An extract on #yzk
Polymer concretes are mixtures of aggregate and any of various polymers and may be reinforced. The cement is more costly than lime-based cements, but polymer concretes nevertheless have advantages, they have significant tensile strength even without reinforcement, and they are largely impervious to water. They are frequently used for repair and construction of other applications such as drains.
Energy requirements for transportation of concrete are low because it is produced locally from local resources, typically manufactured within 100 kilometers of the job site. Similarly, relatively little energy is used in producing and combining the raw materials (although large amounts of CO2 are produced by the chemical reactions in cement manufacture). The overall embodied energy of concrete at roughly 1 to 1.5 megajoules per kilogram is therefore lower than for most structural and construction materials.
Once in place, concrete offers great energy efficiency over the lifetime of a building. Concrete walls leak air far less than those made of wood frames. Air leakage accounts for a large percentage of energy loss from a home. The thermal mass properties of concrete increase the efficiency of both residential and commercial buildings. By storing and releasing the energy needed for heating or cooling, concrete's thermal mass delivers year-round benefits by reducing temperature swings inside and minimizing heating and cooling costs. While insulation reduces energy loss through the building envelope, thermal mass uses walls to store and release energy. Modern concrete wall systems use both external insulation and thermal mass to create an energy-efficient building. Insulating concrete forms (ICFs) are hollow blocks or panels made of either insulating foam or rastra that are stacked to form the shape of the walls of a building and then filled with reinforced concrete to create the structure.
The use of latex condoms by people with an allergy to latex can cause allergic symptoms, such as skin irritation. In people with severe latex allergies, using a latex condom can potentially be life-threatening. Repeated use of latex condoms can also cause the development of a latex allergy in some people.
In March 2010, the Swiss government announced that it was planning to promote smaller condoms intended for boys and youths of 1214 years old following concern about the pregnancy rate among adolescent girls, and also about the potential spread of AIDS among this age group. This was due to the fact that standard condoms were too wide and consequently failed to afford protection to adolescent boys during vaginal and anal intercourse. Family planning groups and the Swiss AIDS Federation had campaigned to have a narrower condom produced for youths after a number of studies, including a government study researched at the Centre for Development and Personality Psychology at Basel University, found that standard condoms were unsuitable for boys in this age range, and that the condoms either failed during use or that the boys rejected them altogether because they were too wide, and consequently they used no protection at all.
As a result of these studies, a condom aimed at 12- to 14-year-old boys is now produced and is available in Switzerland and in certain other countries. Manufactured by Ceylor, the "Hotshot" is a lubricated, teat-ended latex condom which is narrower than a standard condom and has a tight band at the opening to ensure that it remains on the youth's penis during intercourse. A standard condom has a diameter of 2 inches (5.2 cm) whereas the Hotshot has a diameter of 1.7 inches (4.5 cm). Both are the same length7.4 inches (19 cm). In 2014, in response to demand for condoms from a younger age-group, German condom manufacturer Amor started producing another condom aimed at young people. Known as "Amor Young Love", these lubricated condoms have a diameter of 1.9 inches (4.9 cm).