如何控制好混凝土工程的施工質(zhì)量

1、如何控制好混凝土工程的施工質(zhì)量 作者： 日期：15 個(gè)人收集整理 勿做商業(yè)用途如何控制好混凝土工程的施工質(zhì)量如何控制好混凝土工程的施工質(zhì)量？首先控制好原材料的質(zhì)量.其次科學(xué)配制混凝土是保證質(zhì)量的先決條件.三、抓好工地試驗(yàn)室的工作。四、混凝土試件合格，結(jié)構(gòu)物混凝土不一定全部合格。五、和易性是決定混凝土質(zhì)量的主要因素。六、混凝土澆筑振搗過程是混凝土質(zhì)量的主要環(huán)節(jié).最后強(qiáng)調(diào)，要想保證混凝土質(zhì)量，人的質(zhì)量意識(shí)也是很重要的；同時(shí)設(shè)計(jì)單位、監(jiān)理單位、施工單位共同努力才能保證混凝土的質(zhì)量。 工民建中的民用住宅、辦公樓（梁、板、拄、基礎(chǔ)），水工建筑中的廠房(基礎(chǔ)、梁、板、柱)。大壩、隧洞襯砌、渡槽、橋梁等工程

2、建筑物的結(jié)構(gòu)安全和防滲等絕大多數(shù)由混凝土和鋼筋混凝土承擔(dān)，因此混凝土的質(zhì)量在工程建筑物中顯得尤其重要。混凝土施工的工藝水平、施工隊(duì)伍的素質(zhì)、原材料的質(zhì)量等因素給混凝土施工的質(zhì)量控制帶來一定困難.本人參考資料及結(jié)合在小浪底工程混凝土施工的質(zhì)量控制經(jīng)驗(yàn),就如何搞好混凝土的質(zhì)量控制論述如下：一、          原材料的質(zhì)量控制:原材料的質(zhì)量及其波動(dòng)，對(duì)混凝土質(zhì)量及施工工藝有很大影響。如水泥強(qiáng)度的波動(dòng)，將直接影響混凝土的強(qiáng)度;各級(jí)石子超遜徑顆粒含量的變化,導(dǎo)致混凝土級(jí)配的改變,并將影響新拌混凝土的和易性，骨料

3、含水量的變化，對(duì)混凝土的水灰比影響極大。為了保證混凝土的質(zhì)量，在生產(chǎn)過程中，一定要對(duì)混凝土的原材料進(jìn)行質(zhì)量檢驗(yàn)，全部符合技術(shù)性能指標(biāo)方可應(yīng)用。骨料中含有害物質(zhì)，超過規(guī)范規(guī)定的范圍內(nèi),則會(huì)妨礙水泥水化，降低混凝土的強(qiáng)度，削弱骨料與水泥石的粘結(jié),能與水泥的水化產(chǎn)物進(jìn)行化學(xué)反應(yīng)，并產(chǎn)生有害的膨脹的物質(zhì)。如果粘土、淤泥在砂中超過3%，碎石、卵石中超過2%，則這些極細(xì)粒材料在集料表面形成包裹層，妨礙集料與水泥石的粘結(jié).它們或者以松散的顆粒出現(xiàn)，大大地增加了需水量.如使用有機(jī)雜質(zhì)的沼澤水，海水等拌制混凝土,則會(huì)在混凝土表面形成鹽霜。對(duì)混凝土集料來說，影響配合比組成變異而導(dǎo)致混凝土強(qiáng)度過大波動(dòng)的主要原因是含

4、水率，含泥量的變化和石子含粉量的影響。在混凝土生產(chǎn)過程中,對(duì)原材料的質(zhì)量控制，除經(jīng)常性的檢測(cè)外，還要求質(zhì)量控制人員隨時(shí)掌握其含量的變化規(guī)律，并擬定相應(yīng)的對(duì)策措施。如砂石的含泥量超出標(biāo)準(zhǔn)要求時(shí)，及時(shí)反饋給生產(chǎn)部門，及時(shí)篩選并采取能保證混凝土的其它有效措施。砂子含水率，通過干炒法,及時(shí)根據(jù)測(cè)定的含水率來調(diào)整混凝土配合比中的實(shí)際用水量和集料用量.對(duì)于相同標(biāo)號(hào)之間水泥活性的變異，是通過膠砂強(qiáng)度試驗(yàn)的快速測(cè)定，根據(jù)水泥活性結(jié)果予以調(diào)整混凝土的配合比.水泥、砂、石子各性能指標(biāo)必需達(dá)到規(guī)范要求。本文為互聯(lián)網(wǎng)收集，請(qǐng)勿用作商業(yè)用途本文為互聯(lián)網(wǎng)收集，請(qǐng)勿用作商業(yè)用途二、   

