Hydraulic Binders Research Articles

Impact of cementitious materials on the resilient modulus and damping ratio of weak subgrade

Pavement structures are constantly subjected to cyclic loadings. The resilient modulus and damping ratio are frequently used to evaluate the stress–strain relationships and energy dissipation for pavement subbase and subgrade. This paper presents an experimental study on the resilient modulus characterization, and damping ratio calculation for hydraulic road binder (HRB) treated weak subgrade soils. Results indicated that similar to General Use (GU) cement, HRB significantly enhanced the soil’s resilient modulus by increasing internal structural stability in cementitious treated soils. Using current stress-dominated constitutive models, a fair prediction can be achieved for GU- and HRB-treated soils, especially for lower MR values (<500 MPa). In addition, there is a concave downwards relationship between the damping ratio, total axial stress, and resilient modulus, respectively. Under repeated loading, higher energy dissipation for treated soils is anticipated within a certain range of axial stress levels.Furthermore, the mean resilient modulus of GU- and HRB-treated soils highly correlated with moisture content and with the actual content of cementitious materials: cement clinker and ground-granulated blast-furnace slag (GGBFS) in the treated soils. Their contributions could be further quantified by efficiency factors. Overall, the outcomes of this study could be a reference for the future investigation and development of hydraulic road binders and contribute to the future substitute of conventional Portland cement in pavement engineering.

Method of choosing soils as CEB or pavement layers based on geological and environmental information and mode of treatment

During research on the geological, mineralogical, mechanical and geotechnical nature of thick layers of soils developed on the rocks of the lower zone of the southern slopes of Mount Bambouto (West Cameroon), a couple of observations were made. The mechanical behavior of soils as construction materials is linked to the nature of the parent rock and its environment of formation. Four different types of rock have been noted: trachybasalt, orthogneiss, anatexite, and biotite-hornblende granitoid. These rocks in a hot and humid mountain climate, exposed to the monsoon wind, have weathered to give soils with exploitable characteristics in compressed earth bricks (CEB) and pavement layers. This article proposes a method of choosing a soil for pavement layers and for the production of fired earth bricks / earth bricks treated or not with hydraulic binders, based on the nature of the bedrock and the climatic environment. Several formulation models have been defined. The performance, fairness, accuracy and adequacy of these models with real values were made by metric evaluation. So, it is:•Preliminary method for quickly and easily formulating masonry units in clay soil.•Preliminary method for quickly and easily formulating pavement layers in clay soil.•Simple and reliable method for choosing clay soils as construction materials from elementary geological information.

Optimizing and coordinating the location of raw material suitable for cement manufacturing in Wasit Governorate, Iraq

Abstract The cement industry is considered one of the strategic industries, because it is directly related to construction work and cement is used as a hydraulic binder. However, it is a simple industry compared to major industries and depends on the availability of the necessary raw materials. This study focuses on optimizing and coordinating the location of raw materials needed for the cement manufacturing in Wasit Governorate in Iraq. Field works include detailed reconnaissance, topographic work, and description and sampling of 24 lithological sections that represent the carbonate deposits, which crop out in the area. The investigated area has the following specifications: The weighted averages of chemical components in the industrial bed are as follows: CaO = 47.83%, MgO = 1.12%, SiO2 = 7.28%, SO3 = 0.34%, Fe2O3 = 1.85%, Al2O3 = 1.85%, L.O.I = 39.26%, Na2O = 0.29%, and K2O = 0.38%. The average thickness of the investigated raw materials is 15.68 m. The average bulk density of the investigated raw materials is 2.32 g/cm3. The compressive strength of the investigated raw materials ranges from 6.182 to 55.21 MN/m2. The positive area is 922,552 m2. The volume of the industrial bed is 14,466,242 m3. The economic reserve of the industrial bed is 33,561,682 tons.

