High Amount Of Cement Research Articles

Effect of water to cement ratio on mechanical properties of FRC subjected to elevated temperatures: Experimental and soft computing approaches

The deterioration of concrete is greatly dependent on the cracks and microcracks development owing to loading or environmental influences. An effective step to avoid the spread of cracks and microcracks is employing of different fibers in concrete and the manufacture of fiber reinforced concrete. On the other hand, fire is one of the cases that always threatens engineering structures. Elevated temperatures cause obvious chemical and physical changes that lead to concrete deterioration. In this study, the effect of adding various fiber with different volume contents in concrete mixture with various cement content was evaluated experimentally. Results indicate that spalling was more dominant in mixture containing steel fiber and with higher amount of cement, while there is not any spalling in mixture containing polypropylene (PP) fibers. Moreover, the reduction in tensile strength of fiber-free concrete specimens is less pronounced in mixtures with higher cement content. In addition, the positive performance of PP fibers compared to steel fibers was proved at higher temperatures and cement contents. Furthermore, by conducting a comprehensive and accurate survey, this research pinpoints gaps in the current literature. Moreover, the gathered dataset serves as input for training a machine learning approach known as Group Method of Data Handling (GMDH). The GMDH network demonstrates a satisfactory accuracy in predicting experimental results, with a MSE of 0.0044.

Analysis of fly ash-treated SDCM pile behavior through laboratory model tests

Fly ash, an industrial byproduct, has resulted in significant environmental pollution and poses a threat to human health due to its low recovery and utilization rate. Stiffened deep cement mixing (SDCM) piles, leveraging both the high lateral friction resistance of cement mixing pile socket and the high strength of concrete core pile, are widely employed in practice of soft ground improvement. However, to avoid damage to cement mixing pile socket, a higher amount of cement is often required, leading to not only elevated project costs but also conflicting with low-carbon environmental objectives. In tackling this concern, the introduction of fly ash as a partial substitute for cement in cement mixing pile socket offers a solution. This study delves into the vertical bearing mechanism of fly ash-treated SDCM piles through laboratory model tests. Results reveal that as the curing duration extends, the hydration rates of fly ash decrease relative to cement, being demonstrated by larger settlements at the top of fly ash-treated SDCM pile compared to that of standard SDCM pile. It is also found that elevated levels of hydration in cement mixing pile socket results in a heightened stiffness and an enhanced pile end resistance.

The Development of Soil-Based 3D-Printable Mixtures: A Mix-Design Methodology and a Case Study

Concrete 3D printing is one of the newest technologies in the field of construction. However, despite the various opportunities that this technique offers today, it still has a high environmental impact, as most 3D-printable materials contain high amounts of cement. On the other hand, due to the large volumes of soil excavated each year across the world, there is a pressing need for proper management to dispose of it or reuse it efficiently. This study aims to develop sustainable and resistant 3D-printable materials with low environmental impact using excavated soil. Firstly, a series of tests were carried out to find the most appropriate superplasticizer and the amount required to develop the printable mixtures. Next, the extrudability and buildability were evaluated and verified to validate the printability of the developed mixtures. A 3D laboratory printer was also used to validate the printability of the mixtures on a larger scale. Then, the fresh and hardened properties of the printable mixtures were investigated. Three printable mixtures were developed, with the most environmentally friendly mixture having a soil content of 1602 kg/m3 and a cement content of 282 kg/m3. The mixtures demonstrated satisfactory characteristics and properties in both fresh and hardened states. On the one hand, the mixtures were extrudable and buildable at two laboratory scales. On the other hand, the mixtures presented sufficient compressive strengths, ranging from 16 MPa to 34 MPa, despite their high soil content and low cement content. In addition, their compressive strengths were found to be higher than the minimum strength required for structural concrete. Consequently, this study highlights the possibility of developing ecological, sustainable and resistant mixtures that can be used in 3D-printing construction applications using excavated soil.