5、60;      科學(xué)配制混凝土是保證質(zhì)量的先決條件1、     混凝土施工配合比的換算 試驗(yàn)室所確定的配合比，其各級(jí)骨料不含有超遜徑顆粒，且以飽和面干狀態(tài).但施工時(shí),各級(jí)骨料中常含有一定量超遜徑顆粒,而且其含水量常超過飽和面干狀態(tài)。因此應(yīng)根據(jù)實(shí)測(cè)骨料超遜徑含量及砂石表面含水率，將試驗(yàn)室配合比換算為施工配合比。其目的在于準(zhǔn)確的實(shí)現(xiàn)試驗(yàn)室配合比，而不是改變?cè)囼?yàn)室配合比。調(diào)整量=（該級(jí)超徑量與遜徑量之和)（次一級(jí)超徑量+上一級(jí)遜徑量）2、混凝土施工配合比的調(diào)整試驗(yàn)室所確定的混凝土配合比，其和易性不一

6、定能與實(shí)際施工條件完全適合，或當(dāng)施工設(shè)備、運(yùn)輸方法或運(yùn)輸距離，施工氣候等條件發(fā)生變化時(shí)，所要求的混凝土坍落度也隨之改變。為保證混凝土和易性符合施工要求,需將混凝土含水率及用水量做適當(dāng)調(diào)整（保持水灰比不變）。3混凝土配合比，需滿足工程技術(shù)性能及施工工藝的要求，才能保證混凝土順利施工 及達(dá)到工程要求的強(qiáng)度等性能。水工素混凝土和少筋混凝土配制坍落度一般為35cm,配筋率超過1%的鋼筋混凝土配制坍落度一般為79cm，對(duì)于橋梁施工中的箱梁采用泵送施工 ,混凝土配制坍落度一般為1014cm，初凝時(shí)間在4小時(shí)以上，強(qiáng)度為45Mpa的緩凝早強(qiáng)混凝土;灌注樁要求配制強(qiáng)度為35Mpa，凝結(jié)時(shí)間在10小時(shí)以上,坍落

7、度一般為1822cm的大坍落度超緩凝混凝土。按通常的配制方法使混凝土達(dá)到上述工程技術(shù)性能是困難的，為改善混凝土性能，提高混凝土強(qiáng)度，達(dá)到工程各部位對(duì)混凝土各種性能的要求,在混凝土中摻入不同類型的外加劑，改善混凝土性能的科學(xué)配制,優(yōu)化混凝土的配合比,在施工中效果明顯。 灌注樁用混凝土，按通常的配制方法，當(dāng)水泥用量為420kg/m3（水灰比為 0。56）時(shí)，混凝土的強(qiáng)度才能達(dá)到35Mpa，但由于坍落度（1822cm）過大,均質(zhì)性差，和易性不好，凝結(jié)時(shí)間也達(dá)不到緩凝10h，以上的超大型緩凝要求。在配制混凝土中摻入1的減水劑優(yōu)化配合比。水泥用量每1m3混凝土可節(jié)省40公斤左右，而且在坍落度達(dá)到1822

8、cm情況下，均質(zhì)性、和易性良好，凝結(jié)時(shí)間也可以緩凝到10h以上。優(yōu)化配合比后的混凝土和易性、緩凝作用良好，在灌注樁混凝土施工中消除了卡管或斷樁等事故,保證了順利施工。并且混凝土的7天強(qiáng)度也比通常不摻外加劑配制的混凝土提高20%左右?？梢姡茖W(xué)配制混凝土，早期強(qiáng)度明顯提高,加快模板周轉(zhuǎn)，加快施工速度，其技術(shù)、經(jīng)濟(jì)綜合效益十分顯著。三、        抓好工地試驗(yàn)室的工作混凝土質(zhì)量控制的好壞與試驗(yàn)室的工作是分不開的。首先使用的原材料要符合要求，特別是砂、石材料變異性較大,試驗(yàn)室人員必需按照技術(shù)規(guī)范的要求，經(jīng)常取樣進(jìn)行檢驗(yàn),不符合

