Natural Cement Research Articles

Historic Concrete Science: Opus Caementicium to “Natural Cements”

The history of mineral components in cementitious materials begins with clays and bitumen in the most ancient mortars, followed by gypsum- and lime-based plasters, mortars, and concretes. Romans perfected the fabrication of extremely durable mortars that form the basis of audacious architectural monuments in Rome, massive harbor constructions, and water-proofed cisterns in the Mediterranean region. During the industrial revolution, “natural cements” were developed through the burning of impure limestone or Si- and Al-bearing materials blended with pure limestone. Delving into the past of concrete science and the composition, durability, and resilience of historic binders, mortars, and concretes can inspire the development of modern environmentally friendly cementitious materials.

Preliminary characterization of hydraulic components of low-temperature calcined marls from the south of Italy

Natural cement and hydraulic lime are considered proper candidates to be used in conservation and restoration of historical buildings cause their compatibility with original materials. Four marls with different percentage of calcite and clay were collected in the south of Italy and calcined at low temperatures (850 °C and 1050 °C). Unhydrated and hydrated products were characterized by X-ray diffraction and thermogravimetric analysis to identify hydraulic components; Rietveld analysis was performed to evaluate the amount of each phase; morphology and elemental composition of hydrated pastes were studied by scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. Belite (β-C2S, α′-C2S) and amorphous aluminates resulted the principal hydraulic components. The presence in cement pastes of hydration products such as calcium hydroxide, ettringite and calcium silicate hydrates suggested the possibility to use the analyzed marls as hydraulic lime and natural cements for the restoration and conservation of historical buildings.

No evidence that seaweed cover enhances the deterioration of natural cement‐based mortar in intertidal environments

AbstractThe breakdown of rocks and engineering materials in marine environments is both enhanced and retarded by surface‐colonizing marine organisms (seaweed, barnacles, etc.). However, the impact of marine growth on the deterioration of materials used to construct and repair maritime heritage assets, such as natural cement, is poorly understood.This study assesses whether seaweed cover (Fucus vesiculosus and Fucus serratus) influences the breakdown of mortar prepared using natural cement through an exposure trial at Portland Port, Dorset, UK. Using microclimate monitoring and three different indicators of weathering and material breakdown (surface hardness, surface roughness and ultrasonic pulse velocity), samples of mortar with and without a cover of seaweed were compared after 6 months of exposure to intertidal conditions. Our results show that temperature variations were significantly dampened under seaweed canopies compared to uncovered substrate both in summer and winter. As mechanical rock weathering processes are influenced by surface temperature regimes, we infer that these stabilizing effects may translate to a reduction in the efficacy of particular rock breakdown processes. Seaweed cover was not found to have significant effects on the surface hardness of the samples. Conversely, significant differences in surface roughness and pulse velocity were observed, indicating that the seaweed‐covered samples experienced less surface and subsurface breakdown.Overall, we found no evidence that seaweed significantly enhances the deterioration of natural cement‐based mortar during the first few months of exposure. Instead, we present the first empirical evidence of the bioprotective potential of seaweed covering materials commonly used in maritime built heritage restoration. Future work is now needed to examine the geomorphic roles of seaweed and other marine organisms on different types of materials used in maritime heritage conservation, and the extent to which their impacts on different deteriorative/protective processes vary in time and space, particularly under future climatic scenarios.

The Use of Waste Ceramic Optimal Concrete for a Cleaner and Sustainable Environment - A Case Study of Mechanical Properties-

The present study aims to find out the optimal use of ceramic powder and ceramic aggregate (both fine and coarse) as a possible substitute for Ordinary Portland Cement (OPC 43 grade) and natural aggregate (fine and coarse), respectively, in concrete, where focused on investigating the mechanical properties of waste ceramic concrete. The performance of this modified concrete was evaluated in terms of Compressive Strength (CS), Tensile Strength (TS), Flexural Strength (FS), and Combined Flexural and Torsional strength (FTS) obtained based on various experimental tests conducted on a total of 192 samples (48 cubes, 48 cylinders, 96 beams). The test results showed that ceramic waste material as a partial replacement for natural aggregate, cement, and fine aggregate provides better performance in terms of CS, TS, and FTS at optimal percentages- 20% ceramic aggregate, 10% ceramic powder, and 10% ceramic fine aggregate (Fineness Modulus 2.2) respectively in M25 grade concrete. Using ceramic waste as a partial replacement to prepare concrete has a lot of benefits from the economic, environmental, and technological point of view. Moreover, it offers a possibility for improving concrete's durability, which is vital.

