Natural Pozzolana Research Articles

Ultrahigh Performance of Concrete using Manufactured Sand

The resistance and durability of concrete structures can be improved by using ultra-high performance concrete (UHPC). A crucial component of energy conservation and concrete cost reduction is the use of locally available materials. In this study, the effects of a common type of locally accessible manufactured sand (MS) on the characteristics of UHPC were investigated from both a physical and chemical standpoint. The main objective of the current study is to use locally available materials to create a UHPC with a compressive strength of 100MPa. The impact of fine materials, binder type and content, mixer type, steel fibres, and curing regimes on the concrete’s compressive strength was examined in this study. The use of high strength concrete has various benefits, including a reduction in the size of beams and columns and an increase in the height of buildings with multiple stories. In recent years, high strength concrete has seen increased use in civil engineering. By minimising non-homogeneity, porosity, and micro-cracks in the concrete and its zone of transition, high strength is made achievable. Super plasticizers and additional cementing substances such granulated blast furnace slag, silica fume, and natural pozzolana can be used to achieve it. Concrete with a high modulus of elasticity is strong. On cement, fine aggregate, and coarse aggregate, preliminary studies have been conducted. In the current study, 920KK is employed as a chemical admixture and silica fume is used as a mineral admixture. For M100 concrete, the w/c ratio is taken to be 0.25. The mix proportion for M100 grade concrete can be calculated by following the design process suggested by the ACI Method as 1:0.454:1.527.

Effectiveness Assessment of Superplasticizer Admixtures: Case of Self-compacting Concrete Reinforced with Fine Mineral Fillers

Abstract The use of superplasticizers in concrete production has become a common practice, especially when a high fluidity is required. On the other hand, the risk of segregation and the stability of these mixtures is ensured by the incorporation of a large volume of fine mineral additions. The present investigation is devoted to the study of the influence of three types of superplasticizers of different chemical compositions, namely: Combined Synthetic Polymers (CSP), Poly-Carboxylate Ether (PCE), and Modified Poly-Carboxylate Ether (MPCE) on the rheological behavior of self-compacting concrete (SCC) as well as on the mechanical properties at 3, 7, and 28 days of curing. Natural pozzolana (NP) and ground granulated blast furnace slag (GGBFS) were used as additions to stabilize the mixtures. The results revealed that the ether-based superplasticizer PCE gave the best workability and mechanical performance with low amounts (high efficiency). In addition, blast furnace slag promotes the obtaining of better properties whether in the fresh or hardened state compared to natural pozzolana.

Effects of Lysinibacillus sphaericus on Physicomechanical and Chemical Performance of OPC Blended with Natural Tuff and Pulverized Fly Ash

This paper reports study findings on the use of Lysinibacillus sphaericus (at 1.0 × 107 cells/ml concentration) to enhance and improve the physicomechanical and chemical properties of blended Ordinary Portland Cement (OPC). Blending was done separately with pulverized fly ash (PFA) and natural pozzolana (volcanic tuff) at substitution levels of 10%, 20%, 30%, 40%, 50%, 60%, and 70%. Mortar prisms of dimensions 40 mm by 40 mm by 160 mm were prepared and cured for the 2nd, 7th, 28th, 56th, and 90th days using Lysinibacillus sphaericus solution as mixing water and curing media. Commercial OPC and PPC mortar prisms cast and cured using distilled water were used as controls. Results showed that prisms treated with bacteria exhibited the highest performance on compressive strength development. Further microstructure analysis of blended cement incorporated with Lysinibacillus sphaericus bacteria showed significant amounts of reacted secondary cementitious materials compared to samples without bacteria. Bacteria presence was also found to reduce water demand during mixing and setting times and exhibited low porosity in relation to samples without bacteria. These results showed that the presence of alkaliphilic bacteria in the blended cement resulted in synergistic effect in enhancing the physicochemical and mechanical properties.

