摘要
基于改进的竖向膨胀率(εv)测试方法,获得了高强风电灌浆料0~24 h、1~7 d的εv发展全曲线;并研究了掺合料比例及组合膨胀剂比例对灌浆料εv、流动度、力学强度的影响.结果表明:灌浆料0~24 h竖向膨胀率曲线呈“四阶段”特征;在0%~20%掺量范围内提高硅灰掺量,灌浆料流动度下降,0~24 h内εv曲线峰值先增大后减小;塑性膨胀剂(PEA)对24 h内εv发展起主导作用,复掺氧化钙-硫铝酸钙双源膨胀剂(HP‑CSA)后,εv峰值减小,24 h εv下降、3 h εv增大,有利于控制24 h与3 h的εv差值;在1~7 d内,0.03%掺量的PEA即可促进HP‑CSA膨胀效能的发挥,6%以上掺量的HP‑CSA可较好补偿竖向自收缩变形而获得净膨胀灌浆料;PEA与HP‑CSA组合,可发挥时间上接力、效果上协同的膨胀调控作用,可分阶段、按需设计,从而实现对灌浆料7 d内竖向膨胀率的精细调控;随组合膨胀剂掺量增加,灌浆料初始和30 min流动度无明显变化,28 d抗压强度先增大后减小;在本文研究范围内,0.06%PEA+6%HP‑CSA是最优掺量组合.
灌浆料的微膨胀性能往往会显著影响灌浆连接部位接触的饱满程度、共同工作效应、节点承载力和耐久性等,是风电灌浆料的核心性能之
风电灌浆料的抗压强度一般设计为80~130 MP
基于以上分析,本研究首先对GB/T 50448—2015《水泥基灌浆材料应用技术规范》中εv测试方法进行了改进,使其可对风电灌浆料7 d内的εv进行分阶段精细测试,然后研究了掺合料组合(微珠+硅灰)与膨胀剂组合(PEA+HP‑CSA)对风电灌浆料0~24 h及1~7 d两阶段内εv发展曲线的影响,并进行流动度、力学强度试验,以综合分析其作用机理.在满足初始流动度不小于290 mm的条件下,使其28 d抗压强度不小于100 MPa,在此目标下实现对风电灌浆料早期膨胀性能的可设计调控.
水泥(C)为江苏产P·Ⅱ 52.5水泥;细骨料采用唐山产粒径0.850~0.300 mm(20~50目)和0.300~0.212 mm(50~70目)的石英砂,分别记作S1和S2;硅灰SF和微珠FFA均为河北唐山某厂家生产;氧化钙-硫铝酸钙双源膨胀剂HP‑CSA为天津某化学品公司生产,其矿物组
CaO | Ca4Al6O12SO4 | CaSO4 | Ca(OH)2 | CaCO3 |
---|---|---|---|---|
47 | 7 | 36 | 7 | 3 |
首先,为研究不同比例的掺合料组合对PEA 1 d内膨胀效能发挥的影响,先用20%微珠替代水泥,记为F20S0,再依次用5%、10%、15%、20%的硅灰替代微珠,分别记为F15S5、F10S10、F5S15、F0S20,共设计5个配合比,见
Mix No. | C | FFA | SF | S1 | S2 | W | PEA | RPP | DA | PS |
---|---|---|---|---|---|---|---|---|---|---|
F20S0 | 880 | 220 | 0 | 550 | 550 | 176 | 0.33 | 1.10 | 1.10 | 5.50 |
F15S5 | 880 | 165 | 55 | 550 | 550 | 176 | 0.33 | 1.10 | 1.10 | 5.50 |
F10S10 | 880 | 110 | 110 | 550 | 550 | 176 | 0.33 | 1.10 | 1.10 | 5.50 |
F5S15 | 880 | 55 | 165 | 550 | 550 | 176 | 0.33 | 1.10 | 1.10 | 5.50 |
F0S20 | 880 | 0 | 220 | 550 | 550 | 176 | 0.33 | 1.10 | 1.10 | 5.50 |
然后,从试验结果中优选强度较高、流动度达标的基础配合比,进一步研究膨胀剂组合对风电灌浆料7 d龄期内膨胀曲线的影响.其中PEA掺量wP(外掺,以胶凝材料总质量计)取0%、0.03%、0.06%,分别标记为P0、P3和P6;HP‑CSA掺量wE(内掺,以胶凝材料总质量计)取0%、3%、6%、9%,分别标记为E0、E3、E6和E9.共12个配合比,分别记为P0E0~P0E9、P3E0~P3E9、P6E0~P6E9.
1 d龄期内的竖向膨胀率εv根据GB/T 50448—2015附录A.0.6测试.在此基础上进行如

