Concrete distress is a common problem that occurs due to improper joint design, construction, and maintenance. These include pumping, spalling, faulting, corner breaks, mid-panel cracking, and blowups. These problems occur due to improper joint construction or excessive joint spacing.
A delay in placing the concrete due to traffic or job site problems, as well as hot weather conditions, may cause the concrete to begin to set prematurely. This creates a mix that may be too stiff to pump because it won't fill the pumping cylinders, causing excessive pumping pressures. Problems with the Pipeline. The entire pumping system must
Concrete Pump Blockage - Causes & Clearing - The Concrete
A delay in placing the concrete due to traffic or job site problems, as well as hot weather conditions, may cause the concrete to begin to set prematurely. This creates a mix that may be too stiff to pump because it won't fill the pumping cylinders, causing excessive pumping pressures. Problems with the Pipeline. The entire pumping system must be evaluated for the job it is to perform.
For example, joints provided in the design and installed during construction force cracks to occur in places where they are inconspicuous. Cracks that occur before hardening usually are the result of set-tlement within the concrete mass, or shrinkage of the surface (plastic-shrinkage cracks) caused by rapid loss of water while the
Expansion joint failure can happen for several reasons, but regardless concrete needs a buffer as it goes through the natural cycles of expansion and contraction. So, this has always been the case, and this is why expansion joints are necessary.
Contraction/Control Joints. Contraction/control joints are placed in concrete slabs to control random cracking. A fresh concrete mixture is a fluid, plastic mass that can be molded into virtually any shape, but as the material hardens there is a reduction in volume or shrinkage. When shrinkage is restrained by contact with supporting soils, granular fill, adjoining structures, or reinforcement within the concrete, tensile stresses develop within the concrete …
Dec 18, 2017 · The most common problem of pumping concrete is blockage. If the pump is mechanically sound, the failure of concrete to emerge at the end of the pipe line is called blockage. The increase in the pressure shown by the pressure gauge of the pump is the indication of the blockage of the pipe line. Most blockages take place or occur at the tapered sections of the pump end.
Expansion joints are full-depth, full-width joints placed at regular intervals along the pavement, usually 50 to 500 ft (15 - 150 m) with contraction joints in between. This is an out-dated practice that allows slabs to migrate and transverse contraction joints to open too wide causing joint pumping…
Pumping of Concrete: System, Working and Problems
Pumping at joints in concrete carriageway occurs in the presence of the following factors: (i) Fine-grained subgrade; (ii) Seepage of water into subgrade due to improper or inadequate drainage design; (iii) The presence of heavy vehicular loads. (more…)
Pumping of concrete is economical if the quantity of concrete required is more than about 1150 m 3 or uninterrupted supply of concrete is needed over a long period as at the beginning of each period of pumping the pipes have to be lubricated by mortar (at the rate of about 0.25 in 3 per 1000 m length of 150 mm diameter pipe) and also at the end of the operation considerable effort is needed
Apr 09, 2021 · Apr 09, 2021 · A cold joint is an adhesion-adhesion deficiency that visibly occurs at the joining surfaces of these castings into different parts at different times. The preferred situation continues without cutting and no element is incomplete. If this is not achieved, there is insufficient adhesion subsequently poured over this concrete, and a manufacturing
Why does pumping sometimes occur at joints in concrete carriageway? Pumping at joints in concrete carriageway occurs in the presence of the following factors: (i) Fine-grained subgrade; (ii) Seepage of water into subgrade due to improper or inadequate drainage …
Joints may also be sawed into the hardened concrete surface. It is important to understand that the longer sawing is delayed the higher the potential for cracks to establish themselves before sawing is complete. This means that any cracks that occur before the concrete is sawed will render the sawed joint ineffective. Timing is very important.
These tests found that expansion joints progressively close over the years causing greater openings at nearby contraction joints. This led to spalling, loss of aggregate interlock, and sealant failure, which in turn allowed water and incompressibles into the joint causing pumping, faulting, and corner breaks.
Apr 19, 2020 · Apr 19, 2020 · and corners at joints or cracks. Curling is primarily its occurrence may occur over a period of time. The terms curling and warping are used interchangeably. WHY do Concrete Slabs Curl placed on an absorptive subgrade will reduce …