An injection material to be used in historic building restorations

Abstract

The present invention relates to an injection material which is suitable for use in repair, renovation or restorations of historical rock-cut and masonry structures and which is unique for materials of historical structures.

Description

[0001] AN INJECTION MATERIAL TO BE USED IN HISTORIC BUILDING RESTORATIONS

[0002] TECHNICAL FIELD

[0003] The present invention relates to an injection material which is compatible with the materials of historical structures and compliant for use in repair, renovation or restorations of historical rock-cut and masonry structures.

[0004] PRIOR ART

[0005] Historical structures, which could have remained standing for centuries, can deteriorate and be damaged due to various reasons like the function change of the structure, the construction method, the conditions of the region, and the subsequent repairs. The general principle in restoration is firstly to eliminate these factors which led to damaging of the structure and then to intervene to the damaged region.

[0006] In order to develop repair a consciousness of restoration and conservation of historical structures, the studies which has been started in Europe in 19thcentury have gained a legal identity by means of Carte Del Restauro (1932) and Venice (1964) Charters. The general principles of conservation have been provided and the restoration rules have been accepted. Afterwards, studies have been made in the area of restoration and preservation of historical buildings by means of various laws, regulations, charters, etc. prepared until today. In the view of all these studies, it has been determined that the originality of the structure must be protected with its all features in the interventions related to architectural heritages and the materials, which are to be used within this context, must be determined by means of the tests which shall be defined in a unique manner for the related project. The new materials which are to be used during repair must be compliant to the original materials, and thanks to this, new damages which may occur due to inappropriate materials must be avoided.

[0007] Injection method (grouting) is one of the frequent methods used in restoration of historical structures. Although this technique is not reversible, it is accepted since it provides recovery of the strength and continuity without changing the construction and load carrying capacity of the damaged structure. As long as the used injection material is used in a compliant manner to the original material in historical structures, it has been mentioned that the grout application has also been accepted by Venice Charter which is one of the most important regulations realized for developing the modern restoration doctrine.

[0008] The injection material which shall be used in the damaged historical structure must be analyzed for each historical building, and injection materials, whose characteristics are compliant to historical ones, must be selected. Features to be considered for injection materials are compliancy, injectability and durability characteristics in terms of the physical, chemical, mechanical and mineralogical characteristics of the original material.

[0009] Today, in repair and restoration processes of historical structures, it is seen that commercial ready-made injection materials are generally used without taking into attention the original material characteristics and the necessary searches are not made before / after application. This unfavorable condition leads to usage of materials, which do not have suitable characteristic and composition, in restoration and repair works in historical structures, and cause irreversible damages. Accordingly, before the restoration, the characteristics of historical structure material must be well analyzed by the specialists who are skilled in the related technical field, and injection materials which are compliant to historical materials must be used. Then restoration processes can be started.

[0010] In the related technical field, there are various studies about injection materials produced by adding natural pozzolan and non-historic brick powder, metakaolin, fly ash, silica fume along with natural hydraulic lime is used as binder, and these injection materials are used in various historical structures; limited performance is obtained from these injection materials.

[0011] As a result, by means of the present invention, it is desired that additional advantages are provided for the related technical field and the product range is widened.

[0012] BRIEF DESCRIPTION OF THE INVENTION

[0013] The present invention relates to a new injection material which can be used in restoration, renovation and repair of historical structures, for bringing new advantages to the related technical field and for expanding the product range.

[0014] An object of the present invention is to reveal an injection material which shows high pozzolanic activity. By means of this, an injection material can be obtained which can be used in restoration, renovation and conservation of historical structures and which is compatible with the original structure. An object of the present invention is to provide re-evaluation of excavation waste earth, which reveals as a result of mechanical carving of rock-cut structures in Cappadocia Region whose amount is rapidly increasing and more than 10 millions cubic meters, as a component in injection material. By means of this, while low-cost injection material is being obtained, environmental pollution can be prevented.

[0015] The present invention relates to an injection material which comprises volcanic tuffs, obtained from Cappadocia Region, as pozzolan component and which is appropriate to be used in restoration of rock-hewn and masonry structures. By means of this, an injection material can be obtained which can be used in restoration, renovation and repair of historical structures and which is compatible with the original material / structure. In a preferred embodiment of the present invention, the injection material comprises volcanic tuffs, obtained from Cappadocia Region, at a value between 30% and 45% by weight.

[0016] In a preferred embodiment of the present invention, the volcanic tuffs of the injection material obtained from Cappadocia Region comprises S1O2 component at proportion of at least 50% by weight. By means of this, the injection material can have pozzolanic activity.

