Amount Of Cement Research Articles

Application of Artificial Intelligence Methods for Predicting the Compressive Strength of Green Concretes with Rice Husk Ash

To promote sustainable growth and minimize the greenhouse effect, rice husk fly ash can be used instead of a certain amount of cement. The research models the effects of using rice fly ash as a substitute for regular Portland cement on the compressive strength of concrete. In this study, different machine-learning techniques are investigated and a procedure to determine the optimal model is provided. A database of 909 analyzed samples forms the basis for creating forecast models. The derived models are assessed using the accuracy criteria RMSE, MAE, MAPE, and R. The research shows that artificial intelligence techniques can be used to model the compressive strength of concrete with acceptable accuracy. It is also possible to evaluate the importance of specific input variables and their influence on the strength of such concrete.

EXPERIMENTAL STUDY ON BEHAVIOR OF RECYCLED AGGREGATE IN CONCRETE

Concrete is one of the most widely used construction material in the world. Increase in population growth is leading to increase in various demands like cultivation, transportation, construction etc. Nowadays, there is a tremendous increase in the demand for construction works like residential buildings, bridges, dams, roads etc. and because of this increase in demand the availability of sources for concrete ingredients is getting difficult. Hence people are looking for alternative sources for the concrete ingredients in order to full fill their requirements. This dissertation work deals with the study of strength of concrete incorporating Recycled Aggregate concrete(R.A.C).The main objective of this investigation is to find out up to what percentage the Natural Coarse Aggregate(N.C.A) can be replaced by recycled coarse aggregate(R.C.A) in the concrete mix and to find out the extra quantity of cement to be added for each percentage replacement byR.C.A. to achieve its target mean strength. In this ongoing project work it is concentrated only on the use of R.C.A. A series of tests were carried out to determine the compressive strength, split tensile strength, flexural strength with and without recycled aggregates. Natural coarse aggregates in concrete were replaced with 0%, 20%, 40%, 60%, 80% and 100% of crushed concrete coarse aggregates. For the strength characteristics, the result showed a gradual decrease in compressive strength, split tensile strength, flexural strength and modulus of elasticity as the percentage of recycled aggregate is increased. Key Words: Natural Coarse Aggregate, Recycled coarse aggregate, compressive strength, split tensile strength, flexural strength.

Dolomitic Limestone Powder: Cement Substitute in the Production of Structural Concrete Paving Blocks

Manufacturers are replacing or combining cement with mineral additives such as slags, natural pozzolans, sand, diatomaceous earth and limestone to reduce carbon dioxide emissions and energy usage. Due to its high magnesium content, dolomitic limestone has long been utilized in concrete production to reduce costs and environmental risks associated with making cement. This study aimed to produce a reliable and appropriate concrete mixture for concrete paving blocks using dolomitic limestone powder that passed the no. 24 sieve as cement replacement at replacement levels of 0 (control mix), 8, 12, 16, 20, 24, 28 and 32%, satisfying the minimum compressive strength requirement for structural concrete of 20.7 MPa (3,000 psi). The ASTM E877-13 was used to sample the dolomitic limestone, and the 1:1.5:3 concrete class combination was utilized to proportion the quantities of cement, sand and aggregates (3/8”). After 28 days, the specimens were cured and the compressive strength, through the varying water-cement ratios in the concrete mixture, was determined. Results showed that dolomitic limestone powder can substitute cement by 16% by weight, using a concrete mix of 523-g cement, 936-g sand, 1,868-g gravel, 100-g dolomitic limestone powder, and 166-g water with a water-cement ratio of 0.318, exceeding the minimum necessary compressive strength of concrete of 20.7 MPa by 24.9% or 5.16 MPa. Therefore, it is advised to utilize this proven concrete mixture as a basis for a potential business venture in the production of concrete paving blocks for structural concrete applications such as walkways, sidewalks, parking lots and commercial areas, as well as in places where loads are very high, like airports, courtyards, docks and freight yards.