图1 竖向膨胀率测试流程
Fig.1 Flow chart of εv test
风电灌浆料初始流动度、30 min流动度参照GB/T 50448—2015附录A.0.2测试.抗压强度、抗折强度参照GB/T 17671—2021《水泥胶砂强度检验方法(ISO法)》测试.
为保证风电灌浆料εv测试结果的可靠性,选取试件F15S5,对其0~24 h内εv进行了3次重复试验,结果见

图2 试件F15S5在24 h内重复试验εv结果对比
Fig.2 Comparison of repeated test results of εv of specimen F15S5 within 24 h

图3 不同掺合料组合下风电灌浆料24 h内εv发展曲线
Fig.3 Development curve of εv of grouting material with different proportions of admixture within 24 h
Mix No. | Initial fluidity/mm | εv‑max/% | Δεv/% | tεv‑max/h | tΔεv/h |
---|---|---|---|---|---|
F20S0 | 335 | 0.227 | 0.054 | 12.13 | 9.02 |
F15S5 | 310 | 0.499 | 0.086 | 11.03 | 8.02 |
F10S10 | 275 | 0.748 | 0.111 | 10.15 | 7.50 |
F5S15 | 178 | 0.481 | 0.066 | 9.00 | 5.00 |
F0S20 | 115 | 0.126 | 0.035 | 5.72 | 2.50 |
对以上结果,结合风电灌浆料流动度与塑性膨胀发展特征相关关系做如下基础分析.硅灰的比表面积大,需水量较大,对减水剂吸附效应也较大,且本文掺量范围内硅灰起到一定的促进水泥水化的作用.单调增加硅灰掺量,即减少微珠的掺量,会削弱其滚珠促流效应,并产生增黏、早强效果,这会导致两方面的结果.一方面,硅灰掺量的增加(wSF≤10%时)提高了浆液的黏稠度,降低了浆液初始流动度,并对流动度占据主要影响.流动度下降将有利于浆液在塑性阶段滞留PEA产生的气体,减少其逸散,从而降低体系的自身模量,增大塑性膨胀效应,εv‑max和Δεv均增大;同时,在0%~10%掺量范围内,硅灰的早强作用还将促使tεv‑max和tΔεv缩短.另一方面,当硅灰掺量较高(wSF≥15%)时,硅灰的早强作用可进一步凸显出来,并占据主要影响,体系早期强度和模量发展加快,带来对初期塑性膨胀过程更高的自身约束,这也促使其快速发展窗口期和短暂回落窗口期均进一步缩短,由此引发εv‑max和Δεv逐渐减小以及tεv‑max和tΔεv继续单调减小.
由试验结果还可看出,F10S10组似乎可以相对充分地发挥PEA效能.但是,流动性也是风电灌浆料的核心指标之一.F10S10组初始流动度为275 mm,不满足GB/T 50448—2015标准要求(290 mm以上),其3 h竖向膨胀率εv‑3也不达标.综合以上分析,优选F15S5作为基础配合比,进行后续PEA与HP‑CSA组合膨胀剂调控风电灌浆料早期膨胀性能的试验研究.
不同膨胀剂组合下风电灌浆料24 h内εv发展曲线如

图4 不同膨胀剂组合下风电灌浆料24 h内εv发展曲线
Fig.4 Development curves of εv of grouting material under different dosages of composite expansive agent within 24 h
Specimen | Initial fluidity/mm | 30 min fluidity/mm | εv‑max/% | Δεv/% | tεv‑max/h | tΔεv/h | εv‑3/% | εv‑24/% | εv‑(24-3)/% |
---|---|---|---|---|---|---|---|---|---|
P0E0 | 292 | 289 | -0.004 | -0.007 | -0.003 | ||||
P0E3 | 288 | 287 | -0.008 | -0.016 | -0.008 | ||||
P0E6 | 306 | 295 | -0.006 | -0.006 | 0.000 | ||||
P0E9 | 301 | 284 | -0.010 | -0.004 | 0.007 | ||||
P3E0 | 310 | 300 | 0.499 | 0.072 | 11.5 | 6.0 | 0.013 | 0.405 | 0.392 |
P3E3 | 300 | 292 | 0.297 | 0.083 | 8.4 | 6.0 | 0.065 | 0.201 | 0.137 |
P3E6 | 292 | 292 | 0.252 | 0.086 | 8.0 | 6.0 | 0.063 | 0.163 | 0.100 |
P3E9 | 293 | 288 | 0.220 | 0.089 | 7.5 | 6.0 | 0.051 | 0.128 | 0.077 |
P6E0 | 293 | 289 | 1.476 | 0.107 | 11.5 | 7.5 | 0.302 | 1.367 | 1.065 |
P6E3 | 297 | 297 | 1.349 | 0.112 | 10.0 | 7.5 | 0.533 | 1.236 | 0.703 |
P6E6 | 300 | 288 | 1.152 | 0.124 | 9.0 | 7.5 | 0.454 | 1.021 | 0.567 |
P6E9 | 299 | 287 | 1.039 | 0.105 | 8.0 | 7.5 | 0.492 | 0.936 | 0.444 |
由
不同膨胀剂组合下风电灌浆料1~7 d竖向膨胀率曲线如

