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Concrete and Its Application in Concrete Gravity Dam
Published in Suchintya Kumar Sur, A Practical Guide to Construction of Hydropower Facilities, 2019
Water-Cement Ratio is the most important factor that controls the concrete's properties. Water-Cement Ratio is the ratio of the weight of cement and weight of water. Water-Cement Ratio has tremendous influence on the strength of concrete. Compressive strength of concrete is inversely proportional to the Water-Cement Ratio. While the overall strength of concrete increases with a lower Water-Cement Ratio, low Water-Cement Ratios lead to high strength and low workability, while high Water-Cement Ratios lead to low strength but high workability. Water-Cement Ratio=Weight of waterWeight of cement
Precast segmental bridge construction in seismic zones
Published in Fabio Biondini, Dan M. Frangopol, Bridge Maintenance, Safety, Management, Resilience and Sustainability, 2012
Fabio Biondini, Dan M. Frangopol
The hydration curve parameters (au, P, t) in Equation 3, represent the amount of acceleration, retardation, rate and ultimate degree of hydration in different mixes, with t being relevant to the time when the acceleration stage starts, and P indicating the rate of hydration (Folliard et al. 2008). In practice, the hydration process almost always stops before the cement is totally consumed, and a degree of hydration of 100% may never be reached Taplin 1959. au has been introduced to the equation to allow for this effect to be considered in the hydration curve mathematical model. This variable is strongly affected by the water-cement ratio of the mix, though it remains unaffected by the curing temperature (Kjellsen et al. 1991, Mills 1966). Hydration curve parameters can also be computed knowing the cement chemical composition and GGBS content of each mix, using Equations 5 to 7 provided in (Schindler & Folliard 2003): where te = equivalent age at the reference temperature (Tr); au = ultimate degree of hydration; P = hydration shape parameter; t = hydration time parameter (hours).
Strength and failure of concrete
Published in Marios Soutsos, Peter Domone, Construction Materials, 2017
Increasing the volumetric proportion of aggregate in the mix will, at constant water/cement ratio, produce a relatively small increase in concrete strength (typically a 50% increase in aggregate content may result in 10% increase in strength). This has been attributed, at least in part, to the increase in aggregate concentration producing a greater number of secondary cracks prior to failure, which require greater energy, that is, higher stress, to reach fracture. This effect is valid only if the paste content remains high enough to at least fill the voids in the coarse/fine aggregate system, thereby allowing complete consolidation of the concrete. This therefore imposes a maximum limit to the aggregate content for practical concretes.
Characterization and prediction for the strength development of cement stabilized dredged sediment
Published in Marine Georesources & Geotechnology, 2021
Xiao Cheng, Yonghui Chen, Geng Chen, Bingyi Li
Horpibulsuk et al. (2005) found that W/C is a microstructure parameter, which takes into account the influence of moisture content in the mixture on the micro-fabric and the cement content required for cementing clay particles. Similar parameters are often seen in concrete and cement mixing pile projects. The water/cement ratio in concrete which is the amount ratio of water to cement, is the main parameter determining strength, durability, and a series of other major physical and mechanical properties of concrete. Clay-water/cement ratio can reflect the degree of hydration reaction in clay, which is introduced for analysis in this study, and expressed by Eq. (1): where W/C is the mass ratio of water in the clay sample to dry cement powder, is the mass of water in the clay, is the mass of dry cement added to the clay, is the natural moisture content of the clay (the mass ratio of water to dry clay) before adding cement, and is the mass of cement powder to wet clay. The W/C was calculated, ranging from 4.35 to 28.57.
Utilization of waste paper ash as supplementary cementitious material in C-25 concrete: Evaluation of fresh and hardened properties
Published in Cogent Engineering, 2021
A certain minimum quantity of water is required to be mixed with cement to ensure a complete chemical reaction between water and cement. Less water than this quantity would lead to an incomplete chemical reaction, thus resulting in the reduction of strength. Also, more water would increase the water-cement ratio and so would reduce its strength. The correct proportion of water to cement is required to achieve proper strength while using cement in structure. To get the proper amount of water, a normal consistency test of blended cement pastes was carried out. The normal consistency of blended pastes containing WPA is shown in Figure 1. The control paste or the paste without WPA had a normal consistency of 29%. All the pastes containing WPA showed normal consistency higher than the control paste. The usual range of water to cement ratio for normal consistency is between 26% and 33% (Sumit & Raut, 2013). The pastes with replacement up to 10% showed consistency within this range; however, after 10% replacement the results showed higher values of consistency.
Open-graded asphalt concrete grouted by latex modified cement mortar
Published in Road Materials and Pavement Design, 2020
Sang Luo, Xu Yang, Ke Zhong, Jun Yin
Fluidity is a very important property for cement mortar as a grouted material. In this study, the fluidity was measured via a cement mortar fluidity tester, which is a circular cone shaped container with a valve controlled outlet. The container was filled with cement mortar first and then the valve was open to allow the cement mortar to flow out. The time for the cement mortar to flow out was recorded and regarded as an indicator of the fluidity. In addition, the 7-day flexural and compressive strength of the cement mortar was also tested using the beam bending test and compressive strength test. The fluidity and the strength results are shown in Table 5. It can be seen that the fluidity of the third and fourth designs cannot meet the requirement of fluidity. The low fluidity of the third design is due to the high amount of the latex powder, which reduces the fluidity. The low fluidity of the fourth design is due to the relatively lower water cement ratio. It is well known that the water cement ratio is an important factor affecting the fluidity of cement mortar or cement concretes. The comparison between the first and the second designs shows that the fluidity was slightly compromised when some latex powder was added. However, the 7-day flexural strength was significantly increased from 1.65 MPa to 2.81 MPa, which is a remarkable improvement compared to the tensile strength of ordinary cement mortar. This is also an indication of the improvement in the flexibility of cement mortar after the addition of latex. On the other hand, the compressive strength was also improved slightly. The second design was used to prepare the latex modified cement mortar.