A few days ago, a customer called us to inquire. The concrete sent to the construction site by their mixing plant was returned. I don't know how to deal with it. First of all, none of us wants such a thing to happen, but in case of such a thing, how should our concrete mixing plant deal with it? I believe this is a headache for many mixing plants.
今天kaiyun就這個混凝土被退回的事情專門 說一下解決辦法。
Today, let's talk about the solution to the return of concrete.
首先kaiyun應該積極地處理被退回的混凝土，以達到科學合理地利用退回混凝土，減少廢料，增加效益。退回站內的混凝土，均應首先考慮降低等級使用。 在無法降低等級使用時，應根據情況分清原因，判斷混凝土的性能，然後進行合理的處理。
First of all, we should actively deal with the returned concrete, so as to make scientific and rational use of the returned concrete, reduce waste and increase benefits. For the concrete returned to the station, the grade shall be reduced first. When the grade cannot be reduced, the reason shall be distinguished according to the situation, the performance of concrete shall be judged, and then reasonable treatment shall be carried out.
因混凝土出站前未經檢查或檢查不嚴、判斷失誤等原因，致使不合格的混凝土發往工地，造成施工方拒收。退回後，應分以下兩種情況處理：
The unqualified concrete is sent to the construction site and rejected by the construction party due to the reasons such as the concrete is not inspected before leaving the station, lax inspection, wrong judgment and so on. After returning, it shall be handled in the following two cases:
1、坍落度過大（或離析），應根據實際情況增加同配比的幹料或稠砂漿，快速攪拌不少於90s，經檢查無幹料塊，坍落度符合設計要求，且實際水膠比不大於理論 水膠比方可出站。如果處理後坍落度小於出站要求，應加入適量外加劑調整到滿足施工要求的坍落度方可出站。
1. If the slump is too large (or segregation), the dry material or thick mortar with the same proportion shall be added according to the actual situation, and the rapid mixing shall not be less than 90s. After inspection, there is no dry material block, the slump meets the design requirements, and the actual water binder ratio is not greater than the theoretical water binder ratio, so it can leave the station. If the slump after treatment is less than the outbound requirements, an appropriate amount of admixture shall be added to adjust the slump to meet the construction requirements before outbound.
2、坍落度過小，應適當增加水泥，然後加外加劑，並強製攪拌，直到坍落度達到出站要求為止。但應注意，外加劑的摻量不得超過推薦摻量的*大值。
2. If the slump is too small, the cement shall be added appropriately, then the admixture shall be added, and forced mixing shall be carried out until the slump meets the requirements of the station. However, it should be noted that the dosage of admixture shall not exceed the * maximum value of the recommended dosage.
因運輸、泵送、澆築等各種原因造成的退回混凝土，首先由罐車司機過磅，質檢員根據罐車司機提供的過磅單及該罐車的皮重計算剩餘方量，然後根據同等級或 降低等級使用，分別采用以下處理方法：
For the returned concrete caused by transportation, pumping, pouring and other reasons, the tank truck driver shall weigh it first, and the quality inspector shall calculate the residual volume according to the weighing sheet provided by the tank truck driver and the tare weight of the tank truck, and then use it according to the same grade or lower grade, and adopt the following treatment methods respectively:
1、同等級使用，延誤時間在2h以內，處理後應保證水泥用量比原配合比提高10～15kg/m3，外加劑提高0.1%～0.3%。或直接降低一個強度等級，適當增加外加劑摻量 進行調整。延誤時間在2～4h，處理後應保證水泥用量比原配合比提高20～40kg/m3，外加劑提高0.4%～0.6%。或直接降低兩個強度等級，適當增加外加劑摻量進行調整。
1. For the same grade of use, the delay time is within 2H. After treatment, the cement dosage shall be increased by 10 ~ 15kg / m3 compared with the original mix proportion, and the admixture shall be increased by 0.1% ~ 0.3%. Or directly reduce one strength grade and appropriately increase the amount of admixture for adjustment. The delay time is 2 ~ 4H. After treatment, the cement dosage shall be increased by 20 ~ 40kg / m3 compared with the original mix proportion, and the admixture shall be increased by 0.4% ~ 0.6%. Or directly reduce two strength grades and appropriately increase the amount of admixture for adjustment.
2、降低等級使用，必須以降低等級後的混凝土與原等級混凝土所用原材料完全相同為基礎，且僅適用於C40及C40以下的混凝土的處理。
2. The use of reduced grade must be based on the fact that the raw materials of the reduced grade concrete and the original grade concrete are exactly the same, and it is only applicable to the treatment of C40 and below.
3、延誤時間超過4h，應報廢或用作非承重低等級混凝土使用。
3. If the delay time exceeds 4h, it shall be scrapped or used as non load-bearing low-grade concrete.
4、若坍落度低於設計要求30～50mm，可按運輸單上的方量，每方添加0.5kg泵送劑。把接料鬥部位的泵送劑衝入罐內，開動罐體快速旋轉3min，上車觀察混凝土拌合物 是否合適，若符合要求，即可使用。混凝土在卸料槽中不流淌時，應先估計罐內混凝土方量，然後按每方加1kg計算加入泵送劑數量，加泵送劑後按上述方法要求的加水、 快轉、觀察等步驟操作。
4. If the slump is less than 30.5kg per cubic meter, it can be pumped according to the design requirement. Flush the pumping agent at the receiving hopper into the tank, start the tank to rotate quickly for 3min, get on the vehicle and observe whether the concrete mixture is suitable. If it meets the requirements, it can be used. When the concrete does not flow in the discharge tank, the concrete volume in the tank shall be estimated first, and then the amount of pumping agent added shall be calculated by adding 1kg per square. After adding pumping agent, the operation shall be carried out according to the steps of water addition, fast rotation, observation and so on required by the above method.
在初凝時間內的混凝土，由於氣溫較高、運距較遠、壓車時間較長等造成混凝土坍落度損失較大，可通過試驗添加同型號的泵送劑或減水劑， 但添加與原先已加的總和摻量不能超過外加劑*大摻量的20%。應逐漸添加，先少加，摻入後，攪拌運輸車必須快速轉動2min左右，測定坍落度是否符合要求。 對超過初凝時間的混凝土應廢棄，不能再使用。混凝土澆築前停滯的時間越長，混凝土強度損失越嚴重，應當引起足夠重視。
For the concrete within the initial setting time, due to the high temperature, long transportation distance and long rolling time, the concrete slump loss is large. The pumping agent or water reducing agent of the same model can be added through the test, but the total amount of added and previously added shall not exceed 20% of the large amount of admixture. It shall be added gradually and less at first. After mixing, the mixer truck must rotate quickly for about 2min to determine whether the slump meets the requirements. The concrete exceeding the initial setting time shall be discarded and cannot be used again. The longer the stagnation time before concrete pouring, the more serious the loss of concrete strength, which should be paid enough attention.
萊州kaiyun機械http://www.skar-bnat.com有限公司是一家專門生產混凝土攪拌站設備，混凝土攪拌車設備，以及混凝土攪拌站所需的各種配套設備的廠家，產品研發經驗豐富，設備性能 優良，使用壽命長久，業界口碑良好，案例遍布各地。如果您有設備需要，請及時撥打網站熱線，聯係kaiyun！
Laizhou Jufeng Machinery Co., Ltd http://www.skar-bnat.com Ltd. is a manufacturer specializing in the production of concrete mixing plant equipment, concrete mixing truck equipment and various supporting equipment required by concrete mixing plant. It has rich product R & D experience, excellent equipment performance, long service life, good reputation in the industry and cases all over the world. If you need equipment, please call the website hotline in time and contact us!