Characteristics of the açai seed (Euterpe precatoria Martius) after thermal processing and its potential in soil-cement brick

The management of the açai palm, a species of the Euterpe genus, has grown in recent years mainly for the extraction of palm heart and the pulp of the fruit called açai. After the extraction of the’ pulp, there is a significant generation of residues, as the discarded seeds account for approximately 85% of the fruit. Therefore, this research aims to characterize the açai seed after fruit processing, as well as to evaluate the potential of thermally processed seed for use in soil-cement bricks. The seed morpho-anatomy tests were performed, including moisture content, loss of ignition, ash content, thermogravimetry, fluorescence, and X-ray diffraction of the ground seeds. Tests on thermally processed seeds included readings by X-ray diffraction and laser granulometry. After evaluating the properties of the ash, it was incorporated into soil-cement mixtures in proportions of 5%, 10%, 15%, and 20%, replacing the clinker content of LC3 (Limestone Calcined Clay Cement). Based on the results obtained, soil-cement bricks were produced with a composition of 90% soil and 10% LC3, with the LC3 cement clinker being replaced by 20% açai seed ash. The results indicate the potential for the application of açai seed ash in soil-cement bricks on a practical scale, demonstrating that the ash enhances soil stabilization and increases the compressive strength of the soil-cement matrix due to its smaller particle size compared to that of the soil grains. This not only reduces the amount of cement required for the matrix but also offers environmental sustainability through the utilization of seed waste. The study underscores the potential of applying açai seed ash in the context of environmentally significant alternative technologies and sustainable practices, emphasizing the promise of the properties found in discarded açai seeds.

Mechanics and road performance of mudstone modified stabilized gravel subgrade in arid desert areas

This study investigates the feasibility of using mudstone to enhance poorly graded gravel in certain arid regions of the S21 Altay-Urumqi Highway project in Xinjiang. Despite mudstone typically being considered a poor-quality rock, its combination with higher-performance materials like cement, lime, and fly ash can stabilize expansive soils for use as roadbed fill. In the experiments, 30% and 40% mudstone were added to the gravel mixture. The experiments were compared with unmodified K80 and 35% crushed rock mixes. The findings reveal that adding 30% mudstone substantially increased the California Bearing Ratio (CBR) of the gravel mix by over 20%. However, excessive mudstone inclusion could weaken load-bearing capacity. Moreover, mudstone-modified specimens exhibited superior unconfined compressive strength (UCS), splitting strength, compressive resilience modulus (CRM), drying shrinkage resistance, and temperature shrinkage resistance. Under optimum cement dosage, the UCS of mudstone-modified specimens outperformed unmodified specimens, consistently surpassing fly ash-altered groups. Although mixed fly ash initially exhibited lower strength, it gradually approached cement-stabilized strength with an extended curing time. Incorporating crushed stone into the grading curve significantly increased splitting strength due to its high strength and hardness. In contrast, adding mudstone introduced a notable proportion of fine aggregates, resulting in a looser grading skeleton prone to early cracking. This research demonstrates that mudstone enhancement significantly improves roadbed performance, including increased CBR, splitting strength, and crack resistance. The use of mudstone in arid desert areas enhances overall performance while reducing shrinkage coefficients. The suggested approach for semi-rigid pavements in arid deserts recommends specific mineral proportions, various aggregate sizes, an appropriate amount of cement, and 30% mudstone to create dense structures with a higher quantity of coarse aggregate.

Clinical efficacy of percutaneous vertebroplasty versus percutaneous kyphoplasty treating osteoporotic vertebral compression fractures with kyphosis.

