Weathering and conservation of tuff stone

Tuff stone, a porous pyroclastic rock, is a light and soft material. Hence, tuff is easy to handle and to transport. It is used as construction material in numerous historical buildings. Due to its high water absorption and retention potential, heterogeneous pore structure, and clay mineral content, tuff is highly sensitive to weathering by moisture expansion and salt crystallization [1; 2]. The search for a protective agent for tuff stone has been subject to scientific studies for several decades. Yet, due to the high variability and heterogeneity of tuff stone, no generally applicable means to protect tuff against weathering has been found to date. Instead, case specific solutions are developed to preserve historical buildings. Often it is necessary to remove weathered parts of the stone or exchange whole tuff ashlars to ensure the stability of the construction. Since tuff is a limited resource, it is crucial to find suitable protective agents that prolong the life-cycle of tuff stone to preserve historical buildingsTo favourably influence water absorption, effective porosity, and the pore structure of tuff stone, a thorough impregnation of the stone with the protective agent is desirable. This can be achieved by the application of silica sol products, which are dispersions of colloidal amorphous silicon dioxide particles. The small particle sizes (between 10 and 100 nm) facilitate a high penetration depth. Despite of the promising results of several studies, colloidal silicas are rarely used as protective agents for tuff stone in the restauration practice [3; 4]. This may be due to the lack of long-term experiences with these materials. Furthermore, the performance of protective agents is closely related to the pore structure and chemical and mineralogical composition of the rock [5; 6]. To understand these interactions, further research is needed.The aim of a current research project is to study the application of colloidal silica as protective agent for Weiberner tuff. In first tests, penetration depth and changes in the pore structure are analyzed. Furthermore, the influence of the treatment on the hygric and mechanical properties and on the durability of the stone is studied. The new data will contribute to a better understanding of tuff stone deterioration and conservation.&#160;[1] Wedekind et al. (2013) Environ. Earth Sci. 69. [2] P&#246;tzl et al. (2018) Environ. Earth Sci. 77. [3] Iucolano et al. (2019) Contr. Build. Mater. 202. [4] Zornoza-Indart & Lopez-Arce (2016) J. Cult. Herit. 18. [5] T&#246;r&#246;k et al. (2007) Geol. Soc. London, Spec. Publ. 271. [6] St&#252;ck et al. (2008) Environ. Geol. 56.

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Rock Pore Structure as Main Reason of Rock Deterioration

Studia Geotechnica et Mechanica ◽

10.2478/sgem-2014-0010 ◽

2014 ◽

Vol 36 (1) ◽

pp. 79-88 ◽

Cited By ~ 9

Author(s):

Martin Ondrášik ◽

Miloslav Kopecký

Keyword(s):

Tensile Strength ◽

Pore Structure ◽

Water Absorption ◽

Pore Water ◽

Construction Material ◽

Adsorbed Water ◽

Rock Properties ◽

Exclusion Criterion ◽

Hydraulic Pressure ◽

Freeze Thaw

Abstract Crashed or dimensional rocks have been used as natural construction material, decoration stone or as material for artistic sculptures. Especially old historical towns not only in Slovakia have had experiences with use of stones for construction purposes for centuries. The whole buildings were made from dimensional stone, like sandstone, limestone or rhyolite. Pavements were made especially from basalt, andesite, rhyolite or granite. Also the most common modern construction material - concrete includes large amounts of crashed rock, especially limestone, dolostone and andesite. However, rock as any other material if exposed to exogenous processes starts to deteriorate. Especially mechanical weathering can be very intensive if rock with unsuitable rock properties is used. For long it had been believed that repeated freezing and thawing in relation to high absorption is the main reason of the rock deterioration. In Slovakia for many years the high water absorption was set as exclusion criterion for use of rocks and stones in building industry. Only after 1989 the absorption was accepted as merely informational rock property and not exclusion. The reason of the change was not the understanding of the relationship between the porosity and rock deterioration, but more or less good experiences with some high porous rocks used in constructions exposed to severe weather conditions and proving a lack of relationship between rock freeze-thaw resistivity and water absorption. Results of the recent worldwide research suggest that understanding a resistivity of rocks against deterioration is hidden not in the absorption but in the structure of rock pores in relation to thermodynamic properties of pore water and tensile strength of rocks and rock minerals. Also this article presents some results of research on rock deterioration and pore structure performed on 88 rock samples. The results divide the rocks tested into two groups - group N in which the pore water does not freeze even when the temperature decreases to -20 ºC, and the second group F in which the pore water freezes. It has been found that the rocks from group N contain critical portion of adsorbed water in pores which prevents freezing of the pore water. The presence of adsorbed water enables thermodynamic processes related to osmosis which are dominantly responsible for deterioration of rocks from group N. A high correlation (R = 0.81) between content of adsorbed water and freeze-thaw loss was proved and can be used as durability estimator of rocks from group N. The rock deterioration of group F is caused not only by osmosis, but also by some other processes and influences, such as hydraulic pressure, permeability, grain size, rock and mineral tensile strength, degree of saturation, etc., and the deterioration cannot be predicted yet without the freeze-thaw test. Since the contents of absorbed water and ratio between adsorbed and bulk water (of which the absorbed water consists) is controlled by the porosity and pore structure, it can be concluded that the deterioration of some rocks is strongly related to rock pore structure.