Utilization of Silica Fume, Fly Ash, Rice Husk Ash as SCMs (A Tertiary Mix) in Plastic Aggregate Concrete

For sustainable development and protection of environment, plastic reuse is the best alternative for plastic waste management. Over the years extensive research has been carried out on the use of plastic in civil constructions. Also, the main challenges in the construction sector are caused by the Portland cement production. The obvious, basic and suitable solution is the less consumption of the same and by partial replacement of cement by SCMs (supplementary cementitious materials). Though utilization of plastic waste, fly ash, rice husk ash, silica fume and reduction in cement usage is advantageous from environmental point of view but their properties and behavior together as a construction material requires extensive investigation. In this study, keeping in view the environmental effects caused by the plastic wastes, cement production, various industrial and agricultural wastes; an investigation has been carried out to study the effect of partial replacement of cement by three different wastes i.e., Silica Fume, Fly Ash and Rice Husk Ash in combined proportions along with partial coarse aggregate replacement with plastic waste and to obtain optimum proportions of waste replacement. The research is carried out in two stages. In the first stage only the binder/cement is focused upon and replaced by different percentages in combined proportions of SF, FA and RHA. It was found out that the optimum percentage of cement replacement is 40% in which combined proportion is (10%SF, 10%RHA, 20%FA). In the second stage, the (10%SF, 10%RHA, 20%FA) replacement of cement is kept constant and the natural coarse aggregate is replaced by PP Plastic in proportions 20%, 30% and 40% respectively. Consequently, the optimum proportion of plastic was found to be 20% for the cement replaced plastic induced concrete (CRPIC). Physical characteristics of this cement replaced plasticinduced concrete (CRPIC) were determined by compressive strength tests, flexural tests, slump test. The chemical and water absorption properties along with weight of hardened concrete was assessed and the latter was compared with traditional concrete. This research, in general, will decrease the amount of natural coarse aggregate and cement quantity that are used in the construction industry and will consequently reduce the waste that is disposed into the surroundings.

Biocement treatment for upcycling construction and demolition wastes as concrete aggregates

Reutilisation of the construction and demolition (C&D) wastes as aggregate in concrete is a vital step towards sustainability as it prevents depletion of natural resources as well as alleviates wastes. However, the attached mortar on the aggregate surface renders certain shortcomings like excessive water absorption, high porosity, and weak interfaces. Recycled aggregates can be treated to improve these shortcomings. However, the minimisation of the drawbacks involves huge energy, materials, and cost. Moreover, the efficacy of such adopted method is sometime questionable, and which needs further research. This study demonstrates bio-treatment of recycled coarse aggregate (RCA) as a means of upcycling and compares it with conventional cement slurry treatment. A novel spraying technique has been applied that significantly economises biocement treatment. The experimental results show that biocement treatment reduced the water absorption by 70%. The treatment has filled the pores of RCA and has prevented water absorption. In contrast, cement slurry coating treatment shows increase in water absorption of RCA by 19%. The compressive strength of concrete with 100% biocement treated RCA surpasses that of concrete with natural coarse aggregates. The genesis of this dramatic improvement in case of biocement has been established through micro-scale studies including scanning electron microscopy and energy-dispersive X-ray spectroscopy. The cost analysis demonstrates that RCA upcycled with biocement treatment is more economical than natural aggregates or cement treated ones. Findings of the present study led to the conclusion that 100% replacement of natural coarse aggregates can be achieved by upcycling C&D wastes as coarse aggregate through bio-treatment.

Effect of silica fume inclusion on the strength, shrinkage and durability characteristics of natural pozzolan-based cement concrete

In the present work, effect of inclusion of silica fume on the performance of natural pozzolan-based cement concrete was investigated. Natural pozzolan, obtained from volcanic rocks, was used as the main supplementary cementitious material to partially replace the Portland cement. Silica fume was admixed at an optimum dosage, optimally selected based on the performance of several trial mixtures, in an attempt to improve the performance of the natural pozzolan-based cement concrete. Compressive strength, drying shrinkage, water penetration depth, coefficient of chloride diffusion, carbonation depth, reinforcement corrosion, loss of strength due to exposure to sulfate and salt weathering were measured to evaluate the performance of the concrete mixtures. Inclusion of silica fume to the blend of natural pozzolan and Portland cement significantly improved the performance of concrete. Reduction in the early age compressive strength of natural pozzolan-based cement concrete was compensated for by the addition of silica fume. Inclusion of silica fume to the natural pozzolan-based concrete significantly improved the durability characteristics without significant increase in the shrinkage. Though the addition of silica fume increased the carbonation depth, the increased carbonation depth was much less than the cover thickness normally provided over reinforcing steel, ruling out the possibility of reinforcement corrosion.

