Good Frost Resistance Research Articles

Research on the performance of sand-based environmental-friendly water permeable bricks

This paper examines the effects of the amount of admixture, the water cement ratio, the aggregate grading, and the cement aggregate ratio on the mechanical service properties and of porous concrete pavement bricks including strength, water permeability, frost resistance, and wear resistance. The admixture can enhance the performance of water permeable brick, and optimize the design mix. Experiments are conducted to determine the optimal mixing ratios which are given as; (1) the admixture (self-developed) within the content of 5% of the cement quality; (2) water-cement ratio equal to 0.34; (3) cement-aggregate ratio equal to 0.25; (4) fine aggregate of 70% (particle size 0.6-2.36mm); and coarse aggregate of 30% (particle size: 2.36-4.75mm). The experimental results that the sand-based permeable concrete pavement brick has a strength of 35.6MPa and that the water permeability coefficient is equal to 3.5×10-2cm/s. In addition, it was found that the concrete water permeable brick has good frost resistance and surface wear resistance, and that the its production costs are much lower than the similar sand-based water permeable bricks in China.

Frost durability of steel fiber self-compacting concrete for pavements

The paper presents the results from the research on self-compacting concrete with different steel fibre type addition. The reference self-compacting concrete mix with water/binder = 0.33 was prepared, then modified with steel fibres in the amounts of 0–60 kg/m3 and air entrained with polymer microspheres (40 μm diameter). The major objective of the research was to determine the effect of steel fibre and air content on the self-compacting concrete mix properties and hardened concrete frost durability. The tests also included internal cracking and scaling resistance evaluation for concrete specimens subjected to cyclic freeze-thaw process − two beams were frozen in air and two beams were partially submerged in water and then frozen. The scaling resistance was tested using the slab method on the specimens with sawn surface and on the specimens with natural finished surface. Non-air entrained steel fibrereinforced concretes, despite their high strength class (C55/67–C60/75) and medium absorption (4.34–5.11%), showed unsatisfactory resistance to internal cracking and scaling tests. The beams partially submerged in water failed after 100 freeze-thaw cycles, which confirms a significant influence of water uptake from moist environment during freeze-thaw cycles and the acceleration of the damage process. Test results indicate that air entrainment with polymer microspheres is a very effective method and allows obtaining very good air pore structure parameters and frost resistance results. The specimens with top − finished surface exhibited less damage in the scaling resistance tests in relation to the specimens with sawn surface.

Study on microstructures and macro-properties in cement-based materials adding phosphorous slag

Microstructures and macroproperties of cement-based materials adding phosphorous slag were studied in this paper. As the results show that the hydration heat decreased with the increase of the mix amount of phosphorus slag, and the reducing rate of hydration heat was lower than that of volume percentage. Set cement hydration products include more tabularly cumulated Ca(OH)2 crystals. The hydration products start to form compact tabular structures and the number of holes reduces visibly at the age of 28 days. Meanwhile, phosphorous slag concrete has good frost resistance and anti-permeability. Mixing fly ash and phosphorus slag can improve the wear-resisting strength of the concrete. The self-grown volume of phosphorus slag concrete shrinks slightly in the early age the expansion rate tending to be stable. Air shrinkage of the phosphorus slag concrete is slightly lower in the early period, and it is fairly the same as that of the fly ash concrete in late period.

The Characterization of Porosity and Frost Resistance of Concrete with Fly Ashes Modified

The paper presents the influence of fly ashes for the parameters which define the characteristics of the air pore and frost resistance of aerated concrete. Concrete which was used in the maximum allowable amount of fly ashes and different amounts of air admixture have been evaluated. Test of concrete mix have been performed such as the slump cone consistency and air content with pressure method used. Compressive strength, the depth of water penetration under pressure, at 150 cycles freeze resistance and the characteristics of the air pores have been evaluated for concrete. Parameters characterizing the pore structure have been marked: the total air content in concrete A, the ratio of pores location L, the content of micropores A300. The results of the study have shown that it is possible to provide good frost resistance of concrete containing fly ashes. Air content of about 4% provides increased resistance to frost well as the use of fly ashes. The condition of frost resistance is to ensure the proper pore structure of the aircraft.

