Strength Development Of Concrete Research Articles

A study and analysis of groundwater parameters in concrete structures around Uttar Pradesh region

Water is an essential component of concrete and of life in general. It not only actively takes part in the hydration of cement but also helps make fresh concrete workable. The reaction of cement with water causes it to set and harden. Cement is a mixture of complicated compounds such as tricalcium aluminate, tetracalcium aluminoferrite, sodium oxide, and gypsum. Water quality must be closely monitored and managed throughout the production of concrete because it contributes to the formation of the cement gel that gives the material its strength. Generally speaking, the water used to mix concrete must adhere to Indian regulations (IS 456-2000) and other pertinent water rules. The guidelines set forth for different characteristics of groundwater do not accurately reflect their claims regarding concrete setting and strength development. The use of groundwater of poor quality, both during construction and during curing, has been linked in the literature to structural deterioration of a number of concrete components. There have been reports of numerous structural elements failing as a result of groundwater contamination coming into continual touch with concrete buildings. There are some fascinating case studies in the literature where the durability and strength of concrete constructions were damaged beyond repair by filthy water. In this investigation, ten distinct locations in the Greater Noida area were initially chosen, and ground water samples were collected from these areas. The potential impact of groundwater quality on concrete constructions is suggested by the current investigation. Additionally, it suggests a realistic water quality for the buildings. pH, Chloride, Sulphate, Acidity, and Alkalinity are the main chemical components found in groundwater. It is suggested that these factors be taken into account in the current study to evaluate the impact on concrete's setting times and compressive strength. The construction site of the buildings in greater Noida and future development projects will both benefit from this study.

Deconvolution of Main Hydration Kinetic Peaks in Properly Sulfated Portland Cements with Boundary Nucleation and Growth Models and Relation to Early-Age Concrete Strength Development

Deconvolution of Main Hydration Kinetic Peaks in Properly Sulfated Portland Cements with Boundary Nucleation and Growth Models and Relation to Early-Age Concrete Strength Development

Applicability of existing models for the strength development of 3D-printed thixotropic concretes during hardening

The special properties of 3 D-Printed Concrete in terms of rheology, deposition technology, and dosage substantially modify its mechanical properties after hardening. In this paper, comparisons are drawn between different concrete strength development models specified in the main Building-Codes and Standards and experimental data from tests on various thixotropic mortar mixes suitable for 3DPC. The aim was to develop an empirical procedure to improve the current models, so that their results could predict the properties of the 3DPC bulk materials more closely. An updated set of parameters for the models was obtained via curve-fitting of the models to the experimental data.

Compressive strength development and durability properties of high-calcium fly ash incorporated concrete in extremely cold weather

This research paper takes into account of three mineralogically different high calcium fly ashes (HCFA) consisted of anhydrite, generated in power plants in Ulaanbaatar, Mongolia. The purpose of this research is to understand how the morphology and mineralogy of HCFA influence the fresh and hardened properties of concrete; how pre-curing condition influences the long term strength development in different seasons; and to investigate the durability of HCFA concrete in extreme outdoor exposure conditions and freezing and thawing environment. Compressive strength development of fly ash concretes up to 540 days in extremely cold weather, strength dependence on pre-curing condition, freezing and thawing durability and the influence of ash mineralogy on durability were investigated. As a part of the investigation, the concrete specimens were kept outdoor at sub-zero temperature for more than four months. This paper concludes that strength approximately equal to that of the control can be obtained at early ages by 20 wt% replacement of total cementitious content by fly ash. When a comparison is made with equal mixtures, but equal pre-curing, winter concrete can only be achieved approximately 80% strength of autumn concrete after 3 months and then no considerable improvement happens even at one year. When a comparison is made with equal mixtures, but different pre-curing, the specimens exposed to the outdoor a day after placement show a permanent strength loss of 24%, with compare to the specimens cured in water at 20 °C for 28 days before exposing to the outdoor in winter. Durability factors of all fly ash incorporated concretes determined by freezing and thawing test were in the range of 78–91 at 300 cycles, satisfying the threshold in which concrete is likely to perform well.

Microstructural Investigation of High-Volume Fly Ash Composites Containing Nano-Calcium Silicate Hydrate Crystals

AbstractThis paper reports on the effect of addition of nano-calcium silicate hydrate (nano-CSH) seeds on the early-age strength development and microstructural evolution of concrete containing hig...

