Special Mortar Research Articles

Adhesion Analysis between Concrete Layers Generated by a 3D Printing

On 3DPC, the layers are made through a process where the cement mortar is extruded through a nozzle that follows a predetermined circuit. The classic method of formwork generates a uniform element, while 3D printing generates a non-homogeneous element. Such an innovative process offers new horizons to explore. One of these is the cohesion between the two printed layers and all their mechanical properties. The objective of this work is to study the shear action of two printed layers. To understand the mechanisms, the tested specimens were made in four different ways. The first using a formwork made for the occasion. The second way involves the creation of a printed specimen with a continuous printing path. The third has a time interval of about an hour between the second and third layer. The fourth also has an interval of one hour between the same layers with the addition of a special additive mortar used for the casting recovery. The results obtained reflect on the differences between different specimens and regulations. The differences between the specimens that are studied concern the single printed specimens, the formwork specimens and the printed ones. At a regulatory level, the results of the printed specimens are compared with the regulations concerning the same tests carried out on specimens made of masonry and mortar.

Application of electrical fields to reduce chloride ingress into concrete structures

In the context of a joint research project, a system for monitoring, protection and strengthening of bridges by using a textile reinforced concrete interlayer has been developed; the system consists of two carbon layers with a spacing of 15 mm and a special mortar. This setup led to the idea of building up an electrical field between the carbon meshes, to suppress the ingress of chlorides into the concrete. This paper focuses on the question of which voltages and electrical field strengths are necessary to prevent critical chloride contents at the reinforcing steel. For this purpose, extensive laboratory tests have been performed, followed by a numerical simulation study. By applying an electrical field, the negatively charged chloride ions are forced to move to the upper carbon mesh, which is polarised as an anode. It has been investigated whether the voltages to implement an electrochemical chloride barrier are smaller than they have to be for the common preventive cathodic protection. One advantage of this chloride barrier is that, because of the lower current densities, the anodic polarisation of the carbon meshes can be reduced. Therefore, different voltages, electrical field strengths, anode materials and anode arrangements were investigated.

