Cement Concrete Composites

To overcome the inherent limitations of gypsum-based self-leveling mortars (GSMs) in floor heating applications, specifically high porosity and inadequate thermal regulation capacity, highperformance GSMs were developed by incorporating two innovative inorganic-shell microencapsulated phase change materials (MPCMs): octadecane@SiO 2 and sodium acetate trihydrateurea@SiO 2. The systematic investigation elucidates the correlation between MPCM content and thermo-mechanical properties in GSMs. Experimental results reveal that increasing MPCMs content significantly reduces the flowability of GSMs (decreases of 22.8 % for octadecane@SiO 2-GSMs and 15.9 % for sodium acetate trihydrate-urea@SiO 2-GSMs), while the setting time exhibits a non-linear trend: decreasing initially and then increasing. Appropriate MPCMs incorporation enhances mechanical properties via a physical filling effect: GSM with 1.5 wt% octadecane@SiO 2 and GSM with 2.0 wt% sodium acetate trihydrate-urea@SiO 2 specimens achieved flexural/ compressive strength increases of 37.1 %/17.6 % and 54.1 %/30.1 %, respectively. Microstructural characterization verified that MPCMs form stable interfaces with the matrix through van der Waals forces. However, excessive content (octadecane@SiO 2-GSMs >2.0 wt%, sodium acetate trihydrate-urea@SiO 2-GSMs >3.0 wt%) induces agglomeration defects, leading to performance degradation. Thermal analysis demonstrates that sodium acetate trihydrate-urea@SiO 2-GSMs, benefiting from the higher phase change enthalpy of sodium acetate trihydrate-urea@SiO 2 (286.80 J/g), exhibit optimal temperature regulation balance at 2.0 wt% content, showing a surface temperature difference reduction of 6.5 • C during heating and an increase of 4.4 • C during cooling compared to the control group. This study reveals how MPCMs dispersion, pore structure, and interfacial bonding work together, providing a theoretical basis for developing novel energyefficient building materials with high thermal storage efficiency and structural stability.

The construction industry is a major contributor to global environmental impacts, particularly through the production and use of cement-based materials. In response to this challenge, this study provides a comprehensive synthesis of recent advances in the integration of Life-Cycle Assessment (LCA) and Artificial Neural Networks (ANNs) for optimizing cementitious composites containing Supplementary Cementitious Materials (SCMs). A total of 14 case studies specifically addressing this topic were identified, reviewed, and analyzed, spanning various binder compositions, ANN architectures, and LCA frameworks. The findings highlight how hybrid ANN-LCA systems can accurately predict mechanical performance while minimizing environmental burdens, supporting the formulation of low-carbon, high-performance cementitious composites. The diverse SCMs explored, including fly ash, slag, silica fume, waste glass powder, and rice husk ash, demonstrate significant potential for reducing CO 2 emissions, energy consumption, and raw material depletion. Furthermore, the systematic comparative matrix developed in this work offers a valuable reference for researchers and practitioners aiming to implement intelligent, eco-efficient mix designs. Overall, this study contributes to advancing digital sustainability tools and reinforces the viability of ANN-LCA integration as a scalable decision-support framework for green construction practices.

Aerated autoclaved concrete is used as one of basic materials of partition constructions. Its characteristics contribute for energy consumption decrease of construction work. Bulk density and humidity of aerated autoclaved concrete (AA concrete) are significantly influencing its thermal conductivity and other thermo-technical characteristics. This article shows the results of measurements of thermal conductivity of AA concrete (based on fly ash) at different bulk density and variable humidity of the material. The ISOMET 2104 (www.appliedp.com) a portable measuring device was used in this experiment. Acquired results demonstrate functional relationships between thermal conductivity of AA concrete, bulk density and humidity. The reliability and accuracy of the method of measuring and the measuring device was also vindicated.

The strength development of slag cement has a great consideration for the scheduling of formwork removal, prestressing operations, and other practical aspects of slag cement usage. The prediction of slag concrete strength, using the Feret's model has been studied by introducing the concept of the equivalent binder. This has led to define an efficiency coefficient of slag which distinguishes the latter with the regard to the cement. Thus, this obtained coefficient characterizes well the slag and lets to predict the slag concrete strength from strength values of a normal concrete made without slag for a given age and replacement rate. At 90 days age, the test results show that for 15% replacement rate, the slag is activated completely and gives 67% of efficiency more than the cement. For higher replacement rate, the efficiency of the slag decreases and becomes similar to that of cement for 50% replacement rate.

Geological materials are a potential source of pollutants, among which there is the radioactive isotope 222 Rn, which result of radioactive decay of daughter radionuclides of uranium ( 238 U). It is emitted as a gas that it can be released to the air to enter the human body, with the potential to affect internal organs (mostly the lungs) by alpha particles production. While the presence of uranium in the materials is a necessary condition for the production of Rn-222, the amount of gas emitted by the material depends on other characteristics that allow the migration of the gas. The main aim of this communication concerns a statistical analysis of results from diverse types of rocks.

This study introduces a biomaterial-assisted self-healing strategy for lightweight concrete using porous aggregates as micro-reservoirs. By embedding healing agents such as bacterial spores within the aggregate pores, the system enables autonomous crack repair triggered by moisture. The framework balances structural performance with healing efficiency, showing promising results in crack closure, strength recovery, and durability enhancement. This approach offers a scalable solution for sustainable infrastructure, especially in precast and 3D-printed applications.

This paper investigates the development of biopozzolanic inks for extrusion-based 3D concrete printing (3DCP) using fly ash (FA) and rice husk ash (RHA) as supplementary cementitious materials (SCMs). We synthesize current knowledge on rheological windows for pumpability, extrudability, buildability, and interlayer adhesion; situate FA-RHA systems within evolving standards and codes; and propose a design-of-experiments (DoE) for FA-RHA blends covering 10-50% binder replacement. Literature indicates that optimized SCMs can reduce cement content while maintaining printable rheology and structural performance, lowering cradle-to-gate CO2 intensity by displacing clinker. Acceptance criteria are aligned with printable rheol

The usage of Supplementary Cementitious Materials (SCM) is very much acknowledged due to the several improvements possible in the concrete composites, and because of the general economy. Research work till date suggests that utilization of SCMs enhance a significant number of the performance characteristics of the hardened concrete. The idea of efficiency can be utilized for comparing the relative performance of different pozzolans when incorporated into concrete. The efficiency concept, which was initially developed for fly ash, can be effortlessly connected to other advantageous s as well, such as silica fume, slag and natural pozzolans. A quantitative understanding of the efficiency of SCMs as a mineral admixture in concrete is essential for its effective utilization. The paper reviews the literature pertaining to the different efficiency concepts and models present to date that evaluates the strength of concretes containing different SCMs. This short survey demonstrates that there is a need for a superior comprehension of the SCMs in concrete for its powerful usage. Also, it is an effort directed towards a specific understanding of the efficiency of SCMs in concrete.