This study aimed to investigate the clinical efficacy of percutaneous vertebroplasty (PVP) and percutaneous kyphoplasty (PKP) in treating osteoporotic vertebral compression fractures (OVCFs) with kyphosis. The clinical data included 63 patients in the PVP group and 70 in the PKP group. The study assessed the pain visual analog scale (VAS), Oswestry Disability Index (ODI), wedge angle (WA), local kyphotic angle (LKA), and vertebral height. The operative time was significantly less in the PVP group (p < 0.05). Meanwhile, more bone cement was injected into the PKP group (p < 0.05), with significantly higher surgical costs (p > 0.05). Post-operative VAS, ODI, WA, LKA, and vertebral height were significantly improved in PVP and PKP groups compared with pre-operative measurements (p < 0.05). The results revealed insignificant VAS and ODI improvement differences between the two groups at each follow-up time (p > 0.05). Vertebral height, WA, and LKA improved more significantly in the PKP group at day 1 and 3months post-operatively (p < 0.05), with insignificant group differences at subsequent time points (p > 0.05). The improvements in VAS were unrelated to those in WA, LKA, or vertebral height in either group (p > 0.05). The improvement in VAS was unrelated to the amount of bone cement injected (p > 0.05); the PKP group demonstrated a lower incidence of cement leakage (12.9%; p < 0.05). PVP and PKP can restore partial vertebral height and improve kyphosis with similar clinical outcomes. PVP has a shorter operating time, is more economical, and can represent a therapeutic choice.

Diagenetic evolution of tight sandstone and the formation of an effective reservoir in the lower member 3 of the Shahejie Formation, Bohai Bay Basin, East China

Heterogeneity in the physical properties of tight sandstones is mainly caused by complex diagenetic interactions in various combinations during the burial process. The tight sandstone oil in the Linnan Sag of Bohai Bay Basin has great development potential but it is unclear how effective reservoirs were formed, and this is a significant reason why exploration in the deep reservoir is so difficult. Here we studied the diagenetic evolution of the tight sandstone of Lower Member 3 of the Shahejie Formation, Linnan Sag, Bohai Bay Basin, by using cores, thin sections, XRD, SEM, grain-size analysis, high-pressure mercury intrusion porosimetry, fluid inclusions, and carbon and oxygen stable isotopes. Compaction, replacement, cementation and dissolution diagenesis are identified; all four processes mainly occur in the A phase of mesodiagenesis. The interaction of formation burial, thermal evolution of organic matter and dehydration of gypsum leads to the alternating presence of three stages of alkaline fluids and two stages of acidic fluids. The average dissolution porosity of the dissolution sandstone facies is greater than the lower limit of the porosity for the effective reservoir in the study area, which is key to the formation of effective reservoirs. By determining differential diagenetic evolution sequences of tight sandstone reservoirs under the constraints of different lithologies where sandstone is interbedded with mudstone, we are able to elucidate the formation of the effective reservoir as follows: (1) In the eodiagenetic stage, a large amount of early carbonate cement developed in the sandstone adjacent to the mudstone, filling the primary pores and forming a cementation sandstone facies. Smaller amounts of early carbonate cement developed in the interior of the sandstone, which “fixed” the primary pores, and has a positive effect on the formation of a large number of secondary pores in the dissolution stage. (2) In the early stage of mesodiagenesis (A1), due to the filling of primary pores, it is difficult for acidic fluids to enter the cementation sandstone facies adjacent to mudstone, and the dissolution is weak. But dissolution within the sand body was strong, producing a large number of dissolution pores and forming a dissolution sandstone facies that clearly enhanced the physical properties. (3) In a second early stage of mesodiagenesis (A2), dissolution still played a dominant role in the dissolution sandstone facies, due to the development of dissolution pores in the previous stage (it is easy for acidic fluids to enter the dissolution sandstone facies). The physical properties of the dissolution sandstone facies were once again enhanced and an effective reservoir gradually began to form. (4) At the end of mesodiagenesis stages A1 and A2 (26.2–24.6 Ma; 7.5–2.8 Ma), the reservoir experienced two phases of petroleum charging. The charging of the cementation sandstone facies developed at the margins of the sandstones was difficult due to the filling of primary pores. The dissolution sandstone facies are oil-bearing, with higher porosity, which indicates an effective reservoir. By coupling the thermal evolution of organic matter and the dehydration of gypsum with differential diagenetic evolution and the porosity evolution of reservoir, we are able to establish a reservoir genetic model that involves alternating seepage of organic acids and alkaline brines.

