EP3366843B1 - Polymer-modified ground stabilisation - Google Patents

Description

The invention relates to a method for solidifying a substrate and a substrate consolidator.

In the manufacture of roads, a layer of soil is usually removed first, and after the surface is leveled, a gravel base layer is applied, followed by an asphalt base layer, an asphalt binder layer and an asphalt surface layer. The ballast base layer often has a thickness of 50 to 70 cm.

When manufacturing foundations, the soil is usually also excavated because a layer of gravel is applied before the foundation is made.

These known methods lead to high construction costs, since a soil exchange has to be carried out and expensive material deliveries, earthworks and soil disposal as well as numerous transports are necessary. Existing soil typically has to be removed and stored in landfills.

Thus, the production of roads and base layers is expensive. Some road surfaces and foundations also tend to form cracks in the subsoil or have inadequate pressure resistance and tend to damage when exposed to frost.

DE 10 2008 016 325 A1 discloses a ground or foundation stabilizer comprising a latex polymer. The soil or foundation stabilizer can be worked with water and cement. A proportion of the hardener based on the cement can be 0.1 to 20% by weight, particularly preferably 0.3 to 10% by weight .

DE 10 2004 009 509 A1 discloses a process for solidifying sand-containing soil materials by incorporating a water-insoluble film-forming polymer in an amount of 0.1-10% by weight, based on the solid components of the sand-containing soil material, in the sand-containing soil materials. The process is carried out by incorporating a cement in an amount of 0.5-10% by weight, based on the solid components of the sand-containing soil material, in the sand-containing soil materials. The soil contains water during or after incorporation in an amount of 0.1-30% by weight, based on the solid components of the soil.

It is an object of the present invention to produce a subsurface consolidation with little effort and high quality with regard to frost resistance with sufficient crack prevention and sufficient compressive strength.

This object is achieved by the subject matter according to the independent patent claims. Preferred configurations result from the dependent patent claims.

According to the invention, a method for solidifying a subsurface (for example a road and / or a foundation base layer) is created. In the process, a polymer-based elastic network former (a subsurface hardener) is processed with a binder and water to form a solidified subsurface. An amount of network former used, an amount of binder used and an amount of water used are made dependent on the nature of the substrate.

Furthermore, according to the invention, there is provided a subsurface hardener for hardening an subsurface (which can be used in the above method), the subsurface hardener comprising a binder and 2% by weight to 3.5% by weight of an elastic (in particular rubber-like) network former an amount of the binder with which the network former and water can be processed to form the solidified substrate.

According to one exemplary embodiment of the present invention, a subsurface stabilizer with the features described above is used, wherein between 2% by weight and 10% by weight of binder, based on the subsurface to be consolidated, is used.

A subsurface stabilizer with the features described above can be used as an additive to increase the frost resistance of a subsurface to be consolidated.

A subsurface stabilizer with the features described above can be used as an additive to increase the modulus of elasticity of a subsurface to be consolidated.

A subsurface stabilizer with features described herein can be used as an additive to increase the tensile strength of a subsurface to be consolidated.

In the context of this application, the term "subsurface hardener" can be understood to mean, in particular, a material or a material composition that can be taken alone or already mixed with water and placed on and / or in a subsurface to be hardened, so that there is an interaction between the subsurface hardener and that too consolidating subsoil, a solidified subsoil is formed. Such a subsurface hardener can be present, for example, in a solid phase, in particular a granulate or a powder. Alternatively, a subsurface hardener can also be in a liquid phase or be a viscous material, and during hardening of the subsurface hardener it can be converted into a solid phase. In particular, the subsurface hardener can be present as a suspension (or as an emulsion).

In the context of this application, the term "polymer-based elastic network former" can in particular be understood to mean a material which, as part of a subsurface hardener, has a polymer component which cross-links when it hardens and, in addition to a sufficient stability, has a certain stability to the subsurface hardener on or in the subsurface Gives degree of elasticity. The crosslinking of the polymer of the network former can lead to hardening of the subsurface hardener and to hardening of the subsurface interacting with it.

In the context of this application, the term "binder" can in particular be understood to mean a medium which, as part of the subsurface hardener and / or as part of the subsurface to be hardened, forms a bond between the components of the subsurface hardener with one another and between the subsurface hardener and the one to be hardened Underground is configured. Such hydraulic binders can contain cement and / or lime, for example. Lime already contained in the subsoil can provide the hydraulic binding effect in addition to an externally added cement. Portland cement CEM I 32.5 R, for example, can be used as an externally added cement. For example, 3 to 10% by weight can be Cement as a hydraulic binder and 2 to 3.5% by weight of a polymer-based network former.

In the context of this application, the term “condition of the subsurface” can in particular be understood to mean a property of the subsurface which has an influence on the amount of water to be formed in order to form a reliable, in particular optimal, connection between the subsurface and the subsurface hardener. The condition can relate to temporary soil properties, such as a currently increased moisture due to precipitation or a currently reduced moisture due to a dry period. The condition can also affect permanent soil properties, such as a natural moisture content of the soil. If the water content of the subsoil is taken into account when measuring the amount of water that is processed with the subsurface stabilizer to solidify the subsoil, a soil-specific adjustment or optimization of the relative amounts of the individual components can take place.