Comparative Analysis of Coal, Fuel oil and Natural gas for Cement Production

This study is a comparative analysis of the use of coal, fuel oil and natural gas cement production that marks their physical and chemical properties, costs and availability, impact on the environment and human health. In seven cents manufacturing industries in Nigeria. Based on the research analysis, it appears that between these Three (3) oil, petroleum is currently expensive even though it is available, while coal once natural gas is cheap, but coal is not available due to the closure of Nigerian coal mine. In terms of environment and health, coal oil and petrol pose a significant risk gas in the environment also cause additional health problems to cover the employee however natural gas slowly releases these harmful gases into the environment and causes little health problems for employees. Research therefore shows that natural gas is at the forefront gasoline because it is cheaper, more easily available and creates fewer problems nature.

Mortars for Conservation of Late 19th and Early 20th Century Buildings-Combination of Natural Cements with Air Lime.

With the availability of commercial Natural cements (NC) for the conservation purposes raises a fundamental question about the compatibility between historic and repair mortars. The properties of Natural cements are dependent on the geological location of the raw material extraction and also on the production parameters, both having an impact on the final properties of the mortars produced from each distinct. Therefore, the significance of preservation of 19th and 20th century heritage and selection of the proper binder compatible with the original materials necessitate the study of existing NCs, that nowadays are produced by several manufacturers. This work provides a complex study of the mortars prepared from three NCs available in the market: Groupe Prompt Vicat, France (NCPV); Cemento Collet Marfil (NCM) and Cemento Natural Tigre (NCT), both from Spain. Various mortar sets based on individual NC containing different binder/aggregate ratios and air lime additions were analyzed after 28, 60, and 90 days of curing with the focus on their mineralogical composition (XRD), morphology (SEM), mechanical (flexural and compressive strength), and physical properties such as water absorption by capillarity, water vapor permeability, and water vapor diffusion resistance. Mortars prepared from NCPV, NCM, and NCT show distinct physical-mechanical properties with varying binder/aggregate ratio and air lime addition. This study shows that the NC variability should be taken into consideration when selecting materials for the conservation and rehabilitation of historic renders and plasters. Based on the comparison with original NC mortars, several NC mortars developed in this study show adequate properties for conservation of the buildings from late 19th and early 20th century in terms of compressive strength (>12 MPa), water absorption by capillarity (<20 kg·m−2·h−0.5), water vapor permeability (<4 × 10−10 kg·s−1·m−1·Pa−1), and water vapor diffusion resistance (<28) values.

Soft computing techniques to predict the compressive strength of green self-compacting concrete incorporating recycled plastic aggregates and industrial waste ashes.

Rapid urbanization and industrialization with corresponding economic growth have increased concrete production, leading to resource depletion and environmental pollution. The mentioned problems can be resolved by using recycled aggregates and industrial waste ashes as natural aggregate and cement replacement in concrete production. Incorporating different by-product ashes and recycled plastic (RP) aggregates are viable options to produce sustainable self-compacting concrete (SCC). On the other hand, compressive strength is an essential characteristic among other evaluated properties. As a result, establishing trustworthy models to forecast the compressive strength of SCC is critical to saving cost, time, and energy. Furthermore, it provides valuable instruction for planning building projects and determining the best time to remove the formwork. In this study, four alternative models were suggested to predict the compressive strength of SCC mixes produced by RP aggregates: the artificial neural network (ANN), nonlinear model, linear relationship model, and multi-logistic model. To do so, an extensive set of data consisting of 400 mixtures were extracted and analyzed to develop the models, various mixture proportions and curing times were considered as input variables. To test the effectiveness of the suggested models, several statistical evaluations, including coefficient of determination (R2), scatter index, root mean squared error (RMSE), mean absolute error (MAE), and Objective (OBJ) value were utilized. Compared to other models, the ANN model performed better to forecast the compressive strength of SCC mixes incorporating RP aggregates. The RMSE, MAE, OBJ, and R2 values for this model were 5.46 MPa, 2.31 MPa, 4.26 MPa, and 0.973, respectively.Graphical

Sustainable Alternatives for Green Mortar: Quarry Waste and Ultra high fly ash utilization