9、要求的材料杜絕使用。試驗(yàn)室必需根據(jù)工程結(jié)構(gòu)各部位對(duì)混凝土性能的要求進(jìn)行各項(xiàng)試驗(yàn)，提出性能好，成本低的混凝土配合比。水灰比是影響混凝土強(qiáng)度的一個(gè)主要因素，所以,每天工地進(jìn)行混凝土攪拌前，試驗(yàn)室必需檢驗(yàn)砂、石料的含水量，調(diào)整混凝土的用水量,以控制混凝土的水灰比，施工中當(dāng)混凝土坍落度大于規(guī)定的范圍時(shí)，不準(zhǔn)入倉(cāng)澆筑。因?yàn)槿襞渲苹炷恋脑牧腺|(zhì)量得到控制,稱量準(zhǔn)確，則坍落度變化大的原因必然是混凝土中水量的增多，這樣則水灰比變化大，必然導(dǎo)致混凝土強(qiáng)度的降低.所以在混凝土澆筑過程中工地試驗(yàn)室人員一定要經(jīng)常進(jìn)行混凝土坍落度的檢驗(yàn)，坍落度符合要求才能入倉(cāng)。四、    &#

10、160;   混凝土試件合格，結(jié)構(gòu)物混凝土不一定全部合格 合同文件中技術(shù)規(guī)范規(guī)定，混凝土的質(zhì)量是依靠混凝土試件的強(qiáng)度來評(píng)定，并代表結(jié)構(gòu)物混凝土的強(qiáng)度,這是認(rèn)為在正常施工情況下,實(shí)際工程結(jié)構(gòu)物混凝土強(qiáng)度可以表現(xiàn)出混凝土試件強(qiáng)度特性.但應(yīng)當(dāng)指出,當(dāng)結(jié)構(gòu)物混凝土澆筑成型不夠密實(shí)，或有缺陷時(shí),試件強(qiáng)度的代表性就要隨著降低，因?yàn)樵嚰w形很小，容易澆筑成型和養(yǎng)護(hù)振實(shí)。但在澆筑結(jié)構(gòu)物的混凝土?xí)r，特別是當(dāng)結(jié)構(gòu)物形狀及配筋情況復(fù)雜，混凝土運(yùn)輸入倉(cāng)條件，氣溫變化較大和施工很不方便時(shí)，就很難把結(jié)構(gòu)物各部位的混凝土澆筑成如同試件的質(zhì)量一樣，如在一座橋墩的施工過程中,橋墩混凝土設(shè)計(jì)強(qiáng)度為C25，原材

11、料檢驗(yàn)無問題，承包商在按規(guī)定取樣試件28d的強(qiáng)度均達(dá)到了27.0一28.0Mpa，按照合同技術(shù)規(guī)范要求達(dá)到了合格要求,但在工程師鉆芯取樣時(shí)混凝土的強(qiáng)度只達(dá)到了19。0Mpa，不能滿足合同要求，造成了工程返工重新澆筑。因此，結(jié)構(gòu)物的混凝土質(zhì)量只依靠試件強(qiáng)度保證是不夠的,還必需對(duì)結(jié)構(gòu)物的混凝土施工全過程進(jìn)行妥善控制，特別是對(duì)澆筑振實(shí)成型過程尤需嚴(yán)格控制。對(duì)于成品采取回彈法，射釘法，拉拔法等輔助手段進(jìn)行必要及時(shí)的檢查，對(duì)關(guān)鍵部位的結(jié)構(gòu)物，有必要進(jìn)行鉆芯取樣檢查試驗(yàn),以確?；炷两Y(jié)構(gòu)物的質(zhì)量。本文為互聯(lián)網(wǎng)收集，請(qǐng)勿用作商業(yè)用途個(gè)人收集整理，勿做商業(yè)用途五、    

