Roman Cement Research Articles

Possibilities of retarding the setting of PROMPT natural cement by dosing lignosulfonates

Abstract Roman cement (also Natural cement) is a highly hydraulic binder produced by firing limestone rich in clay minerals. A low firing temperature ranging from 800 °C to 1200 °C is typical for Roman cements. This binder has beneficial functional properties: lower CO2 emissions during production, relatively high strength at a lower bulk density compared to Portland cement, resistance against degradation due to salinity, and better durability. A typical property for this binder is fast setting. This is a problem with the application of natural cement in mortars and concretes, as it significantly shortens their workability time in construction site conditions. The beginning of the setting time of mortars based on PROMPT natural cement can be influenced by retarding additives. Citric acid is currently the most used. Citric acid can negatively affect the properties of hardened mortar and its retarding effect may not be satisfactory. The results of the experimental study are presented in this article, where lignosulfonate-based substances were used as setting retarders. It was investigated that selected types of lignosulfonates are effective as a setting retarder. They have, compared to citric acid, a more pronounced effect of delaying the setting. They also have a significant effect on the strength of the hardened mortar after 28, 56 and 90 days.

Natural Cement in Portugal: Context in Cement Production and Architectural Use

Natural cement, also known as “Roman cement”, was used across Europe during a historic period, mainly in many building facades, due to its hydraulic properties and aesthetic qualities. In Portugal, the use of natural cement occurred in buildings from the second half of the 19th century to the beginning of the 20th century, a period during which the use of lime binders decreased and before the massive use of Portland cement. Recent conservation and rehabilitation actions resulting from necessary interventions in heritage buildings from this period have played an important role in revealing evidence of the use of natural cement and clarifying the lacunae of information about this material. Due to the inadequate use of reparation materials in previous conservation and rehabilitation interventions, this study summarizes the historical production, study, and use of natural cement in Portugal. Natural cement results from the calcination of clay-rich limestone (marlstone) without any compositional changes after extraction, distinguishing itself from hydraulic lime due to its higher clay content and allowing for the formation of higher quantities of hydraulic reactive phases without free lime. Although this topic has been approached at a European level, mainly focusing on the production and use of natural cement in Central Europe, in Portugal, it is still necessary to produce and disseminate information on this specific subject. Therefore, this study focuses on the evolution of cement production in Portugal and an analysis of the existing knowledge of the binders used in architectural heritage based on the scientific and historical bibliography.

ПРОБЛЕМИ РЕСТАВРАЦІЇ СКУЛЬПТУР З РОМАНСЬКОГО ЦЕМЕНТУ В АРХІТЕКТУРІ ЛЬВОВА ДРУГОЇ ПОЛОВИНИ ХІХ – ПОЧАТКУ ХХ СТ.

For the architecture of Lviv II half 19 - the beginning of the 20th century characteristic use of roman cement as a decorative material. Thanks to this, a significant amount of sculptural decor in Lviv during this period was made using roman cement. According to various classifications, architectural decor is architectural, monumental or decorative- monumental sculpture, which in turn is divided into relief and three-dimensional sculpture. Depending on the type of sculpture, the methods of its manufacture, mounting and placement on the facade differ. This affects the state of preservation and the processes of destruction of sculptures. The purpose of the article is to consider the types of sculpture made of roman cement found in the architecture of the 2nd half 19 century - the beginning of the 20th century. To analyze the factors affecting the destruction of sculptures and the possibility of applying preventive measures to stop their destruction. It is necessary to consider the technological features of the restoration of voluminous sculptures made of Roman cement on the facades of buildings and the problems that arise during the work. The article examines the peculiarities of placement of sculptures made of roman cement in the architecture of Lviv. Factors affecting the state of preservation of these sculptures are indicated. Based on the analysis of four restored objects, cartograms of their losses are given, classification of the state of preservation of the sculptures and the generalized technology of their restoration are proposed. The problems of restoration of sculptures made of Roman cement are outlined. To save such sculptures from further destruction, a number of preventive measures are proposed. Taking into account the difference in the preservation of the sculptures, it is possible to single out the main factor of their destruction - the destructive influence of water caused by drainage problems. Therefore, the main task of the preventive protection of sculptures is to inspect the facades for the presence of jamming, in case of their detection, to carry out urgent repair work to eliminate it. It is recommended to conduct a search for roman cement sculptures in the architecture of Lviv, their cataloging and condition monitoring.

