effect of water cement ratio on durability of concrete

According to this law the strength of concrete will not increase by simply increasing the quantity of cement unless the water cement ratio is reduced. Therefore adequate amounts need to be used to gain the best results. Hence giving rise to normal distribution curves for the compressive tests. Therefore the flowability and workability properties were the best observed for all 3 mixes, but too much water content is not good either. From table 2 the results obtained from all mixes had compacting factors between 0.70 and 0.98 hence indicating that all the tested concrete mixes would be acceptable under the BS 1881. The deflection/ flexural strength test was carried out to evaluate the strength of the concrete beam (mini beam sample) and find the failure load of the mini beam (100mm by 100mm by 500mm). Aggregates were readily weighed and placed into buckets. More water would be required in drier conditions where aggregate is not saturated. It Shows how easily the concrete can be pumped from a concrete skip into shutters, how easily the concrete will pass through the skip trap door when on casting real structure on site. M25) We all know that water cement ratio will directly affect the strength of concrete. For cylinders used for the investigation of the effect of water content on strength, the concrete was hand compacted with a tamping rod and rubber mallet. Water content = (water/cement ratio) x cement weight. Concrete was scooped out of the mixer into oiled moulds on the vibrating table (ensuring even spread). Curing concrete under water over time allows hydration to continue hence giving it strength. Left: polished section of concrete specimen. Therefore concrete pours during these seasons are not suitable as the concrete will not set. On the other hand the slump best indicates how workable the concrete is in terms of its cohesive nature and segregation of its aggregates. The mould/cone was carefully and slowly lifted vertically upwards. Water was measured into a bucket using measuring cylinders. The properties of cement and sand are listed in Table 2. With higher w/c ratio, chloride diffusion coefficient linearly increases to 157%. 13th Aug 2018 Cement content. It should also be considered that the loading Pace Rates for cubes (and cylinders were varied. Water is often added to concrete placing for easy workability and finishability in construction site. The larger water content in cement mortar leads coarse pore distribution. From the results in table 2 it shows that changing the water/cement ratio affected the compacting factor. Whereas increasing water to cement ratio, resulted in reducing the compressive strength of concrete. The water loss and saturation are presented in Figure 5 and they are plotted with measured porosity in Figure 6. For this test, cubic mortar samples (50 × 50 × 50 mm) are prepared and their weights at the age of 91 days are measured after 1-week submerged condition. The water and cement are mixed together to produce a thick paste, to which then measured out aggregates are added to. Pressure pipe (for striking cubes and cylinders), 3. For an evaluation of resistance to chloride attack, diffusion coefficient is essential for prediction of service life and quantitative understanding of chloride behavior [12, 17, 29]. Chloride diffusion coefficient is dependent on pore structure since pore can be both room for holding chloride ion and route for ion diffusion [29, 38]. Otherwise, cylinders were vibrated using a vibration table. Kwon, K.-J. Workability increases with the increase … This indicates that the mix was too wet and this affected its cohesive properties. Therefore no need for determining aggregate moisture content as aggregate is assumed to be laboratory dry to SSD. Water cement ratio of such concrete is more than 0.55. There are different kinds of slump a collapsed slump, sheared slump and a true slump. • Permeability is the contributory factor to the volume change with higher water-cement ratio … The statistical studies have shown that more than 40% structures have failed due to the corrosion of reinforcement steel. In 2 groups of pore radius (below 0.01 μm and 0.01~0.1 μm), relatively higher increasing ratio is measured with higher W/C ratios. Use of various tests bring out various properties that determine workability, for example, the compacting factor can indicate how workable in the concrete will be in terms of how easily can the concrete be vibrated and compacted. Several durability tests including strength, chloride diffusion, air permeability, saturation, and moisture diffusion are performed, and they are analyzed with changed porosity. 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