Acoustic absorption of hemp-lime construction

Hemp-lime concrete is a sustainable alternative to standard wall construction materials. It boasts excellent hygrothermal properties in part deriving from its porous structure. This paper investigates the acoustic