高强混凝土强度研究与概念分析

研讨了高强砼研究与设计中的几个强度概念，从微观实质上研究了高强砼的高强化基础，从抗压强度实质研究了高强砼的设计等级与标号、抗压强度标准值及抗拉强度等强度概念，并按ＨＳＣＣ９３－１指南进行了分析，供高强砼设计与施工应用时参考。

对南京地区地基基础规范水泥土支护结构强度验算的商榷意见

根据水泥土室内配制的试件与现场搅拌的取芯试件两者无侧限抗压强度差异很大的事实,通过调查分析,提出本地区fcs与fcu的对应关系,避免混淆和便于使用。对南京地区建筑地基基础设计规范水泥土支护结构强度计算,依据本地区的实践经验,提出适当提高抗力设计值和改进剪应力验算方法的建议,在安全的前提下,做到节约投资和符合实际。

压力传感器圆片激光焊接系统设计

针对压力传感器的密封焊接,设计了整套激光焊接系统,主要由焊接头组件、上下料组件、下驱动组件及定位夹具等几部分组成。实现快速上料,取料,自动定位及激光焊接,节约了生产成本并且提高了生产效率。经检测,该激光焊接系统焊接的传感器抗压强度达到3MPa,满足实际生产需求。

对砌体结构设计中三个问题的思考

就砌体结构局部受压计算中局部抗压强度提高系数、抗压强度设计值的取值及配筋砖砌体构件的截面抗震承载力验算等问题进行了分析,并提出了相应的建议,可供设计时参考。

美国混凝土砌体协会技术资料TEK 18-1B(2011年版) 混凝土砌体抗压强度的评价——质量控制和检测

前言 混凝土砌体的结构性能很大程度受以下三个关键因素影响： ●用把工程基本原理引入结构设计； ●用于结构建造的材料（即：砌块、灌孔混凝土、砌筑砂浆和钢筋）的物理特性； ●砌筑施工质量。

Prediction of compressive strength of cement mortars with fly ash and activated coal gangue

The pozzolanic activity of coal gangue, which is calcining at 500 to 1 000 ℃, differs distinctly. The simplex-centroid design with upper and lower bounds of component proportion is adopted to study the compressive strength of mortars made with ternary blends of cement, activated coal gangue and fly ash. Based on the results of a minimum of seven design points, three special cubic polynomial models are used to establish the strength predicating equations at different ages for mortars. Five experimental checkpoints were also designed to verify the precision of the equations. The most frequent errors of the predicted values are within 3%. A simple and practical way is provided for determining the optimal proportion of two admixtures when they are used in concrete.

支撑外挑悬臂梁砖砌体及地基受力分析

通常设计人员对砖混结构建筑物的钢筋砼构件的设计计算较为重视,而对支撑砼构件的砖砌体的设计计算比较容易忽视.

Treatment of bauxite residue dust pollution by improving structural stability via application of synthetic and natural polymers

The residue drying area(RDA)is the major source of fugitive red sand(RS)dust emissions in the bauxite mining industry and causes serious environmental and safety detriments.Polymer stabilizer(PS)is one of the promising non-traditional stabilizers to mitigate such issues.This research investigated the unconfined compressive strength(UCS)of RS using synthetic polymer stabilizer(SPS)and natural polymer stabilizer(NPS),and to determine the optimum application concentration and mixing ratio of the PAM and Guar gum mixture.Results illustrated that PAM apparently outperform Guar gum in stabilizing sand particles.The mixture of PAM and Guar gum is more effective than individual use.The optimum polymer concentration and the mixing ratio are 0.94 wt.%and 0.6(PAM:total(PAM+Guar gum)),respectively.A rigorous regression model was developed to predict the UCS value based on application concentration and mixing ratio for the purpose of cost and time efficiency.

Preparation and microstructure characterization of poly-sialate-disiloxo type of geopolymeric cement

In order to investigate the influence of three key molar ratios （n（SiO2）/n（Al2O3）, n（K2O）/n（Al2O3） and n（H2O）/n（K2O））, a total of nine potassium poly-sialate-disiloxo （K-PSDS） geopolymeric cement matrices were designed according to orthogonal design principle. Subsequently, XRD, ESEM-EDXA and MAS-NMR techniques were employed to further characterize the microstructure of the most fully reacted geopolymeric cement matrix. The experimental results show that n（K2O）/n（Al2O3） has the most significant effect on compressive strength amongst the three ratios. The highest compressive strength （20.1 MPa） can be achieved when n（SiO2）/n（Al2O3）=6.5, n（K2O）/n（Al2O3）=0.8 and n（HEO）/n（K2O）=10.0. The FTIR spectra of nine PSDS geopolymeric cement matrices also indicate that geopolymeric cement matrix with the highest strength is the most fully reacted one and possesses the largest amount of geopolymeric cement products. The microscopic analysis reveals that PSDS geopolymeric cement matrix possesses structural characteristics similar to gel substances in having a wide range of Si endowments, but predominantly the framework molecular chains of Si partially replaced by 4-coordinated Al tetrahedral.

Utilization of Recycled Coarse Aggregate in Concrete Mixes

In this paper, the effect of the source of recycled coarse aggregate on the properties of concrete is investigated. The tests were conducted on concrete made from three sources of recycled aggregates： （1） old concrete with unknown strength, （2） old concrete with a known compressive strength of 21 MPa, and （3） old concrete with a known strength of 42 MPa. The three sources of recycled aggregates were used to produce new concrete with a target compressive strength of 21 MPa. The first and third sources of recycled aggregates were used in producing concrete with target strength of 42 MPa. A control mix was designed with aggregates from natural sources. The research included two methods of making recycled concrete. One concrete mix was produced using the recycled aggregate and adding more water than the control mix, to reach the target slump, while the second concrete mix was produced using the same amount of water as the control mix but with additional superplasticizer to maintain the target slump. The results obtained in this research showed that the concrete compressive strength depends on the source of recycled aggregates; the stronger the source of recycled aggregate, the higher the compressive strength of the produced concrete. Furthermore, the compressive strength of the first concrete mix was about 10%-20% lower than the compressive strength of the control mix. However, when superplasticizers were used, the compressive strength was around the same value as the control mix.

Concrete Containing Marginal Aggregates for Use in Concrete Pavement

The study presented an analysis accessing the feasibility of using concrete containing marginal aggregates in concrete pavement slabs. The physical properties of aggregates were first determined and concrete was produced from them. Marginal aggregates were found to have higher fines, absorption, soundness loss, micro-Deval abrasion loss, LA （Los Angeles） abrasion loss and lower specific gravity and unit weight when compared with standard aggregates. Workability of concrete containing marginal aggregate was found to be similar to concrete containing normal aggregates when Shilstone mix design method was used to optimize the concrete mixes. The compressive strength, splitting tensile, flexural strength and modulus of elasticity of concrete containing marginal aggregates were determined and found to be generally lower than concrete containing standard aggregates. A typical concrete pavement in Florida was modeled in FEACONSIV （finite element analysis of concrete slab） software developed at the University of Florida. Laboratory determined mechanical and thermal properties of concrete were inputted in FEACONS IV and analyzed for maximum induced stresses. Critical stress to strength ratios, i.e., ratio between maximum computed stresses obtained from FEACONS IV to modulus of rupture （strength） of concrete, was used as evaluation criterion for different concrete pavement mixes. It was found that, in general, concrete containing marginal aggregates have higher stress to strength ratios as compared with concrete containing standard aggregates.