Cement CEM Research Articles

Analysing the Effect of Cassava Flour as a Mixture on the Physical, Mechanical, and Durability Properties of High-Strength Concrete

The availability, cost, and environmental impact of chemical admixtures are reduced when natural substitute materials are incorporated into the concrete as an admixture. This paper outlines the findings of a study that looked at the physical characteristics of fresh and hardened concrete made with Portland pozzolanic cement CEM II/B-P blended with cassava flour up to 5% by weight of cement. A low water/binder ratio of 0.35 was used together with a carboxylate-based superplasticizing admixture to produce high strength. In fresh-state concrete, the initial and final setting times, soundness, and consistency were found to increase with increased cassava flour content, whereas the compacting factor and slump were observed to decrease. In the hardened state, compressive strengths were determined at 3, 7, 14, 28, 56, and 90 days, while split tensile and flexural strengths were investigated at 28 days. Similarly, dry density and porosity were also investigated at 28 days. Water absorption was also studied as a potential indicator of durability in hardened concrete. Scanning electron microscopy characterization of cassava flour revealed porous particles of irregular shape. On the other hand, X-ray diffraction imaging showed that the primary chemicals in cassava flour are silicon dioxide (50%), calcium oxide (17%), and aluminium oxide (7%). All of the mixes that incorporated cassava flour were stronger than the control mix, with the 3% cassava flour combination producing the best results. Doi: 10.28991/CEJ-2022-08-12-015 Full Text: PDF

Evaluation of the Immobilization of Fly Ash from the Incineration of Municipal Waste in Cement Mortar Incorporating Nanomaterials—A Case Study

Fly ash generated in the process of combustion of municipal waste is classified as hazardous waste. Its management today has become a significant problem. One of the methods of safe management of such ash may be using it for the production of concrete as a partial replacement for cement. Using immobilization, the number of hazardous compounds could be limited so that the obtained new material would be safe for the natural environment. Recovery of byproducts—in this case, fly ash—complies with the business models applied in the production cycle in the circular economy model. Such a solution may result in saving energy, limiting CO2 emissions, reducing the use of natural resources, and management of dangerous waste. It should be added that concretes with the addition of hazardous waste would be used for industrial purposes according to the binding legal regulations. This article presents the influence of the addition of fly ash on the selected mechanical properties of concrete. Fly ash from the incineration of municipal waste was used as a partial replacement of CEM I concrete at amounts of 4%, 8%, and 18% of its mass. The compressive strength and flexural strength of such concretes were tested after 28 days of concrete curing. This article also presents the tests of the leachability of contaminants from fly ash and concretes produced with Portland cement CEM I. The test results confirm that immobilization is an effective process that limits the amount of contamination in the water extract. Zinc, lead, and chrome were almost completely immobilized by the C-S-H (calcium silicate hydrate) concrete phase, with their immobilization degree exceeding 99%. Chloride content also underwent immobilization at a similar level of 99%. The sulfates were immobilized at the level of 96%. The subject matter discussed in this article is essential because, to protect the natural environment and, thus, reduce the use of natural resources, it is increasingly necessary to reuse raw materials—not natural, but recycled from the industry. Waste often contains hazardous compounds. A proposal for their safe disposal is their immobilization in a cement matrix. An important aspect is reducing leachability from concrete as much as possible, e.g., using nanomaterials. The effectiveness of reducing the leachability of hazardous compounds with the proposed method was checked in this study.