Improvement of Earth into Concrete as an Eco-friendly Building Material – Effect of Soil Gradation and Chemical Admixtures

Environmental concerns and economic crises have been more critical in recent years, making it impossible to continue construction using traditional resources (cement, sand, and natural aggregates) in the same way as before. However, the use of earth is a cost-effective solution and it can enhance the sustainability of construction materials by employing soil as a building material. This study evaluated soil consistency that would be acceptable to make soil concrete and analysed the effect of chemical admixtures in achieving the maximum possible strength. Hence, the study suggested the possibility of using soil to form concrete as a replacement for cement concrete to the maximum extent with self-compacting properties. The soil was used to produce the concrete, stabilizing with cement and chemical admixtures were used to improve the strength and workability. According to the experimental investigation, it can be concluded that soil can be used as concrete with a characteristic strength of 15 MPa. The recommended native soil consistency for soil concrete should be developed by rearranging the native soil gradation to 5%–10% fines, 55%–71% sand, and 24%–40% gravel. The recommended cement amount as the stabilizer is 16% to 18% of the weight of the improved dry soil mixture. The strength and workability can be further improved by employing suitable chemical admixtures. Finally, this extensive study concluded that soil could be used to produce concrete for the construction industry through applications with minor improvements to the existing soil.

The effect of three dental cement types on the corrosion of dental implant surfaces

Statement of problemOne of the main challenges facing dental implant success is peri-implantitis. Recent evidence indicates that titanium (Ti) corrosion products and undetected-residual cement are potential risk factors for peri-implantitis. The literature on the impact of various types of dental cement on Ti corrosion is very limited. PurposeThis study aimed to determine the influence of dental cement on Ti corrosion as a function of cement amount and type. Materials and methodsThirty commercially pure Ti grade 4 discs (19 × 7mm) were polished to mirror-shine (Ra ≈ 40 nm). Samples were divided into 10 groups (n = 3) as a cement type and amount function. The groups were no-cement as control, TempBond NE (TB3mm, TB5mm, and TB8mm), FujiCEM-II (FC3mm, FC5mm, and FC8mm), and Panavia-F-2.0 (PC3mm, PC5mm, and PC8mm). Tafel’s method estimated corrosion rate (icorr) and corresponding potential (Ecorr) from potentiodynamic curves. Electrochemical Impedance Spectroscopy (EIS) data was utilized to obtain Nyquist and Bode plots. An equivalent electrical circuit estimated polarization resistance (Rp) and double-layer capacitance (Cdl). Inductively coupled plasma mass spectrometry (ICP-MS) analysis was conducted to analyze the electrolyte solution after corrosion. pH measurements of the electrolyte were recorded before and after corrosion tests. Finally, the corroded surface was characterized by a 3D white-light microscope and scanning electron microscope. Statistical analysis was conducted using either one-way ANOVA followed by Tukey’s Post Hoc test or Kruskal-Wallis followed by Dunn’s test based on data distribution. ResultsBased on cement amount, FC and PC significantly increased icorr in higher amounts (FC8mm-icorr = 8.22 × 10−8A/cm2, PC8mm-icorr = 5.61 × 10−8A/cm2) compared to control (3.35 × 10−8A/cm2). In contrast, TB3mm decreased icorr significantly compared to the control. As a function of cement type, FC increased icorr the most. EIS data agrees with these observations. Finally, corroded surfaces had higher surface roughness (Ra) compared to non-corroded surfaces. ConclusionThe study indicated that cement types FC and PC led to increased Ti-corrosion as a function of a higher amount. Hence, the implant stability could be impacted by the selection, excessive cement, and a potentially increased risk of peri-implantitis.

