1、振搗方式
1. Vibration mode
在施工過程中應(yīng)對(duì)混凝土進(jìn)行充分振搗，做到不漏振，不過振。對(duì)混凝土過振造成分層離析、表面浮漿，致使混凝土產(chǎn)生不均勻沉降收縮，在結(jié)構(gòu)厚薄交界處出現(xiàn)裂縫。漏振不利于混凝土密實(shí)，造成混凝土蜂窩、麻面等缺陷。混凝土振搗應(yīng)根據(jù)混凝土工作性，確定振搗時(shí)間。混凝土應(yīng)充分振搗，其標(biāo)志是：混凝土表面出現(xiàn)漿體，沒有氣泡溢出，混凝土充滿試模，不在顯著下沉。
In the construction process, the concrete should be fully vibrated to ensure that there is no missing vibration but no vibration. The excessive vibration of concrete results in layered segregation and floating slurry on the surface, resulting in uneven settlement and shrinkage of concrete and cracks at the junction of thickness and thickness of the structure. Leakage vibration is not conducive to concrete compaction, resulting in concrete honeycomb, pitted surface and other defects. The concrete vibration time shall be determined according to the workability of concrete. The concrete should be fully vibrated, and its signs are: the slurry appears on the surface of the concrete, there is no bubble overflow, the concrete is full of the test mold, and there is no significant subsidence.
2、二次振搗和多次抹面
2. Secondary vibration and multiple plastering
施工人員應(yīng)根據(jù)商品混凝土的特點(diǎn)，商品混凝土坍落度比較大，凝結(jié)時(shí)間比較長（一般8～12h），應(yīng)做好二次振搗和抹壓，使塑性收縮裂縫及時(shí)充分愈合。采用二次振搗可以消除因塑性沉降而引起的內(nèi)分層，阻斷因泌水而留下的連貫通道，改善骨料界面結(jié)構(gòu)，提高混凝土強(qiáng)度和抗?jié)B透能力。
According to the characteristics of commercial concrete, the slump of commercial concrete is relatively large, and the setting time is relatively long (generally 8-12h). The secondary vibration and plastering pressure should be done well to make the plastic shrinkage cracks fully heal in time. The secondary vibration can eliminate the internal delamination caused by plastic settlement, block the continuous channel left by bleeding, improve the interface structure of aggregate, and improve the strength and permeability of concrete.
在干燥的春季，混凝土摻了緩凝減水劑后，表面被風(fēng)干，水分蒸發(fā)很快，表面形成一層“硬殼”。當(dāng)氣溫較高并蒸發(fā)量大時(shí)，應(yīng)采用邊噴水霧的方法，可以解決混凝土“結(jié)殼”的現(xiàn)象。
In the dry spring, the surface of concrete is dried by air after adding high efficiency retarding and water reducing agent, and the water evaporates quickly, forming a layer of "hard shell" on the surface. When the air temperature is high and the evaporation is large, the method of spraying water at the same time should be adopted to solve the problem of concrete "crusting".
3、現(xiàn)場養(yǎng)護(hù)
3. On site maintenance
混凝土澆筑后，若表面不及時(shí)覆蓋、澆水養(yǎng)護(hù)，表面水分迅速蒸發(fā)，很容易產(chǎn)生收縮裂縫。特別在相對(duì)濕度低、風(fēng)速大的情況下，干縮更容易發(fā)生。有資料表明，當(dāng)風(fēng)速為16m/s時(shí)，混凝土中的水分蒸發(fā)速度為無風(fēng)時(shí)的四倍。
After the concrete pouring, if the surface is not covered and watered in time, the surface moisture will evaporate rapidly, which is easy to produce shrinkage cracks. Especially in the case of low relative humidity and high wind speed, drying shrinkage is more likely to occur. Some data show that when the wind speed is 16m / s, the evaporation rate of water in concrete is four times of that in the absence of wind.
目前，有些施工工地在澆筑混凝土?xí)r，不能做到及時(shí)覆蓋保溫養(yǎng)護(hù)。一般總要等到一遍抹光結(jié)束后才覆蓋，還有好多工地根本不覆蓋，或只是派人隔幾小時(shí)去澆一次水。在次抹平后，立即用塑料薄膜覆蓋，不讓水分蒸發(fā)掉，依靠混凝土自身的水分進(jìn)行保濕養(yǎng)護(hù)。需進(jìn)行第二次抹光時(shí)，揭開薄膜，抹完了仍要覆蓋好。保濕養(yǎng)護(hù)不得少于7d，抗?jié)B等有特殊要求
的工程養(yǎng)護(hù)時(shí)間不少于14d。
At present, some construction sites are unable to cover and maintain insulation in time when pouring concrete. Generally, it is necessary to wait until the last finishing time before covering. There are many construction sites that are not covered at all, or only send people to water every few hours. After the first troweling, the concrete shall be covered with plastic film immediately to prevent water from evaporating, and the concrete shall be kept moist by its own moisture. When the second troweling is needed, the film shall be uncovered and covered after finishing. The moisturizing curing time shall not be less than 7d, and the curing time of impermeability and other special requirements shall not be less than 14d.
4、拆模的時(shí)間
4. Time of formwork removal
混凝土拆模時(shí)，要注意拆模的時(shí)間及順序。對(duì)于梁、墻板等結(jié)構(gòu)應(yīng)適當(dāng)延長拆模時(shí)間，拆模后應(yīng)繼續(xù)采取措施進(jìn)行養(yǎng)護(hù)。且不易在樓板上進(jìn)行施工作業(yè)或堆放重物，以減少或避免鋼筋混凝土結(jié)構(gòu)產(chǎn)生收縮變形裂縫。
When removing concrete form, attention should be paid to the time and sequence of formwork removal. For beams, wallboards and other structures, the formwork removal time should be appropriately extended, and measures should be taken to maintain after the formwork removal. And it is not easy to carry out construction work or stack heavy objects on the floor, so as to reduce or avoid the shrinkage deformation cracks of reinforced concrete structure.
5、關(guān)于凝結(jié)的時(shí)間
5. On the time of condensation
春季氣溫多變，晝夜溫差大，晚上氣溫較低，易使凝結(jié)時(shí)間延長，應(yīng)注意做好保溫養(yǎng)護(hù)工作。商品混凝土公司也采取措施，嚴(yán)格控制坍落度及外加劑用量，特別是使用緩凝型減水劑時(shí)，更要注意溫度對(duì)混凝土凝結(jié)時(shí)間的影響。如果混凝土坍落度損失大，工作性不能滿足施工要求，請(qǐng)及時(shí)通知商品混凝土公司，進(jìn)行調(diào)整。工地不要隨意加水或添加外加劑調(diào)整混凝土坍落度，以免出現(xiàn)混凝土質(zhì)量問題。
In spring, the temperature is changeable, the temperature difference between day and night is large, and the temperature at night is low, which is easy to prolong the setting time. Commercial concrete companies also take measures to strictly control the slump and the amount of additives, especially when using retarded superplasticizer, more attention should be paid to the influence of temperature on the setting time of concrete. If the concrete slump loss is large and the workability can not meet the construction requirements, please timely inform the commercial concrete company for adjustment. Do not add water or additives at will to adjust the slump of concrete, so as to avoid concrete quality problems.
山汽官方微信
2022-12-23
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