Study on Properties of Blue-Brick Masonry Materials for Historical Buildings

There are a large number of historic buildings which were mainly made of blue-brick masonry in today’s world.However,for the natural and man-made reasons,these historic buildings have been damaged in different degrees.In order to protect historic buildings more scientifically and learn about the preservation state of existing historic buildings,it is necessary to ascertain the material properties of blue brick in historic buildings.The article takes the blue bricks of historical buildings in Kaifeng area of the Central Plains as an example to study.Through the analysis of physical properties,X-ray fluorescence spectroscopy,X-ray diffraction and scanning electron microscopy of blue brick specimens,the physical properties such as the apparent density,moisture content,porosity,and material structure composition are understood.The results show that the apparent density of blue brick is 1.64 g/cm^(3),the moisture content is 10.23%,the 24 h atmospheric water absorption is 17.86%,and the porosity is 20.99%.The smaller the apparent density is,the larger the porosity is,and the water absorption performance is better.From the microscopic point of view,bonding ability between blue brick mineral particles is relatively weak.The pores between skeletons are large and the pore structure is obvious.From the perspective of material phase,the elements of blue brick are mainly O,Si,Al,Fe,and the composition of blue brick is mainly composed of quartz and feldspar.The softening coefficient of blue brick is 0.80,and the deformation and stability of the structure should be paid special attention in the rainy season or wet environment.Through the frost test,there are salt substances in the internal pores of the brick,and the surface of the blue brick is eroded and pulverized.In this paper,the experimental process and analysis methods for testing the material properties of blue brick can provide reference for the research on the material properties of the same kind of blue-brick masonry in historic buildings and masonry relics.The relevant material property parameters obtained in this paper can provide guidance for making protection schemes and scientific repairs for historic buildings in Central China,enrich the evaluation criteria for maintaining and reinforcing historic buildings,and provide theoretical support for studying the damage and health detection technology related to historic buildings.

Effect of mulching with maize straw on water infiltration and soil loss at different initial soil moistures in a rainfall simulation

Mulching and soil water content(SWC) have a significant impact on soil erosion,and this study investigated the effect of straw mulching on water infiltration and soil loss under different initial SWC treatments in a rainfall simulation experiment conducted in northern China.Increasing initial SWC can decrease soil infiltration and increase soil loss.During an 80 mm rainfall event(80 mm·h–1for 60 min),8%,12% and 16% initial SWC treatments decreased cumulative infiltration by8.7%,42.5% and 58.1%,and increased total sediment yield by 44,146 and 315 g,respectively,compared to 4%initial SWC.However,in all the straw mulching treatments,there was no significant difference in stable infiltration rate between the different initial SWC treatments.For all initial SWC treatments,straw mulching of30% or more significantly enhanced water infiltration by over 31% and reduced soil loss by over 49%,compared to the unmulched treatment.Taking into consideration the performance of no-till planters,a maize straw mulching rate of 30% to 60%(1400–3100 kg·hm–2) is recommended for the conservation of water and soil in northern China.

Field test and evaluation on crop dividers of sugarcane chopper harvester

In South China,the tropical weather and climate result in severe sugarcane lodging problems which greatly hinders sugarcane mechanical harvesting.The main function of the crop divider is to lift lodged canes and facilitate base-cut cane feeding.In this study,a series of field tests were conducted on crop dividers of Liugong 4GQ-180 sugarcane chopper harvester.The tests were designed to identify the relationships of the performance index(maximum lifting height of sugarcane)and the main influencing factors(machine forward speed,rotational speed of inside scrolls,and ground clearance of crop divider toes).The single factor test was conducted to determine optimum range of these test factors:the forward speed(FS)was 2.0-4.0 km/h,the rotational speed of inside scrolls(RS)was 100-140 r/min,and the toe ground clearance(GC)was 0-5 cm.The orthogonal test(three factors and three levels)was carried out to determine the optimal combination of operating parameters:FS was 2.0 km/h,RS was 115 r/min,and GC was 0 cm.In addition,the range analysis of orthogonal test results revealed that the order of each test factor affecting crop divider performance was RS,FS,GC.This study was expected to provide valuable references for the optimal operation of sugarcane harvester crop dividers.