12、;    和易性是決定混凝土質(zhì)量的主要因素和易性是混凝土拌和物的流動(dòng)性,粘聚性,保水性等多種性能的綜合表述.當(dāng)混凝土拌和和易性不良時(shí)，則混凝土可能振搗不實(shí)或發(fā)生離析現(xiàn)象，產(chǎn)生質(zhì)量缺陷?；炷恋暮鸵仔粤己?混凝土易振實(shí)，且不發(fā)生離析，能夠獲得均質(zhì)密實(shí)良好的混凝土澆筑質(zhì)量。通常一些人配制混凝土選用低水量、低坍落度，強(qiáng)調(diào)以振實(shí)工藝來保障混凝土質(zhì)量，其實(shí)這樣易產(chǎn)生蜂窩，孔洞等質(zhì)量缺陷.實(shí)踐表明,和易性良好的混凝土才便于振實(shí)，且應(yīng)具有大些的流動(dòng)性或可塑性，以利于澆筑振實(shí)，且應(yīng)具有較好的粘聚性和保水性，以免產(chǎn)生離析，泌水現(xiàn)象.現(xiàn)在通過摻高效減水劑來提高混凝土的和易性。六、混凝

13、土澆筑振搗過程是混凝土質(zhì)量控制的主要環(huán)節(jié) 混凝土配合比設(shè)計(jì)、原材料的質(zhì)量、配料準(zhǔn)確、攪拌均勻運(yùn)輸，澆筑振實(shí)成型，養(yǎng)護(hù)等整個(gè)施工環(huán)節(jié)中，澆筑振實(shí)成型是主要的環(huán)節(jié).在混凝土澆筑成型時(shí)，由于沒有振實(shí)所產(chǎn)生的外觀上的氣孔、麻面、蜂窩、孔洞、裂隙等質(zhì)量問題,易引起重視，但由于振搗不良，所產(chǎn)生的內(nèi)部蜂窩、孔洞所導(dǎo)致的內(nèi)在質(zhì)量問題，人們?nèi)菀缀鲆?而混凝土內(nèi)在質(zhì)量缺陷，同樣引起混凝土結(jié)構(gòu)物的破壞。所以，混凝土振搗應(yīng)引起施工人員(特別是混凝土振搗工）足夠重視，質(zhì)檢員應(yīng)采取相應(yīng)的有效措施,使混凝土振搗良好.七、        預(yù)防混凝土缺陷的發(fā)

14、生是質(zhì)量控制的重點(diǎn)混凝土工程質(zhì)量的好壞，是由設(shè)計(jì)人員、監(jiān)理人員和施工人員共同努力的結(jié)果?；炷临|(zhì)量的好壞，除外觀上的蜂窩、麻面缺陷外,主要是混凝土強(qiáng)度能否達(dá)到要求，當(dāng)混凝土強(qiáng)度達(dá)不到工程要求時(shí)，監(jiān)理人員只能要求拆毀重作。而確定混凝土強(qiáng)度常是在混凝土澆筑后第三產(chǎn)業(yè)28天進(jìn)行，并得出結(jié)論.在這段時(shí)期，還可能澆筑出大量劣質(zhì)混凝土，這樣一來，拆毀的工程量將很大。所以每一位負(fù)責(zé)質(zhì)量的人員必需注意預(yù)防質(zhì)量缺陷的發(fā)生或盡早地發(fā)現(xiàn)施工中可能出現(xiàn)的缺陷，以不誤時(shí)機(jī)地采取補(bǔ)救措施，所有的施工人員，監(jiān)理人員都應(yīng)當(dāng)隨時(shí)監(jiān)控混凝土的配制、攪拌、澆筑和養(yǎng)護(hù)等過程。監(jiān)理人員、承包商質(zhì)檢人員按時(shí)檢查配制的混凝土材料是否符合規(guī)

15、范規(guī)定的要求，檢查施工中混凝土的成份是否符合設(shè)計(jì)要求的配合比，運(yùn)輸、澆筑和養(yǎng)護(hù)是否符合施工工藝規(guī)定;同時(shí)要檢查是否按時(shí)做混凝土坍落度實(shí)驗(yàn)等，坍落度是最簡(jiǎn)易、最快速判別混凝土質(zhì)量的指標(biāo),坍落度過大，過小將會(huì)產(chǎn)生振搗不實(shí)，出現(xiàn)蜂窩、孔洞、發(fā)生離析、分層或強(qiáng)度是否按技術(shù)規(guī)范的要求做混凝土強(qiáng)度試驗(yàn),并檢查試驗(yàn)結(jié)果。特別是7d齡期的強(qiáng)度表明28天強(qiáng)度有可能低于該工程部位所要求的強(qiáng)度時(shí)，應(yīng)及時(shí)查明原因并在強(qiáng)度不合格工程部位停止混凝土施工。等到28天有試件測(cè)驗(yàn)后再定.個(gè)人收集整理,勿做商業(yè)用途文檔為個(gè)人收集整理,來源于網(wǎng)絡(luò)八、    混凝土受各種因素影響而產(chǎn)生變形也要引起足夠重

