Clay Mortars Research Articles

Water Vapour Sorption and Hysteresis Models Applicable for Silicate Building Materials

Various models of the water vapour sorption isotherms were analysed from the aspect of their applicability for silicate-based building materials like calcium-silicates, burnt clay bricks, plasters and mortars. The analysis included the assessment of the various sorption hysteresis models. They were compared and calibrated with experimental data, consisting of the main adsorption and the scanning curves. For the silicate-based building materials as a fundamental the Brunauer–Emmett–Teller (BET) and Frenkel–Halsey–Hill (FHH) models of adsorption in a combination together with Kelvin-Cohan (KC) model of desorption, with the Independent Domain Model of hysteresis can be applied due to their satisfactory universality.

EXPERIMENTAL INVESTIGATION ON THE COMPRESSIVE STRENGTH OF PRESSED COMPOSITE EARTH BRICK

Earth block is a construction material made primarily from soil. Compressed earth blocks have been widely used to construct many older structures which was found more economical. The present study involves the use of different admixtures which can improve the compressive strength of the pressed composite earth brick. As soil is abundant in nature, the compressed earth bricks can be manufactured in large quantity. By using this method, buildings of uniform component sizes can be made which leads to faster construction with lesser cost. The surface of building can be finished with clay mortar or cement mortar.

Internal curing of mortar with low water to cementitious materials ratio using a normal weight porous aggregate

A normal weight porous aggregate (NWPA), with the saturated surface dry density of 2.3g/cm3, was prepared. Impact of NWPA on performance of mortar with water to cementitious materials ratio of 0.3 was presented in this paper. The results show that NWPA has smaller pores and higher water absorption speed than expanded clay, but lower desorption speed. Strength of mortar accompanying NWPA is higher than or close to that of a plain one. Mortar containing NWPA expand less than that with expanded clay under sealed condition, which suggests the lower internal curing efficiency of NWPA. However, still it could diminish the shrinkage of low w/c mortar and be used as internal curing agent. Variation of water absorption and dynamic modulus from top to bottom of mortar with NWPA is similar to that of plain one, and lower than that of expanded clay mortar, which certifies that NWPA could promote the uniformity of internally cured mortar.

Modern Architecture of Uzbekistan

ISSN: 2168-9717 As far as we know, in traditional architecture of Uzbekistan the special place occupies a principle of the organization of the closed court yard. At the dawn of its history the humanity used natural construction materials, namely timber, natural stone, clay, straw, among which clay was the most widespread and easy one to use. Universally available and cheap, it was actively used in construction not only in Central Asia, but also around many countries all over the world. Statistical data shows that about 30% of the world’s population or around 1.5 million people live in clay houses. Around 20% of the above mentioned population lives in cities and city suburbs. Central Asian rural areas have over 50% of housing and facilities built of natural clay. This is primarily caused by its availability, economic efficiency and excellent insulation qualities. First primitive rounded shape air bricks were first applied in Central Asia ten thousand years ago and are perpetually used since then. An excellent example for entire city built of clay is ancient Khorezmian city Toprak-kala, inhabited up to the 6th century AD. It was surrounded by a clay wall, had one major street with a number of secondary streets perpendicular to the major one. The remainders of clay sculptures, mural paintings, highly developed irrigation systems have been excavated. Some historical sites dated from early Middle Ages still are in more or less good condition. In the period preceding the spread of Islam around Central Asia, Termiz had numerous Buddha temples, stupas and castles, some of which survived till present time. Corner towers, some walls and arch covered corridors of Kyrk-kyz palace in Termiz (10-11 th century AD) maintained their original height, though its last clay dome collapsed in 1980. Chadrah-khovli erected in 18th century near Khiva still demonstrates its exceptional sublimity. Uzbekistan also has numerous houses built up from wooden frames, clay and air bricks spread around its territory and majority of them is over 100 years old. The most popular unburnt construction material was “pakhsa”. It looked like a wall comprised of earthen belts of various height. Widely spread 75×90×100 sm (Ak-tepe castle) and 100×90×300 cm (Tali-barzu castle) “pakhsa” blocks were manufactured directly on site. Air bricks, clay mortars, puddle and “guvalya” (rounded air bricks) were used as well.