According to a method according to the invention, a quantity of water for processing together with a quantity of a polymer-based elastic network former of a substrate hardener and a quantity of binder are not only selected in relation to one another, but also the nature of the substrate to be consolidated when measuring the quantity of water, the quantity of network former and the like Amount of binder included. The nature of the subsurface can include, in particular, its water content. The more water the substrate can contribute to solidifying it using the substrate hardener, the less water has to be added externally, and vice versa. Also on an adequate amount of network formers and on an adequate amount of binding agent has the nature, in particular the Moisture, the subsurface a significant influence, which can be taken into account by selecting the individual quantities of the constituents mentioned, depending on the condition of the subsurface. As a result, the logistically complex provision of large quantities of components of the subsurface hardener which may not be required at all is unnecessary. Rather, for example, with relatively damp substrates, the addition of water regardless of the soil (for example, with a solid premixing of the subsurface hardener with water) can even be counterproductive, since excessive water addition can even have a negative effect on the pressure resistance and robustness against cracking of the subsurface. If, for example, a subsurface has a markedly high level of moisture, the use of a subsurface hardener which has already been non-specifically liquefied in water would impair the holding power in the soil. In this case, a dry subbing agent (e.g. in the form of a granulate or a powder) can provide better processing results than a subbing agent that has already been mixed with water. If the nature of the substrate is taken into account as the basis for determining the amount of network former to be added, binder to be added and water to be added, particularly advantageous properties of the solidified substrate with regard to strength and frost resistance can be achieved.

According to the invention, an elastic network former of the subsurface hardener is provided with a quantity in a corridor between 2% by weight and 3.5 wt% based on a binder in a subsurface hardener in order to harden together with the binder and water to form the hardened subsurface. The modulus of elasticity can advantageously be increased. These significant effects have been proven by experiments. In addition, an improvement in strength can be achieved in part in the range mentioned, but in any case the strength can be kept within acceptable limits. Without the applicant wishing to follow a certain theory To be bound, it is currently assumed that the polymer-based network former forms an elastic network during processing that fills pores or gaps in the soil-binder mixture. More precisely, it is clearly assumed that the network former supplied as a polymer suspension, for example, ensures an orderly release of water to the hydraulic binder (in particular cement), which leads to an orderly hydrophobization. The network builder thus forms a network with binder and substrate, so that an increased modulus of elasticity can be achieved. The solidified subsoil therefore shows increased rigidity without losing its elasticity, which effectively suppresses tendencies towards crack formation. In addition, the network builder clearly fills small gaps in the subsoil, so that water can no longer penetrate into these gaps, resulting in particularly good frost resistance.

According to a preferred embodiment of the invention, the subsurface stabilizer described can be processed with between 2% by weight and 10% by weight of binder, based on the subsurface to be consolidated. The more binder (especially cement) is used, the better the compressive strength. However, a higher amount of binder increases the tendency to crack. However, the polymer-based network agent of the subsurface hardener is able to suppress crack formation in moderate amounts.

Additional exemplary embodiments of the subsurface hardener and the method are described below.

According to one embodiment, the network former can be supplied as a dry powder or as a polymer emulsion or suspension.

According to one embodiment, the water can be mixed with the subsurface hardener before the subsurface hardener is introduced into the subsurface to be hardened - in particular immediately before the subsurface hardener is introduced into the subsurface to be hardened. Mixing of the subsurface hardener with the water can take place directly at a construction site and thus after the, for example, powdery subsurface hardener has been transported from a production site to the construction site. This significantly reduces the logistical effort in connection with moving the subsurface hardener to the place of its processing.

According to one embodiment, the water can be mixed with the subsurface hardener after the subsurface hardener has been introduced into the subsurface to be solidified. Here, the subsurface hardener can be introduced into the subsurface at the same time, but separately from the water. It is also possible to pour the subsurface hardener first and then the water. In yet another option, only a water reservoir in the subsurface is used to liquefy the subsurface solidifier (for example, in the form of granules or powder). Then no external water is required to solidify the subsurface using the subsurface hardener.

According to one embodiment, a degree of moisture in the substrate can be determined and, based on the determined degree of moisture, the water can only subsequently be mixed with the substrate hardener. In other words, the amount of water to be introduced into the subsurface and the amount of network former used as well as the amount of binder used can be adjusted depending on the degree of moisture in the subsurface. Correspondingly, a moisture degree determination of the material of the material can be carried out before or during the solidification solidifying substrate are carried out, and depending on the determined degree of moisture, a lot of water, network formers and binders are determined, which are introduced into the substrate to be consolidated with the substrate consolidator. This makes it possible to determine the correct amount of water, network former and binder to be added not only based on the ingredients of the subsurface hardener, but also on the moisture conditions of the subsurface.

According to one embodiment, the binder can be part or all of the subsurface hardener. Alternatively or additionally, the binder can be part of the substrate to be consolidated. The binder can therefore be at least partially a component of the subsurface hardener, which can then be selected flexibly and suitably to the other components. However, it is also possible to use cement, lime sand, etc. that are already in the subsurface as binders. In this case, the externally added binder can be partially omitted. This reduces the effort in connection with the subsurface hardening. In addition, the use of components contained in the subsurface for consolidation makes it unnecessary to remove and dispose of the subsurface material prior to consolidation.

According to one embodiment, the subsurface hardener can be brought in powder form to the subsurface to be solidified. In this case, the weight-intensive water can only be added to the subsurface hardener and / or the subsurface as required, briefly or during processing.

According to an exemplary embodiment, a mixture can be formed from the network former, the binder and the substrate to be solidified, an analysis can be carried out on the mixture based on a As a result of the investigation, the amount of the network former, binder and water to be mixed with the mixture can be determined, and the specific amount of network former, binder and water can then be mixed with the mixture. After the substrate has been mixed with the substrate hardener as described, a precise amount of water and binding agent can be determined on the basis of the findings of this material introduction, which should be added to the substrate hardener. This makes it possible to find and process an optimal composition of the subsoiler for soil consolidation.

According to one embodiment, the network former and the binder can be processed separately from one another and without premixing into the substrate to be consolidated. The fact that the two components can be introduced directly into the soil independently of one another makes the processing method particularly easy to carry out ("mixed in place"). Alternatively, however, it is also possible to first produce a mixture of network formers and binders in a mixing plant and to already bring the mixture of these components together into the substrate ("mixed in plant").