On the use of fine dune sand in Reactive Powder Concrete: Effect on resistance, water absorption and UPV properties

In this paper is presented an experimental study investigating the impact of dune sand inclusion in engineered Reactive Powder Concretes (RPC). RPCs are built upon specifically proportioned materials such as very fine sand particles and high amounts of cement and mineral admixtures, while maintaining a very low water content through superplasticizer usage. Fibers, whether metallic or synthetic, are a key component of these concretes, as they procure higher mechanical strengths and ductility. The purpose of this experimental work is two-fold. Firstly, to find out the potential positive impact of using dune sand (DS) as a partial substitute for river (alluvial) sand in RPCs. Secondly, to quantify for various substitution rates, to what extent the mechanical, water absorption and ultrasonic pulse velocity (UPV) properties are altered. The results of the experiments point out the positive effect of river sand replacement by dune sand on the compressive strength of both the fiberless and fibered RPC mixtures, with improvement reaching up to +104.43% and +83.91% respectively when high DS proportions are used. The study also reveals the necessity of fibers usage, as the fibers seem to counteract the lesser flexural tensile strengths observed on high dune sand content concretes. Water absorption, porosity, and UPV test results showed improved values as DS proportions increase, revealing a densification of the cement matrix and hence, improved durability properties.

Mechanical properties of ultra-high performance concrete based on reactive powder concrete: Effect of sand-to-cement ratio, adding glass fiber and calcium carbonate

Reactive Powder Concrete (RPC) contains high amounts of cement. This high ratio increases causing issues such as a high hydration temperature and concrete shrinkage. The present investigation is an attempt to study the effect of Sand-Cement ratio, substitution of calcium carbonate with part of Silica sand and adding glass fiber, on the properties of RPC. The study also deals with the microstructure investigation and Thermo-Gravimetric Analysis of RPC. Results indicate that increasing the S/C ratio up to 1.2 can improved the properties of RPC by reducing the amount of cement used. On the other hand, substitution 40%-50% of the silica sand with calcium carbonate can improved the microstructure of RPC. Moreover, the tensile behavior of RPC must be improved using another material due to the limit on the largest grain size in it. Adding glass fibers equivalent to 8%-10% of the cement weight to the mix design of RPC (containing 40%-50% silica sand that was replaced with calcium carbonate) improves the mechanical and durability behavior of RPC.

High‐performance concrete with fine recycled concrete aggregate: Experimental assessment

AbstractHigh‐performance concrete (HPC) is a cement‐based material with excellent properties and durability which determines high‐level structural utilization. However, the necessity of high‐quality natural resources such as quartz powder and sand and a high amount of cement and silica fume and reinforcement by fibers causes a high environmental footprint and costs. One of the possible ways to reduce the environmental footprint and cost of the HPC/UHPC is to replace the powder or sand with secondary raw materials. In this study, the two types and three fractions of fine recycled concrete aggregate (fRCA) are used as supplementary materials in HPC. The reference mixture is based on the UHPC mixture without reinforcement to find out the influence of aggregate replacement. The properties of fresh and hardened concrete are examined. The results show a slight decline of mechanical properties however the autogenous shrinkage decrease with the replacement of natural aggregate by fRCA, which shows the possibilities of natural resources savings and thus leads to a lower environmental footprint of concrete structures as a contribution to the solution of sustainable development goals set by the United Nations in 2015 as an action plan up to 2030.

The First 3D-Printed Building in Spain: A Study on Its Acoustic, Thermal and Environmental Performance

