An Experimental Impact on Strength Enhancement and Properties of Concrete Using Magnetized Water

The purpose of this analysis is to improve the eminence of water as per standards and to enhance the strength of concrete by replacing the normal water through magnetized water. An experimental program is set up to test the outcome of magnetized water with variations in the time of the water passing through the magnetic field. The physical as well as chemical characteristics of water ought to be tested for pH, Total hardness, Total dissolved solids (TDS), chlorides, etc. Test to be conducted on concrete are workability also compressive strength along with different properties of concrete. For this work, magnetized water was used during the concreting of grade M25. The obtained outcomes presented that the workability of mixtures mixed by magnetized water was higher. The compressive strength along with flexural strength of the mixture by means of magnetized water for mixing was noted to be progressive than the one mixed with the non-magnetized water. Also, the Sorptivity test performed on cylindrical discs shows conclusive evidence of capillary rise through pores.

A critical review of the Water Sorptivity Index (WSI) parameter for potential durability assessment: Can WSI be considered in isolation of porosity?

ABSTRACT The Durability Index (DI) approach used in South Africa is linked to transport-related properties of the cover layer of concrete. This performance-based approach utilises three different durability-related parameters, namely Water Sorptivity Index (WSI), Oxygen Permeability Index (OPI) and Chloride Conductivity Index (CCI). In the water sorptivity test, both the sorptivity and the water-penetrable porosity of the concrete are measured. Until now, porosity has not been considered directly as a separate durability-related parameter. This paper analyses these implications and suggests that porosity should be adopted as a further index. The paper concludes that sorptivity cannot be interpreted without also reflecting the porosity value since these two parameters are inter-related. Keywords: concrete durability, durability index, water sorptivity, porosity, absorption

Air Permeability of Air-Entrained Hybrid Concrete Containing CSA Cement

This paper presents the results of research on series of concrete prepared with Portland cement CEM I 42.5R, with partial replacement of this cement with calcium sulfoaluminate cement. In part of the series, an air-entraining admixture was used. It was assumed that the mixture must remain workable for at least 45 min and to ensure that citric acid as the setting retarder was used. Compressive strength tests after 2, 7, 28, 56 and 90 days, tensile splitting strength test and sorptivity test after 28 days were performed. After 56 and 90 days, the moisture content of the specimens was determined, and Torrent air permeability was tested. Freeze-thaw scaling resistance was also investigated. It was found that the addition of 15% and 30% calcium sulfoaluminate cement results in a significant reduction in the relative humidity of the concrete, after storage under air-dry conditions and an increase in air permeability. The series with 30% calcium sulfoaluminate cement in the binder, regardless of aeration, showed significantly lower resistance to cyclic freezing in the presence of salt. A clear correlation between sorptivity, air permeability and surface scaling was not found. On the basis of a multi-criteria evaluation of the tested concrete and performed Performance Index calculations, the best parameters were achieved by concrete series C30-4.5.

Effect of Silica Fume on Mechanical and Durability Properties of Recycled Coarse Aggregate Concrete

Reusing concrete is the best choice to diminish the eagerness on mind blowing standard assets and to oblige the total of waste which is engineered in landfills. Reused concrete has been regularly used as an unbound material as a touch of dams, bases, and sub-bases. RAC has in like way been utilized as a piece of the improvement of asphalts and wastes yet in less case as the examination in this field is not the most outrageous utmost of RAC has not yet been investigated. In this investigation the reused total was utilized as supplanting with 20%, 40%, 60% and 80% by substitution of typical aggregate. Standard Ordinary Portland cement was supplanted with 10% of mineral admixture silica fume. Tests were coordinated to choose the mechanical properties and durability properties such us rapid chloride penetrability test and water sorptivity test. The results show that increasing the recycle aggregate percentage above 40% with natural aggregate, small modifications to the mix design may be adopted to secure that comparable property to natural aggregate concrete is attained

Use of Genetically Modified Bacteria to Repair Cracks in Concrete

In this paper, we studied the crack-repair by spraying bacteria-based liquid around the cracks in concrete. To enhance the repair efficiency and speed up the repair process, the transposon mutagenesis method was employed to modify the genes of Bacillus halodurans and create a mutant bacterial strain with higher efficiency of calcium carbonate productivity by catalyzing the combination of carbonate and calcium ion. The efficiency of crack-repairing in concrete by spraying two kinds of bacterial liquid was evaluated via image analysis, X-ray computed tomography (X-CT) scanning technology and the sorptivity test. The results show that the crack-repair efficiency was enhanced very evidently by spraying genetically modified bacterial-liquid as no microbiologically induced calcite precipitation (MICP) was found within the cracks for concrete samples sprayed using wild type bacterial-liquid. In addition, the crack-repair process was also shortened significantly in the case of genetically modified bacteria.