Mortar mixing using treated wastewater feasibility

• The mortars based on CEMI and CEM II and treated wastewater had a slight increase in setting times. • Treated wastewaters had a slight impact on fresh mortar density for various cement types. • Mortars based on CEM III cement and treated wastewater have better mechanical performance. • The pouzzolanic reactions for mortar made with CEMIII cement and wastewater that produce a supplementary CSH and ettringite in long term. Water scarcity is considered to be one of the most important problems faced by the world today. To alleviate this problem, it is important to study the feasibility of replacing partially or completely potable water for concrete production by treated wastewater. This paper studies the feasibility of using treated wastewater (TWW) from the Artois-Picardy Water Agency in Douai (Hauts de France-France region) for mortar mixing. The aims of this study is to limit watercourse discharges, reduce groundwater over-exploitation, and minimize natural resource pollution. To do this, three series of mortar mixtures have been formulated according to the NF EN 196 standard, varying the type of cement (CEMI CEMII and CEMIII) and mixed with treated wastewaters with a 0.5 water to cement (W / C) ratio. The performance of these mortar mixes were compared to the control ones (mixed with “drinking water” (DW)). The Experimental work included the workability, setting time, and density of different mortar mix designs using treated wastewater. In addition, the dynamic modulus of the mortar (Edyn) was determined, as well as the mechanical properties (compressive and flexural strength) at 7, 28, 60, 90, and 360 days after the mortar samples were made. Furthermore, the environmental assessment of the hardened mortars was evaluated by leaching tests according to the EN 1245–74 standard. The results obtained shown that TWWs had no adverse effect on physical properties (curing time, slump, porosity distribution, and density) of these mortars. On the other hand, the mortar mechanical properties were slightly lower than those of the control for samples made with cement CEM I and CEM II. However, a significant compressive strength increase was recorded for mortars made with CEM III cement. The mortar curing time, slump, and density made with TWW were closer to those of the control.. The hardened mortars were then analyzed by scanning electron microscopy (SEM), and by Thermogravimetric Analysis (TGA) and differential Thermogravimetric Analysis (DTA). According to the obtained findings, the TWW of the city of Douai France could be used for the manufacture of mortar and concrete.

Cement and Clinker Production by Indirect Mechanosynthesis Process

Global cement production has reached 3.9 billion tons. However, the clinkerization process, which is the basis of cement production, is responsible for an approximate annual global CO2 emission of 2 billion tons. As part of CEMBUREAU’s 5C strategy, the European cement industry aims to achieve carbon neutrality throughout the cement-concrete value chain by 2050. This article is a continuation of the previous article on the indirect mechanosynthesis clinkerization process, which combines mechanical activation (high-energy milling) and thermal treatment at lower temperatures (from 900 °C) than those used for conventional clinkerization to produce clinker. With this process, we manufactured cement and clinker from industrial and laboratory raw mixes, which had to be rectified by adding kaolinite in compliance with the different cement indicators (LSF, SM, AM). The cement and clinker produced by indirect mechanosynthesis (15 min of mechanical activation and heat treatment 900 °C or 1200 °C) were characterized. In order to test the hydraulic properties of the cement produced, cement pastes were made. Mechanical and structural studies were carried out (between 70 and 90% of C2S). Mechanical tests revealed for 7 curing days, the values of 3.60 and 7.60 MPa at 900 °C and 1200 °C, respectively, in comparison to commercial cements CEM I and CEM III (23.03 and 19.14 MPa).

On the Properties Evolution of Eco-Material Dedicated to Manufacturing Artificial Reef via 3D Printing: Long-Term Interactions of Cementitious Materials in the Marine Environment

This paper deals with the evolution monitoring of biomass colonization and mechanical properties of 3D printed eco-materials/mortars immersed in the sea. Measurements of tensile strength, compressive strength, and Young’s modulus were determined on samples deployed along the Atlantic coast of Europe, in France, United Kingdom, Spain, and Portugal. The samples were manufactured using 3D printing, where six mix designs with a low environmental impact binder were used. These mortars were based on geopolymer and cementitious binders (Cement CEM III), in which sand is replaced by three types of recycled sand, including glass, seashell, and limestone by 30%, 50%, and 100% respectively. The colonization of concrete samples by micro/macro-organisms and their durability were also evaluated after 1, 3, 6, 12, and 24 months of immersion. The results showed that both biomass colonization and mechanical properties were better with CEM III compared to geopolymer-based compositions. Therefore, the mixed design optimized according to mechanical properties show that the use of CEM III should be preferred over these geopolymer binders in 3D printed concrete for artificial reef applications.

