橡胶粉改性砂浆对半柔性路面病害的针对性研究

用橡胶粉对半柔性路面水泥砂浆进行改性,并添加适当的偶联剂进行实验,在分析半柔性路面病害的基础上,研究橡胶粉改性砂浆对半柔性路面的影响程度和规律.结果表明:橡胶粉掺加的目数,掺量的多少对砂浆的抗裂性,流动性和抗压强度有明显影响,进而抑制半柔性路面病害的发生;用偶联剂进行改性处理,则使橡胶粉等有机物和砂浆等无机物界面粘结良好,在水灰比和橡胶粉掺量等同等条件下,提高水泥胶浆的抗压和抗折强度.     

废旧橡胶颗粒改性对水泥砂浆性能的影响研究

经氢氧化钠(NaOH),四氯化碳(CCl4),聚乙烯醇(PVA)三种溶液改性后的橡胶颗粒加入到水泥砂浆中可改善橡胶颗粒与水泥基体的界面,使橡胶颗粒在水泥砂浆中达到较好的使用效果.试验研究表明,CCl4溶液改性的效果较好,其次是NaOH饱和溶液.综合考虑压折比、抗冲击性能和经济性等因素,在工程中建议使用NaOH饱和溶液对橡胶颗粒进行改性.NaOH饱和溶液改性的40目橡胶颗粒掺量为20％时橡胶集料水泥砂浆的力学性能最好.     

SBR乳液改性砂浆与水泥基体界面粘结性能

通过轴向拉拔及界面剪切试验测试了SBR(styrene-butadiene rubber,简称SBR)乳液改性水泥砂浆与旧水泥基体之间的粘结强度,SBR的掺量为水泥质量的0～12%.对新拌砂浆含气量、0～90 d砂浆的收缩变形及28d龄期砂浆的孔隙率和孔径分布等进行了试验研究与分析.研究认为,SBR乳液的掺入改善了新拌砂浆与旧水泥基体之间界面粘结性能,其作用机理主要有以下几点:1.使新拌砂浆含气量减小、28 d龄期砂浆闭口孔隙率增加,有助于保持砂浆中的水分,减小砂浆因水分丧失而产生的干燥收缩,2.减小砂浆28 d龄期前的收缩变形,从而减少了粘结界面因收缩产生的微裂纹,3.使28 d龄期砂浆的平均孔径变小、有害及多害孔隙数量减少,而无害孔隙增多,使接触界面新拌砂浆有害孔隙减少或孔隙细化或孔隙被封堵,从而增加了界面有效粘结面积.     

橡胶粉砂浆力学性能及导热系数的研究

为了研究不同橡胶粉掺量对砂浆力学性能和导热系数的影响,将回收废旧轮胎破碎成橡胶粉加入砂浆中,制备不同掺量的保温复合砂浆的试样,测定了该类砂浆的力学性能和导热系数.结果表明:橡胶粉保温砂浆的流动性、抗折强度和抗压强度随着橡胶粉的增加而降低;偶联剂添加量为橡胶粉颗粒的5%时,提高界面的强度效果最好,复合砂浆的导热系数达到0.71W/m·℃.     

Performance of the Cement Matrix Composite Material With Rubber Powder

The effect of the deferent rubber content substituted for fine aggregate on the mortar performance was studied. The effects of the rubber coated with the coating materials on the mortar compressive strength, bending strength and impact work were discussed. The optimum rubber powder content and the suitable coating material were found. Throagh the electrical probe test-BEI, SEI and calcium ion distribution, and the slight crack and the interface between the rubber and cement matrix are analyzed. The results show that the rubber powder coated with the surface treatment materials A, B and C has the capability of absorbing a large amount of energy under the compressive and flexural load and the slight cracks of R-C were controlled and restrained.     