The compressive strength of cement is regarded as a principal indicator to determine the quality of cement.  Therefore, efforts were focused to combine the factors which affect compressive strength together in such a form to develop suitable statistical models for predicting strength of cement at various ages (3 and 7 days). Using SPSS16 software, a statistical analysis is performed for (574) observations taken from archive of quality control at Kerbala Cement Plant, which produces low alkalis sulphate resisting Portland cement. These data sets include compressive strength at 3 and 7 days with various independent variables. Stepwise regression results in multiple linear models that explain (99.7 %) and (99.9 %) of variations in 3-days and 7-days compressive strength respectively in function of; C 3 S, C 2 S, C 3 A, SO 3 contents, and Insoluble residue (IR). The developed models show that these contents positive effect on strength, but (I.R) content has a negative one. Such models co...

This letter describes a new organic (1-bromoadamantane) ultrathin film as gate dielectric, which was successfully deposited by sol-gel spin-coating process on a flexible polyimide substrate at room temperature. The metal-insulator-metal (MIM) device with organic (1-bromoadamantane) ultrathin (10 nm) film as gate dielectric layer operated at gate voltage of 5.0 V, showing a low leakage current density (5.63 9 10 -10 A cm -2 at 5 V) and good capacitance (2.01 fF lm -2 at 1 MHz). The chemical structure of the 1-bromoadamantane layer was investigated by Fourier transform infrared spectrometer. The excellent leakage current density and better capacitance, probably due to the presence of polar, non-polar, low-polar groups, and bromine atoms in ultrathin film. Practical properties of the film in MIM capacitor such as dielectric constant as well as bending result of leakage current density and breakdown voltage have been better related to such fundamental adhesion nature over flexible substrate. This permits estimation of the properties of new dielectric in thin film form and short lists of the best materials for low loss and good capacitance flexible capacitors could be drawn up in future.

This letter describes a new organic (1-bromoadamantane) ultrathin film as gate dielectric, which was successfully deposited by sol-gel spin-coating process on a flexible polyimide substrate at room temperature. The metal-insulator-metal (MIM) device with organic (1-bromoadamantane) ultrathin (10 nm) film as gate dielectric layer operated at gate voltage of 5.0 V, showing a low leakage current density (5.63 9 10 -10 A cm -2 at 5 V) and good capacitance (2.01 fF lm -2 at 1 MHz). The chemical structure of the 1-bromoadamantane layer was investigated by Fourier transform infrared spectrometer. The excellent leakage current density and better capacitance, probably due to the presence of polar, non-polar, low-polar groups, and bromine atoms in ultrathin film. Practical properties of the film in MIM capacitor such as dielectric constant as well as bending result of leakage current density and breakdown voltage have been better related to such fundamental adhesion nature over flexible substrate. This permits estimation of the properties of new dielectric in thin film form and short lists of the best materials for low loss and good capacitance flexible capacitors could be drawn up in future.

Öz: Lifli betonlar; sahip oldukları yüksek eğilme dayanımı ve içeriğinde kullanılan liflerin yüksek çekme dayanımı sayesinde çeşitli endüstriyel uygulamalarda, fabrika zeminlerinde, benzin istasyonlarında, prefabrik beton uygulamalarında yaygın olarak tercih edilmektedir. Bu çalışmada, aynı işlenebilirliğe sahip olan rastgele yönlenmiş cam ve çelik lifli betonlar ile tabakalı çelik tel ve cam elyaf ağları içeren beton kompozitlerin eğilme dayanımları incelenmiştir. Hacimce %0.5, %1 ve %1.5 oranlarında lif kullanılarak rastgele yönlenmiş cam ve çelik lifli beton grupları oluşturulmuştur. Çelik tel veya cam elyaf ağları içeren tabakalı beton kompozitler, rastgele yönlenmiş cam veya çelik lifli betonların lif hacmine eşdeğer olması için 3, 5 ve 7 tabakalı olarak üretilmiştir. Sonuçlar incelendiğinde; tabakalı lifli beton kompozitlerin eğilme dayanımlarının, aynı işlenebilirliğe sahip rastgele yönlenmiş lifli betonların eğilme dayanımlarından lif türü fark etmeksizin daha yüksek olduğu belirlenmiş olup tabakalı lifli beton kompozitlerin üretiminde yüksek eğilme dayanımı ve uygun işlenebilirlik için herhangi bir kimyasal katkı kullanımının gerekmediği tespit edilmiştir. Ayrıca tabakalı çelik telli beton kompozitlerin eğilme dayanımlarının, tabakalı cam elyaflı beton kompozitlerin eğilme dayanımlarından daha yüksek olduğu ve tabaka sayısının çelik telli beton kompozitlerde eğilme dayanımı sonuçlarını daha fazla etkilediği belirlenmiştir.

Repairing of reinforced concrete structures is currently a major challenge in the construction industry and is being put back into operation with a slight loss in load carrying capacity. Damage occurs due to many factors that reduce the strength of concrete structures and their durability. The aim of this paper is study the compatibility between three types of reactive powder concrete with (steel fibre, glass fibre and polypropylene fibre) as a repair materials and normal strength concrete as a substrate concrete. Compatibility was investigated in three steps. First: individual properties for substrate concrete were studied, these are (slump test, compressive strength, splitting strength, and flexural strength) also, for repair material these are (compressive strength and flexural strength) were determined by using standard ASTM test methods. Second: bond strength of composite cylinder for substrate concrete with different repair materials were evaluated by using slant shear test. Third: compatibility was investigated by using composite prisms of substrate concrete with different repair materials under two-point loading (flexural strength test). From the experimental results concluded, bond strength between reactive powder concrete with glass fibre as a repair material and normal strength concrete as a substrate layer is higher (17.38 Mpa) compared with RPC with steel fibre (13.13 Mpa) and polypropylene fibre (14.31 MPa). Also, it is more compatible due to flexural strength for composite prisms (having higher flexural strength (8.13 MPa). Compared with steel fibre (7.44 MPa) and polypropylene fibre (6.47 MPa). These results due to RPC with glass fibre have good workability with suitable flowability and glass fibre have higher tensile strength compare with other fibre.

