【正文】 ds may be applied by brushes or pressure sprayers. A gallon will cover 200 to 300 sq ft. Concrete should be placed at a temperature not less than 40 or more than 80176。如果結(jié)構(gòu)還處于工作狀態(tài)并且環(huán)境潮濕時(shí)，會使得堵住漏洞這一工作更加困難。 操作方便 材料應(yīng)當(dāng)易混合和方便使用，這樣可以隨時(shí)填到裂縫和孔隙里去，材料最好是不粘工具，用泥刀修平時(shí)不剝落，填筑后不坍塌。 鋼筋的保護(hù) 對加勁鋼筋的保護(hù)機(jī)理取決于所使用的修復(fù)材料的類型。 5 混凝土結(jié)構(gòu)的修復(fù) 鋼筋混凝土是非常耐用的結(jié)構(gòu)材料，它需要的修復(fù)工作很少。 中國地質(zhì)大學(xué)長城學(xué)院 2021 屆畢業(yè)論文 4 ACI規(guī)范允許使用強(qiáng)度 FY=80KSI的鋼筋。對這些鋼筋表面進(jìn)行了變形處理，其目的是增加鋼筋與混凝土之間的抗滑能力。 使配筋最有效的發(fā)揮作用的基本條件是鋼筋和混凝土的變形要一致，即這兩種材料間要有足夠強(qiáng)的黏結(jié)力，以確保鋼筋和其周圍混凝土間不發(fā)生相對移動。當(dāng)預(yù)計(jì)有寒冷天氣時(shí)必須提供一些適當(dāng)?shù)姆椒▉肀３忠蟮臏囟?。出于這一目的，蓄水池應(yīng)該安裝一個通有蒸氣的蛇形管或?qū)⒄魵饪梢灾苯油ǖ剿?中，這是可以使用多個排氣口以提供良好的熱量分布。養(yǎng)生化合物可以用刷子或壓力噴嘴加到混凝土表面。 較干的混凝土減少混凝土表面處理的費(fèi)用。 當(dāng)向較深的模板中澆筑混凝土?xí)r，就應(yīng)該使用一根 導(dǎo)管來限制混凝土的自由降落高度不超過 3 或 4ft，以防止混凝土離析。 在巴基斯坦這種十分低質(zhì)量的混凝土施工技術(shù)是造成這次極廣破壞的主要原因。其表應(yīng)潮濕，但不應(yīng)有集水，應(yīng)當(dāng)在整個范圍內(nèi)刷上少量的水泥漿，然后立即鋪上一層厚度為 1/2in 的砂漿。 混凝土一澆筑完成，應(yīng)立即用手提振搗器或機(jī)器振搗器進(jìn)行搗密后就應(yīng)該移走，否則就會發(fā)生骨料離析。 較干的混合料允許較早地拆除一些模板，這樣可降低模板的造價(jià)。F以上或 80176。如果砂的表面干燥，則應(yīng)使用實(shí)線計(jì)算混凝土的溫度。另一方面，與混凝土相比，鋼材的成本要高得多。 鋼材以兩種不同方式應(yīng)用于混凝土中：普通鋼筋和預(yù)應(yīng)力鋼筋。 為了對鋼筋進(jìn)行拼接，或者便于制作置于 模板內(nèi)的鋼筋骨架所進(jìn)行的焊接，可能會引起金相的變化而降低材料的強(qiáng)度和延性，因此，必須對所有鋼材的類型和焊接規(guī)程加以特殊的限制。這是將現(xiàn)行的設(shè)計(jì)方法應(yīng)用于這類高強(qiáng)度鋼筋時(shí)必須遵守的。修復(fù)的必要性主要取決于對破壞程度的診斷。大多數(shù)的修復(fù)材料，通過使用合適的粘合手段，其粘合性能已大大地改善了，如環(huán)氧樹脂系統(tǒng)使用未填充的環(huán)氧底漆，普通水泥修復(fù)系統(tǒng)使用普通水泥稀漿加上任何一種乳膠添加劑。 修復(fù)方法的選擇 適當(dāng)?shù)男迯?fù)就是消除與結(jié)構(gòu)使用有關(guān)的所有缺陷。 修復(fù)部位的表面可能很難看，特別是當(dāng)它處于建筑物顯眼的地方時(shí)。F for 5 days after it is placed. Some proper method must be provided to keep the demanded temperature when the cold weather is estimated. 4Reinforcing steels for concrete Compared with concrete, steel is a high strength material. The useful strength of ordinary reinforcing steels in tension as well as pression, the yield strength, is about 15 times the pressive strength of mon structural concrete, and well over 100 times its tensile strength. On the other hand, steel is a highcost material pared with concrete. It follow that the two materials are the best used in bination if the. 中國地質(zhì)大學(xué)長城學(xué)院 2021 屆畢業(yè)論文 10 Concrete is made to resist the pressive stresses and the pressive force, longitudinal steel reinforcing bars are located close to the tension face to resist the tension force. and usually additional steel bars are so disposed that they resist the inclined tension stresses that are caused by the shear force in the beams. However, reinforcement is also used for resisting pressive forces primarily where it is desired to reduce the crosssectional dimensions of pression members, as in the lowerfloor columns of multistory buildings. Even if no such necessity exits , a minimum amount of reinforcement is placed in all pression members to safeguard them against the effects of small accidental bending moments that might crack and even fail an unreinforced member. For most effective reinforcing action, it is essential that steel and concrete deform together, that there be a sufficiently strong bond between the two materials to ensure that no relative movements of the steel bars and the surrounding concrete occur. This bond is provided by the relatively large chemical adhesion which develops at the steelconcrete interface, by the natural roughness of the mill scale of hotrolled reinforcing bars, and by the closely spaced ribshaped surface deformations with which reinforcing bars are furnished in order to provide a high degree of interlocking of the two materials. Steel is used in two different ways in concrete structures: as reinforcing steel and as prestressing steel .reinforcing steel is placed in the forms prior to casting of the concrete. Stresses in the steel, as in the hardened concrete, are caused only by the loads on the structure, except for possible parasitic stresses from shrinkage or similar causes. In contrast, in priestesses concrete structures large tension forces are applied to the reinforcement prior to letting it act jointly with the concrete in resisting external. The most mon type of reinforcing steel is in the form of round bars, somet