【正文】 再生骨料吸附著大量的舊砂漿，導(dǎo)致再生混凝土的彈性模量通常較低，一般為天然骨料混凝土的 70%~80%，平均降 低了 25%。干縮的增大取決于基體混凝土的性能、再生骨料質(zhì)量以及再生混凝土的配合比。 5 結(jié)語 膨脹水泥發(fā)明至今已有 70年的歷史，補(bǔ)償收縮混凝土的應(yīng)用歷史也有 50多年，從其誕生之日，其定位就是一種抗裂防滲的特種混凝土，并形成了一套較為完善的理論體系。 。近年來混凝土技術(shù)發(fā)展迅速，特別是高性能混凝土的應(yīng)用日趨廣泛，對補(bǔ)償收縮混凝土提出了更高的要求，迫切需要補(bǔ)償收縮理論有新突破，指導(dǎo)材料、設(shè)計、施工和檢驗方法有所創(chuàng)新。但如采 用較低水灰比或較高強(qiáng)度的再生骨料，試驗結(jié)果顯示，可以降低再生混凝土的干縮和徐變。再生混凝土的泊松比通常在 ~ 范圍內(nèi)。而且再生混凝土的強(qiáng)度隨再生骨料的基體混凝土強(qiáng)度的提高而上升；并隨再生骨料摻量的增加而降低，當(dāng)再生骨料的取代率小于 30%時，再生混凝土強(qiáng)度降低很少；用再生粗骨料取代天然粗骨料的再生混凝土的強(qiáng)度降低幅度較小，而用再生細(xì)骨料取代天然細(xì)骨料的再生混凝土的強(qiáng)度有較明顯的下降，各齡期均表 現(xiàn)出相同的趨勢；水灰比對再生混凝土強(qiáng)度的影響較大，隨著水灰比的減小，與天然骨料混凝土強(qiáng)度對比，再生混凝土強(qiáng)度降低的幅度越來越小。相同條件下，補(bǔ)償收縮混凝土與普通混凝土的干燥收縮落差大致相同。 養(yǎng)護(hù)條件的影響 與普通混凝土相比，補(bǔ)償收縮混凝土更需要充分的水養(yǎng)護(hù)，因為水分是其產(chǎn)生膨脹的必要因素，長期在水中養(yǎng)護(hù)的混凝土能夠獲得最大的膨脹。 32H2O]或氫氧化鈣 [Ca(OH)2]，使混凝土產(chǎn)生體積膨脹的外加劑。補(bǔ)償收縮混凝土是現(xiàn)代混凝土科學(xué)的一個重要分支，其性能獨(dú)特，是解決高性能混凝土體積穩(wěn)定性、提高混凝土耐久性的一個重要技術(shù)基礎(chǔ)，對它的研究還有待進(jìn)一步深入和完善，本文綜合闡述了補(bǔ)償收縮改性混凝土的一些基本性能。據(jù)統(tǒng)計，90 年代以來，每年全世界總體混凝土的消費(fèi)量己 超過 80 億噸。水泥混凝土結(jié)構(gòu)通常只有幾十年的生命周期，在這些結(jié)構(gòu)完成其使用功能后，舊混凝土就會被廢棄。另一方面，城市建筑業(yè)的迅速發(fā)展以及各種自然災(zāi)害產(chǎn)生了大量的廢棄混凝土垃圾?，F(xiàn)就目前比較成熟的方法是：使用膨脹劑能夠制成 C50的補(bǔ)償收縮再生混凝土。 the water cement ratio of recycled concrete strength with great effect, reducing the water cement ratio, with the natural aggregate concrete strength contrast, more and more small to reduce the strength of recycled concrete. For the recycled concrete with different strength grade, the origin and nature of the influence of recycled aggregate on the strength degree is different: preparation of high strength recycled aggregate concrete, influence on strength of recycled aggregate concrete sources and properties of recycled aggregate。 in addition, due to the hydration expansion hole filling effect of products, the large hole in cement paste is smaller, the total porosity, which can improve the pore structure of concrete, greatly improve the impermeability of concrete, therefore make shrinkage pensating concrete expansive cement in foreign countries is also known as the waterproof cement. The shrinkage pensating concrete is an important branch of modern concrete science, its unique properties, is to solve the volume stability, high performance concrete is an important technical basis to improve the durability of concrete, the research on it has yet to be further and perfect, this paper expounds some basic properties of shrinkage pensating concrete. Expansion agent Physical and chemical properties: refers to the concrete expansion agent in concrete mixing process and the cement, water mixing after hydration reaction of stringier [3CaO ? Al2O3 ? 3CaSO4 ? 32H2O] or calcium hydroxide [Ca (OH) 2], make concrete produce volume expansion admixture. Concrete expansion agent is used to prepare the expansive concrete (including shrinkage pensating concrete and self stressing concrete), shrinkage pensating concrete shrinkage and pacting concrete with, improve concrete anti permeability role pensation concrete, in civil engineering in two aspects mainly used for waterproofing and anti cracking, now use more occasions is preparation of high grade waterproof concrete and appropriate to extend the expansion joint or post cast band spacing. 4 Basic properties of shrinkage pensating concrete Material Concrete before hardening Agen