The use of waste materials from different industries as a replacement of cement has gained much attention all over the world. In addition, many attempts have been done to replace partially or totally one of the ingredients from the mix design to lower the negative impacts of construction industry. In this study, quarry waste and fly ash were used as two different sustainable approaches to replace the maximum volume of natural alluvial sand and cement, respectively, in the traditional mortar matrix. The quarry waste is a by-product of quarries characterized with a large volume of fines, whereas, fly ash is the by-product of coal-fired electric generation plants. The performance of the green mortars containing the maximized volume of quarry waste and fly ash were evaluated with regard to the mechanical properties. The results have clearly indicated the beneficial use of the quarry waste and fly ash as a substitute for siliceous sand and cement respectively in preparation of green mortars. In addition, the cost and parametric analysis was also performed for a multi-story reinforced concrete building using the designed quarry sand and fly ash as concrete ingredients.

Adhesive Materials Inspired by Barnacle Underwater Adhesion: Biological Principles and Biomimetic Designs.

Wet adhesion technology has potential applications in various fields, especially in the biomedical field, yet it has not been completely mastered by humans. Many aquatic organisms (e.g., mussels, sandcastle worms, and barnacles) have evolved into wet adhesion specialists with excellent underwater adhesion abilities, and mimicking their adhesion principles to engineer artificial adhesive materials offers an important avenue to address the wet adhesion issue. The crustacean barnacle secretes a proteinaceous adhesive called barnacle cement, with which they firmly attach their bodies to almost any substrate underwater. Owing to the unique chemical composition, structural property, and adhesion mechanism, barnacle cement has attracted widespread research interest as a novel model for designing biomimetic adhesive materials, with significant progress being made. To further boost the development of barnacle cement–inspired adhesive materials (BCIAMs), it is necessary to systematically summarize their design strategies and research advances. However, no relevant reviews have been published yet. In this context, we presented a systematic review for the first time. First, we introduced the underwater adhesion principles of natural barnacle cement, which lay the basis for the design of BCIAMs. Subsequently, we classified the BCIAMs into three major categories according to the different design strategies and summarized their research advances in great detail. Finally, we discussed the research challenge and future trends of this field. We believe that this review can not only improve our understanding of the molecular mechanism of barnacle underwater adhesion but also accelerate the development of barnacle-inspired wet adhesion technology.

Natural fiber-reinforced light-weight cement blocks prepared from waste for sustainable development

Low density of the light-weight cement blocks offers an advantage in terms of dead load reduction, which is advantageous in structural design-reduction of size and numbers of load-carrying structural components is possible. Production of cement blocks, however, generally requires Ordinary Portland Cement (OPC) which creates harmful environmental impacts. Utilization of waste as alternative raw materials for cement production is a route to alleviate the problem. This research aims at synthesizing eco-friendly cement-like material for production of light-weight cement blocks. The cement-like material were prepared from eggshells, cockleshells, and rice husk ash (RHA). With high content of calcium oxide and silica, eggshells and cockleshells are potential sources of calcium, whereas RHA is a good source of silicon. Additionally, a fuel-efficient solution combustion technique was employed in synthesis of the cement-like material. Phase identification analysis of the synthesized powder indicated that tri-calcium silicate (C3S), di-calcium silicate (C2S), tri-calcium aluminate (C3A),and tetra-calcium alumino ferrite (C4AF), which are main constituents of OPC, were obtained. To fabricate eco-friendly light-weight cement blocks, the synthesized cement-like material were mixed with cement, water, and additional RHA and cast into blocks. The optimal compressive strength and density of the cement blocks were in comparable range with the standard light-weight concrete defined by Thai Industrial Standards Institute (TISI) and American Concrete Institute (ACI 213,2001). With jute fiber reinforcement, enhanced compressive strength of 20% was achieved, while elimination of spalling after compression test was clearly evident, implying a more ductile failure.

The Performance of Concrete Made with Secondary Products-Recycled Coarse Aggregates, Recycled Cement Mortar, and Fly Ash-Slag Mix.