[0017] In a preferred embodiment of the present invention, the particle size of volcanic tuffs obtained from Cappadocia Region is at most 63 mhi.

[0018] In a preferred embodiment of the present invention, the injection material comprises tuffs which are waste or not waste and which can be obtained from Cappadocia Region as components showing pozzolanic activity and besides, the injection material comprises at least one, some or all the material group like silica fume, fly ash, metakaolin and brick powder.

[0019] In a preferred embodiment of the present invention, the injection material comprises volcanic tuffs obtained from Cappadocia Region as the Cappadocia pozzolan component, and polycarboxyl ic ether based super-plasticizer material, viscosity modifier, cellulose based additives and natural hydraulic lime components as the chemical additive material.

[0020] In a preferred embodiment of the present invention, the injection material comprises 1 unit natural hydraulic lime by weight, pozzolan component with 0.30 - 0.45 units, super-plasticizer additive with proportion of 1.2-1.6%, viscosity modifier with proportion of 0.5-07% and water at an amount of 55-65% of the binder. BRIEF DESCRIPTION OF THE FIGURE

[0021] In Figure 1 , XRD analysis graphic of the excavation waste earth which reveals as a result of mechanical carving of rock-cut structures in Cappadocia Region is given.

[0022] DETAILED DESCRIPTION OF THE INVENTION

[0023] In this detailed description, the subject matter relates to an injection material which is compliant for use in repair, renovation or restorations of historical rock-cut and masonry structures and which is compatible with the materials of historical buildings, and is explained with references to examples without forming any restrictive effect only in order to make the subject more understandable.

[0024] The subject matter injection material is a material which is based on hydraulic lime. Preferably, hydraulic lime is natural hydraulic lime. If preferred, lime materials like dolomitic lime, hydraulic lime and fat lime can also be used.

[0025] In the invention, “compounds which show pozzolanic activity” describe the compounds material that in itself possesses little or no cementitious value and but which can form compounds having cementitious properties when they are in finely grained form and combined with the calcium hydroxide in aqueous medium.

[0026] The injection material comprises at least one component of which shows pozzolanic activity. As the component which has pozzolanic activity, volcanic tuffs preferably obtained from Cappadocia Region are used. In the invention, the term “tuff” describes the type of rock which has relatively lower compressive strength and formed by flow deposits, ignimbrites and volcanic ashes which occur as a result of a volcanic explosion.

[0027] In the subject matter injection material, specific experiments have been realized for usage of volcanic tuffs, obtained from Cappadocia Region, as compounds which show pozzolanic activity, and it has been detected that the region tuff are natural pozzolan. The volcanic tuffs, which have such characteristics and obtained from Cappadocia Region, shall be used preferably in rock-hewn structures and in masonry structures formed by the stones obtained from this rock, it is expected that mentioned volcanic tuffs shall have characteristics which are suitable for use in these structures. Preferably such volcanic tuffs are characterized as excavation waste earth and occur while rock-cut structures are being carved and formed in Cappadocia Region. Within this context, these excavation wastes shall be a material which is suitable for use particularly in historical structures.

[0028] The innovative characteristic of the invention is that a component is provided which is proper to be used for injection materials and which shows pozzolanic activity. Said component which shows pozzolanic activity is volcanic tuffs obtained from Cappadocia region, and in Table 1 , the chemical compositions of the tuffs, which shall be used as the component which shows pozzolanic activity, are given.

[0029] Table 1. Chemical composition obtained from XRF analysis of volcanic tuffs obtained from Cappadocia Region and which can be used as a component that shows pozzolanic activity

[0030] Accordingly, it is expected that Si02, which is at proportion of at least 50% by weight, exists in the tuffs which can be used as components which has pozzolanic activity. Thanks to this, said component can show high pozzolanic activity.

[0031] In the invention, it is preferred that the components which show pozzolanic activity are tuffs obtained from Cappadocia Region and the protection scope of the invention is not limited with the methods of obtaining said tuffs. However, it is considered that volcanic tuffs, which can be obtained as waste from other regions and which have the chemical composition given in Table 1 , can be included to the protection scope of the invention and that this can be easily devised by the person who is skilled in the related technical field and who examines the invention.

[0032] The subject matter injection material comprises tuffs which are waste or not waste and which can be obtained from Cappadocia Region as components show pozzolanic activity and besides, the subject matter injection material comprises at least one, some or all the material group like silica fume, fly ash, metakaolin and brick powder.

