Abstract The pump gives a concrete the function being under construction not only being able to improve a concrete's , dense tendon structure stops vibrating or vibrating being under construction , being able to also cut down contraction , guard against a rift , improve anti-permeability , improve durability to thin-wall. But, that some projects indicate a concrete , the pump gives to add no strong , easy agent adaptability gushed spring water water and the problem isolating , grasping the bottom or the tube hardening and stopping up externally is to have happening. The main body of a book priority analyses it's the problem appearing , find the approach resolving the above-mentioned problem's.
Keywords : The pump gives a concrete problem
1 Concrete adds the agent adaptability to cement extra
(1) Cement the stability of ore mineral component whether to stability set, thereby affecting the concrete admixtures and cement adaptability.
(2) Of cement production technology, as with the shaft kiln, cooling system, the control measures in the chill how, gypsum grinding the temperature, causing cement mineral composition, crystalline state, gypsum patterns change, thereby affecting the concrete admixtures and cement adaptability.
(3) Cement additive adsorption capacity : C3A "C4AF" C3S "C2S. Cement hydration rate and directly related to mineral components.
(4) Cement stored for a period of time and the temperature dropped, concrete admixtures improve high temperature adaptability, and CaO in the air to absorb water into Ca (OH) 2, Absorption of CO2 in the air after changing into CaCO3, so that Mwo decline and alsoconcrete workability improve, make fresh concrete slump loss mitigation, the setting time of concrete slightly extended.
(5) Ordinary portland cement water demand grew in the slag cement, water retention, and the general collapse losses faster.
(6) C3A higher cement, slump loss fast, and holds the water well.
(7) Hydrophilic cement mixture holds the water well; Pozzolana cement water retention worse, easy bleeding.
(8) Temperature, humidity will directly affect the concrete admixtures and cement adaptability.
(9) Than with the sand, stone size distribution and sand, stone, water, plastic materials also affects the ratio of cement concrete admixtures adaptability.
2 Concrete prone bleeding, segregation and of the reasons for the two solutions.
2.1 Reasons
(1) Cement fineness easy to secrete large water; Cement C3A easy pil low water; Cement standards consistencey Xiao Yi Pei water; Slag than Pu Yi Si bleeding; Pozzolanic Portland Cement easy to secrete water; I fly ash-doped easy bleeding; Doped - hydrophilic admixture of cement easy bleeding.
(2) The amount of cement less bleeding.
(3) Than the low-grade cement concrete high-grade cement easy bleeding (with the content).
(4) Coordination with the class concrete, high grade cement concrete than the low-grade cement concrete more bleeding.
(5) Units of the excessive consumption of concrete easy bleeding and segregation.
(6) Strength of Concrete low levels caused by bleeding (General).
(7) The rate of small sand concrete caused by bleeding, segregation phenomenon.
(8) Consecutive Stone-size gravel than the small concrete bleeding.
(9) The concrete admixtures water retention, thickening, Bleed the poor concrete prone bleeding.
(10) Super-doped concrete admixture of concrete caused by bleeding, segregation.
2.2 Solution
(1) Is the fundamental way to reduce water consumption units.
(2) Increasing the rate of sand, the sand reasonable choice rate.
(3) Increased water, the amount of cement or doped adequate Ⅱ, Ⅲ fly ash.
(4) Continuous grading of gravel and small needle flake content.
(5) Improving the performance of concrete admixtures, it has better water, thickening, concrete or modest reduction additive (only scene), the mixing station if the lower concrete additive. Concrete also possible loss of Slump fast new problems.
3 Concrete Pumping emerged grasping the end of the compaction causes and solutions
3. 1 Cause
(1) Serious bleeding caused by the concrete grasp end or compaction (clay pot).
(2)The large amount of cement concrete caused by grasping the end of the phenomenon.
(3) Concrete additive large concrete caused by grasping the end of the phenomenon.
(4) The rate of small sand, concrete prone consolidation phenomenon.
(5) Concrete admixtures by high water rates, the high rate of secretion of water, water, thickening, Bleed the poor results caused by concrete or compacted grasping the end of the phenomenon.
3.2 Solution
(1) Reduction in the unit consumption.
(2) Increase the rate of sand.
(3) Adding an appropriate amount of admixture such as fly ash, decreasing the amount of cement.
(4) Reducing the amount of concrete admixtures.
(5) Increase the concrete admixtures bleed thickening thewater function.
4 Slump Concrete Pumping of the reasons for the loss and solutions
4.1 Reason
(1) Concrete admixtures and cement adaptability not concrete good cause faster loss of slump.
(2) Concrete additive enough retardation, formaldehyde is not ideal.
(3)The hot weather, certain additives under high temperature failure; Rapid evaporation of water; Bubble spills caused fresh concrete slump losses faster.
(4) The initial concrete slump too small, too little water units, resulting in the hydration of cement plaster solubility enough; General, sl0 ≥ 20 cm of concrete slump loss slow, on the contrary, fast.
(5) General the loss of slump speed order : high alumina cement "Portland cement" ordinary Portland cement "Slag Portland Cement" mixture of cement.
(6) Mixing station site and poor coordination, ballast cars, traffic congestion is too long, resulting in the loss of Slump Concrete too large.
4. 2 Solution
(1) Adjusting the formula of concrete admixtures, cement and make it compatible. Construction ago, must do concrete admixtures and cement test their adaptability.
(2) Adjusting the concrete mixture ratio, increase the rate of sand water, concrete initial collapse adjustment to 20 cm above.
(3) Adding a suitable fly ash instead of cement.
(4) Concrete modest increase of additive (particularly in temperature than normal temperatures much higher).
(5) Prevent excessive evaporation of water, excessive bubble spills.
(6) Use of slag cement or pozzolana cement.
(7) To improve the concrete transporter water, cooling devices.
5 Pumping concrete blocking the reasons for and solutions
5.1 Reason
(1) Concrete workability poor, segregation, concrete scattered.
(2) Concrete mixture of small slump (dry sticky).
(3) Concrete mixture grasping the end of compaction.
(4) Single-stone tablets, stone size too small diameter pipeline pumping.
(5) Needle stone flake more.
(6) Pump pressure enough, or close to sealing leakage channels.
(7) Cementitious Materials small, low rate of sand.
(8) Bend too much.
(9) Foreign body tube not topical.
(10) Mixing concrete, uneven, not cement blocks loose into water slurry.
(11) First before pumping concrete unused mortar wall lubrication.
5. 2 Solution
(1) Inspect the concrete pipes and pump close to the performance, it is in good working order.
(2) Inspect the distribution pipeline to minimize bending, in particular ≤ 90 ° elbow.
(3) Concrete pumping, must use lubrication mortar pipeline.
(4) Inspect stone size, grain shape with norms, pumping requirements.
(5) Inspection department to pump the concrete mixture workability, sand rate suitability, the availability of large cement block, whether pil mixture of water, grasping the end of compaction phenomenon, and, if so, to take appropriate measures (see concrete bleeding, segregation).
(6) Inspection department to pump concrete slump, the cohesion is whether adequate, if collapse inadequate, adequate and concrete admixture content, or to pump department adding an appropriate amount of superplasticizer, if the concrete lack of cohesion, Sand is modest rate increases or adding appropriate level of the fly ash II.
(7) The initial inspection concrete collapse whether the ≥ 20 cm, if the concrete slump losses arising from the rapid concrete block pump, concrete should first solve the problem of losses (see slump loss).