Hagia Sophia: Byzantine Alterity in the Core of Ottoman Identity

Hagia Sophia:Byzantine Alterity in the Core of Ottoman Identity Bissera V. Pentcheva (bio) KEYWORDS Hagia Sophia, Byzantine, Ottoman Hagia Sophia is a masterpiece of world architecture and art (Fig. 1). Within it, two religions share a vision of heaven: a unity-within-diversity. Remarkably, the chief figure of this conciliatory gesture was no less than Mehmed II the Conqueror. Gülru Necipoğlu, in her important study of the Ottoman use of Hagia Sophia, has shown that "the conquerors chose to define their self-identity in terms of the conquered, while simultaneously remaining meaningful to their own past."1 Mehmed II left most of the figural mosaics uncovered.2 Moreover, he helped promote a new mythology about the building that built on the Greek legends but helped inscribe Hagia Sophia in an Islamic narrative: For instance, the story of the prophet Mohammad and how at his birth the eastern semidome of Hagia Sophia collapsed and was only fixed when a special mortar was procured, which intermixed sand from Mecca, water from the holy well of Zemzem, and the Prophet's saliva.3 Another important legend was that of the follower of the Prophet, Abu Ayyub al-Ansari, who allegedly came as the first Muslim to pray at the site and was then martyred there. Presiding over the composition of these narratives, Mehmed II ensured the preservation of Hagia Sophia as a sultanic mosque and silenced the desire of some segments of his elite and army to destroy the building.4 But how long did the Ottomans allow for the Byzantine extimacy to live at the heart (intimacy) of Ottoman [End Page 223] Click for larger view View full resolution Figure 1. Hagia Sophia 532–537 and 562, interior. The Byzantine Institute and Dumbarton Oaks Fieldwork Records and Papers, ca. late 1920s-2000s Courtesy of Image Collections and Fieldwork Archives, Dumbarton Oaks, Trustees for Harvard University, Washington, D.C [End Page 224] identity?5 This essay seeks answers by focusing on the meaning and experience of the central space of Hagia Sophia (which the Greek called kallichoros) and on two mosaics and their Quranic glosses: the Virgin and Child in the apse and Christ Pantokrator in the dome. Kallichoros Hagia Sophia is a symbol of the universe: an enormous void of over 250,000 cubic meters topped by a soaring glittering golden dome. It is a microcosm of the macrocosm, envisioned as a sphere of unity.6 In Greek this central performance space was called kallichoros, or the beautiful choros.7 Choros means a performance space, a stage, but also the action––dance and song–unfolding in it.8 The kallichoros of Hagia Sophia gives a plastic expression of the cosmos. In the sixth century, Procopius described the newly built Hagia Sophia as having a central performance space alight with three energies: humanity's ascent to the divine, divinity's descent to earth, and the swirling energy of circumscription or perichoreusis uniting terrestrial and celestial. Procopius imagined the interior as clay shaped by the turning of a potter's wheel–apotetorneutai–into a vessel holding a void.9 The generative, circular movement is supplanted by the lifting and ascending energy towards the skies (epairomenos aerobatei). And this ascending vector brings its opposite: divinity descending and hovering over the kallichoros, "loving to dwell in this space emphilochōrein." Thus, Hagia Sophia is experienced as a material shell, whose central void spins and propels humanity to the divine.10 Hagia Sophia's architecture embodies the concept of diversity within unity. The modern engineer and architectural historian, Roland Mainstone perceptively communicated this insight in his analysis of the form: [End Page 225] Unity is achieved on the other hand, by an underlying geometrical discipline that becomes obvious only at the level of the semidomes and dome, and on the other, by details like the horizontal cornices that sweep unbroken across the piers and above the arcaded colonnades, and by the overall unity-in-diversity of the colonnades themselves and the decorative treatment of the wall surfaces––even, perhaps, by a consistent absence of the precise uniformity typical of a modern machine age.11 For Mainstone, Hagia Sophia succeeds in achieving unity without canceling...

Properties of self-leveling mortars incorporating a high-volume of sugar cane bagasse ash as partial Portland cement replacement

Self-leveling mortar (SLM) is a special mortar that can flow and fill under its own weight without the need for any compaction energy. To meet these characteristics and to ensure their stability (no segregation and exudation) these mortars require, in addition to proper mixing design and the use of water reducing assets, a large quantity of fines or viscosity modifying additives, which raises the cost for the production. The use of industrial by products such as sugar-cane bagasse ash (SCBA) is an interesting alternative because they are lower cost materials and act as viscosity modifying agent, providing improvements in the rheological, physical and mechanical properties for SLM. Thus, the influence of SCBA on the rheological, physical and mechanical properties of cement-based and limestone filler (LF) mortars will be investigate in this research. The mortars were produced with a water/binder (cement + LF + SCBA) volumetric ratio of 0.85 and 15%, 20%, 25% and 30% Portland cement (PC) replacement by SCBA. An experimental study was conducted to evaluate the effects of SCBA incorporation on the properties of fresh (viscosity, flowability and filling ability) and hardened mortars (flexural strength, compressive strength, dynamic modulus of elasticity, bond strength and water absorption by capillarity). The results show that the rheological, physical and mechanical behavior of mortars was improved, especially for contents of up to 25% replacement of PC by SCBA. For higher contents, the performance of SLM was reduced.

Optimized Processes for Flame Guncreting and Effective Guncrete Mortars for Hot Repairs to Non-Ferrous Metallurgy Equipment

We have studied flame guncreting and the guncrete mortars used in ferrous metallurgy, as well as the use of flame guncreting to make repairs to linings without shutting down equipment, thereby improving the lining resistance of equipment used in non-ferrous metallurgy. A special guncreting mortar targeted to the specific operating conditions for these equipment linings was developed. It was found that a low-melting-point component or thermite mixture used for self-propagating high-temperature synthesis (SHS) can be added to the guncrete mortar to reduce the temperature. A guncrete machine was designed to handle this guncrete mortar. Testing of the new guncrete machines and guncrete mortars at non-ferrous metallurgy facilities showed a factor of 1.8 – 2.5 increase in the wear resistance of the linings.