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The Influence of Pore Structure on the Waterproof Performance of Polymer Modified Mortar

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.584-586.1130 ◽

2014 ◽

Vol 584-586 ◽

pp. 1130-1134 ◽

Cited By ~ 1

Author(s):

Dao Xun Ma ◽

Yan Liu ◽

Yong Lai

Keyword(s):

Pore Structure ◽

Water Absorption ◽

Penetration Depth ◽

Open Porosity ◽

Linear Growth ◽

Capillary Water ◽

Cement Ratio ◽

Capillary Water Absorption ◽

Cement Mortars ◽

The Relationship

This paper tested the pore structure, capillary water absorption and impermeability of cement mortars modified with three polymers respectively, establishing the relationship between the pore structure and waterproof performance. The results show that with the polymer dosage growing, especially as the polymer/cement ratio (mp/mc) increases from 0% to 5%, the reduction in the capillary water absorption and the penetration depth of water into mortar is significant. In themp/mcrange of 0%~20% the open porosity presents a gradual decrease trend. The capillary water absorption and the penetration depth of water into mortar show linear growth and exponential growth respectively with the open porosity increasing.

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Comparative Study of Strength and Corrosion Resistant Properties of Plain and Blended Cement Concrete Types

Advances in Materials Science and Engineering ◽

10.1155/2017/9454982 ◽

2017 ◽

Vol 2017 ◽

pp. 1-14 ◽

Cited By ~ 3

Author(s):

Velu Saraswathy ◽

Subbiah Karthick ◽

Han Seung Lee ◽

Seung-Jun Kwon ◽

Hyun-Min Yang

Keyword(s):

Water Absorption ◽

Corrosion Behaviour ◽

Blended Cement ◽

Effective Porosity ◽

Chloride Diffusion ◽

Chloride Diffusion Coefficient ◽

Chloride Permeability ◽

Corrosion Resistant ◽

Lower Corrosion Rate ◽

Portland Slag Cement

The relative performances of mechanical, permeability, and corrosion resistance properties of different concrete types were compared. Concrete types were made from ordinary Portland cement (OPC), Portland pozzolana cement (PPC), and Portland slag cement (PSC). Compressive strength test, effective porosity test, coefficient of water absorption, short-term accelerated impressed voltage test, and rapid chloride permeability test (RCPT) were conducted on M30 and M40 grades of concrete designed with OPC, PPC, and PSC cements for 28- and 90-day cured concrete types. Long-term studies such as microcell and electrochemical evaluation were carried out to understand the corrosion behaviour of rebar embedded in different concrete types. Better corrosion resistant properties were observed for PSC concrete by showing a minimum current flow, lowest free chloride contents, and lesser porosity. Besides, PSC concrete has shown less coefficient of water absorption, chloride diffusion coefficient (CDC), and lower corrosion rate and thereby the time taken for initiation of crack extended.

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Corrigenda: Pore Structure and the Disruptive or Cementing Effect of Salt Crystallization in Various Types of Stone

Studies in Conservation ◽

10.2307/1506590 ◽

1994 ◽

Vol 39 (4) ◽

pp. 286

Keyword(s):

Pore Structure ◽

Salt Crystallization

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OPTIMUM PERFORMANCE OF STABILIZED EDE LATERITE AS AN ALTERNATIVE CONSTRUCTION MATERIAL

International Journal of Engineering Technologies and Management Research ◽

10.29121/ijetmr.v3.i8.2016.63 ◽

2020 ◽

Vol 3 (8) ◽

pp. 1-8

Author(s):

Adegbenle Bukunmi O

Keyword(s):