Development of multiple linear regression, artificial neural networks and fuzzy logic models to predict the efficiency factor and durability indicator of nano natural pozzolana as cement additive

The current study aims at predicting the efficiency factor (EF) and durability indicator (DI) of the natural pozzolana when added as a cement replacement at nano scale. Multiple linear regression (MLR), artificial neural networks (ANN) and fuzzy logic (FL) tools were employed in the analytical study. The studied sample was the data collected from an experimental study carried out by the authors, on a local natural pozzolana. Curing time, nano natural pozzoalna (NNP) content, median particle size of natural pozzolana, water/binder (w/b) ratio and the superplasticizer dosage were selected as input variables. The curing times were investigated at 2, 7, 28, 90 and 180 days. NNP was added at six percentages, i.e. 0, 1, 2, 3, 4 and 5%. Two median particle sizes i.e. 100 and 500 nm, were studied. Four w/b ratios and four superplasticizer dosages were examined, i.e. 0.4, 0.5, 0.6 and 0.7, and 0, 0.5, 2 and 4 l/m3, respectively. The correlation coefficients and several performance criteria were computed to evaluate the developed models. Based on the analysis results, it can be concluded that EF and DI of NNP can be effectively predicted using ANN and FL techniques. The results obtained by MLR were far from those obtained by both ANN and FL. In addition, ANN tool was slightly more accurate than FL as far as prediction of EF is concerned. Coefficient of determination (R2) values of 0.992, 0.987 and 0.651 along with mean absolute percentage error (MAPE) values of 18.5, 2.3 and 3.7 were the outcome of ANN, FL and MLR models, respectively, when EF was predicted. Further, the re-evaluation of this study can be done in future, particularly when more data is available in the literature.

Cost-Benefit Analysis of Vibrated Concrete and Self–Compacting Concrete Containing Recycled Aggregates and Natural Pozzolana

The use of vibrated concrete (VC) and self–compacting concrete (SCC) with adequate strength, cost-effectiveness, and sustainability is required to meet the current requirements in the concrete industry. Therefore, the development of an economical and durable concrete while comparing the life cycle cost of the structures, which includes the initial cost of the material, labor, and the cost of maintenance and repair, is of prime importance. The prevailing cost of materials and labor from the local market was collected to calculate the total cost of the concrete mixes. Both vibrated concrete and self–compacting concrete mixes containing conventional materials as well as locally and regionally available materials were developed, and a decision matrix was used for the cost-benefit analysis. The cost analysis of different mixes showed the economic benefit of self–compacting concrete compared to vibrated concrete, and further confirmed the added advantage of incorporating volcanic ash (VA) and recycled coarse aggregates (RCA) for the economic development of concrete mixes.

Types of lime binders in mortars used for the construction of the Ming Great Wall of China and their importance for the development of a conservation strategy

The most obvious characteristics of the Ming Great Wall are external masonry walls made of natural stones, bricks and lime mortars. According to the chemical and mineralogical compositions of the original bedding and pointing mortars, dolomitic lime binder was used dominantly in the construction of the Ming Great Wall in provinces such as those around Beijing and Hebei. Calcium-rich lime and air lime with low natural hydraulically reactive phases, which are hydrated and react slowly with the carbon dioxide in air to form calcium carbonate, were used in some western provinces. Chemical and microscopic investigations show that both dolomitic and calcium-rich lime mortars are almost aggregate-free. Historic dolomitic lime mortars are characterised by high strengths, low porosities and dense micro-scale textures. The most recent conservation principle is to preserve the Ming Great Wall as a ruin. Therefore, the conservation strategy should be redefined in terms of mortars. Since some of the damage to the Great Wall is related to reactions between dolomitic lime mortars and air pollutants, calcium-rich lime binders should be used for conservation and even for restoration of those parts of the Great Wall that were originally built with dolomitic lime. Binders based on natural hydraulic lime and calcium-rich lime gauged with natural pozzolana might be more compatible than other binders” for the structural consolidation of the ruins of the Great Wall.