图5 不同膨胀剂组合下风电灌浆料1~7 d内ε的发展曲线
Fig.5 Development curves of ε of grouting material under different dosages of composite expansive agent within 1-7 d
综合前文,PEA掺量在0.03%~0.06%之间、HP‑CSA掺量不低于6%时,二者组合即可制备出7 d内初期显著塑性膨胀而后期微膨胀的全膨胀风电灌浆料,从而可显著提高风电灌浆料抵抗收缩开裂的性能.复掺适宜掺量的PEA和HP‑CSA,可按需实现对风电灌浆料0~24 h、1~7 d内竖向膨胀率发展的分阶段、可设计性调控.
不同膨胀剂组合对风电灌浆料流动度的影响如

图6 不同膨胀剂组合对风电灌浆料流动度的影响
Fig.6 Effects of different dosages of composite expansive agent on fluidity of grouting material
不同膨胀剂组合对风电灌浆料各龄期抗压、抗折强度的影响如图

图7 不同膨胀剂组合对风电灌浆料28 d抗压强度的影响
Fig.7 Effects of different dosages of composite expansive agent on 28 d compressive strength of grouting material

图8 不同膨胀剂组合对风电灌浆料28 d抗折强度的影响
Fig.8 Effects of different dosages of composite expansive agent on 28 d flexural strength of grouting material
在复掺条件下,P3E3各龄期抗压强度相对最高,其1、3、7、28 d抗压强度依次为25.32、69.64、83.71、112.73 MPa.但从抗压强度和早期7 d膨胀性调控两方面综合来看,P6E6为相对最优的组合.由
(1)对现行灌浆料国标规定的竖向膨胀率测试方法进行了改进,试验得到了高强风电灌浆料前7 d内竖向膨胀率随龄期发展全曲线.高强风电灌浆料0~24 h竖向膨胀率曲线服从“四阶段”模式,即潜伏期、加速发展期、短暂回落期、平稳期.
(2)微珠和硅灰总掺量为20%时,随硅灰掺量增大,其增黏、促凝、早强作用将使高强风电灌浆料初始流动度减小;竖向膨胀率峰值及其与回落平衡值的差值均先增大后减小,且均在微珠与硅灰质量比为1∶1时达到最大值;竖向膨胀率峰值时刻与回落结束时刻均提前.
(3)在塑性膨胀剂PEA的基础上复掺氧化钙-硫铝酸钙双源膨胀剂HP‑CSA,可使高强风电灌浆料竖向膨胀率峰值下降,峰值时刻和回落结束时刻均提前,还可补偿1~7 d的竖向自收缩变形.当PEA掺量为0.03%~0.06%、HP‑CSA掺量不低于6%时,二者组合可使0~7 d内高强风电灌浆料塑性阶段显著膨胀、硬化后微膨胀.PEA对高强风电灌浆料24 h内的竖向膨胀率发展起主要作用,且0.03%掺量即可促进1~7 d内HP‑CSA膨胀效能的发挥.2种膨胀剂存在一定的接力膨胀、协同膨胀的效应.复掺适宜掺量的PEA和HP‑CSA可实现对高强风电灌浆料0~24 h、1~7 d内竖向膨胀率的分阶段、可设计性调控.
(4)随组合膨胀剂掺量增大,高强风电灌浆料初始和30 min流动度无明显变化,28 d抗压强度先增大后减小.在本文研究范围内,综合高强风电灌浆料早期膨胀性能调控效果、流动度和力学强度,PEA掺量0.06%+HP‑CSA掺量6%是最优组合.基于试验结果,可合理推测PEA掺量0.03%~0.06%与HP‑CSA掺量3%~6%之间应存在合理组合,可使得高强风电灌浆料3 h竖向膨胀率以及24 h与3 h竖向膨胀率之差两个指标同时满足现行灌浆料国标技术要求.
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