Composition and diagenesis of ancient Shali city buildings of evaporite stones (kerchief), Siwa Oasis, Egypt

Shali is an ancient fortress, built in the XII–XX century in Siwa, Northwest Egypt. It is built on two Middle Miocene limestone and marl hills, between the wadi plain. The architecture of the fortress buildings is composed of local materials derived from the Miocene, Quaternary, and recent salt lake deposits. The framework blocks of the city are mainly composed of salt (Kerchief), limestone, and bentonite, wood particles, dry date seeds, and bones derived from ancient tombs. In this study, the modification and mineral phases that developed during the diagenetic alteration and cementation of the salt and clay mortars with different framework in the walls of the ancient houses and settlements will be followed and interpreted. Diagenesis included transportation of salt materials from the nearby Fetnas Lake and mixing with some sand and clays as mortar pressed into the voids between the frameworks (Kerchief blocks). This resulted in dehydration, gypsum crystallization, and halite cementation. The continuous crystallization through the epitaxial growth of halite in both cement and framework blocks results in strong adhesion and binding of the framework. At the end of the process the kerchief blocks and the cement will be completely homogenous to a point that they apparently no longer be distinguished.

Study on How to Adapt Raw Clay Housing to Climate Change: Locust Bean Tree (Parkia Biglobosa) Used as Protecting Material

The use of raw clay in housing construction dates back from ancient times and is still living on. Traditional habitat comprising various buildings all over different places of our planet, give evidence. Among any other pathologies affecting naked earthen walls, the rain water wash remains a major concern and deserves careful consideration. Which justifies the interest of this research focused on the protection means of such types of walls. This article relates the experiment conducted on low walls made out of raw clay mixed with composite protecting products (traditional and modern ones as well), being tested to intensive water floods. The result of the tests assessed through efficiency of the protecting materials, shows that the locust bean tree (local tree) fruit husk extract added to raw clay mortar and carefully blended seems to provide better ability to protect walls against water assault. Moreover, consistency check and plasticity reveal better performance in clay material properties.

Elemental analysis of old mortar used in various archaeological sites of Bangladesh by SEM and EDAX

Morphological characterization and mineralogical studies were performed on fifteen mortar samples collected from three ancient archaeological sites (Wari-Bateshwar, Lalmai-Mainamati, and Paharpur) of Bangladesh. Many cracks and pores were found in the mortar samples of Buddhist Lotus temple of Wari-Bateshwar. Energy dispersive analytical x-ray analysis confirmed the presence of C, O, P, K, Al, Fe, Na, Mg, Mn, Si and Ti in the mortar samples. The absence of Ca in the samples indicates that the clay was used in the architecture as binding materials. In the clay mortar, Si played an important role and with the presence of O2, SiO2 was formed, which strengthened the binder. K, Al, Fe, Na, Mg, Mn, Si and Ti might form compounds like SiO2, Fe2O3, K2O, Al2O3, MgO, MnO, Na2O3, and TiO2 with O2. The oxidation of Fe+2 produced Fe2O3 which was responsible for breaking down the bonding of mortars. DOI: http://dx.doi.org/10.3329/jasbs.v38i2.15595 J. Asiat. Soc. Bangladesh, Sci. 38(2): 145-153, December 2012

Procedures and Techniques Used to Increase the Durability of Weak Masonries with Clay Mortars

For the past decades the importance of structural rehabilitation of historical buildings, in order to preserve the cultural heritage, has increased considerably. The weak masonry (made from bricks and bounded with low-strength mortars) were created using mortars which, depending on different external factors, were degraded and there are necessary urgent rehabilitation interventions in order to assure the masonrys durability by protecting the joints with new, compatible and reversible materials and techniques (according to Venice charter requirements). In order to increase the durability characteristics of the weak masonry, the design and application techniques of some particular materials and solutions used will be considered in present paper. The used procedures are based on joints reinforcing using fibre reinforced mortar (fibres made of steel, carbon and glass). The test results have revealed a significant improvement of the structural response and a noticeable increased durability depending on the materials and techniques used.