From concretes to bioreceptive concretes, influence of concrete properties on the biological colonization of marine artificial structures

A main cause of biodiversity loss is artificialization of the marine environment (IPBES 2019). With 39,400 km2 of coastal and marine areas already encroached upon by human infrastructure and an increasing demand on space due to the growing global population – projected to reach 9 billion by 2050 – it is clear that humanity needs to find ways to prevent its activities from endangering biodiversity. To this end, since the 1990s ecologists have been trying to develop a win-win approach that unites ecological engineering with civil engineering. Today, civil engineers have a responsibility to incorporate eco-design processes in all construction projects underway to ensure that the latter benefit both humans and nature. Then, the new challenge of the 21st century is to develop eco-designed concretes that, in addition to their usual properties, provide improved bioreceptivity in order to enhance marine biodiversity without affecting the structure durability. The aim of this study is to master, clarify and classify the intrinsic parameters that influence the bioreceptivity (biocolonization) of cementitious materials in the marine environment. By using biofilm-culture-method (biofilm quantification), this study shows that the use of rough surface or slag cement CEM III and the surface treatment with green formwork oil enhance the biocolonization of cementitious materials in the marine environment whereas the application of curing agent (hydrophobic surface coating) has the opposite effect. Among the influent parameters, surface roughness proved to be the factor that promotes biocolonization most effectively.

Curing Effect on Durability of Cement Mortar with GGBS: Experimental and Numerical Study.

In this paper, supplementary cementitious materials are used as a substitute for cement to decrease carbon dioxide emissions. A by-product of the iron manufacturing industry, ground granulated blast-furnace slag (GGBS), known to improve some performance characteristics of concrete, is used as an effective cement replacement to manufacture mortar samples. Here, the influence of curing conditions on the durability of samples including various amounts of GGBS is investigated experimentally and numerically. Twelve high-strength Portland cement CEM I 52.5 N samples were prepared, in which 0%, 45%, 60%, and 80% of cement were substituted by GGBS. In addition, three curing conditions (standard, dry, and cold curing) were applied to the samples. Durability aspects were studied through porosity, permeability, and water absorption. Experimental results indicate that samples cured in standard conditions gave the best performance in comparison to other curing conditions. Furthermore, samples incorporating of GGBS have superior durability properties. Permeability and water absorption were improved by and , respectively, compared to the reference sample. Thereafter, data from capillary suction experiments were used to numerically determine the hydraulic properties based on a Bayesian inversion approach, namely the Markov Chain Monte Carlo method. Finally, the developed numerical model accurately estimates the hydraulic characteristics of mortar samples and greatly matches the measured water inflow over time through the samples.

МОДИФІКОВАНІ СУЛЬФАТОСТІЙКІ ПОРТЛАНДЦЕМЕНТИ З ДОБАВКОЮ ЦЕОЛІТУ

The article shows that one of the ways to increase the sulfate resistance of cements is to use as an additive of pozzolanic action based on highly dispersed zeolite, which increases the corrosion resistance of concrete. Physical-chemical properties of zeolite tuff as a mineral constituent of Portland cements with the addition of pozzolana are presented. The use of modern grinding technology by separate grinding of Portland cement clinker and natural zeolite in mills with separators of the latest generation allows to obtain high quality Portland cement with zeolite CEM II/A-P 42.5 R PJSC "Ivano-Frankivsk Cement", characterized by high early strength. It is shown that the replacement of the clinker component with zeolite leads to a decrease the content of clinker minerals C3S and C3A in cements, which significantly limit the corrosion resistance of cement stone. Highly dispersed zeolite is characterized by increased pozzolanic activity (after 28 days, the absorption of Ca(OH)2 is 200-250 mg/g). Due to pozzolanic reaction with the formation of C-S-H-phases, the content of calcium hydroxide in the paste based on CEM II/A-P 42.5 R is reduced by 2 times compared to Portland cement CEM I 42.5 R. Decrease in the concentration of Ca(OH)2 in cement pastes eliminates the possibility of the formation of a significant amount of ettringite, which causes sulfate corrosion of cement stone. It was found that during the hardening of Portland cement CEM II/A-P 42.5 R under the influence of sulfate and magnesium media, the coefficient of corrosion resistance Ks after 56 days is 1.16 and 0.98, respectively, while for samples based on Portland cement CEM I 42.5 R Ks decreases by 1.2-1.3 times. The results of researches of influence of aggressive environments on corrosion resistance of Portland cement with the increased content of zeolite type CEM ІІ/В-Р 42.5 are resulted. For Portland cement CEM ІІ/В-Р 42.5 the coefficient of corrosion resistance in the conditions of sulphate environment Кс90 = 1.47. Portland cements with zeolite strength class 42.5, modified with superplasticizers of polycarboxylate type, are characterized by high sulfate resistance and should be used for the manufacture of concrete classes C25/30...C50/60 for construction of dams, hydraulic structures, sewers storage of waste from livestock farms, etc. Modified rapid-hardening Portland cements with the zeolite additive provide technical, environmental and economic effects in the manufacture of concrete and reinforced concretes of hydraulic structures.