16、視.混凝土的變形主要有硬化過程的自生體積變形,濕脹干縮變形，溫度變形和在荷載作用下的變形。混凝土的濕脹干縮是由于混凝土中水分的變形而引起的，干縮裂縫產(chǎn)生的原因是:1、 混凝土成形后，養(yǎng)護(hù)不良,受到風(fēng)吹日曬，表面水分蒸發(fā)快、體積收縮受到內(nèi)部混凝土的約束,出現(xiàn)拉應(yīng)力，引起混凝土表面開裂；或者構(gòu)件水分蒸發(fā),產(chǎn)生的體積收縮受到地基或墊層的約束，而出現(xiàn)干縮裂縫。2、 混凝土構(gòu)件長(zhǎng)期露天堆放，表面濕度經(jīng)常發(fā)生劇烈變化。3、 采用含泥量多的粉砂配制混凝土。4、 混凝土受到過度振搗，表面形成水泥含量較多的砂漿層.5、 后張法預(yù)應(yīng)力構(gòu)件露天生產(chǎn)后長(zhǎng)期不張拉等。對(duì)混凝土裂縫的預(yù)防措施：（1)混凝土水泥用量、水灰比

17、和砂率不能過大，嚴(yán)格控制砂石含泥量，避免使用過量的粉砂,振搗要密實(shí)，并應(yīng)對(duì)板面進(jìn)行二次抹壓以提高混凝土抗拉強(qiáng)度，減少收縮量。(2）加強(qiáng)混凝土早期養(yǎng)護(hù)時(shí)間，長(zhǎng)期堆放的預(yù)制構(gòu)件宜覆蓋,避免曝曬，并定期適當(dāng)灑水,保持濕潤(rùn)。（3)澆筑混凝土前,將基層和模板澆水濕透。(4)混凝土澆筑后，應(yīng)及早進(jìn)行灑水養(yǎng)護(hù)；大面積混凝土宜澆完一段,養(yǎng)護(hù)一段。 大體積混凝土所產(chǎn)生的裂縫，大多數(shù)屬于溫度裂縫，其中表面裂縫又占絕大多數(shù)。由于貫穿裂縫將危及大壩安全運(yùn)行，而少數(shù)表面裂縫在一定條件下，可能繼續(xù)發(fā)展成貫穿裂縫,因此分析工程特性，壩址、氣候和工程特點(diǎn),合理地確定混凝土抗裂指標(biāo)，穩(wěn)定溫度場(chǎng),分縫分塊,溫控標(biāo)準(zhǔn)及防裂措施對(duì)于

18、保證混凝土質(zhì)量至關(guān)重要的?；炷两Y(jié)構(gòu)及構(gòu)件產(chǎn)生裂縫是一種常見的質(zhì)量通病，要進(jìn)行事先控制,從以下幾點(diǎn)注意：1、材料、半成品質(zhì)量的控制。水泥安定性良好；砂石級(jí)配通過試驗(yàn)要優(yōu)良，砂不要過細(xì),砂石含泥土、石粉不能超標(biāo)，不能使用反應(yīng)性骨料，科學(xué)地采用合理的配合比，根據(jù)外界環(huán)境溫度采用水化熱適宜的水泥。2、建筑和結(jié)構(gòu)構(gòu)造進(jìn)行檢查，結(jié)構(gòu)整體性和變形縫設(shè)置應(yīng)合理;結(jié)構(gòu)受力上，應(yīng)進(jìn)行設(shè)計(jì)斷面、應(yīng)力情況、超載、抗裂驗(yàn)算。3、施工工藝方面控制。水泥用量與用水量不宜過多；混凝土拌和要均勻;配合比控制要準(zhǔn)；澆筑要按一定順序進(jìn)行;澆筑方法要妥當(dāng)；澆筑速度不能過快，振搗要實(shí);模板不能變形、漏水漏漿;鋼筋保護(hù)層要適宜，澆筑中