Compressive Strength ◽

Water Absorption ◽

Construction Material ◽

High Water ◽

Good Alternative ◽

Linear Shrinkage ◽

Absorption Capacity ◽

Water Absorption Capacity ◽

Optimum Performance ◽

High Water Absorption

Laterite samples from Ede area with particle components of 19.7% clay, 32.8% silt and 47.5% sand was stabilized with combined cement, lime and bitumen and test for Compressive strength, Linear Shrinkage, Permeability and Water Absorption. The stabilizers were mixed with laterite soil in different ratios and percentage. The laterite carried 90% which is constant while the three stabilizers shared the remaining 10% in varying form. After 28 days of curing, laterite stabilizer with 90% of laterite, 8% of cement, 1% lime and 1% bitumen (LCLB1) possessed compressive strength of 2.01N/mm2. It Water Absorption Capacity was 3.05%. LCLB4 stabilizer (90% laterite, 6% cement, 2% lime and 2% bitumen) has the same compressive strength with LCLB1 stabilizer but with a high Water Absorption Capacity of 4.2%. The stabilizer of 90% laterite, 3.33% cement, 3.33% lime and 3.33% of bitumen (LCLB8) has the lowest compressive strength of 0.74N/mm2 and the highest Water Absorption Capacity of 5.39%. The results shows that LCLB1 stabilizer is a better stabilizer for strength and blocks made from laterite stabilized with it stand a good alternative to sand Crete blocks in building constructions. The combination of these stabilizers in order to determine a most economical volume combination for optimum performance is highly possible and economical.

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Influences of shrinkage reducing admixture on the mechanical properties, drying shrinkage, water absorption and porosity of Portland cement mortar

Journal of Science and Technology in Civil Engineering (STCE) - NUCE ◽

10.31814/stce.nuce2021-15(3)-05 ◽

2021 ◽

Vol 15 (3) ◽

pp. 55-67

Author(s):

Nguyen Van Chinh

Keyword(s):

Compressive Strength ◽

Flexural Strength ◽

Portland Cement ◽

Water Absorption ◽

Drying Shrinkage ◽

Effective Porosity ◽

Minor Effect ◽

Wide Range ◽

Shrinkage Reducing Admixture ◽

A Minor

Drying shrinkage is the main cause of early age cracking of concrete and mortar. A wide range of research has been conducted to reduce the drying shrinkage, including using fibres or chemical admixtures. This paper investigated the effect of shrinkage reducing admixture on the flexural strength, compressive strength, drying shrinkage, water absorption and porosity of mortar. The mix compositions were ordinary Portland cement (OPC) : sand : liquid = 1: 1: 0.38 in which liquid consisted of water and shrinkage reducing admixture (SRA). SRA was used at the proportions of 2%, 4%, and 7% by weight of cement. The test results show that SRA reduces the flexural and compressive strengths of mortar. The reduction in flexural strength and compressive strength at 28 days is 14% and 25%, respectively at 7% SRA dosage. In addition, SRA significantly reduces the drying shrinkage and water absorption of mortar. At 7% SRA dosage, the drying shrinkage at 53 days is reduced by 60% while the water absorption rate at 24 hours is reduced by 54%. However, SRA has a minor effect on the pore size distribution, effective porosity, and cumulative intrusion volume of mortar.

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Synthesis of Polyvinyl Formal Sponge for Wound Care Dressing Application

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.152-153.1650 ◽

2010 ◽

Vol 152-153 ◽

pp. 1650-1659

Author(s):

Qing Hao Yang ◽

Guang Xu Cheng ◽

Zhi Cheng Zhang

Keyword(s):

Mechanical Properties ◽

Mechanical Strength ◽

Porous Structure ◽

Pore Structure ◽

Water Absorption ◽

Wound Dressing ◽

Wound Care ◽

Acid Catalyst ◽

The Other ◽

Polyvinyl Formal

In an effort to seek poly(vinyl formal) (PVFM) foams based wound dressing pad material, a series of foamed PVFM materials have been synthesized under varied conditions. The influence of conditions on the properties of PVFM foam, such as mechanical properties, water absorption, pore structure and bulk density, is well discussed individually. It has been shown that both the reactant and acid catalyst affect the degree and speed of acetalization, therefore the mechanical properties, pores continuity and water absorption of the resultant sample. The addition of Na2CO3, surfactant and CMCNa are mainly influencing the porous structure as well as the mechanical properties and water absorption. One best sample with balanced properties is obtained. It possesses higher mechanical strength and water absorption while the other properties are similar, comparing with a commercial surgical PVFM sponge (YJ-1) currently used.

