【摘要】：建筑垃圾尤其是其中的廢棄混凝土越來(lái)越多,已經(jīng)困擾著城市的發(fā)展。將廢棄混凝土作為骨料來(lái)源實(shí)現(xiàn)再生利用,可有效解決其作為垃圾處置導(dǎo)致的占地、污染環(huán)境等問(wèn)題,又可緩解天然骨料資源短缺的局面,還可避免因開(kāi)采山石而造成的自然生態(tài)環(huán)境破壞。再生骨料應(yīng)用于混凝土,首先要解決再生混凝土的配制問(wèn)題,其關(guān)鍵是配合比設(shè)計(jì)。一般地,由于再生骨料質(zhì)量比天然骨料差,導(dǎo)致配制出的同強(qiáng)度等級(jí)的再生混凝土質(zhì)量劣于普通混凝土,因此對(duì)再生骨料和再生混凝土進(jìn)行性能優(yōu)化具有重要的意義。本文主要基于試驗(yàn)研究的方法,并結(jié)合理論分析,對(duì)再生混凝土的強(qiáng)度影響因素、配合比設(shè)計(jì)及其改性進(jìn)行了較為深入的研究;研究了再生混凝土的細(xì)觀組成和結(jié)構(gòu),基于數(shù)值仿真方法模擬了其壓縮破壞過(guò)程,對(duì)其破壞機(jī)理和特征進(jìn)行了探討。主要工作及結(jié)論如下:對(duì)影響再生混凝土抗壓和劈拉強(qiáng)度的主要因素:水灰比、水泥強(qiáng)度等級(jí)、砂率、骨料最大粒徑、骨料級(jí)配、養(yǎng)護(hù)齡期進(jìn)行了試驗(yàn)研究。結(jié)果表明:水灰比控制在0.45±0.05是比較合適的,低于此值則再生混凝土工作性差,高于此值則強(qiáng)度將急劇下降;砂率為35%時(shí)抗壓強(qiáng)度最高;再生骨料最大粒徑為20mm時(shí)抗壓和劈拉強(qiáng)度都最高;根據(jù)最大密度曲線(xiàn)確定的再生骨料級(jí)配下的混凝土抗壓和劈拉強(qiáng)度最高;隨著養(yǎng)護(hù)齡期的增長(zhǎng),水灰比越小,抗壓和劈拉強(qiáng)度增長(zhǎng)速率越大;90d強(qiáng)度比28d強(qiáng)度均有較大幅度的增長(zhǎng);抗壓和劈拉強(qiáng)度均與灰水比大致呈線(xiàn)性關(guān)系;90d抗壓強(qiáng)度比普通混凝土低約10%�；�7d強(qiáng)度建立了再生混凝土抗壓強(qiáng)度增長(zhǎng)的預(yù)測(cè)公式。建立了再生粗骨料吸水量、(單位體積)附加用水量等同其質(zhì)量、吸水率、含水率的關(guān)系;確定了再生粗骨料混凝土和全再生骨料混凝土抗壓強(qiáng)度與灰水比之間的關(guān)系及這兩種混凝土強(qiáng)度計(jì)算中的骨料系數(shù);提出了基于附加用水量的再生混凝土配合比設(shè)計(jì)步驟和方法及“有效水灰比”和“名義水灰比”的概念。為優(yōu)化再生混凝土性能,分別從制備工藝和強(qiáng)化方法兩方面出發(fā)進(jìn)行了研究。制備工藝的研究結(jié)果表明:二次攪拌工藝不但能提高再生混凝土的抗壓和劈拉強(qiáng)度,還能改善其工作性能,且強(qiáng)度離散性小,是制備再生混凝土的一種較好的工藝,比目前廣泛應(yīng)用的普通工藝好。強(qiáng)化再生混凝土性能方面,采用了:(1)鋼纖維和粉煤灰(增強(qiáng)工作性)強(qiáng)化再生混凝土;(2)DSP和RPC漿液強(qiáng)化再生骨料;(3)DSP和RPC漿液強(qiáng)化再生混凝土等三種方法。結(jié)果表明:(1)以上三種方法均能較好地實(shí)現(xiàn)強(qiáng)化再生混凝土的抗壓和劈拉強(qiáng)度的目標(biāo);(2)對(duì)鋼纖維(粉煤灰)強(qiáng)化再生混凝土而言,鋼纖維摻量越大強(qiáng)度越高,但其工作性大大降低,需要粉煤灰來(lái)增強(qiáng)流動(dòng)性,但粉煤灰取代率不宜過(guò)高,建議小于10%,否則強(qiáng)度會(huì)有大幅度下降;(3)DSP和RPC漿液強(qiáng)化再生骨料均能顯著提高再生骨料的強(qiáng)度;(4)DSP和RPC漿液強(qiáng)化再生混凝土,均能顯著提高再生混凝土的強(qiáng)度�；炷恋暮暧^性能是由其細(xì)微觀結(jié)構(gòu)決定的,通過(guò)SEM觀察分析了再生混凝土和普通混凝土在細(xì)觀組成、砂漿內(nèi)部結(jié)構(gòu)和界面結(jié)構(gòu)上的特征,提出了改善再生混凝土界面性能的方法和途徑。采用隨機(jī)算法,建立了再生混凝土細(xì)觀模型,對(duì)其單軸壓縮破壞過(guò)程進(jìn)行了數(shù)值模擬。探討了再生粗骨料取代率、新砂漿強(qiáng)度、老砂漿強(qiáng)度和界面過(guò)渡區(qū)強(qiáng)度對(duì)再生混凝土壓縮性能的影響。討論了再生粗骨料取代率為100%情況下,新砂漿、老砂漿、新界面和老界面的相對(duì)強(qiáng)度對(duì)再生混凝土單軸壓縮破壞特征的影響;結(jié)果表明:壓縮破壞均先從最薄弱的界面處開(kāi)始;當(dāng)老界面強(qiáng)度相對(duì)最低時(shí),則再生混凝土的抗壓性能最好;當(dāng)新界面強(qiáng)度相對(duì)最低時(shí),則再生混凝土的抗壓性能最差;因此,在配制再生混凝土?xí)r要盡量提高新砂漿和新界面的強(qiáng)度。