Revisiting Ancient Roman Cement: The Environmental-Friendly Cementitious Material Using Calcium Hydroxide-Sodium Sulfate-Calcined Clay

This study proposes an environmental-friendly cementitious material using calcium hydroxide-sodium sulfate-calcined clay based on the idea of ancient Roman cement. The pozzolanic reaction characteristics of calcined clay are studied by adjusting the ratio of calcined clay and calcium hydroxide in both experimental and thermodynamic modeling methods, which demonstrate that 70% calcined clay and 30% calcium hydroxide are the optimal ratio for the pozzolanic reaction of calcined clay to promote the formation of hydration products. Furthermore, the effect of sodium sulfate on the microstructure and mechanical properties of the cementitious materials are also investigated. Results indicate that 5% sodium sulfate (relative to the total mass of the binder) can accelerate the pozzolanic reaction of calcined clay and optimize its mechanical properties. Overall, this study provides a non-clinker cementitious material with high utilization of calcined clay to reduce energy consumption and CO2 emissions.

Characterization of Mortar from Casa Barbot (Portugal), a Case Study from the Beginning of the 20th Century

The popularity of natural cement (Roman cement) in buildings from the late 19th and the beginning of the 20th century and the high diversity of characteristics of natural cement demand research of mortar and binders used in the buildings of this period in Portugal. Understanding the type of binder used in the historic buildings will help the project/intervention team to make the best decisions in terms of the development of compatible mortars for historical conservation purposes. Casa Barbot is one of the Art Nouveau examples of the beginning of the 20th century in Portugal. The garden of this building is characterized by peculiar elements in terms of materials and architecture. Full characterization of the mortars employed in the construction of this building as well as identification of the used binder is the main objective of this study. The study comprises a wide range of laboratory characterization techniques such as X-ray fluorescence (XRF), X-ray diffraction (XRD), petrography, open porosity, density, water absorption by capillarity, and compressive strength. The results show the diversity of compositional characteristics in the mortars used in the decorative elements in the period garden of Casa Barbot. All mortars are composed of Portland cement with a mix of additives such as blast furnace slag, limestone filler, air lime, and the occasional presence of charcoal. The results raise doubt about the use of natural cement as stated in the historical documents. This study will broaden the scientific knowledge of the materials of that period in Portugal to provide a comprehensive plan for the preservation of historical buildings.

STUDY OF THE FIRST BOULOGNE-SUR-MER CEMENTS USED FOR A HISTORIC AQUEDUCT FROM THE 19TH CENTURY

Natural and Roman cements are generally considered as the first binders of the 19th century concrete but their widespread usage was short-lived as they were quickly replaced by artificial cements (Portland), still the most important and predominant today. The Boulogne-Sur-Mer area in the North of France is one of the cradles of the French cement industry where the first French natural cement was produced in 1802 and the first French Portland cement at around 1850. These cements, natural and artificial, quickly gained a national and international fame. This paper presents a case study of a 19th century aqueduct, still in operation, with a focus on identifying the binders of concretes and mortars. Several combined techniques – optical microscopy (OM), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD) – were carried out to characterize and determine the compositions of the binders present in the aqueduct. Phenolphthalein tests were carried out in order to evaluate the depth of carbonation in the concrete. Several concrete and mortar samples, from pinkish to greyish ones, were taken from the outer and inner parts of the aqueduct. Results show several clinker morphologies and compositions, and different types of hydrates. They also reveal important differences in the microstructure between natural and Portland cement, dated from an early period of the cement industry in France. The concomitance of the use of natural and Portland cement, and good durability of these materials highlight the know-how of the engineers in the 1860s on cement performances and characteristics.

Structural investigation of carbonation and hydration process of hydraulic dolomitic binder

The research deals with the microstructural examination of the hardening process of dolomitic binder synthesized from dolomite flour and clay. Such binder based on its suitable properties can be considered as a perspective alternative for restoration purposes of dolomitic Roman cement – a widely used construction binder in Riga during the late 19th and early 20th century.The structures formed during hydration and carbonation throughout the hardening are detected by using scanning electron microscopy (SEM) at every 7 days for 3 months.The low firing temperature of the binder ensures the formation of active and hydraulic phases – CaO, MgO and an amorphous phase in the system CaO-SiO2-Al2O3. The results of structural analysis showed that beginning with the fifth week of hardening a formation of a dense network of prism-type monolithic crystals – the carbonation product of brucite – takes place on the surface of samples. Such structure can contribute to an increased durability.