This work presents a new method based on neutron backscatter measurements to study isothermal water flow and distribution in concretes. Ordinary concrete samples with different percentages of silica fume are used to study the water profiles ( x   ) which describe the water infiltration in the samples along the flow directions, x, for different absorbing times. The macroscopic theory of water infiltration in porous media was used to model the infiltration process. The obtained results show that the diffusion process is anomalous; i.e., the water front position, xp does not follow the square root behavior of the absorption time, t and the water profiles   t x /   do not collapse to the universal one master curves for all samples. It is shown that the diffusion process is a super, the power law, 85 . 0   t x p p  successfully describes the advance of water front with time and the water profiles collapse to universal one master curves (    ). The water diffusivities were derived in an analytical form for the investigated samples. They have the hyperdiffusion behavior; i.e. diffusivities decrease as the water content increase. It is shown that the diffusivity for all water contents deceases with increasing the silica fume percentage up to 15 %. However, for concrete with silica fume  20 % the observed phenomenon is reversed due to the deterioration of concrete physical and mechanical properties.

The dry-wet cycle and high temperature exposure are important factors affecting the normal use and durability of concrete structures. The objective of this work is to investigate the mechanical properties of cement mortar specimens after combinations of dry-wet cycles and high temperature exposures, uniaxial compressive tests on cement mortar specimens were carried out under the following two sets of conditions: (1) high temperature treatment followed by a drywet cycle and (2) a dry-wet cycle followed by high temperature treatment. The results show that the compressive strength of specimens increases with the number of dry-wet cycles. After a dry-wet cycle and then a high temperature treatment procedure, the compressive strength of a specimen will first decrease and then increase with the number of dry-wet cycles. The strain at the peak stress of cement mortar decreases as the number of dry-wet cycles increases. At present, there are few research results about the mechanical properties of concrete first after combinations of dry-wet cycles and high temperature exposures. The work in this paper can enrich the results in this area.

The mixing process of concrete consists of dispersing the constituent ingredients (i.e. cement, admixtures, sand, and gravel) in water to homogeneous and solid product. The properties of the final product depend on mixing parameters such as mixing time and mixing speed. Ready Mixed Concrete (RMC) should be mixed for a long time with limited speed until delivered to the working site. This long time depends on long transport distances and traffic conditions. The present study investigated the effects of long mixing time on the properties of concrete without any change in its proportions during the mixing process and the effects of using the chemical admixtures: super plasticizers and retarders on its effectiveness, using a drum batch mixer. It has two directions of rotation: one for mixing concrete and the other for discharging it. This research identified concrete mixtures with local available materials i.e. cement, sand as fine aggregates, dolomite as coarse aggregates, water and chemical admixtures. Mixtures were prepared with the same cement and water content with constant sand to dolomite ratio with different dosages of chemical admixtures. Chemical admixtures were used to keep concrete flow during mixing. Mixtures were prepared with low mixing speed 1rpm for identified long mixing times more than 90 minutes from adding water to other components Slump and compressive tests were used as measurement tools of fresh and hardened concrete Retempering with extra water or chemical admixtures was prevented through mixing, so mixtures were extracted without target slump value. Findings showed that low mixing speeds made mixtures more effective for long times, the exceeding mixing time led to minimize water to cement ratio due to reduction of water content, and there was an inverse relationship between slump flow and compressive strength in case of no re-tempering. Therefore, slump flow of mixtures decreased by time, but on the other hand, compressive strength enhanced i.e. stiffening took place. The present study proved that the properties of the final product depends on mixing parameters such as mixing time and mixing speed, and that Ready Mixed Concrete (RMC) would be more effective if mixed for a long time with limited speed until transported to the work site. In addition, chemical admixtures with prolonged mixed concrete should be used to improve workability rather than compressive strength.

The important concrete structure in the vicinity of industry, thermal power plant suffers deterioration by the acid rain cause due to combination of CO 2 , SO x and NO x with rain water. A combined attack that is from acid as well as sulphate can be observed under impact of sulphuric acid. It attacks on Calcium hydroxide and form Calcium sulphate, which can be leached out easily and make Interfacial Transition Zone (ITZ) poor. The water retaining structure such as dam, weir should be impermeable and that can be achieved by binary cementitious blends, using Silica fume (SF). Silica fume a by product of silicon industry, proves very effective in improving the microstructure of concrete due to their finer particle size, approximately 100 times finer than cement particles. The SEM image of binary blended high strength concrete (HSC) with Silica fume shows the condensed packing of cement hydration product and a dense microstructure as compare to control mix. The water permeability test result reveals that there is about 87 percent reduction in the coefficient of permeability achieved by inclusion of 10% Silica fume (SF) by weight of cement. Rapid chloride penetration test (RCPT) has been performed to investigate the ingress of chloride ions into the concrete. There was significant reduction in chloride ions penetration recorded due to SF inclusion.