Industrial waste products based concrete: environmental impact assessment

Improving the environmental situation and obtaining hydration hardening composites with new properties for various operating conditions is possible with the use of secondary resources. The work is dedicated to the criteria study for assessing the hydration hardening binders impact on the environment. The methodological approach to the choice of a functional unit for a carbon footprint comparative assessment of cement is substantiated in the work. The study results of the properties that determine the concrete durability in transport construction and the aggressive environment of livestock farms are presented. Concrete based on Portland cement has the least resistance in the aggressive environment of livestock complexes, the cross-breaking strength of which is almost twice after 150 days of curing. Marginally better resistance coefficient indicators in an aggressive environment have binder compositions based on portland blast furnace slag cement and technogenic raw materials. At the same time, if the process of degradation and decrease in the strength properties of the binder samples on Portland cement is progressive until they are completely destroyed, then in the binder samples on modified technogenic raw materials, the strength characteristics stabilize with time, which indicates the decaying nature of the corrosion process. The investigated slag-alkaline concrete satisfies the requirements for paving concrete and concretes for under-rail structures, since compressive strength and frost resistance were 70 MPa and F600 for granulated blast-furnace slag with a basicity modulus of 0.8; 78 MPa and F700 for granulated blast-furnace slag with alkali-lime index 0.9. These concretes had comparable characteristics to concrete on Portland cement CEM 52.5, for which the values were 60 MPa and F600. The presented results contribute to the development of an ecological approach to making design decisions in construction.

Chloride – induced delayed ettringite formation in Portland cement mortars

The present paper reports an obscure new phenomenon herein referred to as chloride – induced delayed ettringite formation (CLIDEF). In the study, mortar mixtures of proportions 1:2.25:0.47 cement to sand to water, were used to prepare 25 × 25 × 285 mm prisms. Incorporated into Portland cement CEM I 42.5R were varied sulphate levels of 2%, 3%, 4%, 5%, 7% and 8% total SO3 content. The prisms were cast and heat – cured at 95 °C then stored in chloride solutions of varied concentrations comprising 0, 0.25, 0.50, 0.75, 1.00, 1.50, 2.00, 3.0 M NaCl. Expansion values of the prisms were monitored for ages of up to 180 weeks.It was found that pessimum expansion occurred at 0.25 to 1.0 M NaCl concentrations. Cementitious systems that were non – expansive under storage in water became expansive upon storage in NaCl solutions of the optimum concentration range 0.25 to 1.0 M NaCl, giving rise to CLIDEF.

Fresh and mechanical properties of low-cement mortars for 3D printing

The trend of concrete science is aimed at reducing the consumption of cement and the use of 3D printing technologies. Based on non-traditional technical silica, 3D printed mortars were designed with a saving of 70% of cement. The binder components were studied by X-ray spectral microanalysis, diffraction granulometric analysis, while the finished mixtures were tested for freshness and mechanical properties. It was established that the PFM-NLK additive at a concentration of 0.7% is characterized by the greatest plasticizing effect; in this case, the maximum slump flow is reached 179 mm. The presence of a larger number of particles with a size of 3 to 12 µm in the developed binders of low water demand provides a more complete interaction of cement particles with water during hydration, significantly reducing the number of non-hydrated grains in the binder. The setting time and rheological parameters of the developed cement pastes make them suitable for 3D printed mortars. The mechanical properties of low-cement mortars indicate their high strength in bending and compression. The compressive and flexural strength of the developed mortars at the age of 28 days reached 62.9 MPa and 7.9 MPa, which is better than the control cement CEM I 42.5 N by 23% and 52%, respectively.

The Influence of the Acceleration Admixture Type and Composition of Cement on Hydration Heat and Setting Time of Slag Blended Cement.