Suitability of modified low carbon Roman cements for architectural restoration

Article is devoted to the investigation of suitability of low carbon Roman cement for restoration and finishing works. The history of the development of Roman cement as a natural hydraulic binder, which was commonly used to decorate building facades in the 19th and early 20th centuries, is presented. The properties of mortars based on Roman cement make it an excellent product for architectural restoration and conservation, as they are characterized by fast setting, high porosity typical for lime mortars, high resistance to weather conditions, high initial strength. At the same time, due to the high surface activity and increased water demand for cement, with the age of hardening, shrinkage deformations can develop, which leads to the formation of main cracks on the surface of the products. It is shown that the addition of gypsum is an effective regulator of the setting time of Roman cement and contributes to an increase in the strength of the cement paste. Analogs of Roman cement based on multicomponent cement binders modified with plasticizing and air-entraining additives are presented.

Mechanical Properties of Mortars Based on Roman Cement with the Addition of Power Plant Fly Ash

Roman cement is a historic hydraulic binder, prepared by firing of limestone with high proportion of clay minerals, usually at temperatures below the sintering point. The firing temperatures of Roman cements range from 800 to 1200°C. At present, this binder is considered to be a promising material with a low carbon footprint and a long lifetime. The properties of Roman cement are influenced by many factors, especially raw materials composition and firing conditions. On the other hand, a disadvantage of mortars based on Roman cement is a slow increase of initial strength. In this paper, the influence of power fly ash admixture on the dynamics of initial strength increase was experimentally investigated. The characteristics of mortars with admixtures were compared with the properties of reference mortar without admixtures. The Roman cement Vicat Prompt TM Natural Cement (manufactured by Vicat SA, French company) was used as a binder. Based on the results of the experiment it can be stated that mortars with the admixture of power plant fly ash show higher dynamics of the increase of initial strengths than the reference mixture.

Modified roman cement

The purpose of this research is to equip the roman cement with properties exceeding the properties of the known analogies.Roman cement’s compositions modified by chemical and mineral additives have been developed and proposed. The mode of calcinations of carbonate and clay raw material with high MgO has been optimized. As a result, the durability of roman cement from 15 to 22 MPa has been received. Mineral additives like slag, zeolite breed and clay dust were chosen and used that rose the durability from 22 to 28 MPa. Plasticizers and hardening accelerators were chosen and used that allowed rising the durability up to 35 MPa relatively. A combination of complex additives have been proposed.To optimize the mode of calcinations and to define a combination of complex additives the method of mathematical planning was used. The dependence of binder’s strength from the temperature, durability of calcinations, saturation rate, type and consistence of modified additives has been acquired.Modified roman cement has the advantages if compared with known analogies and has the following features: strength 35MPa, normal consistency 30%, setting time is not earlier than 35 minutes, the end is not late than 420 minutes, softening rate is 0.98.Modified roman cement can be successfully used to produce dry building mixtures (mortar’s strength 5,10, 15 MPA), low strength mortars (strength 5,7.5 MPa) and concret (strength 10, 15, 20, 25 MPa) and other building materials.Structure of carbonate raw material and clay for the production of roman cement is recommended.

Synthesis, characterization, and thermodynamic study of selected Na-based zeolites

Zeolites are crystalline aluminosilicates with three-dimensional framework structures that can form in alkali-activated cements, Roman cements, and the interaction zone of cements and clays. However, their stability domains are uncertain due to their high structural variability and the lack of experimental solubility data. Thermodynamic data were here determined for selected Na-based zeolites built from six different secondary building units that could possibly form in the interaction zones of cement/clay. The zeolites were synthesized by hydrothermal methods and full-scale characterized with respect to framework structures, extra-framework cations, Si/Al ratios, and water contents. Their thermodynamic properties were determined based on the experimental solubility products at different temperatures using GEMS. Predominance diagrams of zeolite-clay/mica-SiO2/Al(OH)3 minerals in the chemical sub-systems of Na2O-SiO2-Al2O3-H2O were successfully established using PHREEQC-PhreePlot code. The experimentally derived thermodynamic data provide insights on the early stage of the zeolite ageing and predicting zeolite stability domains during cementitious material hydration.