Παρατηρήσεις στη χρήση των υστερορωμαϊκών πήλινων ενσφράγιστων "ιγδίων": η περίπτωση των ιγδίων από τη Βόρειο Συρία

OBSERVATIONS ON THE USE OF LATE ROMAN IMPRESSED CLAY MORTARS: THE CASE OF “NORTH-SYRIAN MORTARIA” Mortars made of clay were largely diffused and used during the Roman Empire. This article focuses on a specific category of clay mortars, identified by their region of manufacture as “North-Syrian Mortaria”. This category, dated to the end of the 3rd and to the first half of the 4th century A.D., was largely diffused in the eastern Mediterranean. This study, after presenting the main characteristics of these mortars (shape, decoration, fabric, production centers, dating, distribution), addresses questions regarding their use. Traditionally, roman mortars were used in order to process (pound, pulverize, grind, mix) either solid or liquid/fluid products related to sustenance. Written sources as well as archaeological evidence support these uses. However, this study attempts to point out that they could also have a more specialised use, connected to the requirements of specific, well-organized workshops. This could be the case of the “North-Syrian Mortaria”. Regardless of the limited data concerning the exact archaeological context in which this type of mortar is found, the case-studies of mortars of this category found in Jalame, in ancient Messene and Olympia support this opinion.

SOME UNUSUAL KIVAS NEAR NAVAJO MOUNTAIN

Sitting astride the border which separates Arizona from Utah is Navajo Mountain, a great rounded dome that rises from the high plateau. The igneous rock never entirely broke through the mass of sedentary deposits that covered the surface as in the case at El Capitan, and several other places to the west in Monument Valley. The tremendous pressure from beneath simply elevated a portion of the surface, leaving jagged cracks on its slopes here and there, and a great rounded crest that can be seen for many miles from every direction. To the north and northwest the surface is cut by deep gashes of West, Long, Forbidden, Nonnezoshi, and Beaver Canyons and their numerous branches. This section is exceedingly rough and affords little sustenance for man or beast. To the east a somewhat broken country extends to Pahute canyon, a deep gorge that zigzags northward to the San Juan river. To the south and southwest the land slopes rather unevenly toward the canyons of the Nitsie (Navajo Creek) which flows northwestward into the Colorado River. Prehistoric human habitations are found in a few small caves on the southern and western slopes of the mountain; and on the mesa to the east and the sloping plains to the south, and to the west are found the ruins of numerous villages which attest that at some time in the past, probably from about 1000 to 1400 A.D., this region supported a considerable population. The largest of these villages show a general plan that can be traced in ruins from lofty Cummings Mesa on the west and Navajo Mountain eastward to Marsh Pass. Two ruins southwest of the mountain, known to the Navajo as Kinclachie (Red House) and Kinklitso (Yellow House) illustrate well this plan. Red House, close to the base of the mountain, may be taken as a sample. These villages were usually located on ground that sloped gently toward the south or southwest. On the highest portion of the area was built a long two-story building. At Red House this building is 100 feet long and 10 feet wide. The walls are of fairly well dressed, red sandstone, taken from a nearby projecting cliff of Navajo Mountain, and laid in clay mortar. The walls are double. The blocks of the outer courses have been carefully selected and some measure four feet in length, while those used on the interior of the building were smaller and more irregular. The interior walls probably had been covered with clay plaster. From each end of this building an enclosing wall, flanked on the inside by groups of rooms, extended

Clay content of argillites: Influence on cement based mortars

The pozzolanic activity of four heated powders containing different clays has been tested. Mineral transformations during calcination from 20 to 900 °C have been followed by X-ray diffraction (XRD) and Differential Scanning Calorimetry (DSC). Compressive strength tests were performed at 1, 7 and 28 days on cement–clay mortars using 30% of pozzolanic material as a replacement by mass for cement. Calcination temperatures corresponded to the stages of potentially high reactivity identified by XRD. Results indicated that there exists incompatibility between clay minerals which can not be activated at the same temperatures. Products of recrystallisation of the earlier activated clay were already formed when the second clay type was activated. Concerning the type and the abundance of clay minerals in the raw material, this study evidences that the compressive strength is, at first approximation, correlated with the percentage of activated clay and less with the nature of the clay assemblage.

