نتایج جستجو برای: shrinkage cracking
تعداد نتایج: 23774 فیلتر نتایج به سال:
because thin plate reinforced concrete members such as walls and slabs are greatly influenced by the drying shrinkage, cracks can occur in these members due to the restraint of the volume change caused by drying shrinkage. therefore, the control of cracking due to drying shrinkage is very important in building construction that the thin plate members are frequently used. however, few researches...
plastic shrinkage is one of the most important parameter which must be considered in hot weather concreting. if plastic shrinkage is not prevented, cracking will be significant, especialy if silica fume is used in the mix. in this paper, the effect of silica fume in bleeding and evaporation was investigated in laboratory. the results showed that in restrained shrinkage, beside relative humidity...
In this study, the early-age strain–stress development of mixtures containing slag cement was measured on uniaxially restrained specimens using a specially designed testing frame starting right after casting. It was found that thermal deformation dominates early-age stress development in low w/cm and low slag cement paste systems. While for concrete, autogenous shrinkage is the major contributi...
Shrinkage of concrete, along with the cracking that often accompanies it, has been a continual concern of the concrete construction community.1,2 In the past 20 years or so, numerous shrinkage-reducing admixtures (SRAs) have been developed with the goal of reducing drying shrinkage and delaying or preventing cracking.2-6 Most SRAs function by reducing the surface tension of the pore solution in...
This paper presents an experimental study conducted to investigate the effect of fiber reinforcement on the mechanical properties and shrinkage cracking of recycled fine aggregate concrete (RFAC) with two types of fiber-polyvinyl alcohol (PVA) and nylon. A small fiber volume fraction, such as 0.05% or 0.1%, in RFAC with polyvinyl alcohol or nylon fibers was used for optimum efficiency in minimu...
The loss of water from hardened concrete (stored in unsaturated air) causes drying shrinkage. Shrinkage of hardened concrete is influenced by various factors in a similar manner to creep under drying conditions. High cementitious materials content, particularly fine particles will reduce bleeding, but increase long term drying shrinkage. (The time of sawing the joints for induced cracking is no...
The early age shrinkage is responsible for the early age cracking of concrete. It is very critical for durability of concrete. The change in volume of concrete due to evaporation of water or dehydration process is known as shrinkage. To reduce the early age shrinkage utilized the supplementary cementitious material (SCM) in concrete. In present research industrial and agricultural waste byprodu...
This paper presents a mixed finite element model for the nonlinear time-dependant analysis of composite beams with partial shear connection. The key idea is to consider, as a first approach, a viscoelastic/plastic model for the concrete slab in order to simulate the interaction between the time effects of concrete, such as creep and shrinkage, and the concrete cracking. Creep is taken into acco...
recent tendencies in concrete technology have been towards to high- performance concrete with a low water-cement ratio. however, high performance concretes have some problems. one of the problems is early-age cracking due to autogenous shrinkage. this study presents the results of an experimental investigation carried out to evaluate the autogenous shrinkage of high-strength concrete. accordin...
Recent tendencies in concrete technology have been towards to high- performance concrete with a low water-cement ratio. However, high performance concretes have some problems. One of the problems is early-age cracking due to autogenous shrinkage. This study presents the results of an experimental investigation carried out to evaluate the autogenous shrinkage of high-strength concrete. Accordi...
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