In this piece of research, n attempt was made to produce a sustainable concrete with the partial replacement of both fine and coarse natural aggregates with two different non-biodegradable wastes. The selected wastes were fine glass and shredded rubber tires. Fine glass passing through 4.75 mm BS sieve was utilised for the partial replacement of fine natural aggregates. Coarse natural aggregates were partially replaced with shredded rubber passing through 20 mm sieve and retained on 6.30 mm sieve. Several mixes with varying % of fine glass but with a fixed 10 % of shredded rubber were tested. Optimum fine glass content was determined to be in the order of 20 %. The resulting concrete exhibited lower plastic and hardened densities (2040 and 2117 kg/m 3 respectively) in comparison to normal plain concrete. The static modulus of elasticity was found to be 18.3 GPa (mean value), while the splitting tensile strength was 2.37 MPa. The flexural strength showed a significant increase of 20.3% compared to the control mix. The results concluded that the concrete thus produced is a viable means of disposing of such non-biodegradable wastes (rubber and glass), thus reducing the loads at landfills. This new genre of concrete was produced at a lower cost than normal concrete because of the very low pre-treatment costs of the recycled wastes used. Furthermore, the properties tend to indicate that the concrete could be applied where lower strength and high durability properties are warranted. Hence precast slabs were made from the new design concrete and were tested along a stretch of a highly trafficable pedestrian walkway on the University campus. The slabs were continuously monitored for defects such as cracks, broken corners and slabs for a period of 24 consecutive weeks. After the test period it was observed that only 4 out of the 80 precast slabs had hairline cracks. Hence concluding the enhanced durability properties of the new design concrete.

The global rapid increase in waste tyres accumulation, as well as the looming social and environmental concerns, have become major threats in recent times. The use of Recycled Steel Fiber (RSF) extracted from waste tyres in fiber reinforced concrete can be of great profitable engineering applications however the choice of suitable length and volume fractions of RSF is presently the key challenge that requires research exploration. The present experimental work aims at investigating the influence of varying lengths (7.62 and 10.16 cm) and dosages (1, 1.5, 2, 2.5, 3, 3.5, and 4%) of RSF on the various mechanical properties and durability of concrete. Test results revealed that the varying lengths and dosages of RSF significantly affect the mechanical properties of concrete. The improvements in the compressive strength, splitting tensile strength, and Modulus of Rupture (MOR) of RSF reinforced concrete observed were about 26, 70, and 63%, respectively. Moreover, the RSF reinforced concrete showed an increase of about 20 and 15% in the yield load and ultimate load-carrying capacity, respectively. The durability test results showed a greater loss in compressive strength and modulus of elasticity and a smaller loss in concrete mass of SFRC. Based on the experimental findings of this study, the optimum dosages of RSF as 2.5 and 2% for the lengths 7.62 and 10.16 cm lengths, respectively are recommended for production of structural concrete.

As the demand for sustainable construction materials rises, hemp-infused concrete has emerged as a promising solution to reduce carbon emissions and promote eco-friendly building practices. This review critically assesses hemp concrete's mechanical, thermal, and durability properties, highlighting its potential for widespread adoption in various industries. Hemp's porous structure contributes to improved thermal insulation, soundproofing, and biological resistance, making it suitable for in-fill materials, plastering, and insulation applications. However, its low compressive and flexural strength remains challenging, limiting mainstream use. Hemp content and composition variations have resulted in differing properties, necessitating further research to optimize the material. The study identifies the growing collaboration among countries to promote bio-based materials but acknowledges the lack of standardized norms for hemp concrete in general construction. It stresses the importance of developing uniform standards to ensure consistent quality, performance, and regulatory compliance. This study explores the properties of hemp-infused concrete. It assesses its potential as a sustainable building material while identifying gaps in research and standardization needed for its widespread adoption in the construction industry. recommends upgrading infrastructure and retrofitting industries by 2030 to ensure sustainability, enhance resource-use efficiency, and promote clean technologies and processes. Concrete is a versatile material formed through the chemical reaction of hydraulic cement and water, with modern production incorporating various cement variants, components like pozzolan, fly ash, blastfurnace slag, micro-silica, additives, recycled aggregate, polymers, fibres, lightweight aggregate, natural fiber-reinforced polymers (FRPs), glass fiber reinforced polymer (GFRP), E-waste fine aggregate and other similar constituents [5-18]. Currently, concrete is extensively utilised as the predominant construction material on a global scale. China's annual consumption of concrete amounts to around 1.4 billion cubic meters, along with 20 billion tonnes of sand and gravel as aggregates [19]. Cement manufacturing uses large amounts of limestone, clay, and coal, resulting in significant CO 2 emissions, causing environmental damage,

Fluid catalytic cracking catalyst residue (FC3R) is a waste that can be used as a Portland cement replacement in pastes and mortars. The flow table results have shown that the FC3R is a water demanding addition; nevertheless it is compatible with the use of superplasticizers. The pozzolanic activity of FC3R was followed by the mechanical strength evolution with time. Pastes and mortars with FC3R incorporated have shown higher mechanical strengths than control specimens, indicating pozzolanic activity of the waste. Cement equivalence factors (k-factor) evaluations were carried out. The k-factor values for the FC3R pastes and mortars were always greater than one, indicating that to maintain the same compressive mechanical strength of the control specimen, it is enough to replace cement with a smaller amount of catalyst residue, due to 2 its high pozzolanic activity. There is a strong agreement between the values obtained in pastes and mortars.

With time, the development of micro-cracks in concrete is a frequently reported problem in the structures due to the ingress of harmful substances, leading to the degradation of its quality and strength, which ultimately declines the construction. The present work is a review paper based on enhancing the self-healing property of concrete by inducing different bacteria alone or incorporating different mineral additives. It has been seen that various rehabilitated methodologies are in queue to surmount concrete's weaknesses and to increase its strength and durability. The latest methodology includes using nonpathogenic microbes in concrete as Microbial induced Calcium Carbonate Precipitation (MICCP). The property of precipitating calcium carbonate (CaCO3) crystals by their metabolic activities helps repair the cracks in harsh conditions and improve their strength. Ureolytic bacteria like Bacillus pasteurii/Sporosarcina pasteurii, Bacillus subtilis, Bacillus megaterium, etc., have a specific property by which they can excite urea when integrated with a calcium source and help in sealing the cracks by CaCO3 precipitation. Different studies have observed that specimens having a bacterial concentration of 10 5-10 7 cells/ml with Natural Zeolite (NZ) replacement (10%) represents better interaction of the microstructure of concrete because of the formation of calcium silicate hydrate (CSH) gel. Further, the reduction in CH bond with reduced pore space has also been observed. NZ alone enhances micro-structural property, but it shows CaCo3 precipitation and more densification of microstructure under bacterial combination. XRD also confirms an increase in the calcite composition when the bacterial concentration of 10 5-10 7 cells/ml is used. The overall properties of standard and high-strength bacterial concrete (10 5-10 7 cells/ml) with 10% Natural Zeolite replacement can provide a better option for the future of sustained and strong concrete.

