Type Of Cementitious Composites Research Articles

Prediction of Hydration Heat for Diverse Cementitious Composites through a Machine Learning-Based Approach.

Hydration plays a crucial role in cement composites, but the traditional methods for measuring hydration heat face several limitations. In this study, we propose a machine learning-based approach to predict hydration heat at specific time points for three types of cement composites: ordinary Portland cement pastes, fly ash cement pastes, and fly ash-metakaolin cement composites. By adjusting the model architecture and analyzing the datasets, we demonstrate that the optimized artificial neural network model not only performs well during the learning process but also accurately predicts hydration heat for various cement composites from an extra dataset. This approach offers a more efficient way to measure hydration heat for cement composites, reducing the need for labor- and time-intensive sample preparation and testing. Furthermore, it opens up possibilities for applying similar machine learning approaches to predict other properties of cement composites, contributing to efficient cement research and production.

Mechanical Properties of Hybrid Structures Incorporating Nano-Silica and Basalt Fiber Pellets

Recently, developing a nonferrous reinforcement system (corrosion-free system) using durable and ductile cement-based materials that incorporate discrete fibers has been a promising option for exposed concrete structures in cold regions or marine environments. Therefore, in this study, properties of a novel type of cementitious composite comprising nano-silica and a high dosage of slag were investigated. The hybrid (layered) composites assessed in this study were composed of two layers of different types of cementitious composites. Normal concrete (NC) was used in the top layer combined with a layer of fiber-reinforced cementitious composite (FRCC) reinforced with either the recently developed basalt fiber (BF) pellets (basalt fiber strands encapsulated by a polymeric resin or steel fibers (SF)) that were used at different dosages. The post-cracking behavior in terms of residual strength, residual index, and toughness are presented and discussed. The analysis of results showed the effectiveness of the BF pellets in enhancing the post-cracking behavior of specimens, as they behaved comparably to counterpart specimens comprising SF, which makes them a good candidate for infrastructural applications including rehabilitation such as new bridge girders or overlays.

Study on the properties of cement composites for immobilization of evaporator concentrates

The disposal of evaporator concentrates (EC) as an intermediate-level radioactive waste requires reliable immobilization in a solid matrix, such as cement. Six types of cement composites were studied in terms of drying and saturation cycling, water absorption, mechanical properties and leaching to assess their suitability to EC immobilization. Composites differed in the binder composition – five of them were based on a mixture of non-gypsum cement with Ordinary Portland cement (NP)/metakaolin (NM) and admixtures of natural zeolite and metakaolin (NP_M, NP_Z, NM_Z). Sulpho-aluminate cement (SAC) was chosen for comparison. SAC composite exhibited superior parameters of compressive strength and water absorption in the reference state, however after cycling severe cracks and disintegration appeared causing this matrix inappropriate for EC immobilization. NM-based mixtures showed highest Cs+ retention capacity, however less resistance to cycling and lower mechanical parameters than NP based composites. In terms of leachability, all mixtures met the requirements according to ANSI/ANS-16.1-2003.

Piezoresistivity performance of cementitious composites containing activated carbon powder, nano zinc oxide and carbon fibre

Intrinsic self-sensing cement-based structures or sensors have a great potential for structural health monitoring applications, which can be achieved by incorporating conductive functional fillers into the cementitious composites. This study examined the mechanical, electrical and piezoresistivity of two types of cementitious composites, one with mono activated carbon powder (ACP)/nano zinc oxide (ZnO) and other carrying a hybrid of both carbon fibre (CF) and ACP/nano ZnO. The performance of mono fillers were investigated by fabricating the cementitious composites with different content of ACP (0.5%, 1%, 2% and 4% by weight of binder) and nano ZnO (0.05%, 0.1%, 0.3% and 0.5% by weight of binder). Moreover, the hybrid effect was studied by incorporating CF at 0.7 wt% with the additional ACP/nano ZnO at various concentration. The result showed that ACP/nano ZnO could improve the mechanical properties of cementitious composites. In terms of piezoresistivity behaviour, composites containing 2 wt% of ACP have favourable performance parameters with a sensitivity of 3.571%/MPa and linearity of 7.849%. Composites containing 4 wt% of ACP can achieve repeatability at 0.952%, which indicate a good reproducibility of the piezoresistivity. Although the developed cementitious composites cannot achieve a sensitivity as high as carbon fibre reinforced cementitious composites (CFRCCs), the linearity of the piezoresistive response of the composites containing hybrid ACP/CF and nano ZnO/CF has improved compared to CFRCCs.

An integrated design method for functional cementitious composites (FCC)

The disease of the operating tunnel lining has seriously threatened traffic safety and needs to be cured urgently. Engineered Cementitious Composite (ECC), due to its excellent deformation ability and high damage tolerance, has the potential to retrofit the linings, but the quite high cost of raw material, mainly involving PVA fiber, has limited the broader application of ECC in the civil infrastructure. This paper proposed a practical design method of integrating four parts: engineering requirements, economical cost, matrix design and environmental assessment. A novel type of cementitious composites with low water absorption, moderate flexibility and light-weigh, named functional cementitious composite (FCC), was exploited to handle the common diseases of tunnel lining economically and environmentally. The results indicated that the cost-effective fiber is available to prepare the FCC, which shows great performance of cost-saving and functional properties. Besides, the functional characteristics, including low water sorptivity, light density and moderate flexibility, were optimized by response surface methodology (RSM) and subsequently the optimized results were proven by the test results. Finally, the environmental assessment emphasized an excellent material greenness of FCC with reduction of 26.9% embodied energy consumption and 26.2% carbon equivalent emission compared to the ECC (M45).