Sorptivity and Durability Assessment of Dolomite Impregnated Ternary Concrete

Traditional testing methods such as absorption test and permeability test are normally not providing accurate results of nature of concrete and there is a need for another type of test to predict the durability of concrete. In this work, industrial by-product like dolomite, marble dust and fly ash are utilized as fraction of cement replacing with 2%, 4%, 6%, 8%, and 10% dolomite, 10% fly ash and 10% marble dust by the weight of cement. The study is conducted on mix designed concrete of M30 grade and compared with conventional concrete. The specimens are casted and tested to examine various properties of concrete like compressive strength, split tensile strength, durability and sorptivity. Durability test is done by hydrochloric acid (HCl) and sulphuric acid (H2SO4 ) on dolomite powder, promising results were obtained in the sorptivity test which shows the dense nature of concrete by the usage of dolomite powder.

Self-Healing Coatings Based on Linseed-Oil-Loaded Microcapsules for Protection of Cementitious Materials

Linseed oil undergoes an oxidative drying reaction upon exposure to air, resulting in a soft film. The reaction conversion after 48 h reached 88% and 59% when it reacted at room temperature and −20 °C, respectively. Linseed-oil-loaded microcapsules were prepared using a urea-formaldehyde polymer as the shell wall material. The microcapsules were integrated into a commercially available protective coating formulation to prepare self-healing coating formulations with different capsule loadings. The coating formulations were applied on mortar specimens to prepare self-healing coatings. The effect of capsule loading on adhesion strength of the self-healing coating was studied. The self-healing function of the coating was investigated by SEM, a water sorptivity test and an accelerated carbonation test. Successful self-healing was demonstrated for both scratch and crack damage in the coatings. Low-temperature self-healing was demonstrated with a saline solution sorptivity test conducted at −20 °C. The linseed-oil-based microcapsule-type self-healing coating system is a promising candidate as a protective coating for cementitious materials.

Strength and Durability Characteristics of Steel Fibre Reinforced Geopolymer Concrete

Owing to the upturn inrepair and rehabilitation of structures that undergoes deterioration even before its intended life span; it has become necessary to study the durability properties of the structures. This paper deals with an experimental approach on the strength and durability characteristics of Geopolymer Concrete and Steel Fibre Reinforced Geopolymer Concrete with varying proportions of Fly ash, Waste Glass powder and GGBS (Ground Granulated Blast furnace Slag) as base material cured at room temperature. Sodium hydroxide (14M) and Sodium silicate are used as alkali activators. Steel fibres of length 60mm, 0.75mm diameter are used in two different proportions (0.25% and 0.50%). The results are compared with that of the Portland cement based plain and fibre reinforced control concrete. The durability characteristic involved in this study is Sorptivity test. The results reveal that Steel fibre reinforced Geopolymer concrete procures surpassing characteristics than that of Geopolymer concrete which in turn possess superior characteristics than that of conventional concrete.

Strength and Durability Behaviour of Nano Silica on High Performance Concrete

Nano silica is a fine convergent material of 10-9m size. Due to its fineness, stiffness gets increased and cracks get reduced. As nano silica is fine, the mechanical strength will be increased and the durability will also be increased. Nano silica will reduce the pores compared to nominal concrete specimens. In this to study strength and durability behaviour of M70 high performance concrete with Nano Silica as admixture partially replacing cement by 0% 5% 10% 15% 20%. The experimental investigation of sorptivity test, alkalinity measurement test, water absorption test, totally 30 cubes and 15 cylinders specimens were casting and testing for strength and durability. Specimens namely cubes, cylinders are cured for 28 days. In standard environment, after this curing period a test to analyze the strength and durability as carried out. The strength and durability start shown in increasing trend with increase in the quantity of nano silica. XRD, XRF Techniques are used to study the micro structure of the concrete. The nano silica addition reduces the pore amount and makes the concrete denser in micro structure level, which in turn increases the strength and durability.

Influence of Microwave Treatment on Properties of Concrete with Non-Cyclic Alkanes

Influence of exposure to microwave (MW) radiation of concrete with paraffin addition was presented. Specimens were exposed to MW after 7 and 28 days from casting. The exposure times were: 20 minutes and 40 minutes. Concretes were made with 1 and 3% addition of paraffin of the volume of concrete mixture. As a reference served concrete with no paraffin addition and concrete containing paraffin but not treated with MW. Paraffin was added in two forms: as a powder (fine paraffin) and as a granules (coarse paraffin). Influence of radiation on compressive and tensile splitting strength was tested as well as its impact on sorptivity and free water absorption. Exposure to MW radiation lowered the mean values of concrete compressive and tensile splitting strength maximum of about 24%. Sorptivity test results showed no general tendency and free water absorption has decreased maximum about 20%.