Massive infrastructure development in East Borneo has reduced the water catchment area. One of the efforts to overcome this is by implementing porous paving with superplasticizer and local materials to improve quality, overcome material scarcity, and save costs. The purpose of this study was to determine the best layer variation of porous paving using Palu and Senoni materials with variations of 1/4, 1/2, and 3/4 of Senoni aggregate. In this study, the test object was made in the form of a beam with a quality of concrete planned at K300 MPa according to the compressive strength, flexural strength, porosity, and permeability values tested at the ages of 7, 14, 21, and 28 days. Based on the results, the variant layer of 1/4 Senoni obtained maximum compressive strength, flexural strength, porosity, and permeability of 17.306 MPa, 3.984 MPa, 18.120%, and 0.216 cm/second at the age of 28 days, respectively. Thus categorized this combination as C quality. Which was included in the C quality group with an application as a pedestrian area. According to the permeability result, double-layer porous paving can accelerate water absorption on the surface to prevent waterlogging when it rains. The increasing variation of layers in double-layer porous paving affects the compressive strength, flexural strength, porosity, and permeability.

The main goal of this work is the understanding of triaxial compression capacity of bedding mortar. It was observed by the experimental tests that the behavior of the stress and strain response is highly nonlinear and depends on the increase of lateral stress. In all studies presented here, the ultimate strength envelope of triaxial mortar can be represented by a linear function with similar angular coefficients. It was observed a significant reduction in the Poisson ratio of mortar with increasing confined stress. This decrease is apparently exponential for mortars types 1:1:6 and 1:2:9 (proportion on volume of cement:lime:sand) and linear for mortars type 1:0.25:3 and 1:0.5:4.5. A simple model is proposed to represent modification of the Poisson ratio throughout the normalized stress range.

The main goal of this work is evaluate numerical model to reproduce the compression test of concrete block prisms, through a constitutive model of materials using the theory of plasticity and compare its results with experimental tests to preview the stress, strain and failure mode of the masonry. The post peak behavior of the material under tensile followed an exponential law and, under compression, a parabolic criterion was specified for the ascendant and descendent parts of the stress diagram and the hardening parameter. The mortar was connected to the block by the interface, for which the discrete model was employed, where the cracking occurred when the normal stress exceeded the tensile strength of the material.

Folashade, Adediran Paul, You all have stood by me through thick and thin. Special thanks to the most beautiful and a wonderful soul, Olatunbosun Oluwabunmi, your unwavering support and belief in me kept me motivated. Thanks to the Family of Olorunfemi's, Toyinbo's, and Olaniran's, for different inspirations received to overcome the challenges and obstacles along the way. To my Spiritual Fathers and Leaders; Pastor (Dr) J.M. Owoyemi, Pastor (Engr) Sola Oladiran, Evang. Cissoko Blessing, and other Pastorates in Christ Apostolic Church, Glory of God, Akure. I say thank you all for your prayers, motivation and support. I am also grateful to all members of CAC Glory of God Akure, The Youth Wing of CACGOGA (Glorious Youth Fellowship), Tutors & Students of Blessed Academy Tutorials (Past and Present) for always identifying with my success and academic achievements towards becoming a distinguished scholar. To my best friends ''Team 4'' Akinola Kayode, Oloruntola Gbolabowale, Orimolade Oluwapelumi., who felt concern for me during this period and somehow assisted me. I also want to thank my colleagues. Included in this list are: Omope Temitope, Agboola Blessing, Hammed Lukman, for their support and love. It would be difficult to find adequate words to convey how much I love you all. May God bless us. I cannot but appreciate Mrs Olaitan (HOD, Health Information Management, Ondo State Teaching Hospital) and Mrs Abegude (Officer in-charge of Health Information records). I would like to thank my Project friends under the same Supervisor, Afolayan Emmanuel, Olaiya Oluwatobiloba, Ayodele-Makun Worship, Ibrhymes, Marvelous, Enioluwafe and others Thanks for your cooperation to work together as a team. I would like to extend my appreciation to my friends and lodge mates (Koko Lodge) for their love, encouragement, and support throughout my academic journey.

The concrete cover is a part of the concrete that provides the required protection for the reinforcing steel within the required element from external effects. This concrete cover can be damaged for an assortment of reasons, one of which is environmental factors. As a result, this research focused on the effect of worn concrete covering on the structural response of beams. Moreover, the possibility of repairing or replacing this concrete cover with a cement material was done by testing seven beams with the exact dimensions (2700 mm long, 250 mm deep, and 140 mm wide). The first specimen was a control specimen, while in the remaining specimens, a part of the concrete cover was removed in the midspan region with a length of 600 mm and in different formats. The part below the neutral axis (tension zone) was removed in the first two specimens. The part above the neutral axis (the compression zone) was removed in the second two specimens. The whole cover was removed within the specified distance for the other two specimens. In one out of every two of these six specimens, the removed concrete cover was replaced with cementitious material. A flexural test was performed for all specimens, and the conclusion was reached that damaging or removing the concrete cover from the tensile region (below the neutral axis) is less harmful than from the compression region since the beam is often designed as a cracked section. Also, removing the concrete cover from the compression region gives cracks a greater width than removing the concrete cover from the tension region at the same loading level. In the case of replacing the concrete cover with a cementitious one, if the replacement is in the compression zone, it will result in cracks when loading with a width greater than that of the rest of the cases. For specimens that removed their concrete covers from the tension zone, compression zone, and the whole section, the failure loads decreased by 39%, 20%, and 23%, respectively, concerning the control beam. In contrast, all these specimens were repaired with cementitious materials, with an ultimate load capacity approximately equal to the control beams. From these results, any damaged concrete cover for beams in any zone with cementitious materials having high strength and a good bond with old concrete sections can be repaired.

In Sweden, there are in all 27 000 bridges. The Swedish Road Administration is responsible for 12 000 of these bridges. 50 percent of them are built between 1950 and 1980 and have, thus, obtained an age at which the need of maintenance and repair usually increases. A hypothesis is that the preventive bridge maintenance could be optimised through thorough analyses of properties of the bridge element, actual mechanical stresses, and ambient microclimate. An active maintenance is defined as the optimised preventive maintenance allowing different measures to be selected for different bridge elements. The opposite is passive maintenance, a form of maintenance that is equal to all bridge elements independent of element properties, actual stresses, and ambient microclimate. Impregnation has been regarded as one of the most suitable methods of active bridge maintenance. This paper summarizes a literature survey on active bridge maintenance with focus on impregnation.