According to the invention, the subsurface stabilizer has between 2% by weight and 3.5% by weight of the network former, based on the binder. Experimental results have shown that when the elastic polymer-based network former is dimensioned in this way, the solidified soil is not only extremely frost-resistant, but also synergistically quickly and long-term shows a significant increase in compressive strength with a simultaneous increase in the modulus of elasticity. These advantageous effects are particularly pronounced in the area of the aforementioned corridor. Particularly advantageous properties can be considered in the described range to increase the compressive strength and rigidity. Particularly good results were achieved with approximately 2.5% by weight of the network former.

In one embodiment, the binder can be selected from a group consisting of cement and lime. The use of cement in particular leads to high compressive strength. In such a preferred exemplary embodiment, one can speak of a polymer-modified cement stabilization. A mixture of cement and lime also represents a technically advantageous solution. However, other hydraulic binders can be used as an alternative or in addition.

According to one embodiment, the subsurface hardener can be in powder form or can be provided as granules. The liquefaction of such a subsurface hardener can then, for example, only take place during processing in the subsurface.

According to one exemplary embodiment, the subsurface hardener can further comprise water. This can be added to the subsurface hardener shortly before or during processing.

According to one embodiment, the subsurface hardener can be free of at least one from a group consisting of stabilizers, a thickener, a defoamer, and a salt or hydroxide of an alkali or alkaline earth metal. The components mentioned are therefore unnecessary for the subsurface hardener. This allows an inexpensive, environmentally friendly and quick production of the subsurface hardener, which only has to be composed of a few components.

According to the invention, the network former is a latex polymer, in particular styrene butadiene latex. It has been found that a latex polymer has particularly advantageous properties with regard to crosslinking and the provision of elasticity to prevent cracking.

According to one exemplary embodiment, the network former can have lignin sulfonate. Ligninsulfonates are the salts of ligninsulfonic acid, a water-soluble, anionic, polyelectrolytic, branched polymer. Lignin sulfonates result from the chemical digestion of lignin, a biopolymer that can be reacted with sulfite acid salts using the sulfite process. During the digestion, chemical bonds in the hydrophobic lignin structure are broken up and the resulting fragments are converted into a water-soluble form by the addition of sulfonate groups. Lignin sulfonate is a pulverulent raw material that can be used conventionally for paper manufacture and, according to exemplary embodiments of the invention, can effectively act as a polymer-based network former of the subbing agent.

According to one embodiment, at most 15% by weight of water, based on the substrate to be stabilized, is used. The exact amount of water to be used can be adjusted depending on the soil properties, especially the moisture already present in the subsoil. The ideally selected amount of water depends, among other things, on the compressibility of the substrate.

Latex polymers which are soluble or dispersible in water can be used as network formers. For example, styrene-butadiene latex (SBR), (meth) acrylate latex, ethylene-vinyl acetate latex, ethylene / propylene latex, ethylene / propylene-diene latex (EPDM), butadiene-acrylonitrile latex (NBR) , Silicone latex (SI), polybutadiene latex (BR), natural rubber latex or a mixture of two or more of them are used. The latex can be uncrosslinked or crosslinked. It is also possible to use an uncrosslinked latex together with a crosslinking agent. Chemical crosslinkers are used in particular. The molecular weight of the polymer on which the latex is based can be 300 to 1,000,000, preferably 500 to 100,000 g / mol (number average molecular weight, determined by gel permeation chromatography).

The subsurface stabilizer (which can also be called a soil stabilizer) can be worked into the subsurface to be consolidated using a milling machine. This eliminates the need to replace the substrate. For example, according to an exemplary embodiment of the invention, the subsurface stabilizer in powder or liquid form can be sprayed into the feed area of a milling machine by means of a processor-controlled pump, for example, and mixed with the soil or soil by the milling machine. In this case, for example, cement or a further or different binder can be strewn, which can then also be introduced into the substrate. When renovating a subsoil, for example roads, the top road layer can be mixed with the milling machine with the addition of a subsurface hardener according to an exemplary embodiment of the invention. Removal of individual layers can be avoided.

A subsurface stabilizer according to an exemplary embodiment of the invention can be advantageous for the substructure and the base course for country roads, federal highways and highways, walkways and cycle paths with and without superstructure, forest, forest and farm roads, parking lots, storage and container areas with / without Superstructure, construction site access, renovation work, preparation of farm roads, gardening and landscaping, stabilization of fly ash, foundations in foundation engineering, taxiways, Access roads and / or the attachment of gravel roads can be used.

1. 1. Entnahme einer Bodenprobe
2. 2. Bestimmung des Wassergehalts der Bodenprobe
3. 3. Bestimmung der Menge des hydraulischen Bindemittels und des elastischen Netzwerkbildners
4. 4. Herstellen einer Suspension (oder Emulsion) auf Basis des polymerbasierten elastischen Netzwerkbildners
5. 5. Einbringen der Suspension (oder Emulsion) in den Boden
6. 6. Einfräsen des hydraulischen Bindemittels

The method for solidifying a substrate can be carried out as follows:

1. 1. Taking a soil sample
2. 2. Determination of the water content of the soil sample
3. 3. Determination of the amount of the hydraulic binder and the elastic network former
4. 4. Preparation of a suspension (or emulsion) based on the polymer-based elastic network former
5. 5. Introducing the suspension (or emulsion) into the soil
6. 6. Milling the hydraulic binder