Stabilization of dune sand using crushed sand, silt and blast furnace slag for use in road field

Soil stabilization is a well-known technique to improve the mechanical properties of soils in road and railway construction by adding a grading corrector and/or hydraulic binders in the soil. In this work, dune treated sand is proposed to be used in pavement layers. For this, a series of tests, including sieve analysis, Proctor compaction, CBR, simple compressive strength, shear strength and compressibility tests are performed to evaluate the effectiveness of the adopted stabilization technique using dune sand, and to determine the optimal mixture for practical purpose. Our results show that for certain mixtures the lift (the CBR index) increases from ∼8% to ∼78% with the increase in resistance.

CO2-curing of carbon-reducing slag-based masonry bricks at elevated pressures in pre-industrial scale

The production of masonry bricks consumes enormous amounts of resources and causes high CO2 emissions. Most of the CO2 emissions are due to the use of hydraulic binders. We substitute conventional binders by different slag types that are a secondary-product of the steel industry to produce masonry bricks and perform CO2-curing. The scale-up from laboratory to pre-industrial scale including a lifecycle assessment (LCA) is focused. Literature values of the global warming potential (GWP) of sand-lime bricks serve as reference for the LCA. All slag-based CO2-cured bricks reach compressive strengths (24 to −49 MPa) higher than those of sand-lime bricks (12 to −20 MPa). The optimal curing parameters are 15 bar, 50 °C and 6 h. For these process conditions, autoclaves of the sand-lime brick industry can be modified for the usage of CO2. The LCA shows a CO2-saving potential of 337 kgCO2,eq/m3brick by carbonation process, compared to the conventional sand-lime bricks. CO2-curing of slag-based bricks has great potential for industrial implementation.

Optimisation of Weak Soil Stabilisation with a Hydraulic Binder for Road Construction Subgrade

Abstract One of the methods of strengthening the subgrade under the road pavement construction is its stabilization with a hydraulic binder. The technology of stabilization with binders is well known in the road engineering, however, it is still beneficial in terms of economical and organisational aspects while considering methods for improvement of the load-bearing capacity of the subsoil. The advantages of this technology are, among others, the possibility of using materials both from recycling and local materials, resulting in the possibility of waste production limitation by the use of weak material (soil) in place. The article presents a case study and the results of research obtained during the process of optimizing the thickness stabilized with a hydraulic binder. Comparative tests were carried out to reveal that non-chemical soil enhancement with the use of aggregate is as important as chemical one with the binder in terms of the quality of the final subgrade for road construction. The results were afterwards confirmed in field with use of heavy machines and full-scale soil stabilisation, leading to economic and environmental benefits.

The effects of arsenic trioxide addition on the mechanical and geochemical properties of the cemented paste backfill

Cemented paste backfill (CPB) technology, a densified mixture of mine tailings, binding material, and water, thickens to form a non-settling paste that is transported to fill mined cavities. CPB could provide environmental advantages by preventing the release of contaminants through hydraulic binder stabilization/solidification. Up to now, only few studies have been carried out to examine the feasibility of arsenic (As) fixation within cemented paste backfills. The main objective of the current study is to assess the impacts of incorporating pure arsenic trioxide on the geomechanical and geochemical properties of cemented paste backfill. CPB samples were prepared using pure ground silica (Sil-Co-Sil®) mimicking mine tailings, general use (GU) cement, deionized water, and reagent-grade pure As2O3 at different arsenic contents (0, 5, 10, and 15%). The samples were cured for up to 28 days and unconfined compressive strength (UCS) tests were conducted after 7 and 28 days of curing. Moreover, to evaluate the geochemical behavior of the pastes, mixtures of GU cement, pure As2O3 (0–15%), and deionized water with the same proportions as the CPB samples were prepared and mixed for up to 28 days. Then, pH, EC and chemical composition of the mixtures were evaluated. Results showed that the addition of pure arsenic trioxide (as a partial substitution for pure silica) leads to a substantial decrease in the mechanical strength of the CPB samples. However, this adverse effect was more substantial for the arsenic content of 5 wt%. The strength of the As2O3-containing samples did not improve significantly after 7 days of curing and arsenic addition lowered the pH of the solutions Microstructural analysis using SEM proved the formation of some C–S–H gels that contained arsenic in their structures as well as some complex mixture of oxides for the case of the As2O3-cement mixtures.

