Reason pumping concrete slump loss, slump instability problems and solutions

1. Causes

(1) concrete admixtures caused by poor compatibility with cement concrete slump loss fast

(2) The content is not enough concrete admixtures, retarding, plastic - not ideal.

(3) the hot weather, some admixture fail at high temperatures; fast evaporation; bubble caused by spills of fresh concrete slump loss quickly.

(4) initial slump of concrete is too small, too little water units.

(5) and concrete batching plant construction site coordination bad, so that the pressure tank car, traffic jam time is too long, leading to concrete slump loss is too great.

(6) concrete mixing weighing system measurement error, instability.

(7) coarse and fine aggregate moisture content changes.

(8) mixed cement storage warehouse, mixed-use.

2. Solutions

(1) The adjustment of concrete admixture formulations adapted it with cement. Before construction machinery, make sure to test the adaptability of cement and concrete admixtures.

(2) The adjustment of concrete mixer, increase or decrease the rate of sand, water, concrete adjustment to the initial slump more than 200mm.

(3) adding an appropriate amount of fly ash, instead of part of the cement.

(4) The amount of content to increase concrete admixtures, retarding admixtures adjustment component (especially when temperatures much higher temperatures than usual).

(5) to prevent excessive evaporation, bubble spills too.

(6) use of slag cement or pozzolan cement.

(7) to improve water retention, cooling device concrete truck.

Accuracy (8) metering equipment should meet the relevant requirements, and have a valid certificate issued by the legal metrology department, to strengthen the self-test to ensure accurate measurement.

(9) To strengthen aggregate moisture content testing, when changes, timely adjust the mix.

(10) into the library should cement manufacturers, varieties and labels are stored separately and use.

3. Lessons Learned

Especially for pumping concrete pumping concrete and underwater pile foundation of concrete slump loss problems. By learning experimented summed up a set with the actual situation to solve problems. Additive manufacturers such as communication to improve and adjust admixture retarding ingredients; adjust concrete construction time, avoid high temperatures not under construction; use in road construction roads far away poor situation of secondary feed additives; the use of large Volume Fly Ash Concrete Mix construction. Concrete slump loss of this thorny issue, to give greater ease. No matter what the cause of the slump caused by the smaller unable to pump or can not meet the construction requirements of the situation we can use admixture slump adjusted so as to achieve the desired slump, add water to prevent arbitrary increases Collapse off of bad habits to determine the quality of the concrete from the fundamental.