Days Of Normal Curing Research Articles

Improvement on Strength, Durability, and Crack Closure Behavior of Bacteria Concrete under Marine Soil Exposures

Abstract In the concrete industry, bacteria-precipitated calcium carbonate (CaCO3) can be used to repair cracks. If cracks in concrete are not repaired in a timely manner, other durability problems arise, necessitating expensive crack repair methods. Bacteria can be isolated from an appropriate physical environment so that they continue to function effectively in concrete. In this study, suitable self-healing bacteria are isolated from a concrete dump yard and incorporated into concrete specimens. After 3 days of normal curing, the specimens were pre-cracked and kept in marine exposure conditions for a period of 56 days. Strength and durability properties such as compressive strength regain, ultrasonic pulse velocity (UPV), and dynamic Young’s modulus were studied, and a water absorption test was carried out for cubes exposed in marine soil conditions. Marine soil treated with a bacteria and nutrient solution (1:9) exhibited improved crack-healing behavior as well as increased strength and durability. Compressive strength regain of 45.98 %, an increased modulus of 54.04 %, and crack healing of 83.05 % were reached with a 60 % reduction in water absorption and 32.49 % increment in UPV values. A microstructure study demonstrates the presence of CaCO3 compounds in healed crack surfaces and treated marine soil, which is primarily due to bacterial action under marine exposures conditions.

A comprehensive investigation on the impacts of steel slag aggregate on characteristics of high-performance concrete incorporating industrial by-products

Steel slag (SS), an industrial by-product of the steel industry, has the potential to serve as a natural aggregate alternative in concrete production to not only mitigate the exploitation of natural resources but also minimize the environmental impact of its treatment and disposal. This study was designed to investigate comprehensively the impacts of using SS as a full replacement for coarse aggregate and of using fly ash (FA) and ground granulated blast-furnace slag (GGBFS) as partial replacements for Portland cement on the engineering properties (i.e., workability, fresh unit weight, porosity, compressive and flexural strengths, ultrasonic pulse velocity, and drying shrinkage), durability (i.e., water absorption, surface electrical resistivity, and rapid chloride ion penetration), and microstructure (i.e., scanning electron microscopy observation) of high-performance concrete (HPC). A comparative analysis of the economic and environmental benefits of SS concrete versus natural aggregate concrete was also performed. The test results revealed that SS, FA, and GGBFS all impacted the properties of HPC significantly. The HPC mixtures in which natural aggregate had been completely replaced with SS exhibited about 20.4–21.3% higher unit weight than the natural aggregate concrete. The HPC samples with added FA and GGBFS exhibited enhanced performance in terms of mechanical strength, durability, and microstructure. Moreover, total material cost, global warming potential (GWP), and ozone depletion potential (ODP) were all found to be significantly lower in the HPC samples produced using SS and either GGBFS or a combination of FA and GGBFS. As a result, after 210 days of normal curing, the 100% SS concrete containing 15% FA and 35% GGBFS as a Portland cement substitution (S100F15G35 specimen) exhibited compressive and flexural strength values of 110.3 and 11.1 MPa, which were approximately 9.0% higher than the corresponding values of the reference concrete. Also, the S100F15G35 specimen registered the respective ultrasonic pulse velocity, surface electrical resistivity, and rapid chloride ion penetration values of 5328 m/s, 113.3 kΩ.cm, and 203 Coulombs, indicating high-quality and durable concrete. Moreover, incorporating 15% FA and 35% GGBFS in SS concrete resulted in a reduction of 15.7% drying shrinkage and 24.4% total material cost, especially reduced environmental impacts with a significant reduction in GWP and ODP by 43.5% and 29.2%, respectively. These findings further demonstrate the potential of using SS in combination with FA and GGBFS to create high-quality HPC that is both more economical and significantly more sustainable than conventional HPC.

Effect of High Calcium Precursor (HCP) Content on Bonding Strength of Geopolymer Concrete Exposed at Different Curing Temperatures

Geopolymer is a green cementitious binder that can be used to replace Portland cement binder and possesses exceptional physical, mechanical, and durability properties. Its mechanical properties such as bonding strength against the substrate were comparable to the Portland cement based repair products which can provide high durability and adhesive strength to the repaired structure. Geopolymer comprises two primary components which are the precursor and alkali activator. High Calcium Precursor (HCP) is the new repair material that was developed by Innovation Construction Materials (INCOM) Research Group to be used as a geopolymer’s precursor in Malaysia. In this research, the effect of HCP contents on the bonding strength of geopolymer concrete was assessed at different curing conditions. Based on the result, it was found that 100 g of HCP gave an optimum bonding strength of 21.3 MPa after 28 days of normal curing. In addition, in this research, the bonding strength also was measured after the geopolymer/substrate composite was exposed at different temperatures (60, 80, and 100 ⁰C). The bonding strength between HCP based geopolymer and the substrate does not significantly affected by the temperature’s exposure. Hence, HCP showed a high potential to be used as a precursor for geopolymer production.

