borrecem SP" yields as good an im¬ provement of the concrete consistency as the commercial 0 super plasticizing substances.

Table 5

Consistency of the concrete 5 Sink value, cm

Time after mixture 10 min. 30 min. 60 min. 90 min.

Adjuvant /dosage

Blind test 4.5 4.0 3.0 2.0

0.4% "Borrecem SP" 9.5 6.0 4.5 3.0 _Q 0.4% of a commercial sulphonated melamine formaldehyde product 7.5 4.5 3.0 1.5

0.4% of a commercial sulphonated naphtalene formaldehyde product 9.5 6.5 4.5 2.5

EXAMPLE 5 5

This example will illustrate how "Borrecem SP" having a composition as in Example 3 results in an improved early strength as compared with non-alkylated lignosulphonates.

The same concrete mixture and mixing conditions were used as in Example 2. The setting of the concrete mixture was deter¬ mined by measuring penetration resistance as stated in ASTM C403-80. Cubes were cast as described in Norwegian Standard 427A, Part 2, Page 1 and Page 5.4. The cubes were stripped immediately before pressure testing.

In the Figure setting and early, strength development of concrete with an admixture of "Borrecem SP" was compared with the results from concrete with an admixture of corresp¬ onding amounts of "Borresperse NA", a commercially sulphonat¬ ed naphtalene formaldehyde product, and concrete without any adjuvants.

The results show that the concrete having an admixture of "Borrecem SP" sets more rapidly and has a more rapid develop¬ ment of strength than concrete where "Borresperre NA" had been added. Concrete with an admixture of "Borrecem SP" sets approximately as rapidly as concrete with an admixture of sulphonated naphtalene formaldehyde product and concrete without any admixture.

The development of strength is more rapid for concrete with "Borrecem SP" and a sulphonated naphtalene formaldehyde pro¬ duct than in concrete without any admixture.

Time, hours

Setting and early development of strength in concrete with an addition of 0.6% "Borrecem SP" ( ), 0.6%

"Borresperse NA" ( ), 0.6% of a commercial sulphonated naphtalene formaldehyde product (- ^• - ^• -) , and without any adjuvant ( ) .

EXAMPLE 6 ^'

This example will illustrate how alkylated lignin waste liquor, here called "Borrecem LP" may advantageously be used as a combined air introducing and water reducing ad¬ juvant in concrete.

The same concrete mixtures and mixing conditions as in Example 2 were used, but the sink, value ₌ was maintained at approx. 15 cm. The air content was measured as in Example 2. The stability of the air in the concrete was determined by securing the air meter to a vibration table. The vibration u table being a part of the so called^Vebe-meter used for measuring the consistency of concrete was used. The concrete in the air meter was vibrated for predetermined periods and read in the conventional manner.

A commercial air introducing adjuvant was used in the tests. Said adjuvant is here called an L-substance.

From Table 6 it can be seen that mixtures of air introducing and plasticizing/super plasticizing substances result in a more unstable air content than is achieved with an air introducing substance alone.

"Borrecem LP" yields a substantially less stable air content than achieved by combinations of air introducing and plasti¬ cizing/super plasticizing substances, and a correspondent water reduction is achieved at the same time.

As compared with air introducing adjuvants alone, "Borrecem LP" yields a correspondingly stable air content and a water reducing effect as well.

Table 6

Water /cement % air in the concrete ratio

Vibration period 0 min. 1 min. 2 min. 5 min.

Adjuvant /dosage

0.1% L-substance 0.62 6.0 5.4 4.9 4.4

0.2% "Borresperse NA" + 0.1% L-substance 0.57 5.9 4.0 3.2 2.5

0.4% of a commercial sulphonated melamine formaldehyde product + 0.1% L-substance 0.58 6.1 4.7 4.1 3.7

0.4% of a commercial sulphonated naphtalene formaldehyde product

+ 0.25% L-substance 0.58 6.0 3.2 3.0 2.7

0.4% "Borrecem LP" 0.58 5.9 5.4 5.0 4.2

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