Model-Based Methods to Produce Greener Metakaolin Composite Concrete

Metakaolin is reactive and is widely used in the modern concrete industry. This study presents an integrated strength–sustainability evaluation framework, which we employed in the context of metakaolin content in concrete. First, a composite hydration model was employed to calculate reactivity of metakaolin and cement. Furthermore, a hydration-based linear equation was designed to evaluate the compressive strength development of metakaolin composite concrete. The coefficients of the strength evaluation model are constants for different mixtures and ages. Second, the sustainability factors—CO2 emissions, resource consumption, and energy consumption—were determined based on concrete mixtures. Moreover, the sustainability factors normalized for unit strength were obtained based on the ratios of total CO2 emissions, energy consumption, and resource consumption to concrete strength. The results of our analysis showed the following: (1) As the metakaolin content increased, the normalized CO2 emissions and resource consumption decreased, and the normalized energy first decreased and then slightly increased. (2) As the concrete aged from 28 days to three months, the normalized CO2 emissions, resource consumption, and energy consumption decreased. (3) As the water/binder ratio decreased, the normalized CO2 emissions, resource consumption, and energy consumption decreased. Summarily, the proposed integrated strength–sustainability evaluation framework is useful for finding greener metakaolin composite concrete.

Compressive Strength Studies on Recycled Binder Concrete

Recycled materials are gradually utilized in concrete. This paper examines the use of recycled binder in concrete. The compressive strength tests on concrete incorporating recycled binder instead of cement were carried out after 7, 14, and 28 days of curing. Cement was replaced by the recycled binder in ratios of 10%, 20%, and 30% by weight. The results show that the compressive strength of concrete is strongly affected by the percentage of the recycled binder. It has been found that the compressive strength decreases linearly with the increasing content of recycled binder. The recycled binder does not affect the strength development of concrete. In order to apply recycled waste to concrete as a binder, it is necessary to perform supplement research with appropriate additives to compensate for the loss of the compressive strength.

A succinct review on the use of NMR spectroscopy in monitoring hydration, strength development, and inspection of concrete

NMR is a very useful technique used in analytical chemistry for quality and molecular structure determination of a compound as well as its chemical environment. It works on the principle of the energy gap between two nuclei of an atom for an applied external magnetic field, due to their opposite spins. The potential of the three sub-categories of NMR (H-NMR or proton NMR, liquid-state NMR, and solid-state NMR) for monitoring hydration reaction in cement paste, early-age strength development in fresh concrete, and the inspection of hardened concrete has been elucidated in this paper. Powerful features of NMR in identifying the chemical environment and structure have made it possible for this technique in the evaluation of concrete subjected to sulfate attack and the estimation of the effect of alumino-silicate precursor on the strength of geopolymer. In this manuscript, various other applications of NMR in the non-destructive testing, quality checks, and monitoring of reactions in concrete and cement have been reviewed.

Investigation on compression properties of seawater-sea sand concrete

This paper introduces the experimental results of the influence of sea sand replacement rate and mixing water on the basic mechanical properties of sea sand concrete. A total of thirty test blocks were designed for uniaxial compression test. In this test two parameters were considered: (a) sea sand replacement ratio (i.e., 0%,25%, 50%,75%, 100%); (b) water for mixing (i.e., freshwater, seawater). The entire stress-strain curve of sea sand concrete under uniaxial compression was obtained. Based on the test results, the influence of sea sand replacement rate and mixing water on the peak stress, peak strain, and deformation performance of sea sand concrete were analyzed. Test results showed that the stress-strain curves of seawater sea sand concrete were steeper than that of ordinary concrete, which indicated that seawater sea sand concrete was slightly more brittle. On the whole, the sea sand replacement rate had no significant effect on the axial compressive properties of sea sand concrete. Under the same sea sand replacement rate, the deformation performance of freshwater sea sand concrete (FSC) was slightly greater than that of seawater sea sand concrete (SSC). Seawater had an enhanced effect on the early strength development of sea sand concrete.