Stabilization of Different Soil Types Using a Hydraulic Binder

This paper presents an analysis of the stabilization of different soil types using a hydraulic binder. A study was carried out on soils that can be classified into two groups: cohesive and non-cohesive soils. Clay soils of medium and low plasticity according to the USCS classification were used as cohesive materials, while the sandy material containing dust was considered as non-cohesive material. Samples were taken from fifteen locations in Vojvodina province, Serbia. A hydraulic binder was used as a binder based on cement and lime. The amounts of the binder were estimated at 3, 5, 7, and 9%. In order to determine the basic physical and mechanical characteristics of the specimens, the following tests were performed: unconfined compressive strength after 7 and 28 days, indirect tensile strength after 7 and 28 days, as well as the California Bearing Ratio. Based on the obtained results, it can be concluded that increasing the amount of binder results in an increase in the subgrade load-bearing capacity. However, it should be emphasized that the subgrade containing non-cohesive material had a lower growth in the load-bearing capacity than those with the cohesive material.

Retarding Effect of Hemp Hurd Lixiviates on the Hydration of Hydraulic and CSA Cements.

Wood wool panels are widely used in the construction industry as sustainable cementitious composites, but there is a growing need to replace traditional Portland cement with a binder that has a lower embodied carbon footprint. In addition, the sustainability of these panels may face serious impediments if the required amount of wood for their production needs a harvest rate higher than the rate at which the tree sources reach maturity. One solution is to use the wooden part of fast-growing plants such as hemp. However, the compounds extracted from the mixture of plants and water are the main cause of the delay observed during the hydration process of hydraulic binders in these cementitious composites. The objective of this study is to evaluate the effect of bio-aggregate lixiviates (hemp hurd) on the hydration kinetics of calcium sulfoaluminate (CSA) cement as a low-embodied-carbon alternative to ordinary Portland cement (OPC). The isothermal calorimeter showed that the hemp hurd lixiviate caused a greater delay in GU's hydration process than CSA's. At a 5% concentration, the main hydration peak for GU cement emerged after 91 h, whereas for CSA cement, it appeared much earlier, at 2.5 h. XRD and TGA analysis showed that after 12 h of hydration, hydration products such as calcium silicate hydrates (C-S-H) and portlandite (CH) were not able to form on GU cement, indicating low hydration of silicate products. Moreover, at 5% concentration, the carbonation of ettringite was observed in CSA cement. The compressive strength values obtained from the mixes containing hemp hurd lixiviate consistently showed lower values compared to the reference samples prepared with distilled water. Furthermore, the CSA samples demonstrated superior compressive strength when compared to the GU samples. After 28 days of hydration, the compressive strength values for CSA cement were 36.7%, 63.5% and 71% higher than GU cement at a concentration of 0.5%, 2% and 5% hemp hurd lixiviate, respectively.

Recent advances in carbonatable binders

Carbonatable binder is relatively a new member of the cement family. This paper aims to review the progress in carbonatable binders given the increasing attention paid to this topic since the last International Congress on the Chemistry of Cement in 2019. Unlike hydraulic binders such as OPC and CSA clinkers, carbonatable binders react with CO2 in the presence of moisture to produce calcium carbonate as the major binding phase. This holds great potential in the utilization of emitted CO2 from anthropogenic sources. This paper will start with the introduction of definition and classification of carbonatable binders, followed by the presentation of phase composition, reactivity, microstructure and reaction mechanism. Lastly, a few cases on the recent production and application of carbonatable binders are introduced in the building industry.