DEVELOPMENT AND RESEARCH OF A COMPOSITE MATERIAL FOR THE LAYER OF A BALLAST-FREE BRIDGE FLOOR

To connect the reinforced concrete slabs of the ballastless bridge deck with the metal girders of the railway bridges, a rubber-wood lining layer, which is convenient for laying and has favorable physical and mechanical characteristics, is traditionally applied, which has insufficient durability due to wood rot. An analysis of the stress-strain state of a reinforced concrete slab of a ballastless bridge deck was performed, and it was established that the strength of the material of the lining layer between the slabs and the bridge girders after 6–8 hours after laying should be at least 1 MPa, at the age of 2 days or more – at least 5 MPa, the modulus of deformation should not be more than 10,000 MPa. The value of the modulus of deformation and compressive strength of the rubber-wood lining layer was determined. Such a lining layer undergoes significant deformations due to the rubber and suddenly breaks down. The modulus of deformation is 58.3 MPa for pine and 144 MPa for oak. A structural and technological solution of the laying layer made of rolled composite material, consisting of a non-woven material of a volumetric structure of NWMVS from anisometrically oriented polyester fibers, cement, fine sand aggregate and hardening accelerator additives, was developed and patented. The dependences of the modulus of deformation and compressive strength of the paving layer made of rolled composite material on the ratio of the amount of sand to the amount of cement in the mineral mixture S/C, the consumption of the mineral mixture per unit of volume of NWMVS M/NM, and the thickness of NWMVS were investigated. Such a lining layer also undergoes significant deformations, however, destruction with a violation of structural integrity is not observed. It was established that the modulus of deformation and conditional compressive strength of the composite material decrease with an increase in the content of S/C sand in the mineral mixture and a decrease in the consumption of the mineral mixture per unit area and volume of NWMVS M/NM. The laying layer made of rolled composite material has a modulus of deformation of 144 MPa for S/C no more than 0.11, M/NM 1000 kg/m3 . Such compositions are recommended to be inserted for the lining layer, the method of which is patented.

Clinical efficacy and safety of kyphoplasty for the treatment of osteoporotic vertebral compression fractures at different surgical timings based on the theory of “dynamic-static integration”

ObjectiveTo investigate the clinical efficacy and safety of percutaneous kyphoplasty at different surgical timings in the treatment of osteoporotic vertebral compression fracture (OVCF) based on the theory of “dynamic-static integration”. MethodsPatients with OVCF who underwent percutaneous kyphoplasty in our hospital were selected and divided into Groups A, B, and C for those undergoing surgery within 7, 7–21, and >21 days of fracture occurrence. The variations in the amount of bone cement injected, pre- and post-operative pain levels, functional activity, deformity correction of the injured vertebrae, bone cement leakage, and vertebral body height loss were compared among the three groups. ResultsRegarding pain relief and functional activity, the postoperative Visual Analog Scale and Oswestry Disability Index scores of the three groups significantly improved. Furthermore, the deformities of the injured vertebrae in the three groups were significantly corrected, with Groups A and B exhibiting superior correction compared to Group C. Moreover, the bone cement leakage rates in groups A and C were higher than that in Group B. At the 3-month follow-up, the loss of vertebral height in Group C was significantly higher than those in groups A and B. ConclusionKyphoplasty is effective for OVCF treatment. Early surgery can effectively restore the vertebral height of the injured vertebra, reduce kyphosis, and reduce height loss of the injured vertebra after surgery; nevertheless, treatment within 1–3 weeks of the fracture can reduce the occurrence of bone cement leakage, making the surgery safer. Therefore, surgical treatment within 1–3 weeks of fracture is safer and can achieve satisfactory therapeutic effects. From the perspective of traditional Chinese medicine, PKP surgery can transform the fracture end from a micromotion state to a fixed state, which fully embodies the theory of “dynamic-static integration”.

The effects of admixtures on the durability properties of phosphogypsum-based cementitious materials

This study involved proportionally blending beta-hemihydrate phosphogypsum (β-HPG) with raw phosphogypsum to prepare a phosphogypsum-based composite cementitious material (PGCM). The admixtures of quicklime (1–3%), cement (12–18%), and silica fume (5–9%) were selected to fabricate the PGCM mixture. The effect of each admixture on the durability performance of PGCM was evaluated using a single-factor experimental approach. The results showed that cement reduced significantly the dissolution rate and increased the strength coefficient, exhibiting the best effect on the antifreeze performance of PGCM. Quicklime and silica fume had no significant effect on the early antifreeze performance of PGCM but improved the later antifreeze performance. Moreover, the quicklime improved the weathering resistance of PGCM, whereas a high content of quicklime reduced the PGCM’s strength coefficient. Silica fume improved the weathering resistance of PGCM in later phases, and cement had little effect on the weathering resistance of PGCM. Additionally, an increasing amount of cement significantly improved the water resistance of PGCM, and quicklime and cement significantly increased the length of PGCM specimens. Microscopic analysis showed that the generation hydration products mainly filled aggregate pores of raw phosphogypsum and enhanced raw phosphogypsum aggregates’ interfacial adhesion, thereby improving the macroscopic mechanical and water resistance properties of PGCM. The findings on PGCM’s durability properties can provide more theoretical foundations and technical supports for advancing phosphogypsum recycling.

