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混凝土研究
商涛平.喷射超高性能混凝土(UHPC)的制备及性能研究[J].混凝土与水泥制品,2023(8):1-5.
SHANG T P.Research on the preparation and properties of sprayed ultra-high performance concrete(UHPC)[J].China Concrete and Cement Products,2023(8):1-5.
王业民1,张 贤1,卢晓磊2,杜 鹏2,*
摘 要:基于水灰比对硫铝酸盐水泥(SAC)修补砂浆界面弯拉强度的影响,确定了SAC修补砂浆最佳配合比,并研究了增大粗糙度、不同溶液浸润的界面处理方式对SAC修补砂浆新旧界面弯拉强度的影响。结果表明:SAC修补砂浆的3 d界面弯拉强度随着水灰比的减小逐渐增大,当水灰比为0.35时,SAC修补砂浆界面弯拉强度达到最高,为3.82 MPa;对界面进行粗糙处理可显著提高SAC修补砂浆1、3、28 d新旧界面弯拉强度,相较于界面未进行处理组分别提高了1.03、1.08、0.64 MPa;与粗糙处理方式相比,对界面进行水浸润或碱溶液浸润处理均对SAC修补砂浆的新旧界面弯拉强度不利。
Abstract: Based on the influence of water cement-ratio on the interfacial flexural-tensile strength of SAC repairing mortar, the optimal mix proportion of SAC repairing mortar was determined, and the influence of interface treatment methods of increasing roughness and different solution infiltration on the interfacial flexural-tensile strength of SAC repairing mortar was studied. The results show that the 3 d interfacial flexural-tensile strength of SAC repairing mortar gradually increases with the decrease of water-cement ratio. When the water-cement ratio is 0.35, the interfacial flexural-tensile strength of the SAC repairing mortar reaches the highest, which is 3.82 MPa. Roughening the interface can significantly improve the new old interfacial flexural-tensile strength of SAC repairing mortar at 1, 3, 28 d, which is 1.03, 1.08, 0.64 MPa higher than that of the untreated group, respectively. Compared with the rough treatment method, water immersion or alkali solution immersion treatment on the interface is not conducive to the new old interfacial flexural-tensile strength of SAC repairing mortar.
王业民,张贤,卢晓磊,等.界面处理方式对硫铝酸盐水泥修补砂浆黏结性能的影响[J].混凝土与水泥制品,2023(8):6-9,14.
WANG Y M,ZHANG X,LU X L,et al.Influence of interface treatment methods on bonding performance of sulphoaluminate cement repairing mortar[J].China Concrete and Cement Products,2023(8):6-9,14.
左彦峰1,2,姚 越1,2,宋天威1,2
摘 要:采用非接触电阻率测定仪测定了掺聚羧酸高性能减水剂(PC)水泥浆体的电阻率。结果表明:在水化早期(<800 min),掺入PC的水泥浆体电阻率较空白组低,之后PC掺量较低(0.05%)的水泥浆体电阻率超过了空白组,1 160 min后,PC掺量0.15%的水泥浆体电阻率也超过了PC掺量0.10%的水泥浆体,且继续增加PC掺量,水泥浆体的电阻率下降;增加PC掺量可以延后水泥浆体的电阻率变化率峰值的出现;在溶解阶段(约0~120 min)中,随PC掺量的增加,电阻率的变化率逐渐下降,水泥水化的瞬时电阻率先增加后降低;掺PC的水泥浆体电阻率最低点出现时间逐渐延长,掺入PC后,0~40 min内水泥浆体瞬时电阻率变化率的绝对值增加。
Abstract: The electrical resistivity of cement pastes with polycarboxylate superplasticizer (PC) was measured by non-contacted electrical resistivity measurement. The results show that in the early stage of hydration(<800 min), the electrical resistivity of the cement paste added with PC is lower than that of the blank group. Afterwards, the electrical resistivity of the cement paste with a lower PC content(0.05%) exceeds that of the blank group. After 1 160 min, the electrical resistivity of the cement paste with a PC content of 0.15% also exceeds that of the cement paste with a PC content of 0.10%. Further increasing the PC content resultes in a decrease in the electrical resistivity of the cement paste. Increasing the content of PC can delay the appearance of the peak of the electrical resistivity change rate of cement paste. During the dissolution stage(about 0~120 min), with the increase of PC content, the rate of change in electrical resistivity gradually decreases, and the instantaneous resistance of cement hydration first increases and then decreases. The time for the lowest point of electrical resistivity of cement paste mixed with PC gradually prolongs, and the absolute value of the change rate of instantaneous electrical resistivity of cement paste after adding PC during 0~40 min.