Temperature effect on compressive strength and quality grading of standard grade concrete with partial replacement of natural coarse aggregate by burnt wood pellet aggregate

This research work aims to experimentally investigate the effect of temperature on the standard concrete grade of M50 with partial replacement of natural coarse aggregate by burnt wood pellet aggregate. Concrete with and without burnt wood pellet coarse aggregate was exposed to a temperature of 250℃ for 24 h after 28 days of normal curing. Partial replacement of natural coarse aggregate with burnt wood pellet aggregate was considered having varying percentages 15, 30, 45, and 60% by weight without altering the w/c ratio and dose of polycarboxylate ether-based superplasticizer. Thirty standard cylindrical specimens of size 150 mm diameter and 300 mm length for control concrete and concrete with different replacement levels of burnt wood pellet coarse aggregate were cast to study the response of this concrete in normal as well as exposed to a temperature of 250℃ in terms of strength and its quality grading. The results show that the compressive strength of concrete decreases significantly with increasing burnt wood pellet aggregate. The decrement in compressive strength incorporating burnt wood pellet aggregate is found more significant at the considered temperature than in normal conditions. However, energy dissipation after attaining the peak load increases with an increase in percentage replacement of burnt wood pellet aggregate. The concrete with 60% replacement level under ordinary condition, the quality grading of the concrete was good while with lower replacement levels it was excellent. Upon exposure to temperature, quality grading of the concretes with the lower replacement levels goes down to good however, for the concrete with a 60% replacement level it remains unaffected.

Effects of cement types and addition of quartz and limestone on the normal and carbonation curing of cement paste

Belite-rich cement (BRC) and carbonation curing are vital in the cement and construction industries for reducing carbon emissions and achieving carbon neutrality. In this study, the effects of quartz, limestone, and the type of cement (BRC and ordinary Portland cement) on the carbonation curing and normal curing of cement paste were systematically studied. The water/binder ratio was 0.5, and the replacement ratio of quartz/limestone was 20%. The experimental results showed that adding 20% quartz/limestone to BRC effectively accelerated the carbonation curing process, and the acceleration effect of quartz was more obvious than that of limestone. The compressive strength of the samples with 20% quartz and limestone added to BRC was 72 MPa and 69 MPa, respectively, after 28 days of carbonation curing. These are respectively 1.7 times and 1.6 times higher than the compressive strength of the samples under normal curing. The late-age strength mainly depended on the amount of cement and marginally depended on the addition of quartz/limestone. Quartz improved carbonation efficiency by increasing the porosity of the cement paste and providing nucleation sites for the silica gel formed during carbonation. Moreover, CH, ettringite, monocarboaluminate, and hemicarboaluminate were fully carbonated, and large amounts of alite and belite were carbonated during carbonation curing. The electrical resistivity after 28 days of carbonation curing was 38–72 times higher than its electrical resistivity after 28 days of normal curing. After carbonation curing, the quartz-blended BRC had a high resistivity of 1562 kΩ·cm. Thus, quartz is an effective supplementary material for the carbonation curing of concrete. Moreover, the combination of quartz and BRC has a greater impact on carbonation curing than the combination of limestone and BRC.

Experimental evaluation of sorptivity for high strength concrete reinforced with zirconia rich glass fiber and basalt fiber

In the abstract mentioned concrete in structures is subjected to various environmental loads such as chloride attack, sulphate attack, and gases during its life are the main idea of the authors. Concrete being weak in tension loses its tensile strength on account of these loads and distress in concrete appears in the form of cracks leading to corrosion of reinforcing steel. The service life span thus of an RCC structure is impaired. To enhance the concrete strength particularly in tension, in this research work, zirconia rich glass fiber, and basalt fiber with 1:1 combination of 12 mm and 18 mm standard cut length with 0.8, 1.2, 1.6, 2.0, and 2.4% by cement weight are used in high strength concrete. Experimental studies are performed on fresh concrete for workability and hardened concrete specimens for demoulded density, compressive strength, pulse velocity, percent voids, and sorptivity after 28 days of normal curing. It is found that 1.2% glass and basalt fiber have the same effect on the workability but a higher percentage of glass fiber produces a lower slump than basalt fiber. The optimum percentage of glass fiber and basalt fiber in this study are found to be 1.2% and 1.6% respectively which impart maximum compressive strength by 10.20% and 11.70% as compared to their reference concretes. Concrete with combined basalt fiber is found to possess a lower coefficient of sorptivity than glass fiber. The same trend has been found in the percentage voids of these concretes.