The first 3D-printed building in Spain is the object of this study, and it is presented and physically described herein from different points of view. This study combines on-site measurements, simulations, and a life cycle assessment to assess some relevant parameters concerning the acoustic, thermal and environmental performance of the 3D-printed house. The main objectives are to analyze whether the house complies with the acoustic and thermal regulations and to assess whether it can act as a sustainable alternative to conventional masonry construction, especially when time plays an important role. The build surface (3D prototype) of the house is approximately 23 m2. The internal space includes a living room (12.35 m2), a bedroom (7.36 m2) and a bathroom (3.16 m2). The total surface of the house is 22.87 m2 and it has a volume of 64.03 m3. The acoustic insulation was measured according to the ISO 9869-1:2014 standard. In terms of the acoustic insulation, the sound reduction index was tested following the guidelines of the ISO 140-5:1999 standard. Additionally, the study includes a comparative life cycle assessment comparing the 3D-printed façade with two conventional wall typologies. The 3D-printed house displays an excellent thermal performance, with a measured thermal transmittance of 0.24 Wm−2K−1, suitable for all Spanish climate zones. Regarding the acoustic insulation, the measured global sound reduction indexes of the façades range from 36 to 45 dB, which is adequate for areas with noise levels of up to 75 dB. The environmental results indicate that 3D-printed façade manufacturing emits 30% more CO2e than a façade constructed using concrete blocks and 2% less than a masonry block wall. Overall, this study shows that, in addition to its multiple advantages in terms of the construction time, the studied 3D-printed house has similar acoustic, thermal and environmental traits to the most common construction typologies. However, it cannot be considered a sustainable construction method due to its high amount of cement.

Multi-Objective Optimization of Sustainable Concrete Containing Fly Ash Based on Environmental and Mechanical Considerations

Infrastructure design, construction and development experts are making frantic efforts to overcome the overbearing effects of greenhouse gas emissions resulting from the continued dependence on the utilization of conventional cement as a construction material on our planet. The amount of CO2 emitted during cement production, transportation to construction sites, and handling during construction activities to produce concrete is alarming. The present research work is focused on proposing intelligent models for fly ash (FA)-based concrete comprising cement, fine and coarse aggregates (FAg and CAg), FA, and water as mix constituents based on environmental impact (P) considerations in an attempt to foster healthier and greener concrete production and aid the environment. FA as a construction material is discharged as a waste material from power plants in large amounts across the world. Its utilization as a supplementary cement ensures a sustainable waste management mechanism and is beneficial for the environment too; hence, this research work is a multi-objective exercise. Intelligent models are proposed for multiple concrete mixes utilizing FA as a replacement for cement to predict 28-day concrete compressive strength and life cycle assessment (LCA) for cement with FA. The data collected show that the concrete mixes with a higher amount of FA had a lesser impact on the environment, while the environmental impact was higher for those mixes with a higher amount of cement. The models which utilized the learning abilities of ANN (-BP, -GRG, and -GA), GP and EPR showed great speed and robustness with R2 performance indices (SSE) of 0.986 (5.1), 0.983 (5.8), 0.974 (7.0), 0.78 (19.1), and 0.957 (10.1) for Fc, respectively, and 0.994 (2.2), 0.999 (0.8), 0.999 (1.0), 0.999 (0.8), and 1.00 (0.4) for P, respectively. Overall, this shows that ANN-BP outclassed the rest in performance in predicting Fc, while EPR outclassed the others in predicting P. Relative importance analyses conducted on the constituent materials showed that FA had relatively good importance in the concrete mixes. However, closed-form model equations are proposed to optimize the amount of FA and cement that will provide the needed strength levels without jeopardizing the health of the environment.

Production of Ultra-High-Performance Concrete with Low Energy Consumption and Carbon Footprint Using Supplementary Cementitious Materials Instead of Silica Fume: A Review

The increase in cement production as a result of growing demand in the construction sector means an increase in energy consumption and CO2 emissions. These emissions are estimated at 7% of the global production of CO2. Ultra-high-performance concrete (UHPC) has excellent mechanical and durability characteristics. Nevertheless, it is costly and affects the environment due to its high amount of cement, which may reach 800–1000 kg/m3. In order to reduce the cement content, silica fume (SF) was utilized as a partial alternative to cement in the production of UHPC. Nevertheless, SF is very expensive. Therefore, the researchers investigated the use of supplementary cementitious materials cheaper than SF. Very limited review investigates addressed the impact of such materials on different properties of UHPC in comparison to that of SF. Thus, this study aims to summarize the effectiveness of using some common supplementary cementitious materials, including fly ashes (FA), ground granulated blast furnace slag (GGBS), metakaolin (MK) and rice husk ashes (RHA) in the manufacturing of UHPC, and comparing the performance of each material with that of SF. The comparison among these substances was also discussed. It has been found that RHA is considered a successful alternative to SF to produce UHPC with similar or even higher properties than SF. Moreover, FA, GGBS and MK can be utilized in combination with SF (as a partial substitute of SF) as a result of having less pozzolanic activity than SF.