左彦峰,姚越,宋天威.聚羧酸高性能减水剂对水泥浆体电阻率的影响[J].混凝土与水泥制品,2023(8):10-14.
ZUO Y F,YAO Y,SONG T W.Influence of polycarboxylate superplasticizer on electrical resistivity of cement paste[J].China Concrete and Cement Products,2023(8):10-14.
李增强1,王海龙1,周月霞2,张珍杰2,辜振睿1,程福星2
摘 要:研究了不同温控材料(WK)掺量(0、0.3%、0.4%、0.5%)对掺MgO膨胀剂的水泥净浆水化热特性、砂浆限制膨胀率及抗压强度的影响,并分析了材料的温度敏感性及WK对MgO膨胀剂的影响机理。结果表明:掺WK后,相较于单掺MgO膨胀剂,水泥净浆水化放热得到抑制,但随着MgO膨胀剂掺量的增加,这种抑制作用受到一定程度的削弱;当入模温度为20 ℃和30 ℃时,M-MgO复掺0.4%的WK对水泥净浆水化热温度的抑温率分别为35.6%和48.1%;在20 ℃和60 ℃养护条件下,M-MgO复掺0.4%的WK,相较于单掺M-MgO,砂浆的120 d限制膨胀率分别增长了0.014%和0.028%;WK的掺入会降低砂浆的早期强度,且随掺量的增大,强度损失越明显,但对后期强度无不利影响;WK对MgO膨胀剂水化有一定的激发效果,通过改变MgO膨胀剂的水化历程,影响水化产物的生成速率,进而改变了结构的密实度。
Abstract: The effects of different temperature controlled material(WK) content(0, 0.3%, 0.4%, 0.5%) on the hydration heat characteristics of MgO-doped expansion agent cement paste, limited expansion rate of mortar and mortar compressive strength were studied, and the temperature sensitivity of materials and the influence mechanism of WK on MgO expansion agent were analyzed. The results show that the hydration heat release of cement paste is inhibited by adding WK compared with the single addition of MgO expansion agent, but the inhibition effect is weakened with the increase of MgO expansion agent content. When the molding temperature is 20 ℃ and 30 ℃, the temperature inhibition rates of M-MgO combined with 0.4% WK on the hydration heat temperature of cement paste are 35.6% and 48.1%, respectively. Under the curing conditions of 20 ℃ and 60 ℃, M-MgO mixed with 0.4% WK increases the limited expansion rate of mortar by 0.014% and 0.028% after 120 d compared with the single addition of M-MgO, respectively. The addition of WK can reduce the early strength of mortar, and the strength loss is more obvious with the increase of mixing amount, but it has no adverse effect on the later strength. WK has a certain excitation effect on the hydration of MgO expansion agent, and by changing the hydration process of MgO expansion agent, it affects the generation rate of hydration products, thereby changing the compactness of the structure.