[0033] In the invention, “super-plasticizer chemical additives” describe the components which provide decreasing of water amount at a high proportion without changing consistency in a specific injection composition or which increase slump value without changing the water amount or which form both of the effects together.

[0034] The subject matter injection material comprises at least one super-plasticizer chemical additive which prevents decrease of strength and increase of water / binder proportion. The injection material comprises polycarboxylic ether based compounds as the super-plasticizer chemical additive.

[0035] In the invention, “viscosity modifier additives” are components which provide increasing of the viscosity of mixture water during obtaining of the injection and which provide protection of the components of the injection material under suspension. The injection material comprises at least one selected from the starch, natural gums, semi-synthetic polymers, cellulose ether derivatives, sodium alginate, ethylene-based polymers and / or vinyl-based synthetic polymers as the viscosity regulating additive.

[0036] The injection material can moreover comprise components like shrinkage preventer, natural water retainer elements known in the art as the additive material.

[0037] TESTS

[0038] The excavation soils, which occur while rock-cut storage structures are being formed, have been obtained from five different determined areas in Cappadocia, and pozzolanic activity of these obtained soils has been examined by means of direct and indirect methods. As a result of the study made, it has been detected that all soils, taken from five different areas in Cappadocia Region, show pozzolanic activity. Before crushing of the obtained material and before the sieving process, drying processes have been applied to material, which is approximately 3 tones, for duration of 5-6 hours at temperatures between 100-110eC in a drying oven until the humidity is lost. Afterwards, breaking is applied to the dried materials, and sieving is applied through the sieve with 63 mhi. Before crushing, sieve analysis has been made in the material, and particle distribution has been determined by means of sieves whose mesh gap changes between 0.125 mm and 31.5 mm, and this has been shared in Table 2. The maximum particle diameter of the raw material has been determined as Dmax= 16 mm. The experiments needed for injection production has been started with the sieved material which is smaller than 63 mhi.

[0039] Table 2. Ranges of particles of volcanic tuffs used in injection material

[0040] Direct and indirect methods have been used for determining pozzolanic activity of the material after obtaining the raw material and after realizing the required experiments. In Frattini experiment which is the direct method, the pozzolanic activity of the material is measured by means of Ca(OH)2consumption. In indirect methods, the pozzolanic activity of the material is explained with changes in mechanical and electrical characteristics like compressive strength increase and electrical conductance. In addition to these methods, X- Ray Fluorescence Spectrometer (XRF) method is used for determining the chemical compositions of the material shared in Table 1 in terms of oxide, X-Ray Diffraction (XRD) method is used for determining the minerals and mineral proportions in the volcanic tuff in Figure 1. In accordance with the results obtained from the abovementioned methods, it has been determined that the waste volcanic material obtained from Cappadocia region shows pozzolanic activity.

[0041] The injection material is obtained by adding natural NFIL-5 hydraulic lime, a super-plasticizer, a viscosity modifier and the obtained tuffs. The raw materials are made homogeneous by means of mechanical mixing; here, the mixing process is realized at speed of 800 rpm in a fixed manner. In productions, mechanical mixer and spiral shaped end have been used.

[0042] In the mixing method for obtaining injection material; first of all, the pozzolanic component and the hydraulic lime materials are put into the mixing vessel and dry mixing has been realized for 1-2 minutes for preventing agglomeration. Afterwards, water has been added slowly into the vessel and has been mixed for 10 minutes. At the end of the 10thminute, the chemical admixtures have been added within 30 seconds without stopping the mixer. After all materials are added, mixing process has been continued for a further 3 minutes.

[0043] As a result, the fluidity, volume stability and penetrability characteristics of the obtained injection material are provided, and physical and mechanical experiments have been realized for this series.

[0044] The fluidity of the obtained injection material has been determined by using methods mentioned in two different standards. “Marsh Funnel” experiment mentioned in ASTM D6910 has been realized, and the “Flow Cone” experiment mentioned in TS EN 445 has been realized. The aim of this experiment is to measure the seconds where specific amount of injection grout passes through the orifice with specific diameter, and to determine the flow duration and to evaluate injectability in accordance with the occurring result. The obtained test results are given in Table 3.

[0045] In practice, in order to prevent problems like segregation and excessive bleeding, the produced injection material must meet the volume stability limit values. The volume stability in the injection materials is determined in accordance with TS EN 445 and / or ASTM C940. The obtained test results are given in Table 3.