The Influence of Water/Binder Ratio on the Mechanical Properties of Lime-Based Mortars with White Portland Cement

Protecting the built cultural heritage is one of the most important tasks in architectural practice. The process of repair is time-consuming, weather-dependent, and sensitive to materials applied. Introducing new materials in historic building repair in order to decrease the time needed for repair, brings some risk in the preservation process. The most common material for masonry repair is lime mortar. Adding cement to lime mortar can improve the mechanical properties of mortar and speed up the repair process. The high amount of cement may increase the strength, but decrease ductility and permeability of mortar, causing damages to protected buildings. An increase in strength with the smallest amounts of cement demands optimization of water content in the mixture. Tests were performed to investigate the influence of the water/binder (w/b = water/(lime + cement) ratio on mortar strength and water permeability. An air-entraining agent (AEG) was introduced to improve permeability. Results confirmed that adding small amounts of cement to lime (20% by weight) and decreasing of w/b ratio, improves the strength, with almost negligible influence on water permeability. The addition of very small amounts of AEG did not decrease the strength, nor the permeability.

Strength and chloride ion penetration resistance of ultra-high-performance fiber reinforced geopolymer concrete

Using high amount of cement is one of the disadvantages of ultra-high-performance concrete (UHPC). To reduce this, it is tried to replace cement with certain alternative materials with industrial waste materials and disposal. In this research, Ultra-high-performance geopolymer concrete (UHPGC) based on ground granulated blast furnace slag (GGBFS) and silica fume containing steel fiber (SF) and polypropylene fiber (PPF) was investigated experimentally. For this purpose, series 1 of mix proportion has been used to determine the reference design with the highest compressive strength. In series 2, nine mixtures were used to investigate the effect of fibers on mechanical properties of the UHPGC including compressive strength, splitting tensile strength, flexural strength and also modulus of elasticity. Moreover, the chloride ion penetration resistance was evaluated through some specific tests such as electrical resistivity (ER), rapid chloride migration test (RCMT) and rapid chloride penetration test (RCPT). The results show that addition of PPF to the samples containing SF improves the mechanical and durability properties. Moreover, the results indicate that replacing the percentage of SF with PPF leads to reduction in the mechanical strength, although it causes the durability to be increased.

Influence of nano material (TiO2) on self compacting Geo polymer concrete containing Flyash, GGBS and wollastonite

In the modern age, concrete has become major component in construction field which results in global warming as it contains high amounts of cement. To reduce the carbon footprint and help environment, In our research, cement is elemenated and this type of concrete is called “Geo-polymer concrete”. Binders like Fly-ash, Wollastonite and Ground Granulated Blast Furnace Slag (GGBS) are used and Alkali activators like sodium hydroxide and sodium silicate are used to improve the binding properties of the concrete. Titanium oxide is used to develop self-compacting Geo-polymer concrete (SCGPC). At ambient curing conditions, Fresh and hardened properties are tested at 7, 14 and 28 days. SCGPC mixes are developed by adding Titanium oxide to mixes with and without wollastonite at 2%, 4%, 6%. To obtain the optimum results we need to perform some Fresh and as well as the Hardened properties. The fresh properties tests include slump flow. Hardened properties of the concrete include the Compressive strength and Split Tensile. The optimum test results were obtained at 4% TiO2 with and without wollastonite. There is 18–20% increase in the strength by incorporation of wollastonite.