邵忠峰1,张国辉2,*,李常兵2,牛和峰1,高 博1
摘 要:混凝土内部湿度迁移与温度传导存在耦合作用,温度、湿度耦合作用下的混凝土内部含水率较单一环境存在显著差异。通过高低温交变湿热试验系统模拟大气环境温度、湿度变化,研究了4种不同大气温度(20、40、50、60 ℃)、4种不同大气RH(30%、60%、90%、98%)条件下混凝土内部含水率的变化规律。结果表明:大气环境温度越高,RH越大,混凝土的含水率越高,且含水率增幅越大;在吸附前5 h内,混凝土的含水率迅速增长,随吸附时间的延长,含水率增长趋势逐渐变缓;当大气温度为40~60 ℃、大气RH为90%~98%时,混凝土的含水率较大;当大气温度为20~30 ℃、大气RH为30%~40%时,混凝土的含水率较小;当大气温度为60 ℃、大气RH为98%时,混凝土的含水率最大,为1.53%;当大气温度为20 ℃、大气RH为30%时,混凝土的含水率最小,为0.09%;由灰色关联度计算结果可知,与大气RH比较,大气温度对混凝土含水率的影响更大。
Abstract: The coupling effect exists between humidity transfer and temperature conduction in concrete, and the internal moisture content of concrete under the coupling effect of temperature and humidity is significantly vary from that in a single environment. The changing atmospheric temperature and humidity were simulated by a fluctuated temperature alternating humidity and heat test system. The evolution law of concrete internal moisture content was researched under four different atmospheric temperatures of 20, 40, 50 and 60 ℃ and four different atmospheric RH of 30%, 60%, 90% and 98%, respectively. The results show that the higher the ambient temperature and RH, the greater the moisture content and the moisture content increasing of concrete. Within 5 h before adsorption, the moisture content increases rapidly, and with the extension of adsorption time, the increasing trend of moisture content gradually slows down. When the atmospheric temperature is 40~60 ℃, and the atmospheric RH is 90%~98%, the concrete moisture content is high. And when the atmospheric temperature is 20~30 ℃, and the atmospheric RH is 30%~40%, the concrete moisture content is low. The maximum moisture content of concrete is 1.53% under the coupling action of diverse atmospheric temperatures and RH, which occurs under the condition of atmospheric temperature of 60 ℃ and RH of 98%. The minimum moisture content of 0.09% occurs when the atmospheric temperature is 20 ℃ and the atmospheric RH is 30%. According to the calculation results of grey correlation degree, the influence of atmospheric temperature on the moisture content of concrete is greater than that of atmospheric RH.
邵忠峰,张国辉,李常兵,等.不同大气温湿条件下混凝土湿度响应试验研究[J].混凝土与水泥制品,2023(8):31-36.
SHAO Z F,ZHANG G H,LI C B,et al.Experimental study on concrete humidity response under different atmospheric temperature and humidity conditions[J].China Concrete and Cement Products,2023(8):31-36.
王松岩,赵 健,焦 红*
摘 要:为了研究结构修补用细石灌浆料高温后的性能,试验分析了不同温度(200、400、600、800、1 000 ℃)、不同冷却方式(自然冷却、浸水冷却)对细石灌浆料表观状态变化、质量损失、强度损失的影响规律,建立了温度与质量损失、温度与残余抗压强度的函数关系式。结果表明:在200~1 000 ℃高温后,试件的颜色由灰色变至黄白色,温度越高,试件表面裂纹越严重;温度的升高以及高温持续时间的延长会导致试件质量损失以及强度损失的加剧;当温度为200 ℃时,两种冷却方式的抗压强度基本一致,升高至400 ℃及以上时,自然冷却试件的抗压强度高于浸水冷却;基于试验数据建立的拟合关系式的拟合效果较好。
Abstract: In order to study the performance of fine stone grouting material for structural repair after high temperature, the influence of different temperatures(200、400、600、800、1 000 ℃) and cooling methods (free cooling, immersion cooling) on the apparent state change, mass loss and strength loss of fine stone grouting material was discussed, and the functional relationships between temperature and mass loss, temperature and residual compressive strength were established. The results show that after experiencing temperatures ranging from 200 ℃ to 1 000 ℃, the color of the specimen changes from gray to yellow white, and the higher the temperature, the more severe the surface cracks on the specimen. The increase in temperature and the prolongation of high temperature duration can lead to an intensification of the loss of specimen mass and strength. At 200 ℃, the compressive strength of the two cooling methods is basically the same. At 400 ℃ and above, the compressive strength of the free cooling specimen is higher than that of the immersion cooling specimen. The fitting relationship established based on experimental datas has a good degree of fitting.
王松岩,赵健,焦红.结构修补用细石灌浆料高温后的性能研究[J].混凝土与水泥制品,2023(8):26-30,36.
WANG S Y,ZHAO J,JIAO H.Study on performance of fine stone grouting material for structural repair after high temperature [J].China Concrete and Cement Products,2023(8):26-30,36.