Optimisation of strength development of bentonite and palm bunch ash concrete using fuzzy logic

ABSTRACT This study presents green-concrete’s mechanical-properties modelling with cementitious portion replaced by PBA/BN ranging from 0-50% using fuzzy-logic. Incorporation of these admixtures in concrete encourages solid-waste derivatives utilization to achieve cost-effective and eco-efficient construction-materials which also mitigates environmental-degradation challenges due to CO2-emission during cement production and hydration. Assessment of the elemental-oxides inherent in the admixtures showed a good pozzolanic-activity with Al2O3+SiO2+Fe2O3 results of 74.75% and 72.03% for PBA and BN respectively. The maximum and minimum strength-responses were derived at 5%-replacement and 50%-replacement with experimental-results of 19.48-4.17MPa, 21.85-4.84MPa, 26.30-8.637MPa, 32.77-12.713MPa and 35.53-18.46MPa for 3-d,7-d,28-d,60-d and 90-d respectively. Fuzzy-logic technique was utilized to evaluate the strength development property of the green-concrete as it takes precisely into account the issue of vagueness of well-defined parameters to develop expert intelligent-model using Mamdani-FIS. The model’s performance was evaluated by using MLR-models, MAPE and RMSE. R2 of 84.905% and 99.1% was calculated for MLR-model and fuzzy-logic model respectively. RMSE and MAPE score of 2.406-2.14%, 6.5935-7.29%, 0.4183-4.62%, 0.2774-1.54%, 0.7544-2.06%, 0.4197-1.48% and 0.7912-1.66% were calculated for the initial and final setting-time, 3-d,7-d,28-d,60-d and 90-d concrete’s compressive-strength target responses respectively. The results obtained from the indicates better performance for the fuzzy-logic model in predicting the setting-time and mechanical-properties of PBA/BN-concrete.

Properties of Concretes Incorporating Recycling Waste and Corrosion Susceptibility of Reinforcing Steel Bars.

In this paper, properties of concretes incorporating recycling waste and corrosion susceptibility of reinforcing steel bars were studied. It was established that fineness of ground granulated blast furnace slag (GGBFS) and fly ash (FA) and their simultaneous combination have an influence on the kinetics of strength development of Portland cements and concretes. The compressive strength of concrete containing 10% by mass of GGBFS and 10% by mass of FA even exceeds the compressive strength of control concrete by 6.5% and concrete containing 20% by mass of GGBFS by 8.8% after 56 days of hardening. The formation of the extra amount of ettringite, calcium hydrosilicates as well as hydroaluminosilicates causes tightening of a cement matrix of concrete, reducing its water absorption, and improving its resistance to freezing and thawing damage.

Compressive strength development and microstructure of magnesium phosphate cement concrete

In order to verify the feasibility of preparing structural concrete with magnesium phosphate cement (MPC), the workability, temperature rise and compressive strength of MPC concrete were studied. The hydration products, pore structure and fractural morphology of MPC concrete were also investigated. The results show that the hardened MPC stone is a ceramic-like structure by cementation of unreacted magnesium oxide and fly ash with the solid solution of the hydration products of fly ash and struvite. The continuity of this kind of ceramic-like structure will be broken when the aggregate is added to prepare concrete, and a weak interface transition zone will be formed between the ceramic-like structure and aggregate due to the “wall” effect, but the 2-hour compressive strength can still reach more than 40 MPa. The heterogeneous structure of MPC concrete results in a power function decreasing of concrete compressive strength in later stage with the increase of specimen sizes.

Effect of a Nitrite/Nitrate-Based Accelerator on the Strength Development and Hydrate Formation in Cold-Weather Cementitious Materials.

Recently, there has been increased use of calcium-nitrite and calcium-nitrate as the main components of chloride- and alkali-free anti-freezing agents to promote concrete hydration in cold weather concreting. As the amount of nitrite/nitrate-based accelerators increases, the hydration of tricalcium aluminate (C3A phase) and tricalcium silicate (C3S phase) in cement is accelerated, thereby improving the early strength of cement and effectively preventing initial frost damage. Nitrite/nitrate-based accelerators are used in larger amounts than usual in low temperature areas below −10 °C. However, the correlation between the hydration process and strength development in concrete containing considerable nitrite/nitrate-based accelerators remains to be clearly identified. In this study, the hydrate composition (via X-ray diffraction and nuclear magnetic resonance), pore structures (via mercury intrusion porosimetry), and crystal form (via scanning electron microscopy) were determined, and investigations were performed to elucidate the effect of nitrite/nitrate-based accelerators on the initial strength development and hydrate formation of cement. Nitrite/nitrate-AFm (aluminate-ferret-monosulfate; AFm) was produced in addition to ettringite at the initial stage of hydration of cement by adding a nitrite/nitrate-based accelerator. The amount of the hydrates was attributed to an increase in the absolute amounts of NO2− and NO3− ions reacting with Al2O3 in the tricalcium aluminate (C3A phase). Further, by effectively filling the pores, it greatly contributed to the enhancement of the strength of the hardened cement product, and the degree of the contribution tended to increase with the amount of addition. On the other hand, in addition to the occurrence of cracks due to the release of a large amount of heat of hydration, the amount of expansion and contraction may increase, and it is considered necessary to adjust the amount used for each concrete work.