Temperature development and cracking characteristics of high strength concrete slab at early age

High-strength concrete (HSC) generally is made with high amount of cement which may release large amount of hydration heat at early age. The hydration heat will increase the internal temperature of slab and may cause potential cracking. In this study, slab specimens with a dimension of 600 ✕ 600 ✕ 100 mm were cast with concrete incorporating silica fume for test. The thermistors were embedded in the slabs therein to investigate the interior temperature development. The test variables include water-to-binder ratio (0.25, 0.35, 0.40), the cement replacement ratio of silica fume (RSF; 5 %, 10 %, 15 %) and fly ash (RFA; 10 %, 20 %, 30 %). Test results show that reducing the W/B ratio of HSC will enhance the temperature of first heat peak by hydration. The increase of W/B decrease the appearance time of second heat peak, but increase the corresponding maximum temperature. Increase the RSF or decrease the RFA may decrease the appearance time of second heat peak and increase the maximum central temperature of slab. HSC slab with the range of W/B ratio of 0.25 to 0.40 may occur cracking within 4 hours after casting. Reducing W/B may lead to intensive cracking damage, such as more crack number, and larger crack width and length.

Does a High Amount of Unhydrated Portland Cement Ensure an Effective Autogenous Self-Healing of Mortar?

It is commonly accepted that the autogenous self-healing of concrete is mainly controlled by the hydration of Portland cement and its extent depends on the availability of anhydrous particles. High-performance (HPCs) and ultra-high performance concretes (UHPCs) incorporating very high amounts of cement and having a low water-to-cement ratio reach the hydration degree of only 70–50%. Consequently, the presence of a large amount of unhydrated cement should result in excellent autogenous self-healing. The main aim of this study was to examine whether this commonly accepted hypothesis was correct. The study included tests performed on UHPC and mortars with a low water-to-cement ratio and high cement content. Additionally, aging effects were verified on 12-month-old UHPC samples. Analysis was conducted on the crack surfaces and inside of the cracks. The results strongly indicated that the formation of a dense microstructure and rapidly hydrating, freshly exposed anhydrous cement particles could significantly limit or even hinder the self-healing process. The availability of anhydrous cement appeared not to guarantee development of a highly effective healing process.

Characteristics Comparison on Mechanical Properties of Mortars using Agriculture Waste as a Cement Replacement Materials

Excessive use of cement makes the price of construction projects expensive. Mortar making using high amounts of cement also has the potential to increase the price of the construction. This study discusses the use of agricultural waste as a substitute for cement in mortar production. The waste used in this study was bagasse ash, fuel ash palm oil, and rice husk ash. Each waste is added as much as 25%, 50% and 75% which are then tested for mechanical properties such as water content, unit weight, absorption, and IRS. Compressive strength was tested when the mortar was 28 days old with a cube-shaped specimen with a size of 50 mm x 50 mm x 50 mm. From the test results, it was found that all of this waste can be used as a substitute for cement. To produce a compressive strength of 100 kg/cm2 can add each waste with a percentage range of 10-12% of the weight of cement.

DEFINITION OF CONCRETE AND COMPOSITE PRECAST CONCRETE PAVEMENTS TEXTURE

In the context of increasing traffic demands and emerging mobility trends road infrastructure has to shift towards the fifth generation of roads, which according to Forever Open Road (FOR) vision are envisioned as adaptable to traffic volumes, resilient to changing weather conditions, quickly built, effectively maintained, suitable for retrofitting, self-monitoring, self-repairing and recyclable. Concrete modular pavements can be defined as an example of such type of road infrastructure. Functional needs are mainly associated with implementation area/location, traffic and mobility demands, environmental constraints and etc. This also has a significant impact on the selection of Precast Concrete Pavements (PCP) texture formation method and materials. Concrete pavement surface texture affects both safety and tyre/road noise characteristics. Exposed Aggregate Concrete (EAC) and porous concrete are the most suitable noise reducing solutions for highways and streets wearing layer even in severe traffic and climate conditions. According to the literature analysis, the algorithm of highways and streets low noise concrete design was created. It is recommended to use the highest quality aggregates with maximum size up to 8 mm, gap-graded gradation, higher amount of cement and lower water/cement ratio. The most important characteristics of EAC are Mean Profile Depth (MPD), Mean Texture Depth (MTD) and profile count, while the most important characteristics of porous concrete are compressive strength, outflow and air void content.

