Uso de Resíduo Madeireiro Amazônico na Fabricação de Tijolos de Solo-Cimento no Município de Alta Floresta – MT / Timber Residue Use in the Manufacture of Soil-Cement Bricks for Civil Construction in the City of Alta Floresta- MT

Resumo: A discussão sobre edificações sustentáveis vem sendo abordada há décadas por diferentes autores, em geral com foco no consumo energético e na vida útil dos materiais, contudo para atender esses objetivos são necessárias novas tecnologias que promovam mais sustentabilidade. Para tanto, a inclusão de fibras vegetais em compostos de solo-cimento se mostram uma alternativa interessante, e pelo fato do setor industrial madeireiro movimentar a economia local no município de Alta Floresta o resíduo serragem passa a ser um possível agregado nos tijolos ecológicos, uma vez que o armazenamento inadequado deste resíduo pode causar sérios impactos ambientais, portanto, este estudo se propôs a desenvolver um tijolo ecológico fabricado a partir da mistura de solo-cimento e serragem de três espécies florestais da Amazônia, Cambará - Vochysia sp., Cedrinho - Erisma uncinatum Warm., Garapeira. - Apuleia sp, e ainda avaliar a resistência a compressão com intervalos de cura de 7, 14, 21 e 28 dias, com o intuito de verificar a viabilidade do material construtivo. Para a realização do experimento, os tijolos foram fabricados com traço de 1:8:2,5, (cimento: solo: serragem) e a serragem utilizada com dois tratamentos, in natura e tratada por imersão e padronização granulométrica. O material misturado foi compactado em uma prensa hidráulica. Como resultado, os tijolos com serragem apresentaram valores de resistência mecânica de: Cedrinho 1,26Mpa, Cambará 1,70Mpa e Garapeira 1,95Mpa e teores de absorção de umidade de 15,7%, 17,6% e 13,8%, respectivamente.Palavras-chave: Sustentabilidade. Tijolo solo-cimento. Serragem. Abstract: The discussion about sustainable edifications has been addressed in decades by different authors, generally focusing energetic consume and the materials lifespan, however to reach these goals it is necessary new technologies that promote more sustainability. For that the inclusion of vegetal fibers in soil-cements composts present as an interesting alternative, and because the timber industry moves the local economy in the city of Alta Floresta the sawdust residue become a possible aggregate of ecologic bricks since inadequate storage of this material can cause serious environment impacts, therefore this study propose to develop an ecologic brick manufactured by the mix of soil-cement and sawdust of three Amazonian species: Cambará - Vochysia sp., Cedrinho - Erisma uncinatum Warm, Garapeira. - Apuleia sp., and also evaluate the compression resistance in 7, 14, 21, 28 days intervals, aiming to verify the feasibility of the constructive material. To carry out the experiment the bricks were manufacture with the ratio of 1:8:2,5 (cement: soil: sawdust), and the sawdust used was treated twice, in natura, treated by immersion and granulometric standardization. The mixed material was compacted in a hydraulic press. As a result, the sawdust bricks showed resistance values of: Cedrinho 1.26 MPa, Cambará 1.70 MPa and Garapeira 1.95 MPa and humidity absorption percentage of 15.7%, 17.6%, and 13.8% % respectively.Keywords: Sustainably, Ecologic Brick, Sawdust

Soil genetics in its complex stabilization

The problem of the inter-repair time of automobile roads in Russia can be solved by the reinforcing the subgrade soils with cement. Soil is a multicomponent system affecting the deformation and strength properties of the composition (cement and soil). The cement-soil composition has drawbacks, especially in seasonal freezing regions, which affects its durability.In order to increase the composition efficiency, the Nicoflok polymer-mineral additive is used to strengthen subgrade with cement. However, the influence of the type regional and genetic soil on strength properties of the cement-soil + Nicoflok composition is yet studied.The paper presents the factor analysis of the influence of soil genetics on the composition strength properties. The study of the multicomponent system includes the response surface of the soil genetics on the strength properties of the composition. Additional studies are required to move from the qualitative evaluation of the soil genetics on the composition (cement-soil + Nicoflok) to the quantitative evaluation. These studies must be carried out according to a single scheme, which regards the seasonal freezing of subgrade soils in the northern regions of European Russia and West Siberia.