WYTRZYMAŁOŚĆ NA ŚCISKANIE I ŚCINANIE PYŁU GRUBEGO STABILIZOWANEGO SPOIWEM TERRAMIX F22,5

Aim of the study: The paper presents the results of testing the compressive strength, frost resistance and shear strength of stabilized fine-grained soil depending on the added hydraulic binder and the time and method of curing. Material and methods: The tests were performed for a coarse silt collected in Boczkowice (Małopolskie Voivodship). The stabilizer used in the tests was Terramix F22.5, added in the amount of 3, 5 and 8% in relation to the dry mass of skeleton. The tests were carried out on samples immediately after stabilization, after 7 and 28 days of treatment with water and after 7 and 28 days with freezing and thawing cycles, as well as for samples without the addition of a stabilizer. Results and conclusions: On the basis of the conducted tests, it was found that the binder content used as well as the length and method of sample curing influence the improvement of geotechnical parameters. Both the compressive and shear strength of the tested soil samples depend on the method of sample care, as well as the value of the binder addition. The method of sample curing had the greatest influence on the compressive strength of the soil. Protecting the stabilized soil against water causes a significant increase in compressive strength, the enhance of compressive strength of the samples was up to 40%. The shear strength, and thus the values of the angle of internal friction and the cohesion of coarse silt, were significantly affected by content of the stabilizer. The both parameters increased with the increase of the binder addition.

Alkali fusion of bauxite refining residue (red mud-RM) to produce low carbon cements

This paper creates hydraulic binders using waste and a low energy input. Cements are produced with a bauxite refining residue (red mud-RM), blended with limestone and lime, and fused at temperatures from 600 to 1200 °C. The Saudi RM investigated has significant Al and Si but low Ca. Therefore, lime (CaO) and limestone (CaCO3) are used, as a source of calcium, to harvest cementing hydrates.When calcining RM alone, reactive aluminium phases begin to form at c.300 °C. However, at c.900 °C, they turn into crystalline corundum (Al2O3), a more stable and less reactive phase. It is hoped that the Ca provided by the lime/limestone will react with the Al in the RM during fusion, to form reactive silicates and aluminates rather than inert corundum. Both types of fusion produced calcium silicates and aluminates with cementing properties. However, lime fusion required higher temperature. Limestone fusion produces cementing phases at lower temperature than lime fusion, due to the lower decomposition temperature of CaCO3 when compared to CaO. High temperature is required to break down CaO (melting point = 2572 °C), whereas CaCO3 decomposes at 600 °C and disappears at 850 °C. Despite the top alkali fusion temperature being much lower than the CaO melting point, the results demonstrate that calcium was released from the lime and entered reactions forming calcium silicates and aluminates. This is probably due to the high alkali content of the RM acting as a flux and lowering the decomposition temperature of the CaO.

Novel Amorphous-Wollastonitic Low-Calcium Hydraulic Binders: A State-of-the-Art Review.

Because of the severe environmental impact of the CO2 emissions associated with the production of ordinary Portland cement (OPC) and the increasing demand for this commodity material, the development of alternative products has become a global concern. One alternative to OPC, or alitic-based clinkers, are amorphous-wollastonitic low-calcium hydraulic binders (AWLCs). This new class of hydraulic binders, described in the literature for the first time in 2015, may significantly reduce the CO2 emissions associated with its production, resulting from its lower calcium content, but also from the fact that its production technology can be fully electrified. In this paper, a state-of-the-art review is presented, providing a comprehensive description of the latest research, summarizing both the physicochemical and mechanical characteristics of this type of hydraulic binder, as well as possible routes for its production at an industrial scale.

Relationship between Porosity and Water Permeability for Deep Soil Mixing Material

The deep soil mixing (DSM) method is used to improve the mechanical and/or hydraulic properties of soils. The DSM method refers to an in situ mixing of soil, water, and hydraulic binder without excavation. After describing the specific microstructure of DSM materials compared with soils or concrete, four porosity–permeability analytical models from literature and based on microstructural parameters (i.e., porosity and pore-size distribution derived from mercury intrusion porosimetry) were applied to predict the water permeability (K) of soil–cement mixtures. After comparing the estimated permeabilities (Kest) with the experimental measurements of such a parameter (Kexp) using a triaxial cell, an indicator parameter A (=Kest/Kexp) was proposed to evaluate the ability of each model to fit the water circulation in DSM material. By calculating the average ratio 〈A〉 from the 24 materials in the studied database, three of the four applied models satisfactorily estimated the water permeability of the studied DSM materials. To reach an 〈A〉 value closer to 1, an extension of the Aït-Mokhtar's model, initially developed for cementitious mortars, was proposed by considering the specificities of the DSM materials. If previous models used only the contribution of nanopores less than 100 nm to the water flow, the extended model considered the contribution of all pore populations in the permeability calculation. Such an approach resulted in a significant improvement in the matching between the calculated and measured permeabilities.