Numerical Simulation of Thermal Theory of Sintered Coal Gangue Self-Insulation Block and Wall

As a new building material, sintered coal gangue self-insulation block can not only make efficient use of industrial waste but also have a stronger heat preservation effect. In this paper, we use sintered coal gangue self-insulation block with staggered rectangle holes and wall as objects which can be seen commonly in the Anhui market. Through studying block type, wall thickness and masonry mortar type's effects on the heat preservation of the wall based on ANSYS numerical modeling, it proves that with special masonry mortar, sintered coal gangue self-insulation block can reach the best energy-saving effect, which meets the need of green building and sustainable building .

SPIRAL PARABOLIC DOME: HISTORICAL STUDIES OF IRANIAN ARCHITECTURE

Ancient Dezful city is located in the SW of Iran (5000BC-2016AC) near Dez River. This spiral domes are used to demonstrate the symbolic special constructions which is similar to the construction of Denial’s holy shrine, the Jewish messenger (500BC), the Lion King Yaghob Saffari’s tomb (800AD) and the Rood-band Syd’s burial place (1409AD). These structures are made by simple local materials. The common materials used are bricks and Sarooj mixture. Sarooj is the main mortar, a man-made concrete. After thousands of years, it still stands all kinds of tension, pressure, wind, rain, conflicts and wars, weapons and rockets effects (1980-1988), and sewage exposure. All bricks were set to demonstrate the cubic elements around the spiral curve. It turns around circles with variable radiuses on the spiral path-line which makes a conic parabolic sharp dome. Two domes constructed in each parabolic dome. The first dome is fixed between the supports that are called the inner dome. It was erected on the semi sphere space. The second dome is constructed by the parabolic conic section to demonstrate a beautiful, cultural and architectural masterpiece of engineering. The Main materials are bricks, dolomite, canes, stone blocks and Sarooj, a special mortar. The height of the Spiral Parabolic Dome (SPD) is about 10m and the radius of the inner dome is measured about 2 m with a ratio of 2.5 that would vary with the Geo-technical conditions and the architectural considerations.

The Experimental Research on Special Polymerized Sulfur Composite- Impregnated Concrete and Cement Mortar

