Concretions, organic content

Spent foundry sand is thought of as a beneficial substitute for fine sand for use in portland cement concrete. Prior to acceptance of inclusion, test standards applied on conventional fine sand shall be referred to as the standards for spent foundry sand to compare the physical properties of conventional sand and spent foundry sand. The most important parameters are particle size distribution, fineness modulus, dust content, density, organics content, deleterious materials content, and grain shape. Although no spent foundry sand satisfies all of the specifications, foundry sand can be blended with conventional sand to be incorporated into the concrete matrix. The replacing ratio normally starts at one-third. 

Using the optimized run protocol, different amount of samples were run to establish the reproducibility. Samples with low proportions of combustible material such as concrete, brick, metal, asbestos etc. show a good H-3 reproducibility for sample masses up to 10 g. However, for samples having high organic contents, such as biota, plastic, organic-rich sediment/soil etc.,... 

Analysis of samples taken from different parts of the carbonate concretions, and from the adjacent host sediment at site 93LD, showed that organic carbon content is higher within the concretions than in the surrounding sediments (Figure 7.17a). Little difference was found between... 

A few individual Loiano concretions (PLIC and PL3C) have a combination of 0-enriched oxygen, C-depleted carbon and Mg-rich, Fe-poor, Mn-moderate trace element contents that are compatible with relatively early precipitation from sea water modified by bacterial oxidation of organic matter and Mn mobilization from the sediment. 

Biofilm samples collected from carbon steel and concrete pipes of the DWSS Yovkovtsy had different appearance, content of water, organic and corrosion products, while ones from concrete pipe and water tank s surfaces were the same. Biofilm community mainly consisted of heterotrophic bacteria and some fungi, actinomyces and autotrophic bacteria. Corrosion related bacteria were determined in some of the biofilm samples. 

Water-reducing admixtures are water soluble organic materials which reduce the amount of water needed to achieve a given workability in plastic concrete without significantly affecting the air content or setting characteristics of the concrete. This effect can be utilized in three ways ... 

The technology is applicable for diffusely dispersed pollutants both in the non-saturated and saturated zone and in clay, sand, and peat soils. Contaminants that can be recovered by ER can be heavy metals, arsenic, nitrates, phosphates, halo-genides, and polar and/or water-soluble organic compounds such as cyanides, phenols, and nitro aromatics (such as trinitrotoluene [TNT]). Minimal moisture content should be 15%-20%. The technology is not economically applicable to heavy metals in metallic form, such as metal grindings, slag and cinder, concretions, and paint particles (putty). 

Latex-modified mortar and concrete are made by using a composite binder of inorganic cements and organic polymer latexes, and have a network structure which consists of cement gels and microfilms of polymers. Consequently, the properties of the latex-modified mortar and concrete are markedly improved over conventional cement mortar and concrete. The properties of the fresh and hardened mortar and concrete are affected by a multiplicity of factors such as polymer type, polymer-cement ratio, water-cement ratio, air content, and curing conditions. 

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