灌注式半刚性路面橡胶粉水泥砂浆物理力学性能试验研究

通过对灌注式半刚性路面橡胶粉水泥砂浆进行物理力学性能试验,研究表明:将不同掺量的橡胶粉代替同体积的砂掺入水泥砂浆所制得的橡胶粉水泥砂浆含气量有所提高,而且具有良好的流动性、较小的干缩率,凝结时间也有所增长;在力学性能方面,抗压强度会随着橡胶粉掺量的增加而降低,而抗折强度则会随着橡胶粉掺量的增加,呈现出先增后减的趋势;在耐磨性能方面,橡胶粉水泥砂浆的耐磨性也是随着橡胶粉掺量的增加,出现先提高后降低的变化趋势;这些都为后续所开展的橡胶粉水泥砂浆最佳配比研究以及灌注式半刚性路面面层复合材料路用性能的研究提供了依据.     

石粉含量对机制砂水泥砂浆抗冻性能的影响

以M5,M10,M15,M20四个强度等级水泥砂浆为试验对象,在相同条件下分别进行0,20,40,60次冻融腐蚀循环试验,研究机制砂石粉含量变化对水泥砂浆抗压强度、抗压强度损失率和质量损失率的影响。结果表明,冻融循环不超过60次时,M5水泥砂浆最佳石粉含量为10%~15%,M10,M15水泥砂浆最佳石粉含量为10%左右,M20水泥砂浆最佳石粉含量为15%~20%。     

水泥粘土砂浆咬合桩应用研究

深基坑工程施工止水问题影响到地下工程的施工质量、施工效率、施工环境和施工安全。文章结合工程实例,提出水泥粘土砂浆咬合桩止水技术。对水泥粘土砂浆成桩性能、水泥粘土砂浆咬合桩特点和施工方法进行研究,开辟一条基坑止水技术新途径。     

改性胶粉对聚苯乙烯结构及力学性能的影响

将微波辐射改性胶粉与聚苯乙烯（PS）共混,通过扫描电镜（SEM）、衰减全反射红外光谱（ATR-FTIR）、X射线衍射（XRD）、拉伸和冲击试验等研究改性胶粉/PS共混材料的结构和力学性能。结果表明,当改性胶粉质量分数为8%时,改性胶粉/PS材料的冲击强度比PS的强度提高了183%,共混材料中改性胶粉以橡胶相分散在PS基体中,二者之间界面粘结良好。     

稳定型橡胶改性沥青混合料设计与工程应用

稳定型橡胶改性沥青混合料的设计决定了其技术性能和使用效果的优劣。文章通过室内试验,设计并测试了SMA-13稳定型橡胶改性沥青混合料的路用性能和力学性能,并与常用的SBS改性沥青混合料进行了对比分析评价。结果表明:稳定型橡胶改性沥青的性能分级为PG 76-28,优于常用的SBS改性沥青;稳定型橡胶改性沥青混合料的动稳定度和破坏应变分别提高了18.5%和12.8%,表明其在高、低温性能方面均具有优势。     

新型橡胶粉和抗车辙剂复合改性沥青混合料级配优化

新型橡胶粉和抗车辙剂改性沥青混合料路面高低温性能稳定,为优化其级配设计并提高路用性能,采用均匀设计法和正交设计法分别确定粗细集料关键粒径的筛孔通过率,对试验数据进行回归分析,通过综合粗细集料级配优化结果确定混合料集料总体最优级配,并通过分析优化级配下的高低温性能指标验证级配的适用性.试验结果表明,混合料嵌挤形成最优骨架结构时,粗集料最大含量占65%;能显著影响混合料高低温性能的因素是粗集料4.75 mm筛孔通过率、2.36 mm细集料筛孔通过率及油石比;建议混合料关键粒径16～13.2、13.2～9.5、9.5～4.75、4.75～2.36、2.36～0.3、0.3～0.075 mm的筛孔通过率分别为95%、67%、32%、20%、13.5%、5%,并给出建议的油石比为4.7%,最后给出了优化级配范围.     