Hybrid binders: A journey from the past to a sustainable future (opus caementicium futurum)

This article describes and interprets data drawn from a thorough characterisation of a series of cementitious materials. The materials addressed can be divided into three major groups: 1) cements/concretes from well-known and historically documented Roman constructions in Italy; 2) cements recently prepared in the laboratory simulating the compositions of Roman cements, stored for 6 months in environmental conditions similar to those to which the Roman materials have been exposed for 2000 years; 3) concretes prepared from an industrial cement manufactured 6 years ago applying today's knowledge of hybrid cements. An analysis of all the data presented in this article has led its authors to conclude that, conceptually speaking, ancient Roman cements can be identified with modern hybrid ‘portland-alkaline’ materials. That conceptual identity is based on the detection of the same cementitious phases in the two types of cements (Roman and Hybrid) and naturally of the inclusion of alkalis in the structures of some of the phases observed.

Processing of Dolomitic By-Products into Porous Restoration Binder

The goal of this work concerns the synthesis of a binder for restoration purposes that is physically and chemically compatible with dolomitic Roman cement, a historical binder used for the construction of significant architectural heritage objects in the 19thand 20thcenturies. Dolomitic marlstone, the traditional raw material of dolomitic Roman cement, is not being obtained anymore and it is also hard to achieve a constant chemical composition. To address these issues, the experimental synthesis of a low temperature hydraulic binder using locally sourced raw materials, namely dolomite flour and clay, was performed. The developed synthesis technology provides economic and ecological advantages compared to other similar materials, such as lime with pozzolan additive, lime and cement mixtures and magnesium oxychloride cements. The raw material, dolomite flour, is a by–product in the manufacturing process; furthermore, the low firing temperature (800 °C) reduces the power consumption required to obtain the binder.The aim of the work is determination of porosity-related physical characteristics of dolomitic binder that is synthesized by using manufacturing by-product – dolomite flour – as basic raw material to evaluate it’s suitability for restoration purposes.

Production of the Roman Cement in Italy: characterization of a raw material used in Tuscany between 19th and 20th century and its comparison with a commercialized French stone material

ABSTRACTAn experimental approach in order to investigate the possibility that some Italian limestones were used for the production of Roman Cement is proposed. Three types of Pietra Alberese, a marly limestone used since Roman times for the production of “lime” in Tuscany (Italy), were selected. By burning of these stones, specimens of binders were realized. The characteristics of these binders were compared with the binder obtained by burning a French marly limestone commercially used for the production of Roman Cement.All samples of carbonate stones were preliminarily characterized from the chemical, mineralogical, and petrographic point of view. The colorimetric coordinates were measured on both rock samples and hardened binder samples. The analysis carried out shows that Pietra Alberese with an high content of clay minerals develops a similar microstructure with respect to that developed by the French marly limestone used for the production of Roman Cement.

Hydration of Cement Minerals in a Hydraulic Dolomitic Binder

Dolomitic Roman cement was a widely used binder for construction purposes during the late 19th/ early 20th century in territory of Latvia. Because of its hydraulic properties and fast setting it was especially favorable for the usage for the cast elements of Art Nouveau style facades. The production of the material was discontinued in the middle of the 20th century. Nevertheless, there is a need of compatible material for restoration purposes that is not currently commercially available. A compatible binder has been synthesized from mixture of dolomite flour and clay. The research gives an insight of the ongoing chemical processes during the hydration of the cement minerals in the binder. The influence of clay content in compositions and of firing temperature on the physico-chemical properties and mineralogical composition of obtained material is estimated.