Alkali-resistant glass fiber high strength concrete and its durability parameters

The use of glass fiber in ordinary and standard concrete had been extensively investigated. Not much research work had been done on high-strength concrete with glass fiber. This research work deals with experimental investigations on the performance of alkali-resistant glass fiber of 12 mm standard cut length with varying percentages of 0.8, 1.2, 1.6, 2.0, and 2.4 by weight of cement in high-strength concrete. Investigations are conducted on fresh concrete for workability and hardened concrete specimens for compressive and tensile strengths, NDT, percent voids and sorptivity after 7 and 28 days of normal curing. It has been observed that the effect of the dose of the fiber on the workability of high strength concrete is similar to its effect on ordinary and standard grade concretes but different for compressive strength. The lower percentage of glass fiber significantly enhances strains without contributing to strength. The higher percentage of the fiber decreases the strength with a lesser increase in corresponding strain than GFRC with a lower percentage of the fiber. The percentage of the fiber which enhances its compressive strength imparts maximum tensile strength to the fibrous concrete after 28 days by 12.24, 13.13, 17.31, 15.82, and 11.94% for the fiber content of 0.8, 1.2, 1.6, 2.0, and 2.4% than non-fibrous concrete. The addition of glass fiber ranging from 0.8% to 2.4% increases the cumulative rate of water absorption and coefficient of sorptivity by 50.0, 54.9, 69.8, 92.1, and 90.6%, and 12.9, 36.3, 34.7, 55.6, and 95.1%, respectively as compared to non-fibrous concrete.

Performance evaluation of ultra-high performance concrete designed with alccofine

This paper presents a study on the development of ultra-high performance concrete (UHPC) by incorporating alccofine. Quartz powder and ground granulated blast furnace slag are used separately along with alccofine and silica fume to design UHPC mixtures. Coarse aggregates of 6 mm and 10 mm diameters are also introduced into UHPC in order to reduce the binder quantity. As part of the performance evaluation, mechanical strength properties of eight UHPC mixtures were investigated. The findings of the study indicate that UHPC containing alccofine produced improved mechanical performance relative to silica fume incorporated UHPC. The UHPC mixture containing alccofine and ground granulated blast furnace slag has produced cumulative values of 136.67 MPa, 15.2 MPa and 31.88 MPa for compressive strength, splitting tensile strength and flexural strength, respectively, at 28 days of normal curing. The use of coarse aggregates in UHPC culminated in a gradual decline in mechanical performance and an increase in slump values of the concrete. Mathematical modeling and statistical analysis were carried out using response surface model to predict the compressive strength values, compare them to experimental outcomes and check their validity. The results of this study indicate that UHPC developed by blending alccofine has yielded an overall better performance.

Strength Assessment of Hypo Sludge Concrete with Water Containing Sodium Hydroxide

This paper presents the effect of sodium hydroxide (NaOH) present in the curing water on the strength of hypo sludge cement concrete. The concrete is produced by mixing of percentage replacement of cement by hypo sludge and curing water containing NaOH of 5% concentration with constant dosages. This research paper describes the feasibility of using the hypo sludge in concrete production as partial replacement of cement by weight. The cement has been replaced by hypo sludge accordingly in the range of 0%, 10%, 20%, 30% and 40% by weight of cement for M40 mix. The compressive strengths were evaluated for 56 days of normal curing and 28 days normal and 28 days 5% NaOH contain water curing. Compressive strengths of hypo sludge Cement Concrete compared with the control specimens. By using Regression Models predict the compressive strength value and the ratio with predicted values.

EVALUATION OF ENERGY DISSIPATION IN FLEXURE FOR TWO STAGE CONCRETE

Concrete is a multiphase material and the energy dissipation in concrete is considered as the index to measure the capability of its ingredients to resist cyclic loading during its service life. This paper presents the results from an investigation conducted on the behaviour of two stage concrete (TSC) subjected to constant and gradual cyclic loading. A total of 128 samples were cast and tested at 28 days of normal curing, using mixes having water/cement ratio (w/c) of 0.55, 0.65, 0.75 and 0.80 and sand/cement ratio (s/c) of 1, 1.25, 1.5 and 2.0. Empirical approach namely ratio of energy dissipation (Rn) has been used to assess the results. In general, the results are comparable either in constant or gradual cyclic loading system regardless of the variation in w/c and s/c. It seems, however, that the rate of energy dissipation was slightly higher in the samples subjected to gradual cyclic loading.