The increasing utilization of Fiber-Reinforced Concrete (FRC) within the construction industry signifies a pivotal shift towards enhancing structural integrity and durability. Despite the predominant use of steel fibers, exploring macro synthetic fibers has gained momentum due to their potential to address critical challenges, such as workability reduction and corrosion resistance in FRC, without markedly affecting its structural performance. Among the forefronts of FRC research is developing an accurate constitutive model encompassing the diverse behavior of fibers, particularly synthetic ones. This discrepancy necessitates a distinct constitutive model for synthetic fibers to precisely characterize their tensile postcracking behavior and regulate their design specifications. In this research, a preliminary constitutive model is derived through an inverse analysis procedure employing a Generalized Reduced Gradient (GRG) optimization method to the loaddisplacement results of the experimental testing of twenty ASTM C1609 beam samples. The results of the inverse analysis are used to correlate the ASTM C1609 residual flexural tensile strength parameters, 𝑓 𝐿/600 and 𝑓 𝐿/150 to the stress-strain points defining the uniaxial tensile curve of macro-synthetic fibers, achieving coefficients of determination exceeding 98.5%. The model is statistically confirmed to be a valid constitutive relation for macro-synthetic fibers via successfully representing the post-cracking load-deflection behavior of standardized concrete beams, thereby outperforming traditional constitutive models in simulating the post-cracking behavior of FRC. Moreover, the model demonstrates robust predictive capabilities for the load-deflection curve of externally standardized samples, showcasing its potential for broader application in FRC design and analysis.

Mortars have many uses in construction: to lighten, sonic and thermal insulation, aesthetic purposes, to protect against environmental attack, repair, conservation, union masonry, etc. Mortar matrices may be Portland cement, lime, gypsum, clay and soil, asphalt or polymers. This work shows the result of the addition of areas of expanded polystyrene spheres (EPS) in three different percentages to the aggregate of a mixture of mortar. Physical and mechanical behaviour is evaluated to assess their behaviour under accelerated attack. The stone aggregate in the mortar was river sand; the cement used was ASTM C150 Type IV; the initial water-cement ratio by weight was 1.01 for each share; all blends met 105 ± 5% flow. The addition of expanded polystyrene spheres (EPS) replaced fine aggregate by 10%, 20% and 30% in each mixture. It was necessary to add a fluidizing agent in cases of adding expanded polystyrene spheres since the fluidity of the mortar decreased. Destructive testing such as simple compression and the accelerated attack took place; non-destructive testing included physical absorption as a percentage and specific gravity were also performed. It is concluded that the addition of expanded polystyrene improved resistance to chemical attack accelerated mortars and reduced the volume and weight, without detriment to the resistance.

Natural zeolite, a type of frame-structured hydrated aluminosilicate mineral, is used abundantly as a type of natural pozzolanic material in some regions of the world. In this work, the effectiveness of a locally quarried zeolite in enhancing mechanical and durability properties of concrete is evaluated and is also compared with other pozzolanic admixtures. The experimental tests included three parts: In the first part, the pozzolanic reactivity of natural zeolite and silica fume were examined by a thermogravimetric method. In this case, the results indicated that natural zeolite was not as reactive as silica fume but it showed a good pozzolanic reactivity. In the second part, zeolite and silica fume were substituted for cement in different proportions in concrete mixtures, and several physical and durability tests of concrete were performed. These experimental tests included slump, compressive strength, water absorption, oxygen permeability, chloride diffusion, and electrical resistivity of concrete. Based on these results, the performance of concretes containing different contents of zeolite improved and even were comparable to or better than that of concretes prepared with silica fume replacements in some cases. Finally, a comparative study on effect of zeolite and fly ash on limiting ASR expansion of mortar was performed according to ASTM C 1260 and ASTM C 1567. Expansion tests on mortar prisms showed that zeolite is as effective as fly ash to prevent deleterious expansion due to ASR.

Noise pollution from traffic is an increasing environmental problem worldwide. The most popular mitigation measure is the control of path by means of construction of noise barriers. Current concrete barrier incorporated with perforated surface infilled with non-mineral fibre sound absorbing material on the highway side are the commonly found. The disadvantage of this type is it’s easily damaged and the non-mineral fibre is so dreadful to human health. On the other hand, palm oil clinker (POC) is a by-product waste material produced in palm oil mills, are currently dump in open land or landfill sites, which leads to environmental problems. POC is internally porous and if it replaces the aggregate in porous concrete it may absorb sound better than standard porous concrete which is the most important characteristic for noise barrier development. This paper discusses how the palm oil clinker substitution will make concrete noise barrier material to be labelled as green and sustainable. ...

Post-cast application of hydrophobic agents onto hardened concrete is successful at reducing external ion diffusion into cement paste, this work examines pre-cast application of hydrophobic admixtures in fresh concrete. Concretes, with water to cement ratios (w/c) 0.45 and 0.50 (CEM I; low C3A), were mixed. Adding alkyltrialkoxysilane or triacylglycerol admixtures ranging from 1 to 3 wt%cem in these concretes were evaluated. Increasing the dosage of hydrophobic admixtures decreased the compressive strength. The usage of these admixtures did not hinder the further development of the microstructure as all concretes gained strength after one year, but not in the same percentage increase as the reference concrete. Chloride ion diffusion, after exposure to 3 wt% NaCl solution at 20 °C for 91 days, in concretes with 1 wt%cem admixture showed slight reductions in diffusion rate (8-17%) compared to the reference. At 3 wt%cem, triacylglycerol admixtures showed better hindering effects of inward chloride diffusion, this was especially evident in w/c = 0.45. Equivalent addition of alkyltrialkoxysilane-based admixtures increased the diffusion of chloride ions transferred into the cement matrix.