Developing a sustainable self-compacting geopolymer concrete with 100% geopolymer-coated recycled concrete aggregate replacement

PurposeConcrete, the second most used material in the world, surpassed only by water, relies on a vast amount of cement. The process of cement production emits substantial amounts of carbon dioxide (CO2). Consequently, it is crucial to search for cement alternatives. Geopolymer concrete (GC) uses industrial by-product material instead of traditional cement, which not only reduces CO2 emissions but also enhances concrete durability. On the other hand, the disposal of concrete waste in the landfills represents a significant environmental challenge, emphasising the urgent need for sustainable solutions. This study aimed to investigate waste concrete's best form and rate as the alternative aggregates in self-compacting and ambient-cured GC to preserve natural resources, reduce construction and demolition waste and decrease pertinent CO2 emissions. The binding material employed in this research encompasses fly ash, slag, micro fly ash and anhydrous sodium metasilicate as an alkali activator. It also introduces the best treatment method to improve the recycled concrete aggregate (RCA) quality.Design/methodology/approachA total of25%, 50% and 100% of coarse aggregates are replaced with RCAs to cast self-compacting geopolymer concrete (SCGC) and assess the impact of RCA on the fresh, hardened and water absorption properties of the ambient-cured GC. Geopolymer slurry was used for coating RCAs and the authors examined the effect of one-day and seven-day cured coated RCA. The mechanical properties (compressive strength, splitting tensile strength and modulus of elasticity), rheological properties (slump flow, T500 and J-ring) and total water absorption of RCA-based SCGC were studied. The microstructural and chemical compositions of the concrete mixes were studied by the methods of energy dispersive X-Ray and scanning electron microscopy.FindingsIt is evident from the test observations that 100% replacement of natural aggregate with coated RCA using geopolymer slurry containing fly ash, slag, micro fly ash and anhydrous sodium metasilicate cured for one day before mixing enhances the concrete's quality and complies with the flowability requirements. Assessment is based on the fresh and hardened properties of the SCGC with various RCA contents and coating periods. The fresh properties of the mix with a seven-day curing time for coated RCA did not meet the requirements for self-compacting concrete, while this mix demonstrated better compressive strength (31.61 MPa) and modulus of elasticity (15.39 GPa) compared to 29.36 MPa and 9.8 GPa, respectively, for the mix with one-day cured coated RCA. However, incorporating one-day-cured coated RCA in SCGC demonstrated better splitting tensile strength (2.32 MPa) and water absorption (15.16%).Research limitations/implicationsA potential limitation of this study on SCGC with coated RCAs is the focus on the short-term behaviour of this concrete. This limited time frame may not meet the long-term requirements for ensuring the sustained durability of the structures throughout their service life.Originality/valueThis paper highlights the treatment technique of coating RCA with geopolymer slurry for casting SCGC.

Improvement in Long Term Bonding and Mechanical Performance by Using Glass Concrete in Combination with Xanthan Gum Exposed to Harsh Environment