19、不能碰撞鋼筋；施工縫處理好;拆模、加荷不能過早;施工不能超載；及時(shí)養(yǎng)護(hù)，不要受凍。4、注意地基變形和溫、濕度變形。5、混凝土不能受到酸堿腐蝕，火災(zāi)、高溫、地震也會(huì)使混凝土受到破壞。最后強(qiáng)調(diào)一點(diǎn),要想保證混凝土的質(zhì)量,除了上述注意事項(xiàng)外，人的質(zhì)量意識(shí)也是很重要的.人是指直接參與施工的組織者、指揮者和操作者。人作為控制的對(duì)象，是要避免產(chǎn)生失誤；作為控制的動(dòng)力,是要充分調(diào)動(dòng)人的積極性，發(fā)揮人的主導(dǎo)作用。為此，除了加強(qiáng)政治思想教育、勞動(dòng)紀(jì)律教育、職業(yè)道德教育、專業(yè)技術(shù)培訓(xùn)、健全崗位責(zé)任制外，還需要根據(jù)工程特點(diǎn)，從確保質(zhì)量出發(fā)，人的技術(shù)水平，人的心理行為，人的錯(cuò)誤行為等方面來控制人的使用。禁止無技術(shù)資質(zhì)

20、的人員上崗操作；對(duì)不懂裝懂，圖省事、碰運(yùn)氣，有意違章的行為必須及時(shí)制止?！鞍倌甏笥?jì)，質(zhì)量第一”這一指導(dǎo)思想要求人們重視工程質(zhì)量。設(shè)計(jì)單位、監(jiān)理單位、施工單位都要重視。施工單位對(duì)施工的各個(gè)環(huán)節(jié)進(jìn)行嚴(yán)格的控制,建立健全質(zhì)量管理體系和規(guī)章制度，質(zhì)量監(jiān)督機(jī)構(gòu)，對(duì)施工中的主要原材料，諸如鋼材，水泥粉煤等都要經(jīng)過嚴(yán)格的檢測(cè)，凡不合格品，一律不得用于工程，混凝土拌和物不合格，一律不得入倉(cāng)，以確保工程的質(zhì)量。試驗(yàn)，質(zhì)控各部門要基本覆蓋所有質(zhì)控點(diǎn)，不但對(duì)原材料的生產(chǎn)，進(jìn)貨，存放等各個(gè)環(huán)節(jié)進(jìn)行了質(zhì)量檢測(cè)，且把現(xiàn)場(chǎng)混凝土質(zhì)量控制作為重點(diǎn)。為保證混凝土質(zhì)量而運(yùn)做的所有生產(chǎn)單位和專職職能部門，都是一個(gè)有機(jī)的統(tǒng)一的整體,

21、試驗(yàn)室通過對(duì)每一個(gè)質(zhì)控點(diǎn)的檢測(cè)分析，及時(shí)把各種信息反饋給有關(guān)部門,發(fā)現(xiàn)一個(gè)問題，解決一個(gè)問題，使生產(chǎn)過程始終處于控制狀態(tài).為了切實(shí)解決問題,還從技術(shù)措施和管理制度約束有關(guān)部門和人員?？傊?要用人的質(zhì)量保證混凝土的質(zhì)量個(gè)人收集整理，勿做商業(yè)用途個(gè)人收集整理，勿做商業(yè)用途How to control the construction quality of concreteHow to control the construction quality of concrete？ First， control the quality of raw materials. Secondly, the pre

22、paration of concrete science is a prerequisite for quality assurance. Third， do a good job site laboratory work。 Fourth, concrete specimens qualified, not all qualified concrete structures。 Fifth， is to determine the workability of concrete quality of the main factors. VI vibrated concrete pouring p

23、rocess is a major part of the concrete quality。 Finally stressed that, in order to ensure the quality of concrete, the human sense of quality is also very important； also design units， supervision units， construction units work together to ensure the quality of concrete.Civil engineering in the resi