橡胶粉、粉煤灰对再生砂浆力学性能影响的试验研究

为了更有效地处理及再利用废橡胶和废弃混凝土,对橡胶粉再生砂浆的力学性能进行了试验研究.选取60目精细胶粉与I级粉煤灰直接掺入到再生砂浆中,通过与素再生砂浆、普通砂浆的对比,研究了其对再生砂浆抗折强度与抗压强度的影响,并探讨了橡胶粉和粉煤灰的作用机理.结果表明:橡胶粉掺量为4%、粉煤灰掺量为15%时,有利于改善再生砂浆的力学性能.     

Experimental study on retarding mortar and its application in prestressed concrete

Based on a large number of orthogonal tests and theoretical analyses, the retarding mortar which meets the requirements of retard-bonded prestressed concrete was prepared. Initial setting time of the retarding mortar may vary from several hours to 15 d at 5 ℃-35 ℃ due to quantities and average curing temperature. And its 28 d compressive strength is above 35 MPa. Thus the influence of quantities on setting time and 28 d compressive strength, and the relationship between setting time and average curing temperature were investigated. The optimum quantities were obtained by studying the interaction of admixtures, and the retarding mechanism was discussed. Based on 52 retard-bonded prestressed strands by manual work from 24 retard-bonded prestressed concrete T-beams, static friction drag, change factor κ and friction factor μ were obtained from the test when retard-bonded prestressed strands were tensioned. Application of the retarding mortar will be vast in practical concrete projects.     

Experimental study on recarding mortar and its application in prestressed concrete

Based on a large number of orthogonal tests and theoretical analyses, the retarding mortar which meets the requirements of retard-bonded prestressed concrete was prepared. Initial setting time of the retarding mortar may vary from several hours to 15 d at 5℃ -35℃ due to quantities and average curing temperature. And its 28 d compressive strength is above 35 MPa. Thus the influence of quantities on setting time and 28 d compressive strength, and the relationship between setting time and average curing temperature were investiga-ted. The optimum quantities were obtained by studying the interaction of admixtures, and the retarding mecha-nism was discussed. Based on 52 retard-bonded prestressed strands by manual work from 24 retard-bonded pre-stressed concrete T-beams, static friction drag, change factor κ and friction factor μ were obtained from the testwhen retard-bonded prestressed strands were tensioned. Application of the retarding mortar will be vast in prac-tical concrete projects.     

废胶粉改性再生粗骨料沥青混合料性能试验研究

基于将建筑垃圾与废旧橡胶循环使用的目的,研究分别以0％,50％和100％取代率的再生粗骨料替换沥青混合料中10mm～20mm的天然粗骨料后沥青混合料的性能试验,并进一步在不同再生粗骨料取代率的沥青混合料中以干法掺入20％,30％的废胶粉及以湿法掺入20％的废胶粉,研究不同废胶粉掺量及干掺、湿掺废胶粉后再生粗骨料沥青混合料的马歇尔及车辙试验.结果表明,当废胶粉掺量为0％时,随着再生粗骨料取代率的增多,马歇尔稳定度和动稳定度先增多后减小,流值增多,马歇尔模数和残留稳定度减小,而不论是干掺还是湿掺,马歇尔稳定度降低,流值增多,马歇尔模数和残留稳定度降低,但是湿法工艺降低程度低,动稳定度先增多后减小.因此,沥青混合料中建议再生粗骨料取代率低于50％,而废胶粉以低于20％的掺量湿法掺入.     