Development of Concrete Incorporating Recycled Aggregates, Hydrated Lime and Natural Volcanic Pozzolan

Recycling of construction and demolition waste is a central point of discussion throughout the world. The application of recycled concrete as partial replacement of mineral aggregates in concrete mixes is one of the alternatives in the reduction of pollution and savings in carbon emissions. The combined influence of the recycled crushed concrete, lime, and natural pozzolana on the mechanical and sustainable properties of concrete materials is firstly proposed in this study. In this research, unconventional construction materials are employed to produce concrete: the recycled crushed concrete is used as coarse aggregate, while lime and natural pozzolana are used as a partial replacement for cement. Substitutions of 10%, 20%, 50% of gravel are made with recycled aggregates, and 2%, 5%, 10% of cement with lime and natural pozzolan. Tests on the fresh and hardened properties, destructive (compressive strength) and non-destructive tests (sclerometer rebound and ultrasound) of mixtures are carried out. It is shown that the use of recycled materials can provide an increase in compressive strength of up to 34% with respect to conventional concrete. Life cycle cost and sustainability assessments indicate that concrete materials incorporating recycled aggregate possess good economic and environmental impacts.

The effect of content and fineness of natural pozzolana on the rheological, mechanical, and durability properties of self-compacting mortar

Mineral admixtures are used in ordinary and self-compacting mortar to reduce carbon dioxide emission and enhance the performance of mortar at the fresh and hardened states. This paper reports the effect of the content and the fineness of natural pozzolana (NP) on rheological, compressive strength, total and autogenous shrinkage properties of self-compacting mortar. Capillary water absorption of self-compacting mortar was also investigated. Natural pozzolana was used as a partial cement replacement with two levels (15%wt. And 30%wt.) and ground to three specific surface Blaine (SSB) fineness measurements 350 m2/kg, 420 m2/kg and 500 m2/kg. Cement content, water to-binder ratio and superplasticizer content were kept constant for all self-compacting concrete mixtures. Rheological tests were conducted by measuring slump flow and V-funnel flow tests as well as using a rheometer to measure plastic viscosity and yield stress. Compressive strengths of self-compacting concretes were determined at 1, 7, 28, 56, 90 and 180 days of curing. Total and autogenous shrinkage were measured during three months and capillary water absorption of self-compacting mortar was also investigated after 90 days of water curing. The results indicated that the increase of replacement level of natural pozzolana affects negatively the rheological properties of self-compacting mortar. The same tendency is observed as the specific surface Blaine fineness increased. However, in the long-term (beyond 28 days of curing), the compressive strength of NP mixes exceeds that of control mortar. The increase of the fineness of natural pozzolana enhances compressive strength at later age but increases both the total and autogenous shrinkage compared with control mortar. It was observed that increasing the percentage of natural pozzolana generates an increase in water capillary absorption. However, increasing the fineness of natural pozzolana results in slightly lower water absorption of mortar.

Effect of natural pozzolana on microstructural behavior and hydraulic conductivity of lime-stabilized clayey soil

Effect of natural pozzolana on microstructural behavior and hydraulic conductivity of lime-stabilized clayey soil

Producing Sustainable Concrete using Nano Recycled Glass

Background: Many tools and techniques have been recently adopted to develop construction materials that are less harmful and friendlier to the environment. New products can be achieved through the recycling of waste material. Thus, this study aims to use recycled glass bottles as sustainable materials. Objective: Our challenge is to use nano glass powder by the addition or replacement of the weight of the cement for producing concrete with enhanced strength. Methods: A nano recycled glass powder is prepared by crushing and storming a glass bottle to obtain a Blaine surface area of approximately 28 m2/g and conforming to the chemical requirements for natural pozzolana class N, according to ASTM C618. The outcome of using nano recycled glass for theaddition and replacement of ordinary Portland cement weight on the compressive and flexural strengths of concrete at 7, 28, and 90 days is investigated. Results: The concrete mixes with 2.5%, 5%, 7.5%, and 10% replacements of cement by nano recycled glass powder show improvements in compressive and flexural strengths of up to 12.77% and 7.66%, respectively, at 28 days. Meanwhile, mixes with the addition of 5% nano glass powder show best improvements in compressive and flexural strengths of up to 11.49% and 7.46%, respectively.