Performance studies on limestone calcined clay based concrete

In the construction field, lot of improvement in sustainable development is going on from last few decades, mainly use of pozzolanic materials are increasing day by day for the production of cement. On the other hand a lot of anthropogenic CO2 gas is liberating in to atmosphere while manufacturing cement. To alter the emission of CO2, use of alternative cementious materials is one of the best practices like fly ash, rice husk ash, GGBS and Metakaolin. Due to the use of such materials there is a lag in early strength development in concrete. Hence there is need to develop a substitute material for cement without negotiating in properties. In the present paper Limestone Calcined Clay Cement (LC3) as an alternative to Ordinary Portland Cement (OPC) is examined for strength and durability and the results are compared with Portland Pozzolana Cement (PPC) for M 50 grade of concrete. From results it is found that the use of LC3 concrete is beneficial in terms of strength and durability.

Improving the properties of concrete using in situ-grown C-S-H

Enhancing the properties of concrete using C-S-H seed has been a challenging task due to its agglomeration in the cement matrix. Here, for ensuring synthetic C-S-H disperse well in the cement matrix, it was first synthesized in situ on fly ash (FA) by co-precipitation method, and the C-S-H grown in situ on FA (C-S-H@FA) was received. And then, its phase composition, morphology and particle size distribution were studied. After that, its effect on the hydration kinetics of cement, and the workability, strength development, pore structure, durability of concrete was explored. The results showed that the hydration of cement can be stimulated more dramatically by C-S-H@FA when compared with C-S-H, as well as the strength development of concrete. Besides, the addition of C-S-H@FA can refine the pores in concrete, and make concrete more compact than incorporating C-S-H. Furthermore, when C-S-H was replaced by C-S-H@FA, the carbonation resistance and drying shrinkage resistance of concrete was improved. Therefore, it can be concluded that the C-S-H grown in situ on FA has better dispersibility than C-S-H in concrete, improving the comprehensive properties of concrete more effectively.

Effects of calcium formate on early-age strength and microstructure of high-volume fly ash cement systems

Replacement of Portland cement (PC) by fly ash (FA) is currently limited to 15–30% by mass, mainly due to low early age strength development of concrete. This research uses calcium formate (Ca(HCO2)2; CF) as an admixture to high-volume FA (HVFA) composites to improve its strength properties. HVFA represents 60–70% of cement replaced by FA and dosage of CF varies from 0.5% up to high dosage of 9% of cement content. Compressive strength, isothermal calorimetry, thermogravimetric analysis, X-ray diffraction and scanning electron microscopy were conducted to investigate the effects of CF on hydration and microstructural aspects. The results show that both HVFA pastes with 60% and 70% FA achieved the highest strength at the CF dosage of 3%. At the age of 28 days, adding 3% CF to HVFA mixes led to higher consumption of FA as well as higher formation of calcium hydroxide (Ca(OH)2), calcium silicate hydrates, calcium carbonate (CaCO3) and ettringite, which contribute to the increase of strength. The addition of very high dosages of CF at 9% increased the hydration of tricalcium aluminate but could hinder the hydration of tricalcium silicate in both PC and HVFA pastes with 60% and 70% FA.

Effect of molarity of sodium hydroxide and molar ratio of alkaline activator solution on the strength development of geopolymer concrete

In the current study, effect of SiO2/Na2O ratio in Sodium silicate (Na2SiO3) solution, Na2SiO3/NaOH ratio and molarity of NaOH on the compressive strength of geopolymer concrete. A geopolymer mix design is formulated with various mixes are casted with alkali activator solution (AAS) / fly ash (FA) =0.5 and constant fly ash content. The molar ratio of SiO2/Na2O in Na2SiO3 solution is altered from 1.50 to 3.00 for different ratios of Na2SiO3/NaOH (2.0, 2.5 and 3.0) and also for various molarities of NaOH (8M,10M,12M,14M,16M and 18M) are studied for their synergic effect on the compressive strength of geopolymer concrete. Results highlighted that the 16M NaOH yields high compressive strength when SiO2/Na2O in Na2SiO3 solution is around 2.00 to 2.40 and Na2SiO3/NaOH=2.5.