24、dential, office building （beams， plates and crabs, basic), hydraulic plant construction （foundation， beams， plates and columns。) Dam, tunnel lining， aqueducts, and bridges and other engineering structures such as the vast majority of safety and seepage of concrete and reinforced concrete commitments

25、， so the quality of concrete buildings in the project are particularly important。 Concrete level of technology， the quality of the construction team, the quality of raw materials， factors such as quality control of concrete construction to bring some difficulties.I refer to the information and combi

26、ne Xiaolangdi quality control of concrete construction experience, on how to improve the quality control of concrete are discussed below:First， the quality control of raw materials:The quality of raw materials and fluctuations in quality and construction technology of concrete has a great influence。

27、 Intensity fluctuations， such as cement， will directly affect the strength of concrete； Johnson Trail Super stones at all levels， changes in particle concentration, leading to concrete changes in gradation, and will affect the workability of fresh concrete， aggregate water content changes， the great

28、 impact on watercement ratio of concrete. To ensure the quality of concrete in the production process， be sure to test the quality of raw materials of concrete, all meet the technical performance indicators before application。 Aggregate containing hazardous substances， more than within the specifica

29、tion， it will hinder cement hydration, reducing the strength of concrete， aggregate and cement weakens the bond, with the cement hydration products of chemical reactions, and harmful expansion of the material。 If the clay， silt， more than 3 in the sand， gravel， pebbles, more than 2， these very fineg

30、rained material in the parcel layer formed on the surface of aggregates， aggregate and cement prevent bond. Them or to loose particles appear, greatly increased water demand。 The use of organic impurities, such as swamp water， seawater mixing concrete， the concrete surface will be Yanshuang。 Concret

31、e aggregate, the impact of the composition variation with the result than the strength of concrete is mainly due to large fluctuations in moisture content, clay content changes and the amount of stones containing powder。 In the concrete production process， quality control of raw materials， in additi

32、on to regular testing, but also requires quality control personnel keep abreast of changes of its content and develop appropriate countermeasures。 Such as sand and gravel containing mud exceeding the standard requirements, and timely feedback to the production sector， in a timely manner to ensure th

33、e concrete filter and take other effective measures。 Sand moisture content, through the Fried method， based on the determination of moisture content in time to adjust the concrete mix in the actual water consumption and aggregate consumption。 Label for the same variation between the activity of ceme

34、nt, mortar strength test by the rapid determination of activity based on the results of the cement concrete mix to be adjusted. Cement， sand and gravel necessary to meet the performance specifications.Second, the scientific preparation of concrete is a prerequisite for quality assurance1, the conver

35、sion ratio of concrete construction with Determined by laboratory mix， the levels of aggregate particles do not contain ultraJohnson Trail, and the saturated surface dry state。 But the construction， often contain a certain amount of aggregate levels of ultraThomson diameter particles, and its w

36、ater content often than saturated surface dry state。 Therefore, Johnson should be based on the measured diameter of aggregate content and gravel over the surface moisture content, will be converted into laboratory construction with the mix ratio. With the aim of achieving accurate laboratory mix, ra

37、ther than changing the laboratory mix.Adjust the volume = (volume and diameter of the Ultra Poor diameter and volume） （second one on an oversized volume + volume of Johnson Drive)2, the adjustment of concrete mixDetermined by laboratory concrete mix, the workability can not completely fit with the a

38、ctual construction conditions, or when construction equipment, transport means or transport distance， construction and climate conditions change, the required slump also change. To ensure the workability of concrete meet the construction requirements, the need to concrete moisture content and water

39、to make the appropriate adjustments (to maintain constant water-cement ratio)。3。 Concrete mix, the performance required to meet the engineering and construction technology requirements to ensure the smooth concrete construction and engineering requirements to achieve the strength and other propertie

40、s.Hydraulic plain concrete and reinforced concrete preparation of a small slump is generally 35cm, reinforcement rate of more than 1 of the preparation of reinforced concrete slump is generally 79cm， box beam bridge construction for the use of pumping construction, concrete preparation of the slump

41、is generally 1014cm, initial setting time of 4 hours or more, strength 45Mpa retarding early strength concrete； pile requires the preparation of strength 35Mpa， the setting time of 10 hours or more, the slump is generally 18 - 22cm extra retarded big slump concrete. By the usual method of preparatio