Specific chemical environments step out in the industry objects. This paper presents experimental investigation results of the chemical resistance of special polymerized sulfur composite impregnated concrete and cement mortar. The special polymerized sulfur composite applied as the industrial waste material. The process of special polymerized sulfur composite as the industrial waste material production is a thermal treatment process in the temperature of about 150-155°C. The result of such treatment is special sulfur composite in a liquid state. Special sulfur composite in a liquid state is mixed with previously heated extender. In the paper there is presented development of the special polymerized sulfur composite as the industrial waste material, along with the practical uses in building industry. Also this paper presents the results of the experimental research and analyses indicating the usefulness of special polymerized sulfur composite to the protection against corrosion of concrete and cement mortar. In this paper the review of the literature have been done, among other things about select using special polymerized sulfur composite in buildings, about the methods of the surface protection against corrosion of concrete and about the methods of the evaluation of protection layer on these materials. Also in paper presents materials also the domain of the personal investigations and the methodology are definite. The research has comprised the compositions and the conditions for the formation of materials. The physical and mechanical properties of special polymerized sulfur composite have been evaluated. After the analysis of the initial results the optimum compositions have been chosen to the experimental research. In this paper the usefulness of special polymerized sulfur composite to the surface protection against corrosion of the concrete and cement mortar have been evaluated. Special polymerized sulfur composite impregnation of lean concrete and cement mortar increases its compressive strength from less than 1/3 to 1-1/2 times that of high strength concrete. Maximum absorption of special polymerized sulfur composite is achieved by carrying out the impregnation in molten sulfur under vacuum. Recent work indicates that satisfactory impregnation levels may also be achieved without the use of vacuum. Studies also show that while impregnation of high strength concrete and cement mortar increases its final strength to a value higher than that of low strength concrete, the relative increase in strength and the amount of special polymerized sulfur composite absorbed are smaller. Special polymerized sulfur composite impregnated concrete and cement mortar (SIC) may be used where high strength, resistance to water penetration, chemicals etc. are required. Available impregnating technology is applicable to precast concrete and cement mortar structures, while suitable technology for impregnating cast-in-place concrete needs to be developed. The impregnation of building materials such as blocks and bricks with melted special polymerized sulfur composite increases the compressive strength by a factor of 2 and modulus of elasticity by a factor of 3. The permeability of special polymerized sulfur composite impregnated materials to water and salt solutions is also greatly reduced. Due to the large surplus of sulphur and the low price, special polymerized sulfur composite impregnation of building materials will find extensive use in tall building construction. The space in concrete and cement mortar resulting from porosity reduces strength, exposes the concrete to chemical attack and, if filled with water, leads to destructive frost action at low temperatures. Filling the pores permanently and completely with an inert solid appears to be an effective way to improve mechanical properties and durability. Laboratory studies of impregnation with polymers have indicated that this is beneficial. New developments in concrete and cement mortar special sulfur polymer materials have declined in the Poland. There are still many products that are widely used, but the growth of these materials seems to have stabilized. A brief summary of new products related to special sulfur polymer composite impregnation, repair, overlays and precast polymer concrete will be presented. Sulfur polymer composite impregnation, which has received little attention in recent years, currently has some very interesting applications. Repair materials, particularly low modulus sulfur polymer concretes, have proven to be very effective. An innovative overlay for use in areas where freezing and thawing is prevalent has been developed.

Properties of Special Mortar Made with Raw Waste Material <sup></sup>

The paper deals with the properties of a special mortar using a Waste Paper Sludge Ash (WPSA) from Waste Paper Recycling Industry and Bottom Ash (BA) from Coal Electric Power Stations. Special mortar with some advantages is proposed to give a significant impact for replacing of normal cement mortar. The advantages are approached due to the problem that occurred from collecting raw material such as pollution problems and environmental impact issues. Besides, the raw material sources of cement and sand is limited and this issue engages with the ideas to produce new material in mortar and masonry engineering. A total 72 cubes mortar is cast and determined their properties of chemical and mechanical. The properties of special mortar are compared with other special mortar made of other waste material. The compression strength of special mortar is conducted at the age 3, 7, 28 and 40 days of curing. From the result of chemical properties, it showed that the special mortar created the high compression strength value for all mixes. The compression strength of special mortar is increased by increasing the percentage sand replacement by BA. But, the compression strength is decreased when WPSA is increased. Finally, the special mortar with 100 % BA and 10 % WPSA showed the appropriate proportion for producing special mortar.

Radiation-Protective Composite Binder Extended with Barium Hydrosilicates

Radiation safety of the rooms with X-ray sources often achieved by means of creating protective coatings. Such coatings are made of special mortar containing barite. There is the alternative for barite – barium hydrosilicates. It is advisable to synthesize barium hydrosilicates from available components – sodium hydrosilicates and soluble salts of barium. To improve the effectiveness of the protective coatings the composition and technology of the shielding material is recommended. In this work the synthesis was carried out by means of precipitation the barium hydrosilicates from solution of sodium hydrosilicates and barium chloride. It is found that composition of the synthesized product obtained by precipitation of sodium hydrosilicates with barium chloride contains barium hydrosilicates, barium carbonate and silicic acid. This is due to technological processes: intensive mixing of solutions leads to air entrapment. The properties of the composite binder made of portland cement and barium hydrosilicates are examined. It is shown that optimal composition for X-ray-protective binder comprises 20-30% of barium hydrosilicates synthesized with precipitant amount close to stoichiometric.

