- 學位論文
以再生磁磚細骨材製成混凝土之研究
A Study on Recycled Concrete Using Crushed Construction Tiles as Fine Aggregates
摘要
本文以廢棄磁磚經反覆破碎後製成再生細粒料，以不同比例取代細粒料以及不同水灰比拌製成再生混凝土，探討其抗壓強度、超音波波速、受高溫後高溫殘餘抗壓強度、高溫超音波波速，並利用微觀試驗燒失量試驗探討不同細骨材取代量對混凝土之影響。 試驗結果顯示再生混凝土早期抗壓強度依照廢棄磁磚的取代比例增加而有所下降，而到中晚期各取代量的混凝土皆有很好的強度發展，其中細骨材取代25%不論是低水灰比0.4或高水灰比0.6在各個齡期的抗壓強度皆超越對照組，而其餘各取代量則在中後期抗壓強度也皆超越對照組，顯示隨著細骨材取代比例增加而增加，中後期的卜作嵐反應越來越明顯。超音波試驗可測出試體內的緻密程度，當齡期越長時超音波波速越快，顯示越到後期其試體內部越緻密相對的抗壓強度也會提升。燒失量試驗是求出水化產物多寡的方法，燒失量越大時表示其水化產物相對的也就越多，而其抗壓強度也應相對較高，這點於中後期的抗壓強度的增長趨勢可以觀察出。 高溫試驗中當溫度加熱至300℃齡期28天的抗壓強度提升的比例約是25℃的4%~16%，而當齡期達91天300℃抗壓強度提升的比例只剩25℃的0.8%~6%顯示中期因水化反應尚未發展完畢因此高溫可以加速水化反應，到了後期水化反應已經趨於完全所以抗壓強度提昇的比例較小，而當試驗溫度到440℃、580℃、800℃抗壓強度隨著溫度的上升而下降，這是因為試體內部的水化產物逐漸被分解的緣故。高溫超音波因試體內部的水分及水化產物的分解，因此波速也是隨著溫度的上昇而下降。此外發現齡期28天300℃的抗壓強度與齡期91天的抗壓強度相去不遠，為求證此結果尋找中原大學7篇碩士論文來探討，發現若取代物為粗骨材二者的抗壓強度相差比例約在10%以內；取代物若為細骨材二者的抗壓強度相差比例約在20%以內。 本次研究於試驗結果上有三點較為顯著的現象首先當細骨材取代量越多則坍度也越大，其次抗壓強度在取代量為25%時水灰比0.4及0.6抗壓強度皆超越對照組，最後當齡期達180天時隨著細骨材取代的比例越大則抗壓強度也越大。
並列摘要
The objectives of this study are to find the compressive strength and ultrasonic pulse velocity (UPV) of recycled concrete with various percentages of natural fine aggregate replaced by recycled discarded tile as well as the residual strength and residual UPV of recycled concrete subjected to elevated temperatures. The effect of various fine recycled aggregate on concrete is investigated by lost of ignition (LOI). The testing results exhibit that the earlier-age compressive strength of recycled concrete will decrease depending on the increase of discarded tiles. The experimental results reveals that recycled concrete had better long-term performance. The recycled concrete replaced with 25% discarded tile is superior than control specimen on compressive strength at all curing ages, either the cement to water ratio is 0.4 or 0.6. However, the remaining substitute amount is superior than the opposing one at the medium/late stages in terms of compressive strength, it shows that the higher ratios of substitute represent the more apparent effects at the medium/late stages of pozzolanic reaction. The result of UPV test could evaluate the density of cement paste of concrete, the longer ages it is, the faster wave speed it imposes, representing that the relative compressive strength of inner density has been increased consequently. LOI is a method to measure the amount of hydration products; bigger amount means great creation of such element, it relative compressive strength becomes incremental trend, this condition is apparent at the medium/late stages. In the high temperature test, when heating to 300℃ under 28 days age, the incremental ratio of compressive strength is that of 25℃ by 4%~16%, whereas it is by 0.8%~6% under 300℃, 91 days age. In other words, the high temperature and immature response may accelerate the hydration, at the late stage; the mature response may decelerate the promotion ratio of compressive strength. As under 440℃、580℃、800℃, the compressive strength will decrease depending on the incremental ratio of heat due to the decomposition of inner hydration products. With respect to high temperature ultrasonic, due to the decomposition of water and its hydration products, hence,the wave speed would decreases while the temperature increase. Besides, it is found that the compressive strength are close between conditions of conditions of 300℃ in the age of 28 days and 300℃ in the age of 91 days. There are seven master dissertations of Chung Yuan University to verify this outcome, and the discovery is that: in case of coarse aggregate, the difference ratio of compressive strength between the two will be within 10%; in the case of fine aggregate substitute, the ratio is within 20%. There are three relatively obvious conditions in the study, 1. The greater substitute amount of find structure it uses, the more slump it will have; 2. The compressive strength of 25% is superior than the opposing one, either ratio 0.4 or ratio 0.6; 3. At the age of 180 day, the greater substitute ratio of fine structure it has, the more compressive strength it will perform.