公路工程石灰土质量控制要点

目前的公路施工过程中,对石灰土的要求非常严格,石灰土的质量关系到公路的质量,公路建设又关系到人们日常生活的各个方面。本文主要分析石灰土施工过程中影响压实与强度的因素,以及对病害产生机理进行认真而系统的探讨与分析,并提出一些相应的解决措施。

Relationships between Application Amount of Quicklime and Soil Nutrients,Flue-cured Tobacco Quality in Panzhihua City

[Objective] This study aimed to investigate the improving effect of quick- lime on acid soil in tobacco-growing areas in Panzhihua City. [Method] The effects of four application amounts （450, 900, 1 350 and 1 800 kg/hm2） of quicklime on soil nutrients and flue-cured tobacco quality were observed for two consecutive years. [Result] In acid soil, the application of quicklime significantly improved soil pH. In addition, it showed significant effects on soil nutrients, flue-cured tobacco quality, tobacco output and tobacco leaf chemical components. When the application amount of quicklime was increased to 1 350 kg/hm2, the improving effect of quick- lime on soil nutrients was best, the flue-cured tobacco yield and quality all reached the highest, and the chemical components of tobacco leaves were closest to the in- herent indicators of high-quality tobacco leaves. [Conclusion] This study will provide certain reference for accurate application of quicklime in tobacco-growing area in Panzhihua City.

Damaging Formula of the Frost Resistant Concrete with Poor Quality of Coarse Limestone Aggregate

In this paper, concrete with limestone coarse aggregate was studied due to frost action in saline and nonsaline environments. The main focus is to explain the damaging formula of concrete with poor quality of limestone aggregate in frost actions. All investigated concretes fulfill the recommendations of the European standard EN 206, Concrete--Specification, Performance, Production and Conformity limiting values for composition and properties of concrete （maximum W/C （water/cement） ratio, minimal class of compressive strength, minimal mass of cement and minimal percentage of entrained air）. The damaging formula of the frost resistant concrete is studied through scaling test of concrete during freeze/thaw process, frost resistant test of coarse limestone aggregate and chemical analysis of limestone. Experiments results showed that there is a correlation between CaO/MgO ratio and Al2O3 of limestone and frost resistance of concrete, using chemical composition for determining potential ACR （alkali-carbonate reactivity） will indicate higher risk of damaging effect of concrete.

Research of Agronomic Characteristics of Peach Rootstocks on Calcareous SoilmTwelve Yearly Results

The experimental orchard on calcareous soils in the Tikves region has been established in 1999, in order to investigate the influence of the rootstocks on the behaviour of the peach trees. In the experiment we evaluated next rootstocks： Nemaguard （Prunus persica × Prunus davidiana）, seedlings of GF 677 （Prunus persica ×Prunus amygdalus）, hybrids BMVA 1, BMVA 2, VAF 215 and Autochthones type and GF 677 （Prunus persica × Prunus amygdalus） clonal. As control rootstocks in our experiment was used seedlings from vineyard peach （Prunus persica）. The experiment was established with one year old trees from Redhaven variety. Agronomical characteristics （vegetative growth, occurrence of leaf chlorosis, tree mortality, yield, productivity and fruit quality） of the trees on different rootstocks have been measured over a twelve-year period （1999-2010）. Significant differences on the level of P 〈 0.05 have been observed on vigour of the trees. The most vigorous trees were those on GF 677 clonal, GF 677 seedling and BMVA 2. The trees on Vineyard peach and Nemaguard was the weakest ones. The highest cumulative yield was recorded on GF-677 clonal rootstock, and the lowest on Nemaguard. Occurrence of chlorosis was the highest at Vineyard peach, Nemaguard and Autochthones hybrid, GF 677 clonal was the only rootstock without iron chlorosis. The percent of tree mortality to twelfth year was the highest at Autochthones hybrid （33.3）, and at GF 677 clonal and BMVA 1 had not tree mortality.

Dynamics of CO_2 Emission and Biochemical Properties of a Sandy Calcareous Soil Amended with Conocarpus Waste and Biochar

Biochar is a carbon-rich product obtained by biomass pyrolysis and considered a mean of carbon sequestration. In this research, a sandy calcareous soil from the Farm of the College of Food & Agriculture Sciences, King Saud University, Saudi Arabia, was amended with either woody waste of Conocarpus erectus L.(CW) or the biochar(BC) produced from CW at rates of 0(control), 10, 30 and 50 g kg-1. The effects of the amendments on soil p H, dissolved organic carbon(DOC), microbial biomass carbon(MBC), CO2 emission and metabolic quotient(q CO2) of the sandy calcareous soil were studied in a 60-d incubation experiment. The results showed that the addition of CW led to a significant decrease in soil p H compared to the control and the addition of BC. The CO2-C emission rate was higher in the first few days of incubation than when the incubation time progressed. The cumulative CO2-C emission from the soil amended with CW, especially at higher rates, was higher(approximately 3- to 6-fold) than that from the control and the soil amended with BC. The BC-amended soil showed significant increases in CO2-C emission rate during the first days of incubation as compared to the non-amended soil, but the increase in cumulative CO2-C emission was not significant after 60 d of incubation. On the other hand, CW applications resulted in considerably higher cumulative CO2-C emission, MBC and DOC than the control and BC applications. With the exception of 0 day(after 1 h of incubation), both CW and BC applications led to lower values of q CO2 as compared to the control. The power function kinetic model satisfactorily described the cumulative CO2-C emission. Generally, the lowest values of CO2 emission were observed in the soil with BC, suggesting that the contribution of BC to CO2 emission was very small as compared to that of CW.