Polish experience with cold in-place recycling

Deep cold in-place recycling using cement and asphalt emulsion has been used for reconstruction of existing roads since the beginning of the 1990s. This paper describes the first Polish requirements for mineral-cement-emulsion mixtures. As requirements stated for the strength of the mineral-cement-emulsion mixtures were quite high, most of the mixtures were designed using high amount of cement and aggregate added for the improvement of gradation. The paper also presents selected results of the visual assessment of existing pavements with bases made of mineral-cement-emulsion mixtures. The mixtures used in bases were designed according to the first Polish requirements. On all of the sections numerous reflective transverse cracks were observed. Most of them resulted from very high requirements stated for the strength. Last part of the paper describes the changes which were introduced to the Polish requirements on the basis of conducted field investigations and other past experiences of using mineral-cement-emulsion mixtures in Polish climatic conditions. Newly developed instruction liberalized the requirements stated for base materials and significantly reduced the amount of cement.

Evaluation of hydration of cement pastes containing high volume of mineral additions

The use of mineral additions is a common practice in the production of cementitious materials. Recently proposed usage of high amounts of cement replaced by mineral additions requires the study of the chemical interaction of these additions with the cement. This study intends to evaluate, by means of TG/DTG techniques, XRD and compressive strength, the effect of high volume of mineral additions in the hydration of cementitious pastes. Pastes with 50–70% of cement replaced by mineral addition and with different combinations of fly ash and metakaolin were evaluated, two pastes without mineral addition and two other pastes with lime addition. Results showed TG/DTG and XRD techniques are more suitable for evaluating kinetics of reactions of hydration, making it possible to quantify the substantial reduction in the levels of portlandite in hydrated pastes containing high volumes of mineral additions. These techniques allowed to find important differences in the evaluation of calcium hydroxide, because its morphology can change in the presence of additions. Also showed that it is possible to achieve, enhanced or even high compressive strength (50–80 MPa) in concretes containing reduced cement contents. As well as more resistance against harmful agents and carbonation attack.

Use of alternative waste materials in producing ultra-high performance concrete

In a corrosive environment similar to that of the Arabian Gulf, use of high-performance concrete is one of the options to ensure a target service life of concrete structures. However, in absence of good quality coarse aggregates, it is a challenging task to produce high-performance concrete. Recently, the possibility of producing ultra-high-performance concrete (UHPC) has been widely reported in the literature. UHPC is produced without coarse aggregates at very low water to cementitious materials ratio, high amounts of cement, mineral admixtures, and superplasticizer along with fine quartz sand as aggregate, quartz powder as micro-filler, a nd steel fibres for fracture toughness. In the present work, an effort was made to utilize local waste materials as alternative mineral admixtures and local dune sand as aggregate in producing different UHPC mixtures without addition of quartz powder. The mechanical properties, shrinkage, and durability characteristics of the UHPC mixtures were studied. Test results indicate that it is possible to produce UHPC mixtures using alternative waste materials, which would have targeted flow, strength, toughness, and resistance against reinforcement corrosion. The information presented in the paper would help in optimum selection of a mixture of UHPC considering the availability of local materials, exposure conditions and structural requirements.

Experimental Investigation and Prediction of Compressive Strength of Ultra-High Performance Concrete Containing Supplementary Cementitious Materials

Ultra-high performance concrete (UHPC) has superior mechanical properties and durability to normal strength concrete. However, the high amount of cement, high environmental impact, and initial cost are regarded as disadvantages, restricting its wider application. Incorporation of supplementary cementitious materials (SCMs) in UHPC is an effective way to reduce the amount of cement needed while contributing to the sustainability and cost. This paper investigates the mechanical properties and microstructure of UHPC containing fly ash (FA) and silica fume (SF) with the aim of contributing to this issue. The results indicate that, on the basis of 30% FA replacement, the incorporation of 10% and 20% SF showed equivalent or higher mechanical properties compared to the reference samples. The microstructure and pore volume of the UHPCs were also examined. Furthermore, to minimise the experimental workload of future studies, a prediction model is developed to predict the compressive strength of the UHPC using artificial neural networks (ANNs). The results indicate that the developed ANN model has high accuracy and can be used for the prediction of the compressive strength of UHPC with these SCMs.