Static and Fatigue Performance of Repaired Reinforced Concrete Beams

Deteriorated concrete structures due to corrosion cracks and with fallen concrete cover are often repaired by removing the cracked concrete around the corroded reinforcement and replacing it with new concrete or with special repair mortar. This process is often referred to as “Mechanical Repair” and is widely used for repairing deteriorated reinforced concrete members. Mechanical repair leads to the formation of an ‘interface’ between the ‘parent concrete’ and repaired material. The structural behaviour of the repaired members is critically depended on the performance of the interface. This paper reports the results of static and fatigue tests performed on a total of 21 beams, cast in two stages to resemble the mechanical repair. Location and dimensions of the repair and the repair material are taken as variables in the study. Results of the static tests on repaired beams reveal that static performance can be restored by the mechanical repair. Compressive face repair can even improve the performance depending on the properties of repair material and the performance of the bond. However, the fatigue performance of the repaired members is found very different to their static performance. All most all repaired beams either the repair of the compression face or of the tension face failed at substantially lower number of cycles compared to the control beam. Among the repaired beam, tension face repaired beams showed the most significant reduction in the fatigue performance.

Cementitious artificial aggregate particles for high-skid resistance pavements

For some critical road sections, a high skid resistance of wearing course is required to minimise the risk of traffic accidents. Nowadays this skid resistance is mainly brought by the use of special aggregates as calcined bauxite, a scarce and expensive material. The paper presents a patented technology, where a special high-performance mortar is produced and crushed at early age. These cementitious artificial aggregates (CAA) can display aggregate properties close to those of calcined bauxite. Various models are presented for the prediction of the aggregate resistance to wear, fragmentation, and polishing, making possible the optimisation of CAA for specific applications.

Study on Special Thermal-Insulation Masonry Mortar for the North Cold Regions Autoclaved Aerated Concrete

Because the difference between the autoclaved aerated concrete and ordinary masonry mortar with thermal conductivity is too large, also easy to cause the bricking-up appearance the cold bridge and even the phenomenon of condensation, the author have study special thermal-insulation masonry mortar for autoclaved aerated concrete, about solving between the aerated concrete and ordinary mortar problem filling cracks, it is more important to resolve the big difference between the thermal conductivity, improving the insulation properties of aerated concrete special mortar. The performance as per special masonry mortar and plaster mortar for autoclaved aerated concrete (China national standard JC890-2001), supporting thermal-insulation masonry mortar effectively improved the cold bridge phenomenon of energy loss occurs.

Diagnosis and rehabilitation of real reinforced concrete structures in coastal areas

A diagnosis and rehabilitation study of two reinforced concrete structures located in coastal areas in two different climates is presented. Building 1 was constructed in the north of Chile in 1949, at a distance of 600 m from the coastline, in a seismic zone. Cracks, steel corrosion, loosening of concrete cover and slab deformations have been identified. Building 2 was constructed in Habana City, Cuba, in 1973. It is located at <100 m from the shore. The structure of building 1 shows severe localised damage: loosening of reinforced cover and intense reinforcement bar corrosion due to high deposits of sea salts. High chloride and sulphate content in the concrete mass, low compressive strength in walls and slabs, high level of steel corrosion and zones with the existence of rust instead of steel were reported. A structural rehabilitation project to ensure an increase in service life is not possible. On the contrary, in case of building 2, a possible rehabilitation procedure is recommended. Elimination of chloride contaminated concrete and the use of special mortar is an option, and electrochemical chloride extraction and incorporation of sacrificial anodes is another. An important conclusion is made: the use of chloride and sulphate contaminated aggregates is more dangerous than the penetration of these two contaminants from the external environment for buildings constructed in coastal zones.