Influence of the Poisson’s Ratio on the Value of the Dynamic Modulus of Elasticity of Cement Materials in the Early Stage of Ageing

The paper deals with the influence of the Poisson’s ratio on the calculated modulus of elasticity of a cementitious composite in the early stage of its ageing. The dynamic modulus of elasticity was determined in the first 24 hours of ageing of the material using the Vikasonic ultrasonic device. Within the experiment, two types of cementitious composites were mixed - cement paste and cement mortar, both having the same water/cement ratio. It is presumed that the value of the dynamic modulus of elasticity calculated on the basis of ultrasonic measurement is closely related to the value of the Poisson’s ratio, which is not constant during ageing of the cementitious composite but varies depending on the degree of hydration of the material. The output of the paper is a comparison of the development of the dynamic modulus of elasticity calculated using different values of the Poisson’s ratio.

Stiffness and Energy Dissipation of Steel Coupling Beam Embedded in the PSH2C and Normal Concrete Shear Wall

Hybrid coupled shear wall with steel coupling beams has often been used as load-resisting system of high-rise buildings under lateral loads. However, joint between steel beam and shear wall is under combined and high stress. Reinforcement details of the joint are very heavy. This study addresses the effect of shear wall cement composites type in hybrid wall system on the seismic performance of steel coupling beams embedded in shear wall. The main test variables were the failure mode of steel coupling beam and types of cement composites, such as PSH2C and concrete, for shear wall.

기존 학교건물 골조와 내진보강요소 일체화를 위한 변형경화형 시멘트 복합체를 적용한 스터드 전단 접합부의 구조성능

Some results of experimental investigation conducted to assess the effect of cement composite strength and ductility on the shear behavior and crack-damage mitigation of stud connections between existing reinforced concrete frame in school buildings and seismic strengthening elements from cyclically direct shear tests are described. The cement composite strengths include 50 for medium strength and 70 MPa for high strength. Two types of cement composites, strain-hardening cement composite (SHCC) and non-shrinkage mortar, are used for stud shear connection specimens. The special SHCCs are reinforced with hybrid 0.2% polyethylene (PE) and 1.3% polyvinyl alcohol (PVA) fibers at the volume fraction and exhibits tensile strain capacity ranging from 0.2 to 0.5%. Test result indicates that SHCC improves the seismic performance and crack-damage mitigation of stud shear connections compared with stud connections with non-shrinkage mortar. However, the performance enhancement in SHCC stud connections with transverse and longitudinal reinforcements is less notable for those without additional reinforcement.

Relationship Between Mesostructure, Mechanical Behaviour and Damage of Cement Composites Under High-Pressure Confinement

This work seeks to determine how the mesostructure of seven types of cement composites containing alumina particles or not controls their deviatoric strength, compaction law, and damage under high-pressure of confinement. First, the method of analysis of quasi-oedometric compression tests is presented. Accuracy of the method for concrete is discussed by means of numerical simulations. The confined compression tests performed show the effects of adding ceramic aggregates. Furthermore, an application of post-mortem analysis by infiltration technique of each specimen is presented, revealing a highly micro-cracked pattern depending of the mesostructure of these materials. From these observations, a discussion is presented on the influence that the addition of ceramic aggregates exerts on the confined behaviour of these composites. The tests showed a highly beneficial effect of the presence of particles, on both the deviatoric strength and the compaction law of the concretes considered.

Tensile stress-strain behaviour of cementitious composites at high loading rates

The influence of loading rate on the tensile stress-strain behaviour of cementitious composites was studied experimentally. The project was undertaken to obtain an insight into the possible relation between internal structure parameters of composites and their loading-rate sensitivity. Five different types of cementitious composites were applied. Composite structure data were obtained by testing porosity and by quantitative observation of fracture surfaces. Direct tensile tests were performed at four different loading rates within the range 0.001–1000 MPa s−1. The tensile stress-strain behaviour was significantly influenced by the loading rate and structure parameters of composites. The relative tensile strength increase due to an increase of loading rate was found to be higher for composites with higher total porosity. Recorded stress-strain diagrams obtained at various loading rates are presented and discussed with the aid of continuous damage mechanics.

Polypropylene-reinforced cement composites for surface reinforcement of concrete structures

Possible uses of fibre reinforced cement as local surface reinforcement to improve the serviceability of concrete structures are reviewed. New types of cement composites, based on polypropylene film, show considerable promise as alternatives to asbestos cement of grc for this purpose. Tensile and flexural tests indicate that these new composites have the high strain capacity required for controlling crack development in the concrete and that the long-term effectiveness is likely to be better than that of currently available grc. The tests described covered a range of curing and exposure conditions, including prolonged immersion in hot water and exposure to ultra-violet radiation. In general no significant changes in strength or strain capacity resulted from any of the accelerated ‘durability’ tests. The use of such materials for permanent formwork on concrete structures such as bridge decks could show substantial economic benefits when related to overall construction and maintenance costs.