Mix design of high performance concrete with different mineral additions

Purpose The purpose of this paper is to present the modeling of statistical variation of experimental data using the design of experiments method to optimize the formulation of a high performance concrete (HPC) using materials that are locally available in Algeria. For this, two mineral additions (natural pozzolana and limestone filler [LF]) were used. Both additions are added by substitution of cement up to 25%. To better appreciate the effect of replacing a part of cement by natural pozzolana and LF and to optimize their combined effect on the characteristics of HPC, an effective analytical method is therefore needed to reach the required objective. Design/methodology/approach The experimental part of the study consisted of substituting a portion of cement by various proportions of these additions to assess their effects on the physico-mechanical characteristics of HPC. A mixture design with three factors and five levels was carried out. The JMP7 software was used to provide mathematical models for the statistical variation of measured values and to perform a statistical analysis. These models made it possible to show the contribution of the three factors and their interactions in the variation of the response. Findings The mixture design approach made it possible to visualize the influence of LF and pozzolanic filler (PF) on the physico-mechanical characteristics of HPC, the developed models present good correlation coefficients (R2 = 0.82) for all studied responses. The obtained results indicated that it is quite possible to substitute a part of cement with LF and PF in the formulation of a HPC. Thanks to the complementary effect between the two additions, the workability could be improved and the strengths drop could be avoided in the short, medium and long term. The optimization of mixture design factors based on the mathematical models was carried out to select the appropriate factors combinations; a good agreement between the experimental results and the predicted results was obtained. Originality/value The coefficient of PF in Cs28 model is closer to that of LF than in Cs7 model, thanks to the complementary effect between LF and PF at the age of 28 days. It was found that the optimal HPC14 concrete (10%LF–5%PF) provides the best compromise between the three responses. It is also worth noting that the use of these two local materials can reduce the manufacturing costs of HPC and reduce carbon dioxide emissions into the atmosphere. This can be an important economic and environmental alternative.

Chloride Diffusion in Cementitious Pastes: Comparative Study between OPC and Blended Cements Containing Natural Pozzolana and Slag

Chloride apparent diffusion coefficient (Dapp) of a porous media is an indicative of its capacity to resist chloride ingress. It is used to predict the service life of reinforced concrete structures. This paper presents experimental study to measure the effect of blended cement paste containing Sudanese Natural Pozzolana (SNP) from Bayuda Desert in the Northern State on Dapp by using Bulk Diffusion Test (Nord–Test NT–Build 443). Three mixes are investigated, each mix contains 3 specimens, the first mix is a reference mix with 100% Ordinary Portland Cement (OPC) compared with second mix having another containing 75%OPC:25%NP, third mix having 50%OPC:50%GGBS. All pastes have water binder ratio of 0.55. The Dapp of 50%OPC:50%GGBS is found to be 1.794*10-6 mm2/s which is lowest among the pastes. The Dapp for 75%OPC:25%NP is 2.80*10-6 mm2/s and the Dapp for 100%OPC is 3.145 *10-6 mm2/s which is the highest.

Influence of temperature on the rheological behaviour of eco-mortar with binary and ternary cementitious blends of natural pozzolana and marble powder

With the advent of new concrete such as low-impact environmental concrete, and the new implementation techniques of cementitious materials such as 3D printing and pumping, it becomes crucial to control the rheological behaviour of these materials taking into account the different climatic conditions. The main objective of this study is to investigate the influence of mineral additions and temperature on the rheological parameters (yield stress, plastic viscosity) and the fresh properties (slump, flow time) of low-impact environmental concrete using concrete-equivalent mortar (CEM) concept. For this purpose, fifteen mixtures of CEM were prepared by substituting the cement with natural pozzolana (PZ) and marble powder (MP) in binary and ternary blend systems. The rheological and fresh properties of CEM mixtures were investigated at different temperatures ranging from 10 °C to 50 °C. The results obtained revealed that, the use of binary and ternary blended cements based on PZ and MP increased the fresh properties and decreased the rheological parameters of CEM tested in a standard environment of temperature 20 °C. In addition, the increase in temperature affected negatively the fresh properties and rheological parameters of all binary mixtures. However, at low temperature (10 °C), the viscosity and yield stress of ternary mixtures have been enhanced.

