The cement temperature is too high, resulting in the loss of concrete slump too fast.

某工程在6月份浇注C30梁板过程中，发现混凝土坍落度损失很快，造成滚筒内混凝土结料。

In the process of pouring C30 beam and slab in June, it was found that the slump loss of concrete was very fast, resulting in the concreting in the roller.

原因分析：经查所进水泥温度达80℃，且水泥普遍偏细，造成需水量增大，当用水量不足时产生坍落度损失过快。

Cause analysis: the temperature of cement is 80 ℃ and the cement is generally fine, which increases the water demand. When the water consumption is insufficient, the slump loss is too fast.

防止措施：在夏秋季节5-10月份，对直接从水泥厂或粉磨站短途运输进货的水泥，必须每车测量水泥温度要小于65℃。

Preventive measures: from May to October in summer and autumn, for cement directly transported from cement plant or grinding station for short distance, the temperature of cement must be less than 65 ℃.

外加剂冬期时结晶，堵塞管道。

The additive crystallized in winter and blocked the pipeline.

在11月到次年2月份，由于气温下降较快，在外加剂泵抽料到秤斗时会出现较多结晶，堵塞管道和蝶阀，造成计量缓慢。

From November to February of the next year, due to the rapid drop of temperature, more crystals will appear when the additive pump pumps the material to the scale bucket, blocking the pipeline and butterfly valve, resulting in slow metering.

原因分析：公司在用的萘系减水剂中Na2SO4在气温较低时，达到过饱和而析出晶体。

Cause analysis: Na2SO4 in naphthalene superplasticizer used by the company reaches supersaturation and precipitates crystal at low temperature.

防止措施：与减水剂供应商协商调整减水剂配方，由含固量由32%降到20%含固量，已基本析晶问题。

Preventive measures: negotiate with the water reducing agent supplier to adjust the formula of the water reducing agent, and reduce the solid content from 32% to 20%, which has basically solved the crystallization problem.

雨水或冲水进入外加剂罐，造成浓度降低，影响混凝土坍落度。

Rainwater or flushing water into the admixture tank, resulting in the concentration reduction, affecting the concrete slump.

某日开始供应工程的混凝土出厂前由检测台检查时均发现坍落度偏小情况。

The slump of the concrete supplied on a certain day was found to be too small when it was checked by the test bench before leaving the factory.

原因分析：检查减水剂罐上方进料口被人打开后未盖好盖子，下暴雨及可能冲洗罐顶的水流入罐内，造成减水剂浓度下降。

Cause analysis: check that the feed inlet above the superplasticizer tank is not covered properly after being opened, rainstorm and water that may flush the tank top into the tank cause the concentration of superplasticizer to drop.

防止措施：进料供应商在将减水剂泵到罐内后，应及时将上方盖子盖严，材料员加强巡察。

Preventive measures: after the feed supplier pumps the superplasticizer into the tank, the upper cover shall be closed in time, and the material man shall strengthen the inspection.

将木钙减水剂误用为萘系减水剂造成缓凝。

The wood calcium superplasticizer was misused as naphthalene superplasticizer to cause retarding.

在供应某工程二层梁板时，施工单位反映凝结时间太长，浇筑后24小时仍未凝固。

In the supply of the second floor beam and slab of a project, the construction unit reflected that the setting time was too long, and it did not set 24 hours after pouring.

原因分析：经检查配合比下料记录，普通减水剂被当作减水剂输入电脑，减水剂主要以萘系为主，按粉剂掺量为0.5%～0.8%，而普通减水剂主要成分为木质素磺酸钙，掺量为0.25%～0.3%。当木钙超过胶结材料用量0.4%时就会出现严重缓凝。

Cause analysis: according to the record of mix proportion cutting, ordinary superplasticizer is input into the computer as high range superplasticizer. High range superplasticizer is mainly composed of naphthalene, with the dosage of 0.5% ~ 0.8% according to the powder, while ordinary superplasticizer is mainly composed of calcium lignosulfonate, with the dosage of 0.25% ~ 0.3%. When the amount of wood calcium exceeds 0.4% of cementitious material, serious retarding will occur.

纠正措施：使用木钙减水剂掺量应严格控制，配合比输入时必须有另外操作员复核。

Corrective measures: the dosage of wood calcium superplasticizer should be strictly controlled, and the input of mix proportion must be checked by another operator.

不同企业防水剂混合使用。

Different brands of waterproof agent mixed use.

某工程地下室外墙C40P8施工，发现一车混凝土坍落度偏大退回。

During the c40p8 construction of the basement exterior wall of a project, it was found that the slump of a truck of concrete was too large.