This paper reports the usefulness of nanoindentation as a characterization and monitoring tool for studying thermal behaviour of Geopolymer materials. The influence of the manufacturing process of Na-Geopolymers in their micromechanical properties and thermal behaviour has been studied. Two types of metakaolin-based geopolymer panels with almost identical composition were prepared by injection and pouring methods. Micro-mechanical properties of the two samples exposed to high temperatures up to 1000 ºC were studied by nanoindentation technique, supplemented by X-ray diffraction (XRD), Nuclear magnetic resonance (NMR), Thermogravimetric analysis (TGA) and Microscopy. Remarkable differences in micro-mechanical properties and thermal behaviour between the two samples were found. Statistical nanoindentation has been successfully used to provide information about the micro-mechanical properties of different phases in the material and their volume distributions.

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Several parameters influence the mechanical properties of hemp concrete. Some are due to the nature of its constituents such as the aggregate size, the type of binders, and other parameters are due to manufacturing method, such as the compaction energy and the molding method as well as the methods used for its properties characterizations. This paper is interested in the study of the variability of hemp concrete properties taking into account the number of specimens used during experimental investigations. The hemp concrete properties considered are: the maximum compressive stress and apparent modulus. A methodology with the goal to evidence how the increase in number of specimens may improve the accuracy for obtained results has been used. The mean, minimum and maximum values, with also standard deviation and the confidence interval have been analysed. Beyond, a comparative analysis between the theoretical distribution and the observed experimental distribution in each set by Q-Q plots allowed a better appreciation of the accuracy in obtained results. With this study, it has been highlighted that at least a set of six specimens is necessary and recommended for accurate results during experimental investigations.

An experimental study was carried out on the fatigue behaviour of multi-axial warp-knitted fabric composites. Composite samples reinforced with multi-axial warp-knitted fabric/matrix were manufactured by the vacuum-assisted resin transfer moulding method. Tensile-tensile fatigue cycling was carried out at different load levels, and S-N curves, tensile stress-strain curve and stiffness degradation of the multi-axial composite samples were obtained. Finally post-fatigue tensile tests were done at a stress level of 75%, at the stages of 1/3N and 2/3N, and the equivalent residual strength and stiffness degradation were obtained.

A multielectrode localized corrosion sensor has been developed for evaluating the performance of corrosion inhibitors for carbon steel in cooling water. Experimental results indicate that the coupled multielectrode sensor provided instantaneous measurement of corrosion ...

In recent years, many research works have been done to investigate the possibility of utilizing a broad range of materials as raw materials in the production of geopolymer cements. The use of artificial pozzolans or aluminosilicate-type industrial waste materials such as granulated blast-furnace slag and fly ash has been reported in many research works. Natural pozzolans are also aluminosilicate-type materials which can be activated with solutions of NaOH and Na 2 SiO 3 . Using a pumice-type natural pozzolan from Taftan Mountain located at the south east of Iran and different alkaliactivators based on combinations of Na 2 SiO 3 and NaOH, a number of natural-pozzolanbased geopolymer cement systems were designed and prepared. Final setting time, workability, and 28-day compressive strength of the systems were studied. The results obtained reveal that Taftan pozzolan can be activated using a proportioned mixture of Na 2 SiO 3 and NaOH resulting in the formation of a geopolymer cement system exhibiting suitable workability and relatively high 28-day compressive strengths up to 63 MPa.

A significant contributing factor to the strength of many reinforced concrete composite structures is the shear stresses that are transferred between concrete-to-concrete contacts. The medium that divides the old and new concretes is known as the interface in composite construction. In order for the interface to withstand the applied loads on the structure, it must guarantee the transmission of shear force. The current requirements prescribed by AASHTO specifications and ACI Code provide a conservative estimate to the shear capacity of composite concrete sections without regarding horizontal shear resistance of the concrete itself. So, the present work examines the feasibility of increasing the horizontal shear capacity between new and old concrete without interface steel reinforcement. Maximizing the shear strength arising at the interface surface will reduce the steel reinforcement and contribute to achieving sustainable concrete structures. The contribution to the horizontal shear capacity provided by the roughness of the interface surface finish and the compressive strength of the slab concrete were investigated experimentally. The aged concrete’s surface was treated with two different surface textures (intended and sandblasted with epoxy). The relationship between the monotonous load and slip was also examined using the "push-off" test method. Also, a finite element numerical model (ABAQUS/Standard) was implemented to compute the theoretically predicted load and slip results. The experimental results showed that the interface surface roughened by sandblasting and epoxy bearded a higher average ultimate load associated with a higher average slip distance. There was a good agreement between the experimental results and the numerical ABAQUS program results for the intended group, while a high difference was registered in ultimate load and slip values for the sandblasted group. The accuracy ranged from (98-99%) for the first group and from (52-89%) for the second group. In light of this low accuracy, we recommend using other numerical analysis programs such as ANSYS or Cohesive Zone Model. Despite the international codes presented so many relation formulae, the interface media needs more studies to reach an accurate understanding of shear strength development.

Steel Fiber Reinforced Concrete (SFRC) is the most often employed method for improving the flexural, shear, and torsional properties of concrete in the modern era. It is capable of withstanding cracks and crack propagation. As a consequence of this capacity to arrest fractures, fiber composites may improve extensibility and tensile strength, both at the initial crack and at the final load, and fibers can help keep the matrix together after significant cracking. Steel fibers are short in length and are employed in concrete in proportion to their aspect ratio (i.e., the ratio of length to diameter); this ratio ranges from 20 to 100. Torsion is often associated with bending moment and shear force, and so the interplay of these forces is critical. Torsion occurs when a slab or beam is supported on just one side or when stresses acting transverse to the beam's longitudinal axis are applied. Numerous researchers have worked with SFRC to boost the flexural and shear capacities of the m...

The growing environmental concern throughout the globe has led architects & engineers to design energy efficient buildings. Consequently, they are looking for building materials that can reduce the energy consumption in buildings to maintain the comfort level. Use of proper thermal insulating materials can reduce the energy required for heating or cooling of the buildings. Presently mineral wool and various foams are used for this purpose. Efforts are being made to use wastes in making thermal insulation materials so that the impact on environment can be further reduced. Cork granules are obtained as waste from the cork processing industries that make ‘bottle stoppers’ as a main product. These granules have a low density and could be used as lightweight aggregates for making concrete with low thermal conductivity. This article describes the physico-mechanical properties of lightweight cementitious composites made using cork granules. Further, environmental benefits of their applicat...