Experimental Study of Frost-Resistance Properties of Silica Fume Concrete

The frost resistance of low strength concrete is researched. In order to evaluate the effect of different content of silica fume on frost resistance，the quality of the cement 6%, 9%, 12% silica fume are respectively added into concrete. Freezing-thawing test results show that: the silica fume concrete has good frost resistance. Content of silica fume on concrete is not almost effect to quality loss rate. In 0-250 times of freezing-thawing cycle range, it is smaller that relative dynamic elastic modulus change rate. Relative dynamic elastic modulus of ordinary concrete decreases rapidly after 250 times of freezing-thawing cycle while dynamic elastic modulus decrease rate of the silica fume concrete tends to slow. The freezing -thawing cycles up to 350 times, silica fume concrete relative dynamic elastic modulus is 1.5 times that of ordinary concrete that show the silica fume concrete frost resistance is better than that of ordinary concrete.

The Frost Resistance of LYTAG Concrete

This article studies the frost resistance of LYTAG concrete and ordinary concrete respectively used the RILEM recommended test method (CIF) about frost resistance of concrete. The results indicate that the single surface's frost resistance of Lytag concrete with mineral admixture is much better than normal density concrete's. And the rank of the single surface's frost resistance at 56 cycles of Lytag concrete with different mineral admixture is: silica fume and slag> silica fume and fly ash>slag and fly ash>silica fume>fly ash>slag. The important reasons why LYTAG concrete has good frost resistance is that the scope of blending interfacial transition zone of LYTAG concrete between aggregate ceramsite and cement stone was significantly smaller than ordinary concrete.

Experimental Study in Gangue Base-Course Mixture Materials for Pavement

Coal gangue, acting as the solid skeleton of pavement base materials, can efficiently reduce the drying shrinkage. Additionally, similar to fly ash in mixture material, gangue can react with lime (so called pozzolanic reaction), resulting in the formation of pavement base with a certain strength, good water stability and frost resistance, are good overall at the grass-roots level. Many cities in our country has gradually tried to use different kinds of industrial waste residue instead of sand to prepare the pavement base materials. This way, not only the waste residue is recycled, the lack of sand aggregates in road construction can also be overcome, which facilitate technical and economic growths.

Performance Evaluation of Shrub Willow Clones of North America and Yugoslavia Origins in Jilin, China

Abstract Demand for planting elite shrub willows as a resource for industrial use such as bioenergy and pulp has been increasing in Jilin province in northeast China. Toward this end, 12 elite willow clones, representing various species and origins, were imported from New York, USA, and planted at Lushui River, Jilin province. Two indigenous species were included in the test as the controls for comparison. This study was an evaluation of their performance in adaptation, growth potential, and wood traits after one rotation (three growing seasons). Results indicated that (1) all clones, but one, showed a parallel phenology to the control, had excellent survival (> 86%) and displayed good frost resistance; (2) compared to the control, most imported clones were comparable in main stem growth (height and diameter), but developed more stems and main roots; and (3) most imported clones had similar lignin, but higher cellulose content relative to the control. These results imply that some of the imported clones should be considered for further evaluation as good sources for both bioenergy and pulping. Based on cluster analysis, six clones were recommended for the upcoming scale-up site-clone trials for yield evaluation.