原因分析：经检查进货记录，同期进货的两种防水剂用于两个工程中，一种有明显减水作用，另一种减水率较少，工人在搬运袋装防水剂时出现混杂使用的情况。

Cause analysis: after checking the purchase records, two kinds of waterproof agents purchased in the same period were used in two projects, one had obvious water reducing effect, the other had less water reducing rate, and the workers used mixed waterproof agents when carrying bags.

纠正措施：每批防水剂（包含膨胀剂等）进厂时必须复检合格才能使用，仓库物资堆放应隔离和标识，不得混用。

Corrective measures: each batch of waterproof agent (including expansive agent, etc.) must be rechecked and qualified before use. Materials in the warehouse shall be isolated and marked, and shall not be mixed.

[实例6] 砂中含有大块的泥块和卵石。

[example 6] the sand contains large pieces of mud and pebbles.

在某工地泵送施工时发现泵车下料斗上有较多大块鹅卵石和泥块。

During the pumping construction in a construction site, it is found that there are many boulders and mud blocks in the hopper of the pump truck.

原因分析：砂场供应河砂在抽砂时筛网破损，抽料口插入太深，将河床底部的大块石头和泥团抽到砂中。

Cause analysis: the screen mesh of river sand supplied by sand yard was damaged during sand pumping, and the pumping hole was inserted too deep, which pumped large stones and mud masses at the bottom of riverbed into sand.

纠正措施：砂场应定期检查抽砂机筛网是否破损，公司砂石进料口及主机楼待料槽应加装隔栅，防止杂物进入混凝土。

Corrective measures: the sand yard should regularly check whether the screen of the sand extractor is damaged, and the company's sand and gravel inlet and the main building's waiting trough should be equipped with barriers to prevent debris from entering the concrete.

[实例7] 碎石含泥量超标。

[Example 7] the mud content of crushed stone exceeds the standard.

雨天后所进碎石含泥量超过1%，造成混凝土需水量增大，混凝土强度下降。

When the mud content of crushed stone exceeds 1% in rainy days, the water demand of concrete increases and the strength of concrete decreases.

原因分析：下雨后碎石破碎过程含大量砂土，振动筛分时无法分离干净。

Cause analysis: there is a large amount of sand in the process of crushed stone crushing after rain, which cannot be separated completely during vibration screening.

纠正措施：在上料码头增加冲水设备，将含泥量控制在标准范围内。不合格碎石严禁进仓。

Corrective measures: add flushing equipment in the loading dock to control the mud content within the standard range. Unqualified gravel is not allowed to enter the warehouse.

粉煤灰、矿渣质量不合格。

The quality of fly ash and slag is unqualified.

公司采购F类一级灰，进厂时细度、需水量比和烧失量等指标偶尔达不到要求；采购的S95级磨细矿粉，7天和28天活性指标偶尔达不到要求，但检测周期长。

The fineness, water demand ratio and loss on ignition of class F grade I ash purchased by the company occasionally fail to meet the requirements; The activity index of S95 grade ground ore powder purchased in 7 days and 28 days can not meet the requirements occasionally, but the detection cycle is long.

原因分析：电厂燃煤质量出现波动，粉煤灰分选设备出现故障，引起质量波动；矿渣来源不稳定，比表面积偏小。

Cause analysis: the coal quality of the power plant fluctuates, and the failure of the fly ash separation equipment causes the quality fluctuation; The source of slag is unstable and the specific surface area is small.

纠正措施：每车粉煤灰和矿渣粉进厂后应检查细度或需水量比合格才能入库。每车检测矿渣比表面积≥400㎡/kg合格才能进库，定期到供应厂抽样。

Corrective measures: each vehicle of fly ash and slag powder should be checked for fineness or water demand ratio after entering the plant, and then they can be put into storage. Only qualified slag with specific surface area of more than or equal to 400 m2 / kg can it be put into the warehouse and sampled at the supply plant regularly.

水泥、粉煤灰和矿粉等粉状物进仓前须经筛网过滤。

Cement, fly ash, mineral powder and other powder materials must be filtered through the screen before entering the warehouse.

主机楼操作员反映螺运机被杂物卡住，造成电机烧毁。

The operator of the main engine building reported that the screw conveyor was stuck by debris, causing the motor to burn down.

原因分析：散装物料进仓时，含有铁钉、钢球等球磨机中杂物，卡入螺运机间隙。

Cause analysis: when the bulk materials are put into the warehouse, there are impurities in the ball mill such as iron nails and steel balls, which are stuck into the clearance of screw conveyor.

纠正措施：所有进料管口前加装φ10mm孔径的筛网，防止大块杂物进入罐中。

Corrective action: all feed pipe orifices are equipped with φ The screen with a diameter of 10 mm can prevent large debris from entering the tank.