AC-13级配钢渣沥青混合料粘弹塑本构模型研究

为了研究钢渣沥青混合料非线性粘弹塑性变形特性,提出Schapery模型与改进Swchartz模型组合的积分型粘弹塑本构模型。采用钢渣替换AC-13级配中粒径2.36 mm以上的石灰石粗骨料,制作得到钢渣沥青混合料试件。设计并开展一系列的单轴压缩蠕变实验,通过应力递增蠕变回复实验,获得不同应力条件下材料的弹性、粘弹性应变和粘塑性应变,进而拟合确定本构模型参数。利用0.4 MPa、1.0 MPa下的蠕变回复实验验证模型有效性。结果表明,模型不仅能准确刻画钢渣沥青混合料蠕变过程中的弹性、粘弹性与粘塑性变形,还可用于预测不同应力水平下钢渣沥青混合料蠕变变形规律。     

Evaluation of polyphosphoric acid on the performance of polymer modified asphalt binders

The aim of this research is to evaluate the effect of polyphosphoric acid (PPA) on the mechanical performance of styrene–butadiene–styrene (SBS) and styrene–butadiene–rubber (SBR) modified asphalt. Conventional properties, multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and linear amplitude sweep (LAS) tests were conducted to evaluate the performance characteristics of asphalt at different PPA inclusions. Gel-permeation chromatography (GPC), saturates, aromatics, resins, and asphaltenes (SARA), and Fourier transform infrared (FTIR) were carried to reveal the molecular weight, component and infrared spectra of asphalt. Results showed that PPA hardened the asphalt, improved the rutting and fatigue performances of polymer modified asphalt (PMA) binder, but weakened the anti-cracking performances. Besides, storage stability had a significant improvement as the addition of PPA. The addition of PPA brought more macromolecules into asphalt and led to more high-average molecular weight compounds. Furthermore, PPA changed four component ratios of asphalt. Both PMA with or without PPA have similar absorption peaks. This may be due to absorption peak of PMA covered the changes in PPA modification process as the low content of PPA. 0.8% dosage of PPA may be considered optimum for composite modified binder combining the above experimental results for this binder source.     

脱硫胶粉在乳化改性沥青中的应用

考察了不同规格胶粉及不同脱硫程度的脱硫胶粉对橡胶改性乳化沥青性能的影响,结果表明,采用100目胶粉即可制备出橡胶改性乳化沥青,但乳化沥青的性能较差;采用活化度为50%左右的100目脱硫胶粉制备乳化沥青时,脱硫胶粉的用量相比于胶粉可大幅提高;在通过外掺100目50%左右活化度的脱硫胶粉(质量分数15%,以沥青计,下同)和质量分数2%的苯乙烯-丁二烯-苯乙烯嵌段共聚物改性的乳化沥青中添加质量分数1%的丁苯胶乳,所制备橡胶改性乳化沥青无筛上剩余物,5 d储存稳定性为2.9%,蒸发残留物的25℃针入度、软化点和5℃延度分别为55 (0.1 mm)、64.5℃和22.5 cm,能够满足乳化改性沥青的技术指标要求。     

盐冻融与干湿作用下沥青混凝土的高低温力学性能分析

制备了沥青混凝土样品,并进行了不同次数的盐冻融干湿循环试验。在此基础上,测试了沥青混凝土的高温车辙深度、动稳定度和低温抗弯拉强度,得到了车辙深度、动稳定度和抗弯拉强度随盐冻融干湿循环次和盐浓度的变化规律,研究了盐冻融与干湿作用下沥青混凝土的高低温力学性能。研究结果表明:(1)沥青混凝土60min车辙深度随盐浓度的增加和冻融循环次数的增多而呈线性增长的趋势;(2)沥青混凝土的抗高温变形能力随盐冻融干湿循环次数的增多而逐渐弱化;(3)沥青混凝土的抗弯拉强度经历9次和15次盐冻融干湿循环后分别下降22%~26.4%和42.6%~51.5%;(4)冻融干湿循环次数一定时,沥青混凝土的抗弯拉强度随盐浓度的增加而缓慢下降,并且当盐浓度达到12%时,沥青混凝土的抗弯拉强度减小就很不明显。     

响应面法优化制备LDHs-CRMA复合改性沥青及其表征

采用熔融共混法,以克拉玛依90#沥青为原料,Mg-Al水滑石(LDHs)与废橡胶粉(CR)作为改性剂,制备了具有抗紫外老化性能的水滑石/废胶粉复合改性沥青(LDHs/CRMA),并对其软化点、针入度指数(PI)、延度进行了测试。通过Hassan数学方法将三个指标"归一化"得到总评"归一值",采用响应面分析法建立总评"归一值"与各因素之间的Box-Behnken数学模型,得到了LDHs/CRMA的最优制备工艺条件为:剪切温度173℃、剪切时间89 min、剪切速率3500 r/min。通过紫外老化模拟实验对复合改性沥青的抗老化性能进行了评价,结果表明,引入水滑石可以减少沥青老化过程中含氧官能团的产生,抗紫外老化性能得到了明显提高。     