Effect of Alkali Reactions on the Rheology of One-Part 3D Printable Geopolymer Concrete

Yield strength development of 3D printable concrete by the early age activation reactions plays a vital role in the printability of geopolymer concrete. This study presents a rheo-chemical approach to investigate the early age strength development due to alkali reactions for the formulation of suitable 3D printable one-part geopolymer concrete. The influence of design parameters, including activator content, thixotropic additive (Magnesium Alumino Silicate -MAS), and retarder (sucrose) dosage, on the rheological properties of concrete were assessed. The shear stresses of geopolymer concrete were measured with the aid of a rotational rheometer for various shearing protocols that represent the major stages of printing operation (pumping, extrusion and building). The measured rheological properties were related to reaction kinetics of geopolymer mixes using FT-IR spectroscopy and calorimetry. The results revealed that, with MAS, activator and sucrose content of 0.75 wt%, 10 wt% and 1.5 wt% of the binder respectively, the formulated one-part geopolymer showcased enhanced printing properties. This is further demonstrated by printing laboratory-scale specimens and evaluating the hardened properties.

Compressive strength development and durability properties of high volume slag and slag-fly ash blended concretes containing nano-CaCO3

This paper presents the effect of nano-CaCO3 (NC) on the compressive strengths and durability properties of high volume slag (HVS) and high volume slag-fly ash (HVS-FA) blended concretes. The study examined the improvement in early and later age compressive strengths and durability properties such as sorptivity, volume of permeable voids, rapid chloride penetration and drying shrinkage of HVS concrete containing 69% blast furnace slag (BFS) and HVS-FA concrete containing combined BFS and fly ash (FA) content of 69% due to the addition of 1% NC. Results show that the addition of 1% NC improved the compressive strengths of HVS and HVS-FA concretes significantly by 43% and 28%, respectively at 3 days compared to the control HVS and HVS-FA concretes without NC and exceeded the compressive strengths of control OPC concrete at later ages. It is also found that 1% NC inclusion reduced the water sorptivity of HVS and HVS-FA concretes reasonably after 28 days of curing and reduction is greater after 90 days of curing exhibited comparable water sorptivity to OPC concrete. Significant improvement is also observed in reducing the volume of permeable voids and controlling the drying shrinkage strain at early age as well as later ages of both HVS and HVS-FA concretes due to 1% NC inclusion. Outstanding resistance against chloride ion penetration is also observed in HVS and HVS-FA concretes due to addition of 1% NC to the very low level of chloride ion penetration according to ASTM standard. SEM and EDS analysis revealed a denser microstructure of paste and interfacial transition zone (ITZ) around aggregates.

Assessment of the Mechanical Properties of Bagasse Ash Concrete

Sugarcane bagasse ash is found abundantly in Ethiopia. Researchers in the area focus to sustainably use this pozzolan as a raw material for concrete production. This study aims to investigate the early and late age mechanical properties of Bagasse ash concrete. Concrete mixtures containing pure Portland cement, 6.5%, 13%, and 20% dosage of Bagasse ash by volume were proportioned. The compressive, tensile, flexural strength data at one, two, three, seven, twenty-eight days are determined. The experimental outcomes indicate that the tensile strength of bagasse ash concrete for 6.5% and 13% replacement ratio dropped by 6.98% and 22.5% compared to full cement concrete at three days of testing. As well, there is a reduction of third-day flexural strength by 5.96% and 13.1%. In advance, the 28th-day flexural strength increased by 6.38% and 17.02% for 6.5% and 13% replacement ratio. The compressive strength of bagasse ash concrete with 6.5% and 13% replacement ratios exceed the control group's 28th-day strength by 3.46% and 6.64% sequentially. Possibly, the ettringite formed as the base solution reacts with metallic oxides densifies the interfacial transition zone. Bagasse ash also contains inert unburned carbon particles that will fill the voids of hardened concrete. On the other hand, replacing cement with bagasse ash up to 20% reduces both the early and late age flexural strength and tensile strength development of concrete.