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The Heritage Stone of Nossa Senhora de Guadalupe Church, Mouçós, North of Portugal: Characterisation and Glyptography

10.5194/egusphere-egu21-4536 ◽

2021 ◽

Author(s):

David Freire-Lista ◽

Bruno Campos ◽

Patricia Moreira da Costa

Keyword(s):

Water Absorption ◽

Bulk Density ◽

Wave Velocity ◽

Effective Porosity ◽

P Wave ◽

Building Stones ◽

Thin Sections ◽

P Wave Velocity ◽

The Mean ◽

The Church

Granite is the most important building stone in the north of Portugal. The importance of the stones in this region is evidenced by the pre-Roman roots Mor (r), Mur (r) and Mour of place names such as Montemuro, Moreiras, Mou&#231;&#243;s, and Mourelhe. These roots indicate the existence of building stones used since ancient times in these places.The quarries of the main building stones of historical buildings were generally in the vicinity of the buildings. Formerly, stonemasons carved mason's marks on ashlars. The mason's marks are lapidary signs to indicate the work carried out by each one. The mason's marks are generally symbolised by the initial of the stonemason's name. They are often found on dressed stones in buildings and in other public structures.Nossa Senhora de Guadalupe church of Mou&#231;&#243;s (possibly 16th century) has typical characteristics from the late Romanesque. It is located in Vila Real (North of Portugal). It is made up of three volumes: a single nave, a lower rectangular apse, and a sacristy attached to the apse. The exterior of this church is preserved almost unaltered in its original state. Each of the granite ashlars that make up this church has a mason's mark in the center of its face.The mason's marks of the church have been identified; all the ashlars with visible mason's marks have been mapped, and a glyptographic study has been carried out. This has made it possible to calculate the number of stonemasons that worked in the construction of the church and the number of ashlars that were transported in each carriage, and to determine the construction phases of the church.Eight cubic samples have been cut to calculate the granite&#8217;s hydric properties (effective porosity, water absorption and bulk density) according to UNE-EN:1936. Ultrasound wave velocity was measured according to UNE-EN:14579. Furthermore, three thin sections have been made to characterise the granite petrographically under a polarisation microscope Leica DM-4500-P. A mosaic of photomicrographs has been made to evaluate the petrographic properties.There are six main types of mason's marks in Nossa Senhora de Guadalupe Church. All quarrymen extracted the stones from the same quarry, or from nearby quarries. The mean effective porosity of the building granite is 3.2%&#177;0.3, and the mean water absorption is 1.2%&#177;0.1. Its mean bulk density is 2566 kg/m3&#177;61.0 and its ultrasound P wave velocity is 2920 m/s&#177;98.3.The mason's marks are preserved because of the excellent petrographic and petrophysical properties of Mou&#231;&#243;s granite. Further, Nossa Senhora de Guadalupe church was protected with lime plaster during the past centuries, and the plaster was not removed with the projection of abrasive particles.The use of analytical techniques such as petrography, ultrasonic P wave velocity and the determination of hydric properties will guarantee the quality and durability of a sustainable restoration.The historical quarries, forms of traditional stone extraction and uses of Mou&#231;&#243;s granite constitute a heritage that must be safeguarded.Acknowledgements: The Funda&#231;&#227;o para a Ci&#234;ncia e a Tecnologia (FCT) of Portugal. CEECIND/03568/2017.

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Optimization of Protective Agents for The Freeze-Drying of Paenibacillus polymyxa Kp10 as a Potential Biofungicide

Molecules ◽

10.3390/molecules25112618 ◽

2020 ◽

Vol 25 (11) ◽

pp. 2618

Author(s):

Hayatun Syamila Nasran ◽

Hidayat Mohd Yusof ◽

Murni Halim ◽

Nor’Aini Abdul Rahman

Keyword(s):

Fungal Pathogens ◽

Crop Production ◽

Freeze Drying ◽

Fungal Infections ◽

Skim Milk ◽

Paenibacillus Polymyxa ◽

Protective Agent ◽

Protective Agents ◽

Chemical Fungicides

Anthracnose is a fungal disease causing major losses in crop production. Chemical fungicides widely used in crop plantations to combat fungal infections can be a threat to the environment and humans in the long term. Recently, biofungicides have gained much interest as an alternative to chemical fungicides due to their environmentally friendly nature. Biofungicide products in powder form can be formulated using the freeze-drying technique to provide convenient storage. Protective agent formulation is needed in maintaining the optimal viable cells of biofungicide products. In this study, 8.10 log colony-forming unit (CFU)/mL was the highest cell viability of Paenibacillus polymyxa Kp10 at 22 h during incubation. The effects of several selected protective agents on the viability of P. polymyxa Kp10 after freeze-drying were studied. Response surface methodology (RSM) was used for optimizing formulation for the protective agents. The combination of lactose (10% w/v), skim milk (20% w/v), and sucrose (27.5% w/v) was found to be suitable for preserving P. polymyxa Kp10 during freeze-drying. Further, P. polymyxa Kp10 demonstrated the ability to inhibit fungal pathogens, Colletotrichum truncatum and C. gloeosporioides, at 60.18% and 66.52% of inhibition of radial growth, respectively.

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