Impact of Drying and Wetting Cycles on Vegetation Cement-soil Physical and Mechanical Properties

The physical and mechanical properties of the ecological slope protection substrate will be affected by long-term variation of the meteorological condition, resulting in the stability of the substrate being reduced. So an artificial substrate of vegetation cement-soil was selected as the research object to prepare specimens with the different initial moisture content of 13%, 19%, 25%, 31%, 37%, and 43%. And a series of tests are conducted to investigate the evolution of the physical and mechanical properties under drying-wetting cycling conditions. Typical results of the vegetation cement-soil evolution can be divided into three stages: cement hydration stage, shrinkage stage, and stabilization stage. In terms of different initial moisture content, the shrinkage cracks number, cracks length, crack width, and cracks surface area are increased first and then stabilize with the increase of the number of drying-wetting cycles. In contrast, the cohesion and internal friction angle of the vegetation cement-soil is reduced with the increase of the number of cycles. Comprehensive analysis shows that the initial moisture content of vegetation cement soil ranges from 25% to 31% is the optimal choice to ensure substrate stability in production practice.

Analysis of Influencing Factors and Mechanism of Strength of Cement-Modified Silty Sand

The unconfined compressive strength of cement-modified silty sand in Jilin Province was investigated in this study. For this purpose, various tests were conducted, including the screening test, compaction test, CBR test, X-ray fluorescence detection, and unconfined compressive strength test. Effects of compaction degree, soil quality, water quality, cement content, and curing age were considered. The results show that CBR value is positively correlated with compactness. Two kinds of different water qualities have little effect on unconfined compressive strength of cement-improved soil; with the increase in cement content, the unconfined compressive strength increases, and the power function equation established by the two is significantly correlated. The logarithmic relationship between cement-soil strength and curing age is approximately linear. Through regression analysis, the comprehensive characterization parameters of cement-soil strength, such as water-cement ratio, cement content, and curing age, are put forward. The unconfined compressive strength of cement-modified silty sand has a good power function relationship with the comprehensive characterization parameters, and the fitting degree between the strength prediction formula and the existing research and test data exceeds 90%, which verifies the effectiveness of the comprehensive characterization parameters.

Mechanical Performance and Microscopic Mechanism of Coastal Cemented Soil Modified by Iron Tailings and Nano Silica

In order to explore the effect of composite materials on the mechanical properties of coastal cement soil, cement soil samples with different iron tailings and nano silica contents were prepared, and unconfined compression and scanning electron microscope tests were carried out. The results show that: (1) The compressive strength of cement soil containing a small amount of iron tailings is improved, and the optimum content of iron tailings is 20%. (2) Nano silica can significantly improve the mechanical properties of iron tailings and cement soil (TCS). When the content of nano silica is 0.5%, 1.5%, and 2.5%, the unconfined compressive strength of nano silica- and iron tailings-modified cement soil (STCS) is 24%, 137%, and 323% higher than TCS, respectively. (3) Nano silica can promote the hydration reaction of cement and promote the cement hydration products to adhere to clay particles to form a relatively stable structure. At the same time, nano silica can fill the pores in TCS and improve the compactness of STCS.

Influences of Curing Period and Sulfate Concentration on the Dynamic Properties and Energy Absorption Characteristics of Cement Soil

To study the influences of curing period and sulfate concentration on the dynamic mechanical properties of cement soil, this study used a split Hopkinson pressure bar device. Impact tests were conducted on cement soil specimens with different curing periods and different sulfate concentrations. The relationships between the dynamic stress–strain, dynamic compressive strength, and absorption energy of these cement soil specimens were analyzed. The test results show that with continuous loading, cement soil specimens mainly experience an elastic stage, plastic stage, and failure stage; with increasing curing period and sulfate concentration, the dynamic compressive strength and absorption energy of cement soil specimens follow a trend of first increasing and then decreasing. The dynamic compressive strength and absorption energy of cement soil specimens reached maximum values at a curing period of 14 d and a Na2SO4 solution concentration of 9.0 g/L. Increasing the dynamic compressive strength and absorption energy can effectively improve the ability of cement soil specimens to resist damage. This paper provides a practical reference for the application of cement soil in dynamic environments.