[0046] In the produced injection materials, the penetrability characteristic is determined in accordance with EN 1771. The injectability of the injection material is evaluated in three groups in accordance with EN 1771. The injection material is classified as “easily applied” when the injection material passes through the sand column and through the upper end of the tube and is collected at an amount of 20 ml in the collection vessel, the injection material is classified as “applicable” if it reaches the topmost end of the tube but it cannot pass to the collection vessel, and the injection material is classified as “non-suitable for application” if it cannot fill the tube. In accordance with this classification, in order for the injection material to be used in an efficient manner in practice, it must be easily applied or it must be easily applicable. In order to research fluidity, volume stability and penetrability characteristics which are the three basic characteristics of injection materials, measurements have been made by means of experiment methods explained in details as above, and the mixing proportions of the materials are determined. The obtained test results are given in Table 3.

[0047] Table 3. Experiment results for flow, volume stability and penetrability

[0048] The rheological characteristics of injection materials have been determined by using a rotational rheometer (Anton Paar ReolabQC). Vane stirrer has been used in the measurements, and the flow and viscosity curves of the materials have been obtained as a result of measurements. The shear stress shear rate and viscosity-shear rate relations have been determined with the help of Rheoplus software which belongs to the device. The rheological characteristics of materials under different temperatures (5eC, 20eC, 40eC) have been obtained by means of stepped shear proportion macro determined as a result of the realized test measurements. The temperature values have been kept fixed at 5eC, 20eC and 40eC during the experiment with the help of temperature control unit of the rheometer. The rheological behaviors of injection materials have been examined and the plastic viscosity values and yield stresses have been determined by using Modified Bingham model used frequently in the literature and given in equation (1). Moreover, plastic viscosity and yield stresses for different temperature values are respectively given in Table 4.

[0049] Equation 1

[0050] Among the statements given in Equation (1): T: Shear stress (Pa) T0: Yield stress (Pa) m: Plastic viscosity (Pa.s) y\ Defined as shear rate (s1) c: Second degree parameter

[0051] Table 4. Plastic viscosity and yield stress values of the injection material

[0052] In order to determine mechanical characteristics of the injection material, in prismatic samples produced with dimensions 40x40x160 mm, the results of the pressure experiment and bending for 28thday realized according to TS EN 1015-11 are given in Table 5 as the average value.

[0053] Table 5. Bending and compressive strength of the injection material The capillary water absorption proportions of the injection materials have been determined in accordance with TS EN 15801. The prismatic samples, prepared in dimensions which are compliant to standard, have been waited in the drying oven with temperature (60±2)eC until they reach fixed weight, and they have been kept in desiccator until they reach room temperature and have been weighed. Water has been put into a tray and the samples have been placed to the tray. The square-shaped cross-section surface of the samples has been recorded as t=0 at the instant when it contacts water, and weight measurements have been made at specific intervals very frequently within the first 1 hour. The amount (Q,, kg / m2) of water, absorbed by the samples from the unit area at the instant (t,), has been determined by means of equation (2), and Qi-Vt, graphics have been formed for determining capillary water absorption coefficient, and the capillary water absorption curves have been drawn.

[0054] Qi=(mi-m0) / A

[0055] Equation 2

[0056] Among the variables given in equation (2): m,: Weight (kg) of the sample at the instant of (ti). m0: Weight (kg) of the sample dried in the drying oven,

[0057] A: The surface area (m2) where the sample absorbs water by means of capillary way

[0058] Capillary water absorption coefficient (K) has been determined by calculating the inclination of the linear part at the beginning for the drawn capillary water absorption curves and has been found as 0.44 kg / (m2.Vs).

[0059] The standards (TS EN 1936, 2010) which exist in the literature for determination of water absorption ratios, porosity and density of injection materials and the methods are essentially based on the same principle (Borelli, et al (1999), Onaran (2003)). Therefore, the experiments have been made by using the mutual variables provided in all sources. In order to determine the density of the injection material, cube or prismatic samples have been prepared whose minimum edge length is 3 cm. The samples have been waited in the drying oven until they reach fixed weight and have been weighed (W0, g). In order to obtain the net volume (Vnet, cm3) of the samples, equation (3) has been utilized.