Effect of fly ash and silica fume on rheology, compressive strength and self-compacting in cement mixtures

En esta investigación se evaluó el efecto de la adición de humo de sílice (SF) y cenizas volantes (FA) al cemento Portland ordinario (OPC) de manera individual y combinada, sobre la reología, resistencia a la compresión y capacidad de autocompactación en mezclas de cemento. Se realizó la caracterización fisicoquímica de las materias primas mediante FRX, SEM y DTP. Se hizo el análisis reológico para determinar el esfuerzo de fluencia y la viscosidad plástica. Se midió la resistencia a compresión a 7 y 28 días de curado normal. Por último, se realizó la medición de la capacidad de autocompactación por medio cono en V. Se encontró que la FA influye de manera positiva al reducir el esfuerzo de fluencia y los tiempos de prueba en la autocompactación, pero disminuye la resistencia a la compresión respecto a la muestra control. La adición de SF incrementa el esfuerzo de fluencia y los tiempos de autocompactación, pero influye de manera positiva en la resistencia a la compresión. Al analizar las combinaciones de adiciones de FA y SF los efectos de cada adición se mantienen permitiendo encontrar un rango de adición que entregó valores eficientes tanto para el desempeño en estado fresco como endurecido de las pastas.

Experimental Approach to Enhance the Indirect Split Tensile Strength for Cylindrical and Cubic Specimen for Various Fibrous Mortars under Different Environment Conditions

This experimental investigation was carried out to enhance split tensile strength in various environmental condition which is one of the important harden property of mixed fibrous reinforced mortar. Different fibres like Carbon Fibre,Glass Fibre,Polyester Fibre and Steel Fibre were used in normal mortar and tests were conducted for different proportion (i.e.0%,0.3%, 0.4%,0.6%,0.8% and 1.0%)of fibres to enhance the tensile property of mortar.For this investigation 300 cubes and 300 cylindrical specimens were casted.After the mortar specimen immersion to different types of curing for 28 days and tested after applying direct Alkaline and Acidic curing as well as high temperature effect of 200°C. In this study comparison of various fibrous mortars in different environmental condition checked out.And the strength variation in indirect split tensile strength between Cube and Cylinder were compared. It is observed that polyester fibre 0.4% by weight of cement at 28 days curing gives 46.64% increased Split tensile strength for cube specimen and 31.58% for Cylindrical Specimen. Steel Fibre has good increased split tensile strength of 15.34% for Cube Specimen and 17.32% for Cylindrical Specimen compare to plain mortar in 28 days of acidic curing after the 28 days of Normal curing in tap water and 16.44% for cube specimen and 23.55 % for Cylindrical Specimen compare to plain mortar in 28 days of direct NaCl curing.Carbon Fibre has good increased split tensile strength of 17.54% for Cube Specimen and also 21.04% for Cylindrical Specimen compare to plain mortar under the high temperature effect for 2 hours after the 28 days of Normal curing in tap water. For this research different IS codes and books were referred.

Studies on the durability of natural fibres and the effect of corroded fibres on the strength of mortar

This paper presents the results of the variation in chemical composition and tensile strength of coir, sisal, jute and Hibiscus cannabinus fibres, when they are subjected to alternate wetting and drying and continuous immersion for 60 days in three mediums (water, saturated lime and sodium hydroxide). Compressive and flexural strengths of cement mortar (1:3) specimens reinforced with dry and corroded fibres were determined after 28 days of normal curing. From the results it is observed that there is substantial reduction in the salient chemical composition of all the four fibres, after exposure in the various mediums. Coir fibres are found to retain higher percentages of their initial strength than all other fibres, after the specified period of exposure in the various mediums. The compressive and flexural strengths of all natural fibre reinforced mortar specimens using corroded fibres are less than the strength of the reference mortar (i.e. without fibres) and fibre reinforced mortar specimens reinforced with dry natural fibres.

Potential of marble dust to stabilise red tropical soils for road construction

The potential of marble dust as a stabilizing additive to red tropical soils was evaluated. The evaluation involved the determination of the geotechnical properties of three different red tropical soils in their natural state as well as when mixed with varying proportions of marble dust. The parameters tested included the particle size distribution, specific gravity, Atterberg limits, the standard compaction characteristics, the compressive strength and the California bearing ratio (CBR). The strength tests were repeated after normal 28 day curing of the treated samples and also after accelerated 24 h curing at temperatures of 40°C, 60°C and 80°C. Results showed that the geotechnical parameters of red tropical soils are improved substantially by the addition of marble dust; plasticity was reduced by 20 to 33% and strength and CBR increased by 30 to 46% and 27 to 55% respectively. The highest strength and CBR values were achieved at 8% marble dust. Results also showed that normal 28 day curing improved the strength of the marble dust-treated soil with over 80% strength gain achieved after 7 to 10 days of normal curing. Higher strength development was realised following accelerated 24 h curing at 60°C. Although these results imply marked improvement in the geotechnical parameters of red tropical soils, the higher strength developed is not enough for the improved soil to be used as a base material in the construction of heavily trafficked flexible pavements. The improved material may, however, be successfully used as base material for lightly trafficked roads and as a sub-base material for heavily trafficked roads.