沥青储运工程中热载体加热系统设计应注意的一些问题

介绍沥青储运工程中热载体加热系统的特点及在沥青储运工程中的应用,并对其在设计中应注意的一些问题进行分析探讨。     

大堆积密度骨料配制的混凝土的性能(英文)

当今世界对可持续发展的关注促进了低水泥用量混凝土建筑工程的产生。增加混凝土中骨料体系的堆积密度是降低水泥用量的一个策略。增加骨料体系的堆积密度可以降低填充骨料颗粒间隙所需要的水泥浆体的量。研究了大堆积密度骨料配制的混凝土。这些混凝土比普通的结构混凝土低15%～25%的水泥用量,当骨料体系级配合理时混凝土工作性好。水泥浆体体积的降低在明显改进混凝土干缩与徐变性能的同时,也会对其工作性产生不利影响。骨料含量不会显著影响不同配比混凝土的抗压强度和劈裂强度。     

Design of Eu2+-activated broadband orange-emitting phosphors with excellent luminescent performance for warm WLEDs

We report orange-emitting Sr₈La_0.5Na_0.5Mg_1.5(PO₄)₇:Eu²⁺ (SLNMPO-0.5:Eu²⁺) and Sr₇LaNaMg_1.5(PO₄)₇:Eu²⁺ (SLNMPO-1:Eu²⁺) phosphors with broad emission bands covering from 450 to 800 nm. The phosphors can be excited by n-ultraviolet and blue light efficiently. Their crystal structure, diffuse reflection spectra, photoluminescence (PL) spectra, fluorescence decay curves and thermal stability were investigated systematically. Under the excitation of 365 and 400 nm, SLNMPO-0.5:Eu²⁺ and SLNMPO-1:Eu²⁺ both exhibit better PL properties and contain more red emissions than SMPO:Eu²⁺. CIE coordinates of SLNMPO-0.5:Eu²⁺ and SLNMPO-1:Eu²⁺ under 365 nm excitation are (0.460, 0.497) and (0.457, 0.494), respectively. Furthermore, high-quality warm white light can be generated by fabricating warm white light-emitting diode (WLED) devices with 370 nm LED chips, BaMgAl₁₀O₁₇:Eu²⁺ commercial blue phosphor and orange-emitting SLNMPO-0.5:Eu²⁺ (or SLNMPO-1:Eu²⁺) phosphor. The correlated color temperature, R_a and color coordinates are 3880 K, 94.05, (0.3895, 0.3922) and 3736 K, 91.73, (0.4005, 0.4078) for the fabricated WLED devices with SLNMPO-0.5:Eu²⁺ and SLNMPO-1:Eu²⁺, respectively. The excellent performances indicate that SLNMPO-0.5:Eu²⁺ and SLNMPO-1:Eu²⁺ have great potential to be attractive candidates in the application of warm WLEDs.     

Development of lightweight aggregate geopolymer concrete with shale ceramsite

This paper developed a lightweight aggregate geopolymer concrete (LAGC) with shale ceramsite. 18 groups of LAGC specimens with 3 sand ratios (30%, 40% and 50%) and 6 aggregate contents (10%, 20%, 30%, 40%, 50% and 60%) were prepared. A series of static tests (dry density test and uniaxial compression test) and dynamic tests (ultrasonic pulse velocity test) were performed to achieve the dry density, compression strength and P-wave velocity. The effects of sand ratio and aggregate content on the dry density, compression strength and P-wave velocity were discussed. Two optimal mix proportions for the LAGC were proposed. The results show that the dry density and P-wave velocity increase as sand ratio increases. The compressive strength increases then decreases as sand ratio increases. In addition, the dry density and compressive strength decrease as aggregate content increases. The P-wave velocity increases as aggregate content increases. The LAGC with the sand ratio of 30% and aggregate contents of 30% reaches the dry density of 1378.0 kg/m³ and compressive strength of 18.5 MPa. The LAGC with the sand ratio of 30% and aggregate contents of 40% reaches the dry density of 1348.0 kg/m³ and compressive strength of 16.8 MPa. Both of the proportions satisfied the engineering requirements, which are recommended for the potential application in the construction.     

超细硫酸钡化合反应研究

比较了制备超细硫酸钡的两种化合工艺，选择了较易实现的剧烈搅拌法，确定了最佳工艺条件为：间歇反应，在NaSO4溶液和BaS溶液的浓度分别为1．000mol/L和0．5000mol/L、温度为40℃、在300r/min搅拌速度下快速将Na2SO4溶液加入BaS溶液中并连续搅拌1min，所得BaSO4颗粒粒径小、耗能少。探讨了连续化实验方案。