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Special conditions to be considered for concrete pouring construction by trailer

2016-03-16 17:55:38

When construct by trailer concrete mixer pump in winter, the durability and strength of concrete require mixing ratio to meet To meet the construction requirements. It's important that the concrete should have good pumpability. Besides the requirements on climate, raw material, as well as the transmission ratio test, pumping work of small-size concrete pump should refer to the usage of mixture ratio of other construction technology in the industry. It's important to note that not to paraphrase or copy, so as to be consistent with own project requirement. Opposite effect shall not be produced.  

1.Different project characteristics, the requirement is not the same

Requirements to concrete for housing construction engineering and structure engineering are not the same. For example, the reservoir for the factory requires the concrete with high density and permeability resistance; however, mass concrete requires low hydration heat, in order to reduce the temperature stress cracking; generally bearing structure requires good mechanical property for the concrete. Component of rebar overcrowding requires small aggregate particle size and larger slump. Enclosure wall of building requires high-heat preservation.   

2.The influence of raw materials of mixture ratio

Hydration heat of ordinary Portland cement is too high to be used in mass concrete. But the hydration heat of slag, trass volcanic ash and flyash cement is low and applicable to be used in big volume concrete placement. But there is problem of low early strength, not applicable for early-dismantling form work. In different regions the particle size, shape and total surface area of sand-gravel material are different, affecting usage amount of cement. Different proportion of various grain size in aggregate affects aggregate grading and void fraction. The content of organic matter, impurities and moisture content in the aggregate will has different influence on concrete mixture ratio.   

3.The impact of construction work form on mixture ratio

Different material template influences concrete slump differently. Big template construction requires the concrete with suitable slump and fast growing speed on early strength. It is more suitable to adopt the plasticity of concrete concentrated mixer pumped, however, the concrete mixed by forced mixer is with small slump.

4.Cooperate relationship between coarse aggregate size and pumping pipe diameter

Ratio between maximum size of coarse aggregate and pumping pipe diameter: in case of the pumping height is below 50m, clastic rocks should not be larger than 1:3; the cobbles should not be larger than 1:2.5; in case of the pumping height is between 50~100m, coarse aggregate size should be between 1:3-1:4; in case of the pumping height is above 100m, coarse aggregate size should be between 1:4-1:5. Continuity of aggregate gradation should be good. Contents of needle flake and soft particle should be no more than 8%. No ice blocks in the aggregate in winter and etc.