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.

今天我們就這個(gè)混凝土被退回的事情專(zhuān)門(mén) 說(shuō)一下辦法。

Today, let's talk about the solution to the return of concrete.

我們應該積極地處理被退回的混凝土，以達到科學(xué)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，均應考慮降低等級使用。 在無(wú)法降低等級使用時(shí)，應根據情況分清原因，判斷混凝土的性能，然后進(jìn)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(jīng)檢查或檢查不嚴、判斷失誤等原因，致使不合格的混凝土發(fā)往工地，造成施工方拒收。退回后，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(guò)大（或離析），應根據實(shí)際情況增加同配比的干料或稠砂漿，快速攪拌不少于90s，經(jīng)檢查無(wú)干料塊，坍落度符合設計要求，且實(shí)際水膠比不大于理論 水膠比方可出站。如果處理后坍落度小于出站要求，應加入適量外加劑調整到滿(mǎn)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(guò)小，應適當增加水泥，然后加外加劑，并強制攪拌，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(guò)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、澆筑等各種原因造成的退回混凝土，由罐車(chē)司機過(guò)磅，質(zhì)檢員根據罐車(chē)司機提供的過(guò)磅單及該罐車(chē)的皮重計算剩余方量，然后根據同等級或 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(shí)間在2h以?xún)?，處理后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%?；蛑苯咏档鸵粋€(gè)強度等級，適當增加外加劑摻量 進(jìn)行調整。延誤時(shí)間在2～4h，處理后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%?；蛑苯咏档蛢蓚€(gè)強度等級，適當增加外加劑摻量進(jìn)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，必須以降低等級后的混凝土與原等級混凝土所用原材料完全相同為基礎，且僅適用于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(shí)間超過(guò)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、若坍落度低于設計要求30～50mm，可按運輸單上的方量，每方添加0.5kg泵送劑。把接料斗部位的泵送劑沖入罐內，開(kāi)動(dòng)罐體快速旋轉3min，上車(chē)觀(guān)察混凝土拌合物 是否合適，若符合要求，即可使用?；炷猎谛读喜壑胁涣魈蕰r(shí)，應先估計罐內混凝土方量，然后按每方加1kg計算加入泵送劑數量，加泵送劑后按上述方法要求的加水、 快轉、觀(guān)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(shí)間內的混凝土，由于氣溫較高、運距較遠、壓車(chē)時(shí)間較長(cháng)等造成混凝土坍落度損失較大，可通過(guò)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(guò)外加劑*大摻量的20%。應逐漸添加，先少加，摻入后，攪拌運輸車(chē)必須快速轉動(dòng)2min左右，測定坍落度是否符合要求。 對超過(guò)初凝時(shí)間的混凝土應廢棄，不能再使用?；炷翝仓巴臅r(shí)間越長(cháng)，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.

萊州聚峰機械http://www.qirongguanjia.cn有限公司是一家專(zhuān)門(mén)生產(chǎn)混凝土攪拌站設備，混凝土攪拌車(chē)設備，以及混凝土攪拌站所需的各種配套設備的廠(chǎng)家，產(chǎn)品研發(fā)經(jīng)驗豐富，設備性能 優(yōu)良，使用壽命長(cháng)久，業(yè)界口碑良好，案例遍布各地。如果您有設備需要，請及時(shí)撥打網(wǎng)站熱線(xiàn)，聯(lián)系我們！

Laizhou Jufeng Machinery Co., Ltd http://www.qirongguanjia.cn 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!