The role of SCM’s on rheology of sprayed mortar

The role of various SCM’s on rheology of fresh sprayed mortar was studied. The mix design was inspired by recent trends in SCM’s with use of ground limestone, calcined clays and natural pozzolanas. New formulations were correlated to commonly used SCM’s like blastfurnace slag and fly ash. Sprayed mortar designed mostly for thin profile coatings is demanding material in terms of rheology requiring good adhesion, pumpability, shootability, stability after spraying, low segregation and minimum rebound. Particle packing model was used for sprayed mortar mix design. Time and shear rate dependent rheological parameters were calculated using conventional models to describe the properties of fresh sprayed mortars. A procedure for determining the segregation of the mortar using a rheometer was proposed.

Prediction of Compressive Strength of Self-Compacting Concrete (SCC) with Silica Fume Using Neural Networks Models

Self-Compacting Concrete (SCC) is a relatively new type of concrete with high workability, high volume of paste and containing cement replacement materials such as slag, natural pozzolana and silica fume. Cement replacement materials provide a wide variety of benefits such as lower cost, reduced consumption of natural resources, reduced carbon dioxide emissions and improved fresh and hardened properties. SCC is used in many applications such as sections with congested reinforcement and high rise shear walls and there is a need for the prediction of the performance of SCC used. Artificial Neural networks (ANN) are widely used in civil engineering for the prediction of the performance of some engineering materials such as compressive strength and durability. However, currently, studies on SCC containing silica fume are very rare. In this paper, an artificial neural networks (ANN) model is developed to predict the compressive strength of SCC with silica fume using the Levenberg-Marquardt back propagation algorithm based on a database from 366 experimental studies. The model developed was correlated with a nonlinear relationship between the constituents (input) and the compressive strength of SCC (output). To evaluate the predictive ability and generalize the developed model, other researchers’ experimental results were compared with the model prediction and good agreements are found. A parametric study was conducted to study the sensitivity of the ANN proposed model to some parameters such as water/binder ratio and superplasticizer content. The model developed in this study can potentially be used for SCC compressive strength prediction with very acceptable results and a high correlation coefficient R2=0.93. The developed model is practical, easy to use and user friendly. Doi: 10.28991/cej-2021-03091642 Full Text: PDF

Natural pozzolana of micro and nano-size as cementitious additive: resistance of concrete/mortar to chloride and acid attack

Natural pozzolana of micro and nano-size as cementitious additive: resistance of concrete/mortar to chloride and acid attack

Sustainable natural pozzolana concrete – A comparative study on its environmental performance against concretes with other industrial by-products

With increasing environmental sustainability concerns in the construction industry and a demand for producing more durable and sustainable concrete, effort is devoted to producing concrete with Ordinary Portland cement (OPC) being substituted by alternative binder materials. By considering the compressive strength, the comprehensive environmental performance of natural pozzolana in concrete was evaluated comparatively by developing six mix-designs of concrete with OPC, and commonly used industrial by-products as supplementary cementitious materials such as fly ash (FA) and ground granulated blast furnace slag (GGBS) based on the lifecycle assessment (LCA) approach. The results show that comparable compressive strengths can be achieved for the use of 20% and 30% volcanic ash (VA) against conventional SCMs. Using the volume as functional unit, the LCA results have demonstrated that higher environmental savings are associated with VA concrete compared to that of OPC, GGBS (30%) and FA (25%), but almost similar when 50% GGBS is used. For example, 15–24% and 10–19% lower global warming potential are associated with VA concretes compared to that of OPC and FA concretes, respectively, but much higher saving is found when considering the strength of the concrete, as they are about 11–12%, 10–11% and 29–30% compared to that of GGBS, FA and OPC concretes, respectively. The results can be used as valuable guidelines for VA-based in sustainable concrete production, which would further enhance the sustainability of the concrete industry.