This article presents recent research on cements containing GGBFS and their modifications with accelerating admixtures. The initial setting time and hydration heat evolution results are presented for cement CEM II/B-S and CEM III/A manufactured with three Portland clinkers of various phase compositions. The research was carried out at 8 °C and 20 °C. The main objective is to assess the behavior of blended cements in cooperation with modern admixtures that contain nucleation seeds. The authors aimed to compare and evaluate different methods to reduce setting time, namely, the effects of temperature, the specific surface area of cement and GGBFS, the type of Portland clinker, the content of GGBFS, and presence of accelerators. Many of these aspects appear in separate studies, and the authors wanted a more comprehensive coverage of the subject. Those methods of reducing the setting time can be ranked: the most effective is to increase the temperature of the ingredients and the surroundings, the second is to reduce the GGBFS content in cement, and the use of accelerators, and the least effective is the additional milling of Portland clinker. However, of these methods, only the use of accelerators is acceptable in terms of sustainability. Prospective research is a detailed study on the amounts of C-S-H phase and portlandite to determine the hydration rate.

Microstructure modification of cement pastes using nanosilica

The paper describes modifications of cement paste mixtures using nanosilica to affect their physical and chemical properties. Cement pastes from Portland cement CEM I 42.5R with three different substitution ratios of nanosilica 1.5, 3 and 4.5 wt.%/cem. were examined. Micromechanical response and microstructure were characterized using nanoindentation, statistical deconvolution and scanning electron microscopy. About 400 locations were examined on each sample over 40,000 μm2 area. The results indicate an increase of C-S-H phases by 11 vol.% in samples with 4.5 wt.% nanosilica replacement compared to pure Portland cement paste. The increase in C-S-H phases volume was accompanied by the decrease in CH phases by approximately 11 vol.%.

Sulphate corrosion of cement pastes with a high content of waste marble powder

The article focuses on sulphate corrosion of cement pastes with a high content of waste micronized marble powder. Micronized marble powder is used as a substitute for Portland cement CEM I 42.5R. The amount of micronized marble powder used is from 5 to 50 wt. %. The research also tested a reference mixture composed only of Portland cement. The used accelerated sulphate corrosion consists of cyclic saturation and drying with 10% Na2SO4 solution for 56 days. During sulphate corrosion, samples are placed in a controlled environment at 5 ± 1 ◦C and 85 % relative humidity to allow thaumasite to form. During cycling, samples were continuously visually monitored and documented. Subsequently, after 56 days, the samples were destructively tested for compressive strength. The research revealed a negative effect of micronized marble powder on the resistance to sulphate corrosion, where in contrast to the reference mixture the decrease in compressive strength is up to twofold.

Physical, mechanical properties and durability of cement mortars containing fly ash from the sewage sludge incineration process

Pursuant to European Union regulations, waste generated during municipal sewage treatment should be managed in an environmentally friendly manner. In order to eliminate the risk to human health and to the environment, and also to minimise the volume of the resulting sludge, it is subjected to thermal treatment. The resulting ash contains heavy metals, and thus proper management is required. Since it is known that products of cement hydration reactions have a potential ability to immobilise heavy metals, a preliminary verification was conducted of the possibility of disposing of this type of waste by including it in cement composites. For this purpose, suitable tests were carried out on the mechanical properties and durability of cement binders containing ash from the incineration of sludge produced from municipal sewage (Sewage Sludge Ash – SSA). The tests were conducted for a standard mortar composition based on Portland cement CEM I and on ash obtained on a technical scale in a sewage treatment plant at a temperature of about 850 °C. This mineral addition was used to replace 10%, 20%, 30% and 40% of the cement by weight. The physical and mechanical characteristics were measured, such as compressive and flexural tensile strength after 14, 28 and 90 days of curing as well as durability characteristics such as total porosity, the ability to transport chloride ions and resistance to sulphate ions. The results obtained confirm that replacing 10% of the cement with this admixture has a beneficial effect on the mechanical and durability characteristics, but greater amounts are reflected in a clear deterioration of these characteristics.

Engineering properties of soda-lime glass powder on Portland cement CEM IV-B-L mortar

Engineering properties of soda-lime glass powder on Portland cement CEM IV-B-L mortar

Comparison of Testing Methods for Evaluating the Resistance of Alkali-Activated Blast Furnace Slag Systems to Sulfur Dioxide.