[Abstract]:The construction waste, especially the waste concrete in it, is becoming more and more and has been bothering the development of the city. the waste concrete is used as the source of the aggregate to realize the regeneration and utilization so as to effectively solve the problems of land occupation, environmental pollution and the like caused by waste disposal, can alleviate the situation of shortage of natural aggregate resources, and can also avoid the natural ecological environment damage caused by the mining of the rock. Recycled aggregate is applied to concrete. Firstly, it is necessary to solve the preparation problem of recycled concrete, and its key is to mix proportion design. Generally, because the quality of recycled aggregate is worse than that of natural aggregate, the quality of recycled concrete with the same strength grade is inferior to that of ordinary concrete, so it is of great significance to optimize the performance of recycled aggregate and recycled concrete. Based on the method of experimental research and combined with the theoretical analysis, the influence factors on the strength of recycled concrete are studied deeply, and the microstructure and structure of recycled concrete are studied. Based on the numerical simulation method, the compression failure process is simulated, and its failure mechanism and characteristics are discussed. The main work and conclusions are as follows: The main factors influencing the compressive strength and tensile strength of recycled concrete are as follows: cement ratio, cement strength grade, sand ratio, maximum aggregate size of aggregate, aggregate gradation and curing age. The results show that the compressive strength and the tensile strength of the recycled aggregate are the highest when the maximum particle size of the recycled aggregate is 20 mm, the compressive strength and the tensile strength of the recycled aggregate are the highest when compared with the value of 0. 45 and 0. 05. The compressive strength and tensile strength of concrete are the highest according to the maximum density curve. With the increase of curing age, the smaller the tensile strength, the higher the compressive strength and the tensile strength increase, and the 90d strength has a higher strength than the 28d strength. The compressive strength and tensile strength are generally linear with ash-water ratio; 90d compressive strength is about 10% lower than that of ordinary concrete. The prediction formula of compressive strength growth of recycled concrete was established based on 7d strength. The relationship between the water absorption and water absorption and water content of recycled coarse aggregate is established. The relationship between the compressive strength and ash-water ratio of recycled coarse aggregate concrete and all-recycled aggregate concrete and the aggregate coefficient in the calculation of these two concrete strength are determined. The design steps and methods of regeneration concrete mixing ratio based on additional water consumption and the concept of 鈥渆ffective anti-inflammatory agent鈥，

本文編號(hào)：2274314