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The purpose of this research is to enhance the performance of self-compacting concrete (SCC) to make it a more sustainable alternative to traditional concrete. SCC serves the purpose in harsh environments, therefore, requires protection against de-icing agents and harmful saline environments. This paper reports the results from a laboratory study evaluating the efficacy of two impregnants; pure-silane and water-based silane. Both materials were applied on dry and wet SCC specimens manufactured with high and medium doses of superplasticizer. When treatment is applied on dry samples, a significant reduction in chloride penetration was noticed. However, the impregnants were less effective when applied on specimens subjected to intermediate and long-term exposure to water. In dry conditions, pure-silane performed better than the water-based silane, although they had a similar performance when applied on wet specimens. In addition, increasing the internal moisture content has shown an adverse effect on the efficacy of both materials. Key words: self-compacting concrete, protection, impregnation, moisture content, sorption. Cette recherche a pour but d'ameliorer le rendement du beton autocompactant (BAC) pour en faire une solution de rechange plus durable au beton traditionnel. Le BAC fait l'affaire dans des environnements difficiles et par consequent exige une protection contre les agents de deglacage et les environnements salins nuisibles. Cet article presente les resultats d'une etude de laboratoire evaluant l'efficacite de deux substances d'impregnation, soit le silane pur et le silane a base d'eau. Les deux materiaux ont ete appliques sur des specimens de BAC secs et humides fabriques avec des doses elevees et moyennes de superplastifiant. Lorsque le traitement est applique sur des echantillons secs, une reduction significative de la penetration de chlorure a ete remarquee. Toutefois, les substances d'impregnation etaient moins efficaces lorsqu'elles etaient appliquees sur des specimens soumis a une exposition intermediaire et a long terme a l'eau. Dans des conditions seches, le silane pur a donne de meilleurs resultats que le silane a base d'eau, bien qu'il ait eu un rendement similaire lorsqu'il a ete applique sur des specimens humides. En outre, l'augmentation de la teneur en humidite interne a montre un effet nefaste sur l'efficacite des deux materiaux. [Traduit par la Redaction] Mots-cles : beton autocompactant, protection, impregnation, teneur en humidite, sorption., 1. Introduction Self-compacting concrete (SCC) has been implemented in the construction industry for a long time since it was first introduced in Japan in the 1980s (Loukili 2011). Many countries, [...]

Portland Cement Concrete (PCC) pavement was studied with incorporation of an environmentally friendly eco-additive, sodium acetate (C2H3NaO2). This additive was added to PCC pavement in three different percentages of 2%, 4% and 6% of binder weight. For a comprehensive elucidation of the eco-additive incorporation on the performance of PCC pavement, casted samples were cured in three different environments, namely: water, outdoors and pond water. Water absorption tests, flexural and compressive strength tests after 7 and 28 days of curing were conducted and results compared with the control samples without any addition of sodium acetate. Results demonstrated a significant improvement in the impermeability, compressive strength and flexural strength of PCC pavement when sodium acetate concrete is cured in a water bath and outdoors. However, no/little improvement in the impermeability, compressive strength and flexural strength was observed in sodium acetate samples that were cured in pond water. Microstructural analysis of treated samples by using scanning electron microscopy (SEM) illustrated the strengthening effect that sodium acetate provides to the pore structure of concrete pavement. [ABSTRACT FROM AUTHOR]

This article is aimed at investigating the long‐term performance of three original hydrophobic materials, namely, sodium acetate, fluoropolymer, and silicone resin. Their performance was compared with traditional silane when applied to fully dry concrete, fully saturated concrete, and concrete with 2 and 4% moisture content. A recently developed freeze–thaw process, which is based on temperature and humidity variations, was employed in this study to assess the durability of applied materials. The outcomes of the adopted freeze–thaw system were compared with the results obtained from running a conventional freeze–thaw test. Mass change, water absorption, and microcracks development of treated concrete were investigated and compared with untreated concrete after completing 6 months of freeze–thaw cycles. Results confirmed the high affinity of the proposed materials to moisture at application time compared with silane. Additionally, it was demonstrated that moisture content has a critical impact on the bonding between applied materials and concrete, hence their efficacy in enhancing the durability of concrete. [ABSTRACT FROM AUTHOR]

Despite excellent service history, concrete pavement faces accelerated deterioration due to water and chemical ingress through micro cracks and surface voids. Surface protection could be an inexpensive way of enhancing the durability of concrete pavement. This research focuses on evaluating the performance of three surface applied hydrophobic materials with different chemistries; fluoropolymer, silicate resin and sodium acetate crystallising material. Tests consisted of a microscopic study to assess the mechanism of treatment, contact angle and pendulum tests to evaluate the hydrophobicity and frictional properties of treatment respectively. Also, surface absorption and water intake tests were conducted to appraise the resistance of treatment to absorb water. It was found that all three materials are capable of developing a hydrophobic effect in concrete, but with different efficacy in reducing water absorption. The rate of water absorption was minimum for sodium acetate compared to fluoropolymer and silicate resin treatments. Scanning Electron Microscope (SEM) analysis revealed different interaction approaches for the three materials with concrete. [ABSTRACT FROM AUTHOR]