• Figur 1 zeigt einen Behälter mit einem Untergrundverfestiger und einen Behälter von damit zu vermischendem Wasser gemäß einem exemplarischen Ausführungsbeispiel der Erfindung.
• Figur 2 zeigt einen Untergrund, der mit einem Untergrundverfestiger gemäß einem exemplarischen Ausführungsbeispiel der Erfindung zu erfüllen und zu stabilisieren ist, und dessen Feuchtegrad gemessen wird.
• Figur 3 zeigt einen Behälter mit einem bereits mit einer Menge von Wasser vermischten Untergrundverfestiger gemäß einem exemplarischen Ausführungsbeispiel der Erfindung, welche Menge basierend auf einer Feuchtigkeitsbestimmung des Untergrunds bestimmt worden ist.
• Figur 4 zeigt einen mit einem Untergrundverfestiger gemäß einem exemplarischen Ausführungsbeispiel der Erfindung verfüllten Untergrund.
• Figur 5 zeigt ein Diagramm, in dem für einen herkömmlich zementstabilisierten Untergrund und für einen mit einem Untergrundverfestiger gemäß einem exemplarischen Ausführungsbeispiel der Erfindung sowie mit einem Vergleichsbeispiel verfestigten Untergrund eine Druckfestigkeit in MN/m² nach 7 Tagen und nach 28 Tagen aufgetragen ist.
• Figur 6 zeigt ein auf Figur 5 bezogenes Diagramm, in dem für den herkömmlich zementstabilisierten Untergrund und für den mit dem Untergrundverfestiger gemäß dem exemplarischen Ausführungsbeispiel der Erfindung sowie gemäß dem Vergleichsbeispiel verfestigten Untergrund die Spaltzugfestigkeit nach 7 Tagen und nach 28 Tagen aufgetragen ist.
• Figur 7 zeigt ein auf Figur 5 und Figur 6 bezogenes Diagramm, in dem für den herkömmlich zementstabilisierten Untergrund und für den mit dem Untergrundverfestiger gemäß dem exemplarischen Ausführungsbeispiel der Erfindung sowie gemäß dem Vergleichsbeispiel verfestigten Untergrund das Elastizitätsmodul in MN/m² aufgetragen ist.
• Figur 8 zeigt ein auf Figur 5 bis Figur 7 bezogenes Diagramm, in dem für den herkömmlich zementstabilisierten Untergrund und für den mit einem Untergrundverfestiger gemäß dem exemplarischen Ausführungsbeispiel der Erfindung sowie gemäß dem Vergleichsbeispiel verfestigten Untergrund die lineare Ausdehnung infolge Frost-Tau-Wechsel aufgetragen ist.

Exemplary embodiments of the present invention are described in detail below with reference to the following figures.

• Figure 1 shows a container with an underground solidifier and a container of water to be mixed therewith according to an exemplary embodiment of the invention.
• Figure 2 shows a substrate which is to be fulfilled and stabilized with a substrate consolidator according to an exemplary embodiment of the invention, and the degree of moisture of which is measured.
• Figure 3 shows a container with a substrate hardener already mixed with a quantity of water according to an exemplary embodiment of the invention, which quantity has been determined based on a moisture determination of the substrate.
• Figure 4 shows a substrate filled with a subsurface stabilizer according to an exemplary embodiment of the invention.
• Figure 5 shows a diagram in which a compressive strength in MN / m ^{2 is applied} after 7 days and after 28 days for a conventionally cement-stabilized substrate and for a substrate consolidated with a substrate hardener according to an exemplary embodiment of the invention and with a comparative example.
• Figure 6 shows one on Figure 5 Related diagram in which the splitting tensile strength is plotted after 7 days and after 28 days for the conventionally cement-stabilized substrate and for the substrate consolidated with the substrate hardener according to the exemplary embodiment of the invention and according to the comparative example.
• Figure 7 shows one on Figure 5 and Figure 6 Related diagram in which the modulus of elasticity is plotted in MN / m ² for the conventionally cement-stabilized substrate and for the substrate consolidated with the substrate hardener according to the exemplary embodiment of the invention and according to the comparative example.
• Figure 8 shows one on Figure 5 to Figure 7 Related diagram in which the linear expansion due to freeze-thaw change is plotted for the conventionally cement-stabilized substrate and for the substrate consolidated with a substrate hardener according to the exemplary embodiment of the invention and according to the comparative example.

The same or similar components in different figures are provided with the same reference numbers.

• vorzugsweise 2-10 Gewichts-% Bindemittel in Bezug auf einen zu stabilisierenden Untergrund (insbesondere Boden);
• 2-3,5 Gewichts-% Polymer als elastischer Netzwerkbildner (trocken), in Bezug auf eingesetztes Bindemittel;
• vorzugsweise gelöst in einer Wasserzugabemenge, die zum Beispiel basierend auf einem Proctor-Test des Untergrund-Bindemittel-polymerbasierter Netzwerkbildner-Gemisches ermittelt werden kann. Die Wassermenge bewegt sich dabei vorzugsweise im Bereich von 0-15 Gewichts-% in Bezug auf zu stabilisierenden Untergrund.

Before exemplary embodiments of the invention are described with reference to the figures, some general aspects of the invention will be explained:
According to an exemplary embodiment of the invention, a subsurface stabilizer is created in which polymer-modified soil stabilization with hydraulic binders can be achieved by the following composition:

• preferably 2-10% by weight of binder in relation to a substrate to be stabilized (in particular soil);
• 2-3.5% by weight of polymer as elastic network former (dry), in relation to the binder used;
• preferably dissolved in a quantity of water added, which can be determined, for example, based on a Proctor test of the substrate-binder-polymer-based network former mixture. The amount of water is preferably in the range of 0-15% by weight in relation to the substrate to be stabilized.

The remaining (for example at most 70% by weight) of the solidified substrate can be provided by the substrate to be solidified itself.

In a Proctor test, a soil sample, the dry bulk density of which has previously been determined, can be supplied with pre-defined energy in a defined vessel using a Proctor compressor (in particular a drop weight with a guide rod) and then the density can be determined. The test can be carried out at least five times with different water contents. If the densities achieved are plotted against the associated water content, a curve results that initially rises, reaches a maximum and then falls again. The The maximum of this curve is the Proctor density of the subsurface with the corresponding optimal water content. Here a connection between compressibility and water content becomes visible.