Abstract Concrete is the mostly used construction material composed of a mixture of cement, water, aggregates (such as sand, gravel, or crushed stone), and often additional additives or admixtures. It is widely used in the construction industry for various applications due to its strength, durability, and versatility. Key characteristics of concrete include strength, durability, versatility, fire resistant, cost effective, weather resistant, insulation and decorative options. Concrete plays a vital role in the construction industry, providing the foundation for most buildings, infrastructure, and many other structures worldwide. Its composition and properties can be tailored to meet specific project requirements, making it an indispensable material in modern construction. Various fibers can be used to enhance the mechanical and bonding properties of concrete. Also waste fibers after recycling can be reduced the environmental burden. Keeping in this view, glass powder sodium silicate glass (SSG) is used as replacement of cement with different percentages 0%,4%,8%, and 12% in combination of xanthan gum 0.2% for all mixes. An experimental study is conducted to investigate the mechanical and durability properties of concrete by performing compression test, flexural test, alkali silica reactivity test, sulfate resistivity test and drying shrinkage test. For this, forty-eight concrete cylinders are prepared for compression test, forty-eight concrete prisms for flexural test and thirty-six mortar bars of four mixes are prepared for durability testing. Workability is checked of fresh concrete during the pouring of concrete cylinders. Poured cylinders’ samples are left for 7, 14, 21 and 28 days of curing. Different tests are performed on hardened concrete and mortar samples to evaluate the mechanical and durability properties. Results concluded that workability of four mixes lies between 60-80mm and compressive strength of concrete has been improved using glass powder (SSG). Optimum results have been achieved at 12% as compared to other mixes 4% and 8% of concrete samples. Fibrous material is used as a binding agent and fibrous concrete is suitable for humid environment where high strength and voids less concrete are required. Quantity of cement can be reduced by using different fibers as a replacement of cement. Research recommended that recycled glass powder can be used in concrete as construction material and 12% replacement is suitable for optimum results.

Reduction of the cement content in Selective Cement Activation

AbstractThis work systematically investigates possibilities for the reduction of the cement content in Particle bed 3D Printing by Selective Cement Activation. To do so, the amount of cement is decreased (i) by increasing the aggregate content or (ii) by substitution with quartz flour of similar particle size to the cement. Both variants were then produced with constant water content and constant w/c ratio of 0.5, i.e. decreasing water content with decreasing cement content. To characterize the effect of the cement reduction, the compressive strength, as well as the dimensional accuracy are analyzed.It is shown that at constant w/c‐ratio the compressive strength decreases with decreasing cement content compared to the reference mix, while the dimensional accuracy is increasing. For a constant water content during printing, the compressive strength of cement‐reduced specimens is similar or only slightly lower compared to the reference. The dimensional accuracy, however, is decreasing.

Temperature dependance of 3D printed concrete produced with copper tailings

Abstract3D printed concrete is being applied in an increasing amount worldwide. While in theory, there are environmental and economic benefits associated with using this technology, in practice, the amount of cement in printable concrete is much higher than in a conventional one, leading to increased environmental and economic costs. Furthermore, cement's performance relies heavily on climate variables, specifically temperature. One way to solve this issue is to include local alternative low‐CO2 materials, such as processed mine tailings, as cement replacement. This paper presents an experimental approach to assess the use of copper tailings as cement replacement in printable concrete under different ambient temperatures. Three levels of cement volume replacement have been researched. The copper tailings' rheological effect has been measured using standard printability tests and a rheometer. Four mixtures have been printed in a controlled‐climate chamber to evaluate print‐ability, buildability and extrudability. The mechanical effect has been assessed with compressive and flexural strength tests of samples collected from the printed specimens. The results show that copper tailings are a promising alternative to cement in printable concrete in countries where this by‐product is abundant.

Study on the optimisation of cement and binder content to develop a sustainable high-performance concrete

According to ACI concrete terminology, “High Performance concrete (HPC) is defined as a concrete meeting special combinations of performance and uniformity requirements that cannot always be achieved routinely using conventional constituents and normal mixing, placing, and curing practices”. It is a new generation of concrete that has been evolved recently and are well received for its exceptional performance of strength and durability. Due to these characteristics, HPC are utilized in the construction of bridges, hydropower structures, pavements, mass concrete projects etc. HPC is a cementitious composite material composed of an optimized gradation of granular constituents, a water-to-binder ratio of less than 0.3, a high percentage of discontinuous internal fiber reinforcement and HPC can hold compressive strength of more than 60 MPa. HPC considered in this study is made with high-strength steel fibers, fine sand, cement, mineral and chemical admixtures and water. The conventional mix design used for normal concrete cannot be adopted for HPC because of the high compressive strength to be achieved. The main objective is to develop a sustainable HPC mix with optimum particle packing density to achieve the desired strength with the lowest cement and binder content. As part of the investigation, the impact of different constituents of HPC such as cement content and binder content on the compressive strength were examined. Also, the optimum particle packing density of mixes with different amount of cement and binder content were studied using EMMA software. From the results it is observed that the increase in cement or binder content beyond a particular level will have minimal impact on the compressive strength.