Repair and restoration of deteriorated structures is drawing lot of attention in recent years. A variety of repair materials are available in the market. Therefore, testing, evaluation and selection of a suitable repair material is very important. Various researchers use different evaluation methods, whilst most of the material suppliers quote the property values, but the test standard and method is not reported. It makes difficult to compare the repair materials. Moreover, there is no required specification established so far. Recently research has been carried out throughout the world to address this problem. The paper covers some important parameters regarding the testing and evaluation of repair materials. The need of a unified standard code and to select tests according to the applications is emphasised. Work carried out at CBRI in this direction is also briefly discussed.

High pressure liquid chromatography Mock-up panel test Zeolite and Zeocarbon Microcapsules a b s t r a c t Anti-fungal mortar and concrete are developed using micro-encapsulated fungus-resisting material. D-Limonene is selected for the core anti-fungal material and Zeolite and Zeocarbon are used for reinforcing the capsule membranes. Damage and survival possibilities of microcapsules in the casting stage of mortar and concrete are examined by scanning electron microscopy (SEM) and high pressure liquid chromatography (HPLC). Several tests are conducted to evaluate the effects of microcapsule additions on the properties of fresh and hardened mortar and concrete. Anti-fungal effectiveness of the developed mortar is verified by mock-up panel tests, in which resistance to fungus growth on the panel surface is studied.

One of the most damaging environmental conditions to concrete structure is cyclic freezing and thawing. This paper discusses the influence of the high volumes of fly ash (FA) and micro poly-vinyl-alcohol (PVA) fibers on the cyclic freeze-thaw resistance and microstructure of the Engineered Cementitious Composites (ECC). ECC mixtures with two different FA-cement (FA/C) ratios (1.2 and 2.2 by weight), and at constant water-cementitious materials (fly ash and cement) ratio of 0.27 are prepared. To compare the behavior of ECC with ECC matrix, all of the preceding properties are also investigated for ECC matrix mixtures of same composition without PVA fiber. For frost resistance, mixtures are exposed to the freeze and thaw cycles up to 300 cycles in accordance with ASTM C666, Procedure A. Experimental tests consist of measuring the residual mechanical properties (flexural strength, mid-span beam deflection and flexural stress -deflection curve), ultrasonic pulse velocity and mass loss. The roles of PVA fibers and FA are discussed through the analysis of microstructure and fiber-matrix interactions as function of frost exposure. The microstructural characterization by measuring pore size distributions is examined before and after exposure to frost deterioration by using mercury intrusion porosimetry (MIP). The air-void characteristics of mixtures are also studied using linear transverse method. Test results confirm that both ECC mixtures with high volumes of FA remain durable, and show a tensile strain capacity of more than 2% even after 300 freezing and thawing cycles. On the other hand, before completing 300 freezing and thawing cycles, matrix (ECC without fiber) specimens have severely deteriorated, requiring removal from the freezethaw machine. Therefore, results indicate that the addition of micro PVA fiber to the ECC matrix substantially improved the frost resistance. The results of freeze-thaw tests also indicated that the reduction of residual physical and mechanical properties with increasing number of freeze-thaw cycles is relatively more for ECC mixture with FA/C ratio of 2.2 than for ECC mixture with FA/C ratio of 1.2.

The fracture response of cementitious composites containing compliant microencapsulated inclusions and its influence on the fracture process zone (FPZ) are reported. The incorporation of small amounts of phase change material (PCM) microcapsules (replacing up to 10% by volume of sand) is found to slightly improve the strength, fracture toughness, critical crack tip opening displacement (CTODc), and the strain energy release rates. Digital image correlation is used to examine the FPZ at the tip of the advancing crack, to better explain the influences of compliant microscale inclusions on energy dissipation. The FPZ widths are found to slightly increase with PCM dosage but its lengths remain unchanged. The increase in FPZ width is linearly related to the CTODc, showing that inelastic deformations of the crack-tip in the direction of crack opening are indeed influenced by microscale inclusions. It is shown that cementitious systems containing microencapsulated PCMs can be designed to demonstrate mechanical performance (including fracture) equivalent to or even better than their PCM-free counterparts, in addition to the well-described thermal performance.

The use of particles from agricultural lignocellulosic resources in concrete gives it desirable environmen-tal and multiphysics qualities. In this study, parallels are drawn between particles derived from hemp and sunflower stems, in terms of their morphological and physical properties. A pumice-lime binder is proposed as an alternative to the traditional cement or lime based solutions for both environmentally friendly and mechanical qualities. Compaction is applied during casting and its effects on mechanical properties are analysed. A principal finding of this study is that the hemp and sunflower materials show large similarities in terms of morphology and mechanical performance of the resulting concrete. The pumice-lime binder provides desirable properties even with raw pumice sand, which represent 90% of the binder mass proportion. Compaction level during casting induces an orthotropy, even with low plant content, and increases the compressive strength. A simple analytical model using Powers' equation is proposed to predict plant concrete compressive strength with low plant quantities.

An aluminosilicate precursor, such as metakaolin, can be transformed into a cement-like geopolymer binder via a phosphate activation approach. This paper identifies the effect of the addition of aluminum species into the phosphate activating solution on the formation of such geopolymers, from the fresh to the hardened state. Activating solutions with Al/P molar ratios of 0, 0.1, and 0.3 were prepared by blending monoaluminum phosphate (MAP) and orthophosphoric acid (OPA). The rheological properties, fluidity, and setting times of the fresh geopolymer pastes and the compressive strength of the hardened geopolymer matrices were studied. Liquid-state 27 Al and 31 P nuclear magnetic resonance (NMR) measurements for the chemical environments of Al and P, and spectroscopic, thermal, and microscopic analyses revealed that the soluble aluminum in the phosphate activating solution played an important role during the geopolymerization process. Seeding of aluminum species through inclusion in the activating solution allowed a rapid sol/gel transition that improved the rheological properties and setting time of the fresh geopolymer pastes at ambient temperature. However, although the increased concentration of aluminum phosphate oligomers promoted by the soluble aluminum addition contributed to the formation of a compact matrix with high early strength, it hinders the ongoing reaction of metakaolin in the later period, which has a detrimental influence on ongoing strength development beyond 7 days of curing.