Experimental Study on the Performances of Cement Stabilized Iron Ore Tailing Gravel in Highway Application

Iron ore tailings as a kind of waste products after ore dressing is one of the major industrial solid wastes. Iron ore tailings not only cover huge land and pollute environment, but also give rise to security risks. The comprehensive utilization of iron ore tailings need to be studied systematically. According to the method in Test Methods of Materials Stabilized with Inorganic Binders for Highway Engineering, the technical performances of cement stabilized iron ore tailing gravel in highway application were studied by systemic experiments in this paper. These include the strength, modulus, and frost resistance property, water stability. And the influencing factors of the mixture strength were analyzed, too. The results show that the mixture of cement stabilized iron ore tailing gravel has higher strength and modulus, good frost resistance property and water stability. The technical performances of cement stabilized iron tailing gravel conform to the current specification, so it can be used as sub-base course or base course material.

Study on Frost Resistance of Concrete Used in Pavement of Northeast China

According to the cycles of freezing and thawing frequently happened during early spring and late autumn in northeast china, this paper studies on the frost resistance of concrete using in highway pavement. Making experiments by adding flyash, silicon powder, air entraining and water reducing agent to normal concrete with different proportions and using flexure strength, compression strength and mass loss rate of concrete as evaluating indicators, a reasonable and economic concrete proportion is determined, which reaches high flexure strength and compression strength, good frost resistance. On the bases of the experimental results and economic analysis, it is shown that the concrete proportion can effectively enhance the frost resistance of concrete. Therefore, it has good use value and it is promising with a good prospect of application.

The Effect of Freeze-Thaw Cycles on Mechanical Properties of Concrete

Freeze-thaw cycles have the impact on mechanical properties of the concrete in northern areas of China. In this paper, on the basis of the damage degree of freeze-thaw cycles and experiment data, for C30~ C50 concrete after freeze-thaw cycles, the loss rate of relative dynamic elastic modulus and the relation between compressive stress-strain are analyzed. Compounding good frost resistance of concrete is one of important measures to improve durability of concrete, and degradation patterns of mechanical properties are found. This study may serve as prediction of the service life of concrete in cold regions.

Changes in the activity of antioxidant enzymes in cereal species during the winter

The quantity of four enzymes belonging to the antioxidant system (glutathione-S-transferase, ascorbate peroxidase, guaycol peroxidase and glutathione reductase) was determined in plant material raised and hardened under field conditions. One variety each of the winter cereal species wheat, barley, rye, triticale, durum wheat and oats were used for the analy ses. The varieties were sown in small plots at the optimum date (in mid-October) in 1999 and 2000. Plant samples were taken at three dates at the beginning (December), in the middle (January) and at the end (late February or March) of both winters. The exact dates were determined on the basis of the state of hardening and the weather conditions. When the frost resistance of the cereal varieties was determined in the phytotron, the rye variety Motto was found to be the most resistant, followed by the winter wheat Martonvasari 18, the triticale Presto, the durum wheat Odmadur 1, the winter barley Hardy, the winter durum wheat GK Basa, the winter oat varieties, which had very poor frost resistance, and finally the spring oat variety Freja. The activity of the antioxidant enzymes was greater in cereal species with good frost resistance than in those with poor resistance. Differences in enzyme activity were also found within the varieties at different stages of hardening, but these were smaller than those between the varieties. It can be seen from the results that antioxidant enzymes help to protect cereals from the damaging effect of the active oxygen species produced in substantial quantities during exposure to frost.

Excess nitrogen affects the frost sensitivity of the inner bark of Norway spruce

The sensitivity to frost in the living inner bark of trees have been hypothesised to be influenced by acid rain and N deposition through changes in nutrient balance and carbon metabolism. At the Skogaby experimental site, situated in southern Sweden, Norway spruce in control plots, plots fertilized with ammonium sulphate and plots fertilized with mineral nutrients except N were compared in this respect. Frost sensitivity was measured by electrolytic leakage and expressed as an index of injury. The results showed increased sensitivity to frost in the bark of trees treated with continuous applications of ammonium sulphate for 11 years. This was probably not only a direct effect of high nitrogen availability, but also caused by insufficient levels of other nutrients due to the rapid growth and changes in soil chemistry induced by the addition of ammonium sulphate. Mainly Mg and K seemed to be of importance for retaining a good frost resistance, supporting the hypothesis that nutrient imbalances increases the risk for development of frost related bark lesions in southern Sweden.