The Effects of the Rice Husk Ash (RHA) and Cement on California Bearing Ratio in Laterite Soil Stabilization

Lateritic soil is a problematic type of soil because it must be stabilized in order to meet geotechnical criteria for engineering purposes. As a result, cement has been frequently utilized to increase soil strength in order to make it more stable. As a result, several ways for minimizing the amount of cement used, such as the utilization of waste materials or industrial by-products, such as Rice Husk Ash (RHA), have been developed. The purpose of this study was to investigate the properties of laterite, rice husk ash, and cement, as well as the effect of different percentages of RHA and cement on the California Bearing Ratio (CBR) of laterite soil. In current soil stabilization, different amounts of RHA and cement are used, specifically 5%, 10%, and 15%, to determine an appropriate combination that will function. Soil samples were tested using the CBR and preliminary tests such as the Liquid limit and Plastic limit to identify index characteristics and the proctor test to determine Maximum Dry Density and Optimum Moisture Content. Data analysis was carried out to assess how well the RHA/cement mixture performed in CBR. The soil sample with 2.5% RHA and 2.5% cement produced the highest result in California Bearing Ratio, 34.45 % at 2.5mm penetration and 28.48 % at 5.0mm penetration. Hence, the objective of this study was met when using RHA as a partial replacement for cement in laterite soil stabilization enhanced the value of the California Bearing Ratio.

Effect of Addition of Cement in Binary Blended Geopolymer Concrete

The construction industry contributes significant greenhouse gases to the climate by consuming vast amounts of cement. Researchers are looking at alternative cement methods to decrease the adverse effects, one of which is Geopolymer Concrete (GPC). The GPC is made from industrial waste materials high in silica and activated with sodium hydroxides (NaOH) to form sodium silicate (Na2SiO3) because Geo polymer is a material that is just two decades old and is an area of extensive research. To study the effect of the addition of cement to GPC’s mechanical properties by replacing up to 50% of the ground granulated blast furnace slag (GGBFS) and fly ash with ten per cent increments. The outcomes are contrasted with the Geo Polymer Concrete control mix. For this study, an analysis of activators to fly ash at 0.35, NaOH to Na2SiO3 at 2.5, and the molarity of sodium hydroxide was set at 8M. At different ages, the compressive strength of cubes was calculated, as well as their split and flexural strengths following a 28-day curing period. The findings revealed that adding cement to the mix improves the mechanical properties. The best results are obtained at 40% cement, fly ash, and GGBFS at 60%.

The Utilization of Silica Fume in Mortar Mixed with Rubber Crumb

This study looks closely at how rubber crumbs and additives might improve the mechanical properties of mortar concrete. It is focused to help the concrete industry transition this form of mortar concrete from a research laboratory level to a more useful usage. On the compressive strength, density, and water absorption of mortar concrete, the effects of various mixing techniques, mechanical which was before mostly on crumb rubber, and the use of fiber additions have been investigated. Mixing duration and order were two factors in the mixing technique. The replacement of fine aggregate with rubber crumb in the mortar was conducted from 0% (control sample), 5%, 10%, and 15% with fixed 5% of silica fume (replaced cement amount). A size of 50mm x 50mm x 50mm was used as a designing size cube sample in the current study. All blends should be subjected to a slump test before being used to determine the combination's level of durability. The water absorption and density value showed a good result giving benefits and advantages on increases of crumb rubber amount. However, compressive strength decreased when the amount of crumb rubber increased. In the application of roof tiles, lower density values provide an advantage for workability during installation.