The purpose of this research is to enhance the performance of self-compacting concrete (SCC) to make it a more sustainable alternative to traditional concrete. SCC serves the purpose in harsh environments, therefore, requires protection against de-icing agents and harmful saline environments. This paper reports the results from a laboratory study evaluating the efficacy of two impregnants; pure-silane and water-based silane. Both materials were applied on dry and wet SCC specimens manufactured with high and medium doses of superplasticizer. When treatment is applied on dry samples, a significant reduction in chloride penetration was noticed. However, the impregnants were less effective when applied on specimens subjected to intermediate and long-term exposure to water. In dry conditions, pure-silane performed better than the water-based silane, although they had a similar performance when applied on wet specimens. In addition, increasing the internal moisture content has shown an adverse effect on the efficacy of both materials. [ABSTRACT FROM AUTHOR]

A novel approach has been presented to add a dual‐crystalline hydrophobic admixture in fresh concrete for improving hydrophobicity against chloride and harmful chemicals. Dual‐crystalline material can utilize water of the fresh concrete to form crystals, but the challenge is to maintain adequate hydration and strength while improving hydrophobicity. This study presents the results from a comprehensive laboratory investigation on the application of 1, 2 and 8% of crystallizing aqueous and cementitious hydrophobic mineral in fresh concrete. Despite the high slump in the fresh mixture, no segregation was observed in the matured concrete. There was a marginal reduction of strength when a high percentage of admixture was used. Despite this, significant reduction of water absorption was observed indicating greater hydrophobicity. The optimum performance was found in mixtures with 2% admixture. Mixture with 2% aqueous hydrophobic admixture revealed marginal strength gain compared to 2% crystalline cementitious hydrophobic admixture, although water protection appears to be better in cementitious mixture. [ABSTRACT FROM AUTHOR]

Treating concrete surfaces with cementitious coating, especially those are used as a reservoir for potable and recreational water, is increasingly gaining popularity as a safer and better alternative to conventional coating material formulated from epoxies, urethanes, acrylics and polyureas. Despite good resistance to weathering, scratches and loads, deficient curing of cementitious coating can lead to reduced performance and undesirable release of pollutants from the coating to water. In this study, the performance of a dual crystalline cementitious coating, which combines hydroscopic (water combining) and hydrophobic (water chasing) properties, for concrete protection was evaluated in an attempt to evaluate whether water affinity of the material can overcome the issue of reduced performance. The results were compared with a polymer modified cementitious coating. The influence of early exposure to water, after 24 h of curing, was assessed by coating pull-off testing and level of pollutants for the first 21-days. The water quality was found “good” to “excellent” according to World Health Organization (WHO) standard at all curing times for both materials with no surface cracking or other defects were noted. The crystalline coating needed 120–240 h for optimum curing, whilst polymeric coating needed 72. In terms of pull-off strength, the polymer coatings on the rough and smooth substrates yielded results greater than 1-MPa after 120-h curing, while crystalline coating took 240-h. However, compared to polymeric coating, the crystalline coating absorbed less water thought out the test duration, indicating that good overall performance. [ABSTRACT FROM AUTHOR]

Discusses the role of dominant-negative androgen receptor coagulator 70 in reducing the agonist activity of antiandrogens in prostate cancer cells. Aberrant phosphorylation of the dominant-negative mutant; Androgen response element; Prostate-specific antigen.

In patients with prostate cancer who manifest disease progression during combined androgen blockade therapy, discontinuation of antiandrogen treatment might result in prostate-specific antigen decline, often associated with clinical improvement. The response called antiandrogen withdrawal syndrome is thus acknowledged as a general phenomenon. However, molecular mechanisms responsible for this syndrome are not completely understood. This article outlines the proposed mechanisms, including alterations of androgen receptor gene and its coregulatory proteins and activation of the signal transduction pathway, and the potential therapeutic approaches based on the specific mechanisms., (Copyright 2003 Wiley-Liss, Inc.)

12-O-tetradecanoylphorbolacetate (TPA) influences proliferation, differentiation, and apoptosis in a variety of cells including prostate cancer cells. Here, we show that androgen treatment potentiates TPA-induced apoptosis in androgen-sensitive prostate cancer LNCaP cells but not in androgen-independent prostate cancer cell lines DU145 and PC-3. The use of the antiandrogen bicalutamide (Casodex) rescued LNCaP cells from 5-alpha-dihydrotestosterone (DHT)/TPA-induced apoptosis, suggesting that DHT/TPA-induced apoptosis is mediated by androgen/androgen receptor (AR). In addition, a caspase-3 inhibitor (Ac-DEVD-CHO) reduced the level of apoptosis, suggesting that DHT/TPA-mediated apoptosis occurs through a caspase-3-dependent pathway. A functional reporter assay using nuclear factor (NF) kappaB-luciferase and an electromobility gel shift assay showed that DHT suppressed NFkappaB activity. In addition, apoptosis mediated by combined DHT/TPA treatment was abrogated by overexpression of the NFkappaB subunit p65 in LNCaP-p65 cells, suggesting that NFkappaB may play an important role in regulating the effects of androgen/AR and TPA on apoptosis. Furthermore, use of the c-Jun N-terminal kinase (JNK) inhibitor SB202190 showed that the combination of DHT/TPA increased JNK activation in LNCaP cells but not in LNCaP-p65 cells, demonstrating that NFkappaB may be able to suppress JNK activity. These results indicate that androgen/AR facilitates TPA-induced apoptosis by interruption of the NFkappaB signaling pathway, leading to activation of JNK in LNCaP cells. These data describe a signaling pathway that could potentially be useful in proposed therapeutic treatment strategies exploiting combinations of different agents that control apoptosis in prostate tumors.