42、n to meet the engineering properties of concrete is difficult to improve concrete performance， increase strength of concrete， to project a variety of different parts of the performance requirements of concrete， in concrete mixed with different types of admixtures to improve concrete performance of s

43、cientific preparation, optimization of concrete mix, the effect is obvious in the construction.Piles of concrete, according to the usual method of preparation， when the amount of cement is 420kg/m3 (cement ratio of 0.56), the concrete strength to achieve 35Mpa， but because of the slump （18-22cm） is

44、too large, homogeneous differential ， workability is not good, can not be achieved setting time retarding 10h， more mega retarded request。 In the preparation of concrete mixed with 1% of the water reducer mix optimization。 Amount of cement per 1m3 of concrete can save 40 kg， and the slump to 18-22cm

45、 in the case, heterogeneity, good workability， setting time can be retarded to 10h or more。 After optimization of concrete mix workability， good retarding effect, the elimination of the pile concrete pile breaking the card tube or other accidents， ensure the smooth construction。 And the strength of

46、concrete than 7 days do not usually mixed with additives to improve the preparation of concrete about 20。Can be seen, the scientific preparation of concrete， early strength was increased to speed up the template working to speed up the construction speed， its technology， comprehensive economic benef

47、it is significant。Third, do a good job of work on site laboratoryQuality control of concrete quality and laboratory work are inseparable。 First use of raw materials to meet the requirements， especially sand， stone materials， the larger variability, laboratory personnel must be in accordance with the

48、 technical requirements, often sampling inspection, does not meet the requirements of the material to prevent use. Laboratories in different parts of engineering structures must be based on concrete requirements on the various tests， make good performance and low cost concrete. Water-cement ratio of

49、 concrete strength is a major factor， so the mixing of concrete on site every day before the laboratory must Jianyan sand， stone water， adjust the water consumption of concrete to control the water-cement ratio of concrete in construction when concrete slump greater than the specified range, are not

50、 allowed to warehousing pouring。 If the preparation of the raw materials for quality control of concrete, weighing accuracy， the variation in the reasons for the slump of concrete in the water must be increased, so that the water-cement ratio changes， will inevitably lead to lower concrete strength。

51、 So in the process of concrete pouring site laboratory personnel must frequently test of concrete slump， the slump to meet the requirements to warehousing.Fourth, concrete specimens qualified， not all the qualified concrete structuresTechnical specifications provided in the contract documents, concr

52、ete quality is to rely on the strength of concrete specimens to evaluate and represent the strength of concrete structure， which is considered normal construction circumstances， and the actual strength of concrete structures can exhibit strength of concrete specimens characteristics。 It should be no

53、ted that when pouring concrete structure forming dense enough, or is defective， the representation of the specimen strength will with the lower figure because the sample is small， easy to shape and conservation of the tap pouring。 However， when the pouring of concrete structures， especially when the

54、 structure complicated shapes and reinforcement, concrete transport warehousing conditions， temperature changes and construction is very convenient， it is difficult to structure into various parts of the concrete pouring as As the quality of the specimen， as in the construction process of a pier, pi

55、er design strength of concrete C25， testing of raw materials is no problem, the contractor in accordance with the provisions of 28d of the strength of the specimen sample has reached the 27.0 a 28.0Mpa, in accordance with the contract specification required to achieve the qualification requirements,

56、 but engineers, drilling core samples in the strength of concrete only reached 19。0Mpa， can not meet the contract requirements, resulting in rework the project to repouring. Therefore， the quality of concrete structures rely only on the specimen strength is not enough to guarantee, but also necessar

57、y for the construction of concrete structures to properly control the whole process， especially for pouring tap the molding process in particular should be strictly controlled. For the finished product to rebound method， nail method， drawing method and other auxiliary means necessary and timely insp

58、ections of key parts of the structure， the need for drilling core sample screening test to ensure the quality of concrete structures.Fifth, the quality of concrete workability is a major factor in the decisionWorkability of concrete mixture mobility， cohesion， water retention and other properties of

59、 the consolidated statements。 When the poor workability of concrete mixing, then the concrete may be vibrated or the occurrence of false Segregation， resulting in quality defects。 Good workability of concrete， concrete easy to tap， and do not occur segregation， to obtain homogeneous dense concrete pouring good quality。 Some people often use low water in preparing the concrete, low slump, stressed the importance tap technology to protect the concr