Field investigation of a deep recycled base course layer containing dedicated three component hydraulic and bituminous binder

This paper provides an analysis and validation test of a recycled mix containing a three-component binder consisting of CEM I 32.5R (40 %), hydrated lime (20 %) and cement by-pass dust (40 %). A monitoring system based on fibre optic sensors was used to verify the strain state of the recycled layer and the effectiveness of the solution. The strain state simulation relied on the information from additional monitoring of environmental factors, such as temperature and moisture content in the cross-section of the recycled layer. The temperature effect was included in the numerical model based on the Fourier-Kirchhoff model. In addition, the generalized Maxwell model was employed to account for the load application time to describe the pavement layers' stiffness modulus. The strain state findings from the monitoring system were found in good agreement with the laboratory numerical simulation results. The numerical simulation used the results of the Leutner test to quantify the bond between the SMA and the FB-RCM/EB-RCM recycled layer. The analysis presented here was supplemented by nondestructive testing with the Falling Weight Deflectometer (FWD). The results confirmed the convergence between the recycled base course stiffness moduli obtained in the laboratory and the results of FWD identification. The comparative field tests of the strain state and standard properties (Sm, Va and ITSdry) validated the assumed aim of this study: obtaining a recycled layer made with a three-component road binder, which exhibited reduced stiffness and increased indirect tensile strength. Compared to the bitumen emulsion (EB-RCM), foamed bitumen in the recycled mix (FB-RCM) provided more favorable physical and mechanical properties and tensile strain reduction at the bottom of the recycled layer.

Interactions between clay minerals, bacteria growth and urease activity on biocementation of soils

Biocementation is a low carbon footprint soil improvement technique alternative to the use of hydraulic binders such as cement, mainly applied in sandy soils due to the need for vital room for bacteria and easy access for nutrient transport to feed them. This treatment is not suitable for natural clayey soils, however pore clogging caused by the presence of clay in low percentages may not be a problem, and clay minerals can be beneficial to increase the area for bacteria to attach and therefore to precipitate larger quantities of biocement. In addition, clay minerals can also have a positive influence on bacteria activity itself, and this is the novelty of this investigation. The influence of kaolin and bentonite clays on biocementation using Sporosarcina pasteurii was measured by (i) the amount of calcium carbonate precipitated in sandy soil prepared with known percentages of the two clays (1%, 5%, 10% and 20% in dry sand mass), relating it with unconfined compression strength, and (ii) evaluating bacteria growth and urease activity in liquid media with 1% and 5% of each clay. The best enhancement of biocementation was found for kaolin percentage between 5% and 10% and for 5% of bentonite, considering as reference the case where no clay was added. These relatively small percentages were linked to physical aspects related with the room occupied by the clay minerals causing dispersion of the precipitate in the clay matrix, although the presence of clay in the fluids of soil voids could contribute positively for bacteria growth and long-term survival. These results confirm that biocementation treatment may be effective on soils with relatively small clay percentages and opens the possibility that clay can be used in controlled fixed amounts to improve the efficiency of this treatment in clean sands.

Additive Manufacturing with Environmentally Sustainable Materials for Shell Envelop System

This paper presents research on the rheology of earth-based composites for Additive Manufacturing (AM) The study experiment setup is based on using different types of natural fibers with earth hydraulic binders through a pneumatic extrusion system of a 3axis printing machine. The ingredients of the composites are eco-friendly, locally available, inexpensive, and driven from recycled sources. The line tests have been done to improve important parameters related to extrudability, plasticity, and fluidity of the material composite through the printing process.

