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Copyright of Environmental Research, Engineering & Management / Aplinkos Tyrimai, Inžinerija ir Vadyba is the property of Institute of Environmental Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The characterization of aluminum waste (AW) as a supplementary cementitious material (SCM) and its effect on concrete properties were investigated. This paper proposes a model for the prediction of the compressive strength of AW-cement concrete using Scheffe's theory. The powder (material) derived from aluminum smelting waste obtained from the aluminum extrusion plant, Inyishi, in Ikeduru local government area in Imo State, Nigeria was used in this research as partial replacement for cement in various mix proportions. The compressive strengths predicted by this model agreed with the corresponding experimentally obtained values. The optimum compressive strength of AW-cement concrete predicted by Scheffe's simplex model is 28.832 N/mm2. The density of the resulting AW-cement concrete was not significantly affected by the partial replacement of cement with aluminum waste. The addition of AW decreased both the initial and final setting times. The initial and final setting times for 0% cement replacement were 62 and 532 minutes while the corresponding values for 5, 10, 15, 20, and 30% replacement ranged from 36 to 58 min for the initial and 435 to 518 min for the final setting times. It was also observed that the AW absorbed water from the mix and therefore reduced workability. The model developed was tested for adequacy using t-statistic and f-statistic tests and were found to be adequate. [ABSTRACT FROM AUTHOR]

Sourcing of choice timber species is becoming increasingly difficult in the forests of West Africa including Nigeria. There is a need to provide alternative species by investigating the technical qualities of species that are hitherto not harvested. Six trees of Aningeria robusta were sampled at the base, 10, 30, 50, 70 and 90% of merchantable length and partitioned into the inner, middle and outer wood along the radial plane. Specific gravity (SG) and selected mechanical properties, namely, modulus of rupture (MOR), compressive strength parallel to grain (MCS) and impact bending (IB) were investigated. Data were analysed using analysis of variance. The overall mean SG was 0.44, while the mean values for MOR, MCS and IB were 89.05 N mm-2, 27.45 N mm-2 and 0.2 m respectively. Significant variations existed between sampling heights in SG and MOR, while variations in MCS and IB were not significant along the bole. For all properties investigated, no significant variation was found from the inner to the outer wood. The wood properties of this species indicate that it has the potential to substitute some popular species in the market. Its radial and axial uniformity may be exploited in marketing strategy. [ABSTRACT FROM AUTHOR]

An attempt was made to improve the physical and strength properties of a reddish-brown lateritic soil. 15-60% of sand by dry weight of laterite was used as a modifier in the stabilization of the laterite with 3-12% by dry weight of cement. Classification, compaction, California bearing ratio (CBR), and unconfined compressive strength tests were carried out on the specimens. The plasticity index decreased from 17% for untreated laterite to 2.5% when treated with a combination of 60% sand+6% cement. For the two energy levels of compaction, optimum moisture content (OMC) was found to increase with an increase in cement content but decreased as the sand content increased. The OMC at the West African standard (WAS) energy level was consistently lower than the values obtained at the standard proctor (SP) energy level, while the corresponding values of maximum dry density were higher at the WAS energy level than the values at the SP energy level. The CBR requirements for base course material were met when laterite was admixed with 45% sand+6% cement and 30% sand+6% cement, and 15% sand+6% cement, 30% sand+6% cement, and 45% sand+3% cement at the SP and WAS energy levels, respectively. It can be concluded that sand enhanced the effective stabilization of Ikpayongo laterite with cement within the maximum cement content specified by the Nigerian code. [ABSTRACT FROM AUTHOR]