Thermal stability and pozzolanic activity of raw and calcined mixed-layer mica/smectite

Samples of synthetic mixed-layer mica/smectite were calcined at 560°C, 760°C and 960°C. Chemical, physical and mineralogical properties of both untreated and calcined samples, before and after being mixed with Ca(OH) 2 in the presence of simulated cement pore solution, were studied in detail. Technological properties such as rheology and compressive strength of the clay mortars were also studied. The investigation indicates that the mixed-layer mica/smectite is a fairly good pozzolanic material and calcination is an effective approach to improve its pozzolanic activity. Dehydration and dehydroxylation of the sample at 560°C increase its pozzolanic activity considerably. Calcination from 560°C to 760°C does not cause further significant improvement, whereas calcination at 960°C again increases the compressive strength of the mortars to 113% (compared to the reference ordinary Portland cement (OPC) mortar). Most of six studied standard clay minerals are compositionally suitable to be used as pozzolanic materials. The common reaction products of clays and cement are CSH and C 4AH x . The untreated clay minerals with stable layer structures have low pozzolanic activity and have negative effects on the compressive strength. Particle sizes of pozzolanic materials of calcined clay minerals and some other artificial pozzolans correlate well with the compressive strength of their cement mortars.

Pozzolanic reactions of six principal clay minerals: Activation, reactivity assessments and technological effects

Six standard clays, before and after calcination at 3 or 4 temperatures and being mixed with Ca(OH)2 [CH] in the presence of simulated cement pore solution, and with ordinary Portland cement, respectively, were studied in detail. Chemical compositions of most clays conform well to the requirement in ASTM C 618. Water demand of clay-containing mortar varies, depending on the crystal chemistry of raw clays, and on the specific surface area of calcined clays. Measurements of XRD background or alkali soluble Si are rapid methods in evaluation of the pozzolanic activity of clays. Compressive strength of mortars based on the raw clays is affected by structure of clays. Calcination increases the pozzolanic activity of clays and the compressive strength of the Portland cement — clay mortars. A close correlation exists between compressive strength of mortars and particle size distribution of the dehydroxylated clays. The most common reaction products of clay — CH mixtures are C-S-H2 and C4AHx, while C2ASHj8 and C3AH6 were also detected with clays rich in Al.

Simulation of the Thermal Fire Resistance of Building Materials Using the Finite Element Package LIBRA

Application of the microcomputer based finite element analysis program ‘LIBRA’ to predict the thermal fire resistance of building materials is demonstrated in this paper. The thermal behaviours of three samples of aluminium, fired clay brick and cement mortar with one side exposed to afire were predicted. An electric furnace which can induce the transient variation of air temperature following the British Standard Standard fire curve was built. Experimental measurements on the transient temperature distribution in those three samples were performed to verify the predicted results and good agreement was found for the aluminium.

Use of antifriction coatings for reducing friction between pile lateral surfaces and soil

1. All the investigated antifriction materials substantially reduce surface friction and can be recommended for treating piles used under type II collapsibility conditions. 2. Maximum decrease in the friction (50–60% and more) is ensured by BAM-3 plastic consistent lubricant, KO-174 organosilicon enamel, profiled polyethylene, and clay and peat-clay mortars. 3. The displacement values required for total shear and for development of total friction for different antifriction materials and soil water contents vary within narrow limits and amount to about 3 mm. Changes in the water content of collapsible loess soils do not substantially affect their friction on surfaces treated with the investigated coatings.

Et kongebud til Ikaros

Et kongebud til Ikaros

Early chemical industry in America

Shali is an ancient fortress, built in the XII–XX century in Siwa, Northwest Egypt. It is built on two Middle Miocene limestone and marl hills, between the wadi plain. The architecture of the fortress buildings is composed of local materials derived from the Miocene, Quaternary, and recent salt lake deposits. The framework blocks of the city are mainly composed of salt (Kerchief), limestone, and bentonite, wood particles, dry date seeds, and bones derived from ancient tombs. In this study, the modification and mineral phases that developed during the diagenetic alteration and cementation of the salt and clay mortars with different framework in the walls of the ancient houses and settlements will be followed and interpreted. Diagenesis included transportation of salt materials from the nearby Fetnas Lake and mixing with some sand and clays as mortar pressed into the voids between the frameworks (Kerchief blocks). This resulted in dehydration, gypsum crystallization, and halite cementation. The continuous crystallization through the epitaxial growth of halite in both cement and framework blocks results in strong adhesion and binding of the framework. At the end of the process the kerchief blocks and the cement will be completely homogenous to a point that they apparently no longer be distinguished.