Influence of mixed hydraulic binder on the properties of recycled asphalt mixtures with foamed bitumen

Rozwój prac modernizacyjnych dróg różnych kategorii, od autostrad po drogi samorządowe, przyczynia się do powstawania dużej ilości destruktu asfaltowego (RAP) o zróżnicowanej jakości i uziarnieniu. W ramach gospodarki zrównoważonej niezbędne jest jego ponowne wykorzystanie. Obecnie w większości przeznaczony jest on do wytworzenia recyklowanych mieszanek mineralno-asfaltowych wbudowywanych w warstwę podbudowy. Zróżnicowana jakość destruktu wymaga zastosowania odpowiedniego rodzaju spoiwa, tak aby można było go wykorzystać w optymalny sposób. W związku z tym zaistniała potrzeba opracowania spoiwa hydraulicznego mieszanego, które składa się z cementu CEM I 32.R, wapna hydratyzowanego Ca(OH)2 oraz ubocznych cementowych produktów pylastych (UCPP) dobieranych w odpowiednich proporcjach. Badano wpływ składu spoiwa hydraulicznego mieszanego na następujące właściwości mieszanki wytwarzanej z zastosowaniem asfaltu spienionego: zawartość wolnych przestrzeni, wytrzymałość na pośrednie rozciąganie, wytrzymałość na osiowe ściskanie, odporność na oddziaływanie wilgoci i mrozu wg czterech różnych parametrów oraz moduł sztywności w temperaturze -10oC, +13oC, +25oC i +40oC wg metody IT-CY. Na podstawie wykonanych badań ustalono rekomendowany skład spoiwa zapewniający wymagane właściwości recyklowanej mieszanki związanej spoiwem hydraulicznym i asfaltem spienionym.

Municipal Solid Waste Incineration Fly Ash: From Waste to Cement Manufacturing Resource.

This study investigates the possibility of using municipal solid waste incineration fly ash as a supplementary cementitious material to replace part of the clinker in cement. Life cycle assessment has shown that the partial replacement of clinker with blast furnace slag (CEM III) reduces cement's global warming potential by ~30%, while replacing clinker with fly ash reduces it by up to 55%. When using CEM III as the control binder in cement in which 55 wt% of the clinker was replaced with hydrothermally treated fly ash, the flexural strength decreased by ~60% and the compressive strength by ~65%. When the fly ash was mixed with calcined and vitrified demolition materials, flexural strength decreased by ~30% and compressive strength by ~50%. The hardening of the hydraulic binders fixed the heavy metals in the municipal solid waste incineration fly ash.

Fiber-Reinforced Lightweight Calcium Aluminate Cement-Based Concrete: Effect of Exposure to Elevated Temperatures

Calcium aluminate cements (CACs) are a group of rapid-hardening hydraulic binders with a higher aluminum composition and lower ecological footprint compared to their ordinary Portland cement (CEM) counterparts. CACs are commonly known to have higher thermo-durability properties but have previously been observed to experience a major strength loss over time when exposed to thermal and humidity conditions due to the chemical conversion of their natural hydrated products. To address this, in this study, silica fume is added to induce a different hydration phase path suggested by previous studies and utilized in conjunction with fiber-reinforced lightweight pumice to produce lightweight concrete. To closely evaluate the performance of the produced samples with CAC compared to CEM, two different types of cement (CEM and CAC) with different proportions of pumice and crushed stone aggregate at temperatures between 200 and 1000 °C were tested. In this context, sieve analysis, bulk density, flowability, compressive and flexural strength, ultrasonic pulse velocity and weight loss of the different mixes were determined. The results of this study point to the better mechanical properties of CAC samples produced with pumice aggregates (compared to crushed stone) when samples are exposed to high temperatures. As a result, it is found that CACs perform better than CEM samples with lightweight pumice at elevated temperatures, showing the suitability of producing lightweight thermal-resistant CAC-based concretes.