橡胶粉与SBS复合改性沥青路用性能与微观结构

采用废旧橡胶粉和热塑性弹性体SBS复合改性道路石油沥青AH-90,分别进行了性能测试试验和结构分析试验,结果表明:改性后沥青的针入度明显下降,延度和弹性恢复明显增加,软化点升高,T800升高,T1.2降低,沥青的高温稳定性和低温变形能力均有较大改善。     

离子液体改性白炭黑的制备、表征及其在橡胶中的应用

利用[BMIM]Br、[BMIM]BF_4、[BPy]Br、[BPy]BF_44种离子液体改性白炭黑,对改性前后的白炭黑进行了红外及DBP和氮气吸附-脱附比表面积分析,应用改性后的白炭黑与橡胶混炼制得胶样,并考察胶样导热系数的变化。结果表明,4种离子液体均负载在了白炭黑上,并使得橡胶的导热有了一定提高。其中,质量分数为20%的[BMIM]BF4改性白炭黑混炼橡胶的导热效果最好,热传导系数由改性前的0.178 3 W/(m~2·K)提高到0.295 5 W/(m2·K),导热性提高了65.7%;离子液体质量分数为20%的[BMIM]BF4改性白炭黑疏水性由2.00mL/g增加到3.00mL/g;改性白炭黑填充橡胶后橡胶的拉伸强度由13.5 MPa提高到14.3 MPa。     

Pozzolanic Activity of Burned Coal Gangue and Its Effects on Structure of Cement Mortar

The pozzolanic activity of coal gangue burned at different burning temperatures was investigated. The burned coal gangue was mixed with portland cement in different proportions （ 20% - 60% ）. The pozzolanic activity of coal gangue burned and the hydration products were examined, the compressive strengths of the pastes of the mixtures were tested, and the mechanism of the reaction was discussed. The experimental results slum, that the coal gangue burned at 750 ℃ has the optimum pozzolanic activity, and the burned coal ganguc with SiO2 and Al2 O3 is in an active form. When the coal gangue burned at 750℃ is mixed into portland cement, the content of calcium hydroxide in paste is significantly reduced, while the contents of hydrated calcium silk.ate and hydrated calcium aluminate are increased accordingly, hence resulting in the improvement of the microstructure of mortar. The compressive strength of cement paste decreases with increasing the content of burncd coal gangue. The decease in strength is small in the range of 20% - 30% coal gangue substitution and significant in 30%- 60% substitution.     

石灰岩矿粉性质对沥青胶浆性能的影响因素及其技术标准

为了确定石灰岩矿粉性质中影响沥青胶浆抗冻性能的主要因素,并制定石灰岩矿粉分级和选用原则,对不同类型矿粉的沥青胶浆进行了冻融循环试验,分别检测其冻融前后的化学成分、微观形貌、微观力学性质和流变性能的变化,并对试验结果进行随机森林分析。结果表明：矿粉的掺入能够改善沥青胶浆的冻融老化性能,冻融循环后,胶浆粗糙度下降幅度、表面模量提升幅度与矿粉CaCO₃含量(质量分数)呈抛物线下降趋势,沥青胶浆黏附力与矿粉CaCO₃含量呈直线下降关系,为保持沥青胶浆冻融后性能的稳定,矿粉的CaCO₃含量不应低于85%;季冻区的沥青路面比非季冻区更容易发生水损害,与非季冻区相比,季冻区矿粉中CaCO₃含量应提高10%。随机森林方法分析表明,矿粉的物理化学性质对胶浆性能影响的程度排序为比表面积>CaCO₃含量>细度指标>塑性指数,比表面积影响沥青与矿粉的反应速度,而CaCO₃含量影响其反应的充分性。所提出的石灰岩矿粉母岩技术要求与矿粉的综合分级技术标准,可指导路用矿...     

纳米二氧化硅改性及其在丁基橡胶中的应用

对改性的纳米二氧化硅分别用红外光谱和XPS进行表征，测定大气和氨氛围下硫化胶的交联密度，研究硫化胶的物理交联密度和化学交联密度对力学性能的影响，结果发现，随着纳米二氧化硅填充量的增加，总交联密度增大，当纳米二氧化硅填充量大于1．0％时，物理交联密度增大，化学交联密度开始减小，力学性能提高；当填充量提高至3．5％后，力学性能增至最大，随后开始缓慢降低。