Winter hardiness of durum wheat in Hungary

One basic precondition for the reliable cultivation of winter durum wheat (Triticum durum Desf.) in Hungary is for the varieties to have good winter hardiness and frost resistance. Field overwintering experiments carried out in Martonvásár between 1995 and 2003 demonstrated that there was a significant difference every year between the overwintering of varieties with poor and good frost resistance, though only in two years was there a significant difference between that of varieties with medium and better frost resistance. Only a medium correlation was observed between the mean annual values of the air temperature in the winter months and the winter hardiness of the varieties, confirming that winter hardiness is influenced jointly by a number of environmental factors (e.g. cold, snow cover). In the experiments carried out on the winter hardiness dynamics of durum wheat, it was found that in milder winters even T. durum varieties which are sensitive to frost overwintered with little damage, while in the two coldest winters during the experimental period the hardiness of these varieties did not provide sufficient protection even in December, and all the plants were destroyed by January. The early spring frosts experienced in 1996 proved in these experiments that spring frosts may cause considerable damage even to durum wheat varieties with relatively good winter hardiness. Averaged over eight years, the results prove that T. durum genotypes are now available whose average state of hardening and winter hardiness are equal or better than those of winter T. aestivum varieties with moderate frost resistance.

Effect of common bunt on the frost resistance and winter hardiness of wheat (Triticum aestivum L.) lines containing Bt genes.

In order to determine the effects of bunt inoculation on frost resistance and winter hardiness in lines containing resistance genes, the bunt [Tilletia foetida (Wallroth) Liro, T. caries (DC.) Tulasne] susceptibility of wheat lines containing bunt resistance genesBt1 to Bt10 and the effect of the year on the degree of infection were studied over six years from 1991 to 1997 in an artificial inoculation nursery. Uninoculated and artificially inoculated wheat plants were tested for frost resistance in the phytotron in 1995 and in the field in boxes in three years from 1994/95 to 1996/97. The line withBt10 was very resistant, lines with Bt5, Bt6, Bt8 and Bt9 were resistant, the line with Bt4 was moderately resistant, those with Bt2 and Bt3 were moderately susceptible, the line with Bt1 was susceptible and the line with Bt7 was very susceptible to the local bunt population in Hungary. Bunt incidence also varied over years. The frost resistance of the Bt lines was generally lower after bunt inoculation than that of uninoculated plants. The increased frost kill in inoculated plants was not correlated with the extent of varietal susceptibility to bunt. Some lines with resistance, namely those with Bt5 (1.6% infection), Bt8 (0.6%) and Bt10 (0.0%), suffered significantly greater frost kill in the young plant stage as the result of bunt inoculation. By contrast, the Bt7line had excellent frost resistance and winter hardiness but suffered the greatest extent of bunt infection, whereas the Bt6 line had good frost resistance and good bunt resistance.

Effect of Low Temperature on the rRNA Processing in Wheat ( Triticum aestivum L)

Summary In the course of the experiments, studies were made on the effect of low temperature on rRNA processing. The two wheat lines in this work differed from each other only as regards frost resistance. It was proved that in the case of the weakly frost resistant line quantitative and qualitative changes took place in the rRNA maturation process as the result of low temperature. During cold treatment the last precursors (1.4 and 0.9 MD) of the two stable cytoplasmic rRNAs (1.3 and 0.7 MD) accumulated at the expense of the stable rRNA fractions. This accumulation increased as cold treatment proceeded. In the line with good frost resistance this change could not be demonstrated. The results indicate that in the poorly resistant line the cold treatment had an inhibitory effect on the last step in the maturation process, i.e. at low temperature this process is unable to proceed to completion.