With a subsurface hardener according to the exemplary embodiment of the invention described above, a substantial part of the mixture (namely the polymer-based network stabilizer, which can be in the form of a latex polymer) can be introduced and processed directly into the subsurface in liquid or dry form. A liquid introduction is preferred since the hydrophobization of the hydraulic binder can then take place in a particularly regulated manner.

The advantages which can be achieved with such an embodiment of the invention are first of all considerable logistical, since in a liquid mixture the largest part by weight is only water and then no longer arises. In addition, the amount of water introduced into the subsurface, which is used to redisperse the dry latex (or another polymer-based network former) and to set an additional binder (e.g. cement), can be applied to these components and the actual water conditions in the subsurface can be customized.

Figure 1 FIG. 12 shows a container 130 with a subsurface stabilizer 104 and another container 132 of water 108 to be mixed therewith according to an exemplary embodiment of the invention.

The subsurface stabilizer 104 can be used to solidify an subsurface 100 (see Figure 2 ), such as a road or a sandy surface. The subsurface hardener 104 has a schematically represented binder 106, for example cement powder or lime powder. The binder 106 can, however, already partially in the underground 100 are. If the binder 106 is completely in the substrate 100, the addition of binder 106 to the substrate consolidator 104 may also be unnecessary. The substrate consolidator 104 described can advantageously be processed with between 2% and 10% by weight of binder 106, based on the substrate 100 to be consolidated. In addition, the substrate consolidator 104 shown schematically has between 2% by weight and 3.5% by weight according to the invention % of an elastic, clearly rubber-like, schematically represented polymer network former 102, based on an amount of the binder 106. According to the invention, the network former 102 comprises or consists of a latex polymer (preferably styrene-butadiene latex).

Clearly, the network former 102 can form a polymer network while processing the subsurface hardener 100 with the subsurface 100 and thereby solidify the subsurface, but at the same time give it an elastic and thus crack-resistant and frost-resistant character. With the moderate amounts of the network former 102 mentioned, an increase in the compressive strength and an increase in the modulus of elasticity of the substrate 100 solidified by means of the substrate consolidator 104 can be achieved at the same time. It is advantageous that the amount of network former 102 does not decrease too much (in particular, does not drop far below 1% by weight, based on the amount of binder 106) and does not increase too much (especially not above 6% by weight, based on) on the amount of binder 106). The subsurface hardener 104 located in the container 130 is powdery and does not yet have any water 108, which significantly simplifies its transportation from a production site to a construction site.

In addition, according to the exemplary embodiment of the invention described, the subsurface stabilizer 104 can optionally also have a schematically illustrated additive 110 or a certain amount of kaolin.

In contrast, the subsurface stabilizer 104 may preferably be free of stabilizers, a thickener, a defoamer and a salt or hydroxide of an alkali or alkaline earth metal. This simplifies the production of the subsurface hardener 104 without impairing its function and reduces the already low environmental impact of the subsurface hardener 104.

As with Figure 1 It can be seen that the subsurface hardener 104 can be transported from the described components 102, 106, 110 and the water 108 to a construction site in separate containers 130, 132. Mixing of the subsurface hardener 104 with the water 108 can then only take place immediately before being introduced into the subsurface 100, during a separate introduction of subsurface hardener 104 and water 108 into the subsurface 100, or after the subsurface hardener 104 has been introduced into the subsurface 100.

Figure 2 shows a substrate 100 which is to be filled and stabilized with a substrate consolidator 104 according to an exemplary embodiment of the invention and the degree of moisture of which is currently being measured by means of a moisture sensor 134.

In other words, before the in Figure 1 The subsurface hardener 104 shown in the subsurface 100 is first measured by means of the moisture sensor 134, a degree of moisture in the subsurface 100. A moisture degree determination of the material of the substrate 100 to be consolidated is thus carried out by means of the moisture sensor 134 before the substrate is consolidated carried out. Based on the determined degree of moisture, the water 108 is only subsequently mixed with the subsurface hardener 104. This measure is based on the knowledge that a solid premixed mixture of subsurface stabilizer 104 and water 108 can be of considerable advantage for subsurface consolidation with regard to pressure stability, crack resistance and durability of the consolidated subsurface 100, regardless of a degree of moisture in a subsurface to be consolidated to use. Rather, it is advantageous to add a variable amount of water to the granular or powder-like subsurface stabilizer 104, which is dependent on the current degree of moisture of the subsurface 100. The amounts of binder 106 and network former 102 added can also be adjusted depending on the current degree of moisture of the substrate 100. For example, shortly before the subsurface consolidation, falling rain, a high groundwater level or a fundamentally high level of moisture in an subsurface 100 can result in only a small amount of water 108 or even no water 108 being added to the subsurface consolidator 104, which is in a solid phase, before this is introduced into the underground 100. In this way, a significantly more flexible consolidation of substrates 100 with variable soil properties can be achieved.

1. 1. der Wassergehalt des Bodens wird bestimmt
2. 2. die Proctordichte wird bestimmt
3. 3. der Gesamtwassergehalt wird bemessen durch die Summe aus vorhandenem Wasser und einer zusätzlichen Beigabe
4. 4. das zusätzliche Wassers wird mit dem polymerbasierten Netzwerkbildner vermischt

For example, the following process can be performed:

1. 1. the water content of the soil is determined
2. 2. The Proctor density is determined
3. 3. The total water content is measured by the sum of the available water and an additional addition
4. 4. the additional water is mixed with the polymer-based network former

Figure 3 shows the container 130 with the subsurface 104 already mixed with a quantity of water 108 according to an example Embodiment of the invention. The amount of network former 102 used, the amount of binder 106 used and the amount of water 108 added is based on a moisture determination of the substrate 100 (cf. Figure 2 ) was determined.

