Study on the Mitigative Effect of Controlled Permeable Formwork (CPF) Liner on Early-Age Shrinkage of Box-Girder Concrete

Because of its high binder content and severe construction environment, early-age cracking is one of the most important threats to concrete used in continuous box-girder bridge structures. In this study, controlled permeable formwork (CPF) liner was used to mitigate the early-age shrinkage and reduce the early-age cracking risk of box-girder concrete. Early-age shrinkage was measured by a noncontact method and started at 30 min after adding mix water until 7 d. Internal relative moisture content and pore distribution tests were also carried out to reveal the working mechanism of CPF liner. The results show that covering the concrete surface with CPF liner decreased early-age shrinkage significantly. Under the temperature of 20°C and the relative humidity of 60%, two-surface-covering and three-surface-covering CPF liner on concrete decreased the shrinkage by 44% and 48%, respectively, at 7 d compared with concrete without CPF liner covered on it. The main reason is that CPF liner enhanced the internal relative moisture content and resulted in better performance of the surface concrete.

The Study of Corn Cobs and Gypsum AddingIn Some Physical Characters and Organic Matterof Cracking Soils from Middle of Iraq

In order to investigate the role corn cobs and gypsum in some physical charactersand organic matter ofclayey cracks and their properties. Seven soils sites (Afak, Al-Diwaniyah, Al-Taleea, Babel, Agriculture college, Al-Wahda and Al-Raid project) There are three types of treatments as follows: - Corn cobs was applied in four levels (0 . 10 . 20 and 40) g.kg-1 - Gypsum (calcium sulfate) applied in four levels (0 , 5 , 7.5 and 10) g.kg-1. - Treatments of interaction between corn cobs and gypsum. Corn cobs , gypsum and their interaction were applied in same levels above. In this experiment , 2 kg of each studied soil were treated with same levels of corn cobs and gypsum above and incubated at 30 + 2 °C for 90 days and 80% relative moisture content at 33 kpa. The results were summarized as :Soil aggregate stability (MWD) and organic matter values were increased , while modules of rupture and (COLE) values were decreased , with increasing of gypsum and corn cobs applying. Also, results showed that the decreasing of (COLE) values were depending on the clay content and interaction treatments , between corn cobs and gypsum. The decreasing of (COLE) values were the highest in the clayey cracks disappeared treatments.

Role of Gypsum and Corn Cobs in Linkage of Peds in Cracking Soils

To study role of gypsum and corn cobs in linkage of fractions in cracking soils. Three soils (Al-Diwaniya , Al-Wihda and college of Agriculture / Abu Ghraib) were chosen for this study . They were treated with two levels of gypsum (0.5 and 1) % with one level (4%) of corncobs . In this experiment , 2 kg of each studied soil were treated with same levels of corn cobs and gypsum above and incubated at 30 + 2 °C for 90 days and 80% relative moisture content at 33 kpa. And then the soils were sieved with 1 mm sieve to measured the x-ray diffractions . The results showed : The intensity of clay minerals peaks which treated with gypsum and corn cobs were decreased comparing with control sample. We believed that the gypsum should be facculated on clay minerals surfaces and mask them to appear clearly , and suggested that the gypsum was played an important role in conjugated of soil particles. Results of X-ray diffractions showed that there was no evidence of interaction between organic matter (corn cobs) and clay mineral inter layers.

Myxomycetes on the bark of Banksia attenuata and B. menziesii (Proteaceae)

Myxomycetes on the bark of dead Banksia attenuata and B. menziesii from the Perth metropolitan area of Western Australia were surveyed by the moist chamber technique, to determine whether the flora was similar on both hosts and what were the most important variables that determined the distribution of the most common species. Twenty-seven species of myxomycetes were recovered, including six new records for Australia (Comatricha rigidireta, Echinostelium elachiston, Paradiacheopsis cf. cribrata, P. rigida, Stemonitopsis amoena and S. cf. hyperopta). Members of the order Stemonitales comprised the largest number of species, whereas members of the Liceales occurred on the most bark pieces. The most common species were Licea kleistobolus, Echinostelium minutum, Comatricha elegans, Cribraria minutissima and Paradiacheopsis fimbriata. Overall, B. menziesii and B. attenuata had very similar myxomycete productivity, diversity and species assemblage, as did the tops and bottoms of the logs. It was concluded that they provided very similar microhabitats for myxomycetes. Both pH and the relative moisture content of the bark had an effect on myxomycete productivity. Bark decomposition level, pH and bark surface (top or bottom) were the most important variables determining the distribution of the most common myxomycete species.