Cement - steatite composites reinforced with carbon fibres: an alternative for restoration of brazilian historical buildings

Steatite is a mineral which has been employed in the carving of elements in facades of Brazilian historical buildings and churches since the 17th century. Over the years, many of those historical buildings suffered the consequences of weathering with a current need for restoration. Recently a special cement-based mortar containing additions of fine powder waste from mineral extraction of steatite has been developed in Brazil, as a composite material for restoration of steatite elements. However, the incorporation of steatite waste reduces the flexural strength of the mortar and compromises the restoration of elements where gravity imposes tensile stresses. The addition of carbon fibres may overcome this issue and increase the flexural strength of the cement-steatite composite mortar. This work investigates the effect of carbon fibre addition on the bulk density and flexural strength of compacted precast cement-steatite composites. The results show that the addition of carbon fibres (i) effectively increases the mechanical strength, allowing for a higher amount of steatite powder waste in the mixes; (ii) reduces the weight of the structural elements. This new composite material would help to develop restoration techniques of historical buildings and serve as a disposal route of steatite powder waste in Brazil.

Technical Note: Controlling the Impact Sound Insulation of Concrete Slab Floors

This paper investigates the impact sound attenuation of a concrete slab floor with different covering as topping layers. The basic covering is an extruded polystyrene foam board, reinforced with fiberglass mat and painted with special cementatious mortar. The concrete slab floor was tested with extruded polystyrene foam board of different thicknesses, foam board with thin rubber surfaces, and foam board with a thin rubber layer adhered to ceramic or vinyl tiles. Also, multi layers of extruded polystyrene foam board have been tested as a topping to the tested floor. The weighted normalized impact sound pressure level and weighted reduction of impact sound pressure level have been determined and used for comparison between the tested samples.

Assessment of seismic resistance of masonry structures including boundary conditions

The paper is devoted to the investigation of seismic response of the masonry structure and describes experiences with modelling of boundary conditions during the test of large heavy model on 6DOF shaking table. The main aim of the research was how to increase dynamic resistance capacity of old masonry buildings including the medium and strong seismic effects. The results of theoretical and numerical analyses are compared including initial forecasting calculations made before any test started. The emphasis is given to the boundary conditions reached during the excitation of the large masonry model via shaking table. Strengthening and retrofitting procedures and their effects are discussed when special fibre mortar is used for repair and strengthening of masonry parts of structure.

The Tower at Namur World's Tallest Precast Prestressed Concrete Structure

At a height of 171 m (561 ft), the Namur Telecommunications Tower in Vedrin near Namur, Belgium, is believed to be the tallest loadbearing precast, prestressed concrete structure in the world. The tower has a tripod structure up to the 96 m (315 ft) mark and extends as a single cylindrical shape thereafter. The main structure comprises reinforced precast concrete ring segments, spliced with a special mortar and post-tensioned together. This article describes the conceptual development, design features, precasting techniques and erection procedure involved in building this unique tower.

Flexural behaviour of strengthened reinforced concrete beams

A large experimental research programme has investigated the flexural strength of simply supported reinforced concrete beams. The beams were first damaged so that they could be strengthened by means of jackets (cast-in-place shotcrete or pre-packed special mortar plus additional new reinforcement). This paper analyses the flexural strength of these beams. The behaviour in service and ultimate state as well as the bond characteristics are studied.

Very high performance micro-concretes for the confinement of industrial waste

Industrial waste is very often immobilized in metallic casks which are then installed in concrete confinement enclosures. High performance concrete types can provide an elegant solution for the storage of waste, with the possibility of avoiding double-wall confinement. This study analyses the behavioural evolutions of very high performance microconcretes with a fibre content, with particular attention to the nature of the aggregates and the nature, the dimension and the quantity of the fibres. The characteristics obtained, which are generally of a very high order, result from the very low porosity and permeability of the matrix. In a similar manner we deal with the problem of sealing the enclosure, by using a special mortar which provides excellent sealing for the container through perfect binding between the walls of the enclosure and the plug.