By adjusting the amount of water 108, network former 102 and binder 106 to be introduced into the substrate 100 depending on the degree of moisture of the substrate 100, the composition of the mixture of substrate consolidator 104 and water 108 can be adjusted flexibly and in an application-specific and precise manner so that a maximum solid subsurface hardening can be achieved. Depending on the determined degree of moisture, a quantity of water 108, network former 102 and binder 106 is determined, which is introduced into the substrate 100 to be consolidated with the substrate consolidator 104. This is done according to Figure 3 such that the determined amount of water 108 from the container 132 is filled into the container 130 with the previously powdered subsurface solidifier 104 and these components are stirred into a flowable viscous or liquid mass.

In the described method for solidifying the substrate 100, the first step is according to Figure 1 the polymer-based elastic network former 102 of the subsurface hardener 104 is mixed with the binder 106. After determining the degree of moisture of the substrate 100 to be consolidated in accordance with Figure 2 is then according to Figure 3 a defined amount of water 108 dependent on the degree of moisture is added to the subsurface 104 (in an amount also dependent on the degree of moisture of the subsurface 100 to be solidified) and the resulting mixture is processed to a solidified subsurface 100. The amount of water 108 used is adjusted depending on the nature of the substrate 100. For this, the water 108 is mixed with the subsurface 104, and only shortly before the subsurface hardener 104 is introduced into the subsurface 100 to be consolidated. To be more precise, the water 108 is mixed with the subsurface hardener 104 in a defined amount dependent on the subsurface moisture, immediately before the subsurface hardener 104 is introduced into the subsurface 100 to be hardened.

Alternatively, it is also possible to introduce the hydraulic binder 106 (for example cement) on the one hand and the polymer-based elastic network former 102 (in particular as a polymer suspension) separately from one another into the substrate 100 and only to mix them there.

Preferably, the amount of water 108, if any, introduced into the subsurface 104 or the amount of subsurface 104 introduced into the subsurface 100 is such that a maximum of 15% by weight of water, based on the subsurface 100 to be stabilized, is used. Over-watering can be avoided.

Figure 4 FIG. 12 shows a substrate 100 filled with the substrate consolidator 104 according to the exemplary embodiment of the invention.

According to the arrangement Figure 4 to get, the subsurface hardener 100 according to Figure 3 first introduced into the underground 100 (according to Figure 3 and Figure 4 into a cavity 174 of the substrate 100) and, if necessary, brought into a desired shape by rolling or pressing.

The network former 102, which was mixed together with the binder 106 and the water 108, is then processed together with the original substrate 100 to form the solidified substrate 100 and thereby solidified.

Another advantageous exemplary embodiment is described below, which is not shown in the figure. According to this exemplary embodiment, a mixture of a network former 102, a binder 106 and the substrate 100 to be consolidated is first formed. An investigation is then carried out on the mixture. The amount of water 108 to be mixed with the mixture can then be determined based on a result of the examination. The certain amount of water 108 is subsequently mixed with the mixture. This procedure can also be used to create a highly precise mixture.

Figure 5 shows a diagram 600 in which a compressive strength in MN / m ² is plotted after 7 days and after 28 days for a conventionally solidified substrate and for a substrate 100 solidified with a substrate consolidator 104 according to an exemplary embodiment of the invention and according to a comparative example. More specifically, different solidified substrates are plotted along an abscissa 602, whereas the unconfined compression strength in MN / m ^{2 is} plotted along an ordinate 604 after 7 days (left bar in each case) and after 28 days (right bar in each case) . Figure 6 shows one on Figure 5 Related diagram 700, in which the splitting tensile strength is plotted after 7 days and after 28 days for the conventionally consolidated substrate and for the substrate 100 consolidated with the substrate consolidator 104 according to the exemplary embodiment of the invention and according to the comparative example.

Figure 7 shows one on Figure 5 and Figure 6 related diagram 800, in which for the conventionally solidified subsoil and for the with the subsoiler 104 according to the exemplary embodiment of FIG Invention and according to the comparative example solidified substrate 100, the modulus of elasticity is applied in MN / m ² .

Figure 8 shows one on Figure 5 to Figure 7 Related diagram 900, in which the linear thermal expansion as a result of the freeze-thaw change is plotted in parts per thousand for the conventionally consolidated substrate and for the substrate 100 consolidated with a substrate consolidator 104 according to the exemplary embodiment of the invention and according to the comparative example.

The experimental findings according to Figure 5 to Figure 8 on the one hand reproduce the mentioned data for a reference surface. The reference background is along the abscissa 602 according to Figure 5 to Figure 8 each characterized by the number "1". The reference substrate is a conventional, cement-stabilized substrate.

Number "2" in Figure 5 to Figure 8 also relates to a substrate that has been treated with a subsurface stabilizer 104 according to an exemplary embodiment of the invention. This contains a powdery latex-based polymer network former 102 and the cement as binder 106.

Number "3" in Figure 5 to Figure 8 also relates to a corresponding substrate, which was processed with a substrate stabilizer 104 according to a comparative example. This contains a powdery latex-based polymer network former 102 in a different amount than in "2" and the cement as binder 106.

The experimental results of Figure 5 to Figure 8 it can be seen that the subsurface stabilizer 104 according to the exemplary embodiment of the invention shows a significant improvement over the conventionally solidified reference substrate in terms of strength and rigidity. There is also a significant improvement in frost resistance.

In the following, the experimental results are according to Figure 5 to Figure 8 described in more detail.

In order to be able to determine the mode of action of the polymer-based network former as an additive to the soil stabilizer according to an embodiment of the invention with regard to changing the strength and frost resistance of a soil consolidated by means of hydraulic binders, the in Figure 5 to Figure 8 comparative laboratory studies shown have been carried out.