Alkali-activated systems (AAS) represent an ecologically and economically sustainable inorganic binder as an alternative to ordinary Portland cement (OPC). One of the main benefits of AAS is their durability in aggressive environments, which can be equal or even better than that of OPC. In this paper, the influence of the type of alkaline activator in alkali-activated blast furnace slag (AAS) in terms of resistance to sulfur dioxide corrosion was investigated. The durability testing process was based on the CSN EN ISO 3231 standard and simultaneously compared with mortar samples prepared by using Blastfurnace cement CEM III/A 32.5R. The degradation progress was evaluated by employing several different methods such as observing the compressive strength development, weight change evaluation, non-destructive testing methods like ultrasound or impact echo technique, or visual phenolphthalein technique. Subsequently, fundamental characterization of samples by the XRD method was performed during the degradation test. The obtained results indicate that none of the testing methods used could be prioritized over others to determine the resistance of AAS against the action of sulfur dioxide. For this reason, the durability testing of AAS remains an issue, and the development of specific standards considering the behavior of AAS seems necessary.

The Effects of Mineral Wool Fly Ash on Cohesive Soil Strength Behaviour

This research work represents updated results of cohesive soil strength improvement with mineral wool fly ash. In the investigations, these materials were used: Portland cement CEM I 42.5 R, fly ash obtained from a mineral wool production process, sand and clay. Mixtures were prepared as follows: dry mixing of Portland cement and fly ash; dry mixing of sand and clay; adding water into Portland cement and fly ash; adding sand and clay mixture into already prepared Portland cement and fly ash suspension. The content of fly ash replacing Portland cement varied from 0% to 40%, and the content of sand mixture varied from 20% to 60%. After 24 hours, investigated samples were taken out from cylinder forms and kept in a desiccator with a humidity of 90% and at 20 °C temperature. Uniaxial compressive strength of the samples was determined after 548 days and compared to previous research results obtained after 7, 28 and 183 days. The most predictable compressive strength is for samples, which composition is 100% cement and 0% fly ash. In these samples, the highest compressive strength was obtained, comparing them to the other investigated samples. Compressive strength change is minimal for samples with a 10–30% amount of fly ash. The most significant decrease in compressive strength was obtained for samples with a 40% fly ash after 183 days. Nonetheless, the compressive strength of these samples increased after 548 days and is almost the same as for samples with 100% Portland cement.

Use of clay from a local source for calcination and subsequent preparation of the mixed cement

This paper deals with the use of calcinated clay and micronized limestone as supplementary cementitious materials (SMCs) for preparation of blended Portland cement CEM II/B-M (Q-LL). Clay used in this study was calcinated at 700°C and pozzolanic activity after calcination was assessed using accelerated R3 pozzolanic test and modified Chapelle test. The influence of calcinated clay and limestone addition on mechanical properties and hydration process was investigated and an optimal ratio for 35% clinker replacement was found. Initial decrease of mechanical strength at early ages, caused by SCM addition, was almost compensated during maturation of the binder.

Microstructure of CEM II/B-S Pastes Modified with Set Accelerating Admixtures.

The presented paper aims to describe the influence of accelerating admixtures on the properties and microstructure of cement pastes and mortars. Blended slag cement CEM II/B-S containing two different clinkers (differing amounts of siliceous and aluminous phases) and four types of accelerators (calcium nitrate, sodium hydroxide, cement kiln dust, and crystal seeds) were used in research. Compressive strength tests (after 12, 24, 48 h of curing), Scanning Electron Microscope (SEM) observations together with an Energy Dispersive Spectroscopy (EDS) analysis, Mercury Intrusion Porosimetry (MIP) tests, and X-ray diffraction (XRD) analysis were conducted. Results have shown that SEM and EDS examination of the microstructure of cement pastes modified with accelerating admixtures at the observed points did not reveal differences that would be sufficient to explain the changes in compressive strength. Still, the increase in amorphous phase content indicates a faster hydration reaction rate for all pastes modified with accelerating admixture. It is backed up also by lower non-hydrated compounds content. All admixtures accelerate the hydration reaction of calcium silicate phases of cement, but only NaOH and cement kiln dust (CKD) influence the aluminate phase reaction rate. The pore volume is independent of the clinker type, while the pore size distribution is not.