Slaking Lime for Restoration and Conservation of Historical Buildings and Materials, Criticism of an Arabic Historical Manuscripts

Slaking lime is an important and effective process for preparing mortars in conservation of historical buildings and archaeological artifacts based on lime. The lime mortars have been widely used since the Roman era, and lime became one of the important materials for conservation and restoration process to keep the authenticity of the historical materials and sustainability. In many cases, some conservators use black and white cement separately or mix with lime in conservation and restoration, or mix gypsum with lime. They think that will improve the strength of mortars, but all those procedures give bad results on the properties of the mortars, and cause irreversible deterioration for historical materials in both layers and surfaces. Through the mentioned problems, we should go back to historical documents to identify the best method for slaking process to get best results in any intervention needs lime mortars. So we depend on three historical resources from 13th A. H century the first historical manuscript message in architecture) preserved in king Saud university No.3392 without any previous criticism, the second European historical book entitled all kinds of Roman cement) translated to Arabic in 1829 AD, the third Arabic book entitled Summary of ideas in architecture), those resources presented all methods of slaking to give information for researchers to evaluate slaking process after experimental studies which depend on several factors, the main target of the research is to provide conservators with information about slaking process for preparing mortars with good properties in all conservation interventions in artefacts and historical buildings.

Low-firing binders from magnesium containing carbonate raw materials

This paper presents scientific and experimental data for low-firing hydraulic binders: hydraulic lime and Roman cement based on local mineral raw materials. The binders were prepared by firing representative samples of carbonate–clay magnesian raw materials from Tatarstan. Using X-ray diffraction, we identified the firing products, including a hydraulically active phase, and determined the structural characteristics of its minerals. The compositions of the binders were determined as functions of firing conditions. We examined the influence of the firing temperature and duration of magnesian raw materials in the preparation of binders on MgO activity and demonstrated for the first time the possibility of ensuring an active state of the MgO resulting from firing (up to 21%) and suppressing its negative effect on Roman cement and hydraulic lime hardening processes.

Influence of firing temperature on the chemical properties of hydraulic dolomitic binder

The synthesis of a binder from the mixture of dolomite flour and clay is investigated. The main anticipated usage of the binder is for the restoration of historical dolomitic Roman cement objects. During the 19 th /20 th century, in the territory of Latvia dolomitic Roman cement was the main hydraulic binder applied for the construction of buildings. It was processed in Riga since 1865 by firing the local raw material dolomitic marlstone below its sintering temperature (800–900 °C) and by fine milling. Because of its fast setting and good water resistance, the material was used mostly for decorative elements of facades. However, since the middle of the 20 th century its production has been stopped. With the aim to provide a compatible material for restoration needs, compositions from dolomite flour and clay were investigated as a perspective raw material for the synthesis of a low-temperature hydraulic binder. Mixtures from two types of clay and dolomite flour in powder state were synthesized. Clay content in the compositions varied from 13 to 30 %. Samples were prepared by mixing the raw materials, semi-dry pressing and firing at 750–950 °C. The study gives an insight into the chemical processes that occur during the synthesis of a binder from a mixture of clay and dolomite flour. Thermochemical processes in the obtained binder depending on production temperature and clay type were compared by using the XRD analysis and a full chemical analysis. DOI: http://dx.doi.org/10.5755/j01.ct.67.1.14986

Low energy pre-blended mortars: Part 2 – Production and characterisation of mortars using a novel lime drying technique

The presence of free water in mortars destined for silo or bagged storage can lead to the degradation of the binder phase. Such water may be present as a result of using wet, as-delivered sand or as a consequence of prior processes such as de-activation of Roman cement. Thus, water must be removed from the system prior to storage. Part 1 of this paper describes the control of a technique by which quicklime is added to the wet system which principally dries it by both slaking the quicklime and evaporation as a consequence of the exothermic slaking reaction. Two examples of mortars are presented in which excess water is removed from the system by the inclusion of quicklime. In the first, the water is present in the as-delivered sand and the binder is a combination of the slaked lime and ggbs. In the second, the water remains after pre-hydration of a Roman cement which is a process to retard its rapid setting characteristics. It is shown that optimally dried mortars are not subject to degradation following storage of both mortar types.

Influence of substrate and sand characteristics on Roman cement mortar performance

When formulating repair mortars standard test specimens should be used with caution as these cannot be considered representative of samples of mortars collected on site. This work reports an approach to repair mortar formulation which takes into account the influence of porous substrates, sand characteristics and mortar thickness on the properties of both fresh and hardened Roman cement mortars. It is shown that mortars cast on a dry absorbent substrate show modified properties such as increased strength and decreased water absorption coefficient, the degree of which is a function of sand grading and surface characteristics, sample thickness and substrate sorptivity.