Since every naturally grown soil has inhomogeneities, the tests were carried out on test specimens from a reference soil to increase comparability. The reference floor was made from 80% by weight quartz sand (product Siligrans) and 20% by weight quartz powder (product Microsil M300). This soil has a sand content of 80% by weight, a silt content of 17% by weight and a clay content of 3% by weight. It is therefore a silty sand (si SA).

Cement II / B-M (C-L) 32.5 R has been used as a binder. The amount of binder was uniformly 3.5% by weight.

The polymer-based network former in the amount of 0% by weight, 2.5% by weight and 4.0% by weight with respect to the cement content has been added as an additive. The polymer-based network former 102 (which was added at 0% by weight, 2.5% by weight and 4.0% by weight with respect to the cement content) had a relative proportion of approximately 80% by weight. Styrene-butadiene latex (more generally: 70 to 90% by weight of styrene-butadiene latex), approx. 10% by weight of kaolin (more generally: 2 to 20% by weight of kaolin) and approx. 10% by weight of other additives 110 (more generally: 3 to 17% by weight) Additives) (it is clear to the person skilled in the art that the sum of the percentages by weight of styrene-butadiene latex, kaolin and additives adds up to 100%).

The test specimens were produced from these mixtures with the addition of 8% by weight of water and compression according to Proctor conditions in accordance with the standard EN 13286-2: 2012.

• Druckfestigkeit nach 7 und 28 Tagen gemäß EN 13286-41:2003 (vergleiche Figur 5)
• Spaltzugfestigkeit nach 7 und 28 Tagen gemäß EN 13286-42:2003 (vergleiche Figur 6)
• Elastizitätsmodul gemäß EN 13286-43:2003 (vergleiche Figur 7)
• Frosthebungsversuche gemäß TP BF StB, Teil 11, Pkt. 1 (vergleiche Figur 8)

The relevant laboratory tests to characterize the strength and frost resistance of the test specimens were defined as follows:

• Compressive strength after 7 and 28 days in accordance with EN 13286-41: 2003 (cf. Figure 5 )
• Splitting tensile strength after 7 and 28 days according to EN 13286-42: 2003 (cf. Figure 6 )
• Elastic modulus according to EN 13286-43: 2003 (compare Figure 7 )
• Frost lifting tests according to TP BF StB, part 11, point 1 (cf. Figure 8 )

The first three tests are decisive for assessing the strength of the soil body and the latter test for the frost resistance of the soil.

The test results are to be listed below and evaluated from a geotechnical point of view. In addition, the percentage increase compared to the values of the cement-soil mixture without addition of the polymer-based network former is given in brackets.

With reference to the following tables, the effects of the addition of the polymer-based network former on the strength of the floor-cement mixture and the frost resistance are discussed. Table 1: uniaxial compressive strength (see Figure 5) sample 7-day strength (N / mm ² ) 28-day strength (N / mm ² ) cement 2.3 4.2 Cement + 2.5 mass percent polymer-based network former 2.6 (+ 10%) 5.1 (+ 20%) Cement + 4 mass percent polymer-based network former 1.9 (-21%) 4.2 (± 0%) sample 7-day strength (N / mm ² ) 28-day strength (N / mm ² ) cement 0.10 0.30 Cement + 2.5 mass percent polymer-based network former 0.17 (+ 70%) 0.33 (+ 10%) Cement + 4 mass percent polymer-based network former 0.10 (± 0%) 0.27 (-10%) sample 28-day strength (N / mm ² ) cement 228 Cement + 2.5 mass percent polymer-based network former 419 (+ 83%) Cement + 4 mass percent polymer-based network former 356 (+ 56%) sample Linear expansion (% o) cement 23.2 Cement + 2.5 mass percent polymer-based network former 7.9 (-66%) Cement + 4 mass percent polymer-based network former 6.1 (-74%)

With regard to the compressive strength, it should be noted that the addition of 2.5% by weight of the polymer-based network former causes an appreciable increase in strength. This is 10% after 7 days and 20% after 28 days. The 7-day value of 2.6 MN / m ² is only slightly below the requirements for cement-stabilized base layers according to RVS 08.17.01 when adding the polymer-based network former. The target value there is 3.0 MN / m ² . If the cement content is increased, this value can also be reached.

A significantly higher dose of the polymer-based network former, however, has no positive effect on the compressive strength. The values correspond approximately to those without the addition of the polymer-based network former.

In the case of split tensile strength, adding 2.5% by weight of the polymer-based network former results in a short-term increase of 70% after 7 days and a long-term significant increase of approx. 10% after 28 days.

However, a further significant increase in the content of the polymer-based network former no longer has a positive effect with this parameter either. The values are approximately 10% lower than those without the addition of the polymer-based network former.

The modulus of elasticity (deformation behavior), which is decisive for the deformation behavior, increases very significantly through the addition of 2.5% by weight of the polymer-based network former. There is an 83% higher value and thus a significantly lower deformability, which has an extremely positive effect on the load-bearing capacity.

A further increase in the content of the polymer-based network former leads to a somewhat smaller increase of 56% compared to the initial value without the addition of the polymer-based network former.

In summary, it can be stated that the addition of 2.5 (± 0.5)% by weight of the polymer-based network former is the technical optimum.

This addition has a positive effect on the load-bearing behavior and deformation behavior of the cemented floor. Due to the higher load-bearing behavior, the soil replacement or base layer thickness can be reduced.

The lower deformability, on the other hand, has a positive effect on the dimensioning of the asphalt surface or a concrete surface. The layer thickness or, in the case of the concrete slab (hall construction), the reinforcement content can be reduced accordingly.

Furthermore, the frost resistance is exorbitantly increased by the addition of the polymer-based network former. The frost increase is reduced by 66% when adding 2.5% by weight and by 74% when adding 4% by weight.

The target value of 10% (15 mm for sample height 150 mm) specified for frost-resistant aggregates in ÖNORM B 4811: 2013, point 5.4, is in any case notably undercut.

The samples are therefore classified as sufficiently frost-resistant after adding the polymer-based network former for roads.

In summary, it should be noted that the addition of 2% to 3.5% by weight of the polymer-based network former is the optimum from a technical point of view because it can be used to improve compressive strength, splitting tensile strength, modulus of elasticity and frost resistance with little effort.

Furthermore, based on the test results and the geotechnical assessment, an overview of possible areas of application of the polymer-based network former should be given. In the possible applications, the improvement of the load-bearing and deformation behavior on the one hand and the increase in frost resistance on the other must be taken into account.

One possible application is the renovation of subordinate streets with frost damage.

There is a large number of roads in the subordinate road network where there is insufficient structure. This continually leads to frost damage, which is usually temporarily remedied. A complete renovation is provided if the individual damage takes on too great an extent.

In this context, the addition of the polymer-based network former to the cement offers the possibility of stabilizing the existing substructure. On the one hand, the load-bearing capacity can be increased to meet the requirements. However, the polymer-based network former also has the advantage that the substructure is made frost-proof. Accordingly, frost damage can also be minimized in the future.

In addition, the existing materials can be left. This eliminates the need for materials and the disposal of materials. By eliminating transports, the construction time and environmental impact can be minimized.

Further application examples include the construction of roads, commercial and forest roads, parking lots and business areas.

Due to the increase in the frost resistance of the existing substrate by adding the polymer-based network former, the thickness of the frost protection layer can be reduced or limited to a mechanically stabilized base layer (for example 20 cm or less).

In addition, increasing the load-bearing capacity or reducing the deformability enables the asphalt structure to be optimized.

Industrial halls can be considered as a further application example.

In the case of industrial buildings, monolithic or double-reinforced floor slabs are often used.

By stabilizing the soil by means of a hydraulic binder and adding the polymer-based network former, the deformability can be minimized on the one hand, and frost resistance can be achieved. Accordingly, the frost protection layer can be reduced or limited to a mechanically stabilized base layer (20 cm or less). Increasing the load-bearing capacity also enables an optimized dimensioning of the floor slab by increasing the bedding of the slab.

Claims (10)

1. Method of solidifying a ground (100), wherein in the method:

   a polymer based elastic network former (102) of a ground solidifier (104) is processed with a binder (106) and water (108) to a solidified ground (100); and

   an amount of the used network former (102), an amount of the used binder (106) and an amount of the used water (108) is adjusted dependent on a composition of the ground (100);

   wherein the ground solidifier (104) which is used for solidifying the ground (100) comprises:

   the binder (106); and

   the amount of the elastic network former (102) relating to the amount of the binder (106), with which the network former (102) and the water (108) are processed for forming the solidified ground (100), wherein the network former (102) comprises or consists of a latex polymer,

   characterized in that the amount of the elastic network former (102) relating to the amount of the binder (106) is 2 weight percent to 3,5 weight percent.
2. Method according to claim 1, comprising one of the following features:

   wherein the water (108) is mixed with the, in particular powdered, ground solidifier (104) before the ground solidifier (104) is introduced into the ground (100) to be solidified, in particular directly before the ground solidifier (104) is introduced into the ground (100) to be solidified;

   wherein the water (108) is mixed with the, in particular powdered, ground solidifier (104) while the ground solidifier (104) is introduced into the ground (100) to be solidified and/or after the ground solidifier (104) has been introduced into the ground (100) to be solidified.
3. Method according to one of the claims 1 to 2, comprising at least one of the following features:

   wherein a degree of humidity of the ground (100) is determined and based on the determined degree of humidity only subsequently the amount of the network former (102), the amount of the binder (106) and the amount of the water (108), which are determined therefrom, are mixed with the ground solidifier (104);

   wherein the binder (106) is entirely or partially a part of the ground solidifier (104);

   wherein the binder (106) is partially a part of the ground (100) to be solidified.
4. Method according to one of the claims 1 to 3, wherein the ground solidifier (104) is introduced into the ground (100) to be solidified in powdered form or as granulate.
5. Method according to one of the claims 1 to 4, wherein:

   a mixture of the network former (102), the binder (106) and the ground (100) to be solidified is formed;

   an inspection of the mixture is performed;

   based on a result of the inspection, the amount of the network former (102) to be mixed with the mixture, the binder (106) and the water (108) is determined;

   the determined amount of the network former (102), the binder (106) and the water (108) is mixed with the mixture.
6. Method according to one of the claims 1 to 5, wherein the network former (102), in particular dry or in an aqueous suspension, and the binder (106) are incorporated into the ground (100) to be solidified separated from each other and without pre-mixture.
7. Ground solidifier (104) for solidifying a ground (100), wherein the ground solidifier (104) comprises:

   a binder (106); and

   an amount of an elastic network former (102) relating to an amount of the binder (106), with which the network former (102) and the water (108) are processable for forming the ground (100) to be solidified, wherein the network former (102) comprises or consists of a latex polymer,

   characterized in that the amount of the elastic network former (102) relating to the amount of the binder (106) is 2 weight percent to 3,5 weight percent.
8. Ground solidifier (104) according to claim 7, comprising at least one of the following features:

   wherein the binder (106) is selected from a group consisting of cement and lime;

   wherein the ground solidifier (104) is dry, in particular powdered;

   wherein the ground solidifier (104) is a suspension;

   wherein the ground solidifier (104) is free from at least one of a group consisting of stabilizers, a thickener, a defoamer, and a salt or hydroxide of an alkali metal or an alkaline earth metal;

   wherein the latex polymer is styrene-butadiene latex.
9. Method according to one of the claims 1 to 6, wherein between 2 weight percent and 10 weight percent binder (106) relating to the ground (100) to be solidified are used.
10. Method according to claim 9, wherein at most 15 weight percent water (108) relating to the ground (100) to be stabilized are used.

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