Undissolved Ilmenite Mud from TiO2 Production—Waste or a Valuable Addition to Portland Cement Composites?

This paper presents a method of utilising ilmenite MUD created during the production of titanium dioxide (TiO2) according to the sulphate method as an additive for Portland cement composites. After the production process, undissolved MUD was additionally rinsed with water and filtrated in the factory to make it more useful (R-MUD) for implementation and also to turn back some of the by-products of the production of TiO2. R-MUD is less hazardous waste than MUD. It has a lower concentration of sulphuric acid and some heavy metals. The rinsing process raised the concentration of SiO2, which is a valuable part of R-MUD because of its potential pozzolanic activity. This means that the R-MUD might be a reactive substitute of part of Portland cement in building composites. The article presents the results of research on the pozzolanic activity of R-MUD and other materials with proved pozzolanic activity, such as silica fume, fly ash and natural pozzolana (trass). Tests were performed using thermal analysis techniques. The tests showed that the pozzolanic activity or R-MUD after three days is at the same level as silica fume and after 28 days it is twice as high as the activity of fly ash. Beyond the 180th day of curing, R-MUD had the same level of activity as fly ash. The summary is supplemented by calorimetric tests, which confirm the high reactivity of R-MUD compared to other commonly used concrete additives, already in the initial hydration period. In summary, heat of hydration after 72 h of Portland cement with R-MUD is at the same level as the heat of hydration of Portland cement with silica fume and also pure Portland cement grout. The results confirm that the process of formation of micro-silica contained in R-MUD react with calcium hydroxide to form the C-S-H phase, which is responsible for the microstructure of cement composites.

Determination of the Pozzolanic Activities of Trachyte and Rhyolite and Comparison of the Test Methods Implemented

Natural pozzolanas should be evaluated in terms of sustainability as well as their contribution to concrete durability. Therefore, the use of such materials in the production of cement as well as concrete industry has been gaining importance recently. In this study, the pozzolanic activities of ground trachyte and rhyolite, known as volcanic tuffs, were investigated in accordance with TS 25 standard. Pozzolanic properties of such materials, along with their pozzolanic activity indices, are investigated comparatively by the Frattini method, strength activity index, X-ray diffraction and thermogravimetric analysis. The morphologies of ground trachyte and rhyolite were also studied using SEM analysis. Based on the results obtained, the mortar samples containing blast furnace slag (BFS), fly ash (FA), trachyte and rhyolite were met the acceptable pozzolanic activity index at the end of 28 days with values of 90, 87, 89, 87, respectively. On the other hand at the end of 90 days, while the mortar samples containing BFS, FA and trachyte were met the acceptable pozzolanic activity index, that of containing rhyolite did not meet the acceptable pozzolanic activity index, with values of 93, 85, 87, 80, respectively. The pozzolanic activity index of the rhyolite was found to be quite close to that of the FA; however, the trachyte had a pozzolanic activity index close to the BFS. Comparisons of the methods implemented in the analyses were also conducted. According to the statistical evaluation of the test methods, it has been found that the relationships obtained using the direct methods as well as the indirect methods independently are highly correlated. Overall, it can be concluded that the ground trachyte may be utilized as a pozzolanas in the cement industry; however, the ground rhyolite does not meet some limits prescribed by the related standard.

Production of a lightweight masonry block using alkaline activated natural pozzolana and natural fibers

Lightweight geopolymers are alternative low-carbon footprint building materials with high potential to produce value added products for the construction industry such as low-density masonry units. This work focuses on presenting the development of a new lightweight masonry block using natural pozzolana-based geopolymer mortar, hydrogen peroxide as a foaming agent and jute fibers as reinforcement additive. The experimental plan allowed the optimization of the production process and the definition of the optimum quantities of hydrogen peroxide content, pozzolana: fine aggregate ratios and the appropriate amount of fibers to be incorporated. The experimental results demonstrate the feasibility of the production of new masonry units, which can achieve up to 8.1 MPa of compressive strength after 28 days of fabrication with reduced bulk densities of 1269 kg/m3.