[0060] Vnet = (WSH - Wss) / pwater (V)

[0061] Equation 3 Among the variables given in equation (3):

[0062] WSH: The weight of the sample, which is saturated with water, in air (grams),

[0063] Wss: The weight of the sample, which is saturated with water, in water (grams),

[0064] Pwater: Density of water (~1 gram / cm3)

[0065] The density of the injection material (unit volume weight, b) has been found by dividing the drying oven dry weight (W0) of the samples by the net volume (Vnet) of the sample, and the results are given in Table 6. The weight (y) of the void-free volume of materials is described by terms like “specific weight” or “real density”, and the results are given in Table 6. The specific weight of the injection material brought into powder form (<90 mhi) for providing this has been measured by Le Chatelier balloon, and the results are given in Table 6. The porosity of the injection material (total void proportion, p) has been calculated by using the equation (4) below, and accordingly, the obtained results are given in Table 6.

[0066] P (%) = [ 1 — (b / g) ]c100

[0067] Equation 4

[0068] Table 6. Density, porosity and water absorption values of injection material for 28 days

[0069] When the region conditions are taken into consideration, the freezing-thawing effect which is one of the most important strength characteristics has been examined. There is no standard for examining the behavior of lime-based injection materials under freezing-thawing effect. When the literature is examined, it is observed that different methods are used in the tests realized with lime-based mortars. Therefore, the standard TS EN 12371 “Natural stones - experiment methods-freezing strength determination test” has been used. Moreover, in the studies realized for the lime-based materials in the literature, freezing-thawing tests have been realized in accordance with the cycles which are compliant to this standard (Silva, et al, Fonseca, et al). Strength tests have been made in samples of 56 days. For the experiment, three each prismatic samples have been produced with dimensions of 40x40x160 mm. Before beginning the experiment, the samples have been kept in water for at least 24 hours and saturated with water. One cycle of the freezing-thawing test comprises the steps of freezing at -20±5eC for 7±1 hours and at 20±5eC for 17±1 hours and 100% relative humidity. After each cycle, the weights of the samples have been determined. The sample has endured against these aggressive freezing-thawing experiment conditions without breaking. As a result of freezing-thawing experiment, approximately 70% weight loss has occurred as a result of the 56thcycle, and accordingly, it has been determined that the injection material is resistant to freezing-thawing effect.

[0070] When compared with the present commercial products; it is seen that both of the two commercial products (BASF and Techno Structure), used frequently in restoration works, have water / binder ratios of 0.3 and high compressive strength (>13 MPa) values are obtained thanks to low water / binder proportion. However, only flow characteristic has been examined in these products and no technical information has been shared which comprises volume stability (bleeding) and penetrability characteristics. For the application of a suitable injection, the injection material must primarily meet the three basic fresh-state characteristics. When the studies made in relation to lime-based injection materials in the literature are examined, it is seen that these characteristics are provided with the water / binding proportion of at least 0.5. The subject matter injection material produced with relatively higher water / binding proportion (0.6-0.9) meets the limit values of fluidity, volume stability and penetrability characteristics. The mechanical characteristics can be deemed to be compatible with the lime-based mortars.

[0071] The protection scope of the present invention is set forth in the annexed claims and cannot be restricted to the illustrative disclosures given above, under the detailed description. It is because a person skilled in the relevant art can obviously produce similar embodiments under the light of the foregoing disclosures, without departing from the main principles of the present invention.

Claims

CLAIMS1. The present invention is an injection material which comprises volcanic tuffs, obtained from Cappadocia Region, as pozzolan component and which is compliant to usage in repairs of rock-cut and masonry structures.

2. The injection material according to claim 1 , wherein said injection material comprises volcanic tuffs, obtained from Cappadocia Region, at a value between 30% and 45% by weight.

3. The injection material according to claim 1 and 2, wherein the volcanic tuffs obtained from Cappadocia Region comprises S1O2 component at proportion of at least 50% by weight.

4. The injection material according to claims 1-3, wherein the particle size of volcanic tuffs obtained from Cappadocia Region is at most 63 mhi.

5. The injection material according to claims 1-4, wherein the injection material comprises tuffs which are waste or not waste and which can be obtained fromCappadocia Region as components providing pozzolanic activity and besides, the injection material comprises at least one, some or all the material group like silica fume, fly ash, metakaolin and brick powder.

6. The injection material according to claims 1-5, wherein the injection material comprises volcanic tuffs obtained from Cappadocia Region as the Cappadocia pozzolan component, and polycarboxylic ether based super-plasticizer material, viscosity modifier, cellulose based additives and natural hydraulic lime components as the chemical additive material.

7. The injection material according to claims 1-6, wherein the injection material comprises 1 unit natural hydraulic lime by weight, pozzolan component with 0.30 - 0.45 units, super-plasticizer additive with proportion of 1.2-1.6%, viscosity-modifier with proportion of 0.5-0.7% and water at an amount of 55-65% of the binder.

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