The properties of cement concrete using waste materials—namely, recycled cement mortar, fly ash–slag, and recycled concrete aggregate—are presented. A treatment process for waste materials is proposed. Two research experiments were conducted. In the first, concretes were made with fly ash–slag mix (FAS) and recycled cement mortar (RCM) as additions. The most favorable content of the concrete additive in the form of RCM and FAS was determined experimentally, and their influence on the physical and mechanical properties of concrete was established. For this purpose, 10 test series were carried out according to the experimental plan. In the second study, concretes containing FAS–RCM and recycled concrete aggregate (RCA) as a 30% replacement of natural aggregate (NA) were prepared. The compressive strength, frost resistance, water absorption, volume density, thermal conductivity, and microstructure were researched. The test results show that the addition of FAS–RCM and RCA can produce composites with better physical and mechanical properties compared with concrete made only of natural raw materials and cement. The detailed results show that FAS–RCM can be a valuable substitute for cement and RCA as a replacement for natural aggregates. Compared with traditional cement concretes, concretes made of FAS, RCM, and RCA are characterized by a higher compressive strength: 7% higher in the case of 30% replacement of NA by RCA with the additional use of the innovative FAS–RCM additive as 30% of the cement mass.

Predicting Slump Values of Concrete Made by Pozzolans and Manufactured Sand using ANN

Large amounts of natural fine aggregate (NFA) and cement are used in building, which has major environmental consequences. This view of industrial waste can be used in part as an alternative to cement and part of the sand produced by the crusher as fine aggregate, similar to slag sand (GGBFS), fly ash, metacaolin, and silica fume. Many times, there are issues with the fresh characteristics of concrete when using alternative materials. The ANN tool is used in this paper to develop a Matlab software model that collapses concrete made with pozzolanic material and partially replaces natural fine aggregate (NFA) with manufactured sand (MS). Predict. The slump test was carried out in reference with I.S11991959, and the findings were used to create the artificial neural network (ANN) model. To mimic the formation, a total of 131 outcome values are employed, with 20% being used for model testing and 80% being used for model training. 25 enter the material properties to determine the concrete slump achieved by partially substituting pozzolan for cement and artificial sand (MS) for natural fine aggregate (NFA). According to studies, the workability of concrete is critically harmed as the amount of artificial sand replacing natural sand grows. The ANN model's results are extremely accurate, and they can forecast the slump of concrete prepared by partly substituting natural fine aggregate (NFA) and artificial sand (MS) with pozzolan.

Reduced graphene oxide-incorporated calcium phosphate cements with pulsed electromagnetic fields for bone regeneration.

Natural calcium phosphate cements (CPCs) derived from sintered animal bone have been investigated to treat bone defects, but their low mechanical strength remains a critical limitation. Graphene improves the mechanical properties of scaffolds and promotes higher osteoinduction. To this end, reduced graphene oxide-incorporated natural calcium phosphate cements (RGO-CPCs) are fabricated for reinforcement of CPCs' characteristics. Pulsed electromagnetic fields (PEMFs) were additionally applied to RGO-CPCs to promote osteogenic differentiation ability. The fabricated RGO-CPCs show distinct surface properties and chemical properties according to the RGO concentration. The RGO-CPCs’ mechanical properties are significantly increased compared to CPCs owing to chemical bonding between RGO and CPCs. In in vitro studies using a mouse osteoblast cell line and rat-derived adipose stem cells, RGO-CPCs are not severely toxic to either cell type. Cell migration study, western blotting, immunocytochemistry, and alizarin red staining assay reveal that osteoinductivity as well as osteoconductivity of RGO-CPCs was highly increased. In in vivo study, RGO-CPCs not only promoted bone ingrowth but also enhanced osteogenic differentiation of stem cells. Application of PEMFs enhanced the osteogenic differentiation of stem cells. RGO-CPCs with PEMFs can overcome the flaws of previously developed natural CPCs and are anticipated to open the gate to clinical application for bone repair and regeneration.

Plant-based fibres in cement composites: A conceptual framework

The pursuit of sustainability has necessitated more renewable resources in construction materials. Plant-based natural fibres, which can be found globally, are abundant, low-cost and renewable. Moreover, plant-based fibres can improve the mechanical properties of construction materials as a low-cost, environmentally friendly renewable option. Accordingly, a thorough understanding of the characteristics and drawbacks of plant fibres, focussing on their use in cement-based composites, is needed to explore their potential in structural applications. Therefore, this study developed a conceptual framework to assess the factors affecting plant-based natural fibres and cement composites. The paper further demonstrates the application of the proposed framework to predict associated challenges and offers appropriate solutions. Finally, date palm fibres are suggested for future applications of the proposed conceptual framework.

Contribution of Surface Treatment on Physical and Mechanical Properties of Recycled Concrete Aggregates

The demand for virgin aggregates for concrete production worldwide has been increasing. At the same time, there is an increase in the production of rubbles from construction‐related activities. The residues are produced either due to leftovers or from the demolished structures. However, worldwide, the utilization of recycled concrete aggregate (RCA) material for structural concrete has been limited, often considered inferior due to distorted surfaces. The problems with RCA arise because it is a composite aggregate made of natural aggregate and cement, and adhered surface mortar is the discontinuities on the surface that arise from the production technique or the strength of the original concrete. The development of hydrated calcium silicate binder in the concrete matrix has been the critical desire of researchers to make better concrete material. This research focuses on the treatment of RCA from locally available rice husk ash with minimum pozzolanic cement. The objective was achieved by conducting tests on the properties of aggregates that include specific gravity and water absorption, aggregate crushing value (ACV), and aggregate impact value (AIV). The effectiveness of the treatment technique is assessed by the analysis of SEM imagery and XRD analysis of the microstructure cement paste around the RCA. At 20% pozzolan concentration, RCA treatment yields comparable specific gravities, water absorption, ACV, and AIV. Furthermore, the replacement of 5% rice husk ash (in 20% concentration) provided the optimal proportion of treatment for RCA, resulting in a reduction of ACV by 31.4%, AIV by 30.0%, and water absorption by 12.7% compared to the untreated RCA. XRD showed that calcite (CaCO₃), quartz, and portlandite phases were the majority in the untreated RCA. The study indicates that pozzolanic cement with 15% can be used with 5% RHA to produce RCA with characteristics almost similar to virgin aggregates. This research presents a consistent methodology to achieve modified RCA for application in construction.

A review on the influence of copper slag as a natural fine aggregate replacement on the mechanical properties of concrete

Over the years, the construction industry is highly dependent on concrete for meeting the global demand of building new infrastructure. Various advancements in normal concrete have been made to make the concrete industry more efficient and developed. High strength concrete (HSC), and self-compacting concrete (SCC) are two revolutionary developments in the concrete industry that have increased the dependency of the world on concrete due to their enhanced mechanical and durability properties. However, CO2 emissions associated with cement and concrete manufacturing have created an alarming situation, and as the world is looking for sustainability and cleaner production, the pressure on the concrete industry to minimize the use of natural aggregates and cement is also increasing. Geopolymer concrete (GPC) is a type of concrete that uses various industrial wastes as a binder instead of cement and these by-products are activated by alkali. GPC is still under research and yet to be developed as a reliable product, however, the available research validates the lesser environmental impacts in GPC as compared to cement-based concrete. Other efforts have also been made to reduce the environmental impacts in concrete and substitution of natural fine aggregate (NFA) with industrial by-products is one such step that not only provides an efficient method of waste disposal but also reduces the dependency of concrete on natural resources. Copper slag (CS) is a type of nontoxic industrial waste that is obtained during matte smelting and refining of copper. CS resembles the size of NFA and can be used as partial or full replacement of NFA in various types of concrete. Various researchers have investigated the potential use of CS as NFA replacement in conventional concrete, HSC, SCC, and GPC. The current study summarizes the up-to-date trends as reported in available literature wherein CS has been used as fine aggregate in conventional concrete, HSC, SCC, and GPC. Present investigations support the use of CS as a fine aggregate in concrete. Apart from the key findings, various identified gaps, challenges, and future scope challenges have also been discussed to develop CS as a sustainable material in the construction industry.

Rheological, mechanical properties, and statistical significance analysis of shotcrete with various natural fibers and mixing ratios

The rheological properties of concrete with natural fibers is studied herein. Natural fibers improve the concrete performance, moreover it covers the similarity between natural fibers and cement matrix. Natural fibers may decrease the pumpability of shotcrete as they reduce workability, which is a critical factor for shotcrete application in construction. The rheological analysis was conducted on 28 specimens, both with and without natural fibers, considering three natural fibers—kenaf, flax, and jute—three fiber lengths—5 mm, 10 mm, and 20 mm—and three mixing weights—0.5 kg, 1.0 kg, and 1.5 kg. The rheological properties of the specimens, such as flow resistance and torque viscosity, were measured using an ICAR rheometer, and correlated with pumpability and shootability. To adequately compare the recorded data, the rheological parameters were converted to Bingham model parameters. Furthermore, the compressive strength, flexural strength, and chloride penetration resistance of the specimens were determined to evaluate their durability. Slump and air content decreased based on the fiber weight and types compared with OPC. Moreover, rheological properties and mechanical properties of the fiber incorporated concrete are analyzed here. Finally, the statistical significance of the fibers was determined through an analysis of variance (ANOVA). Based on the results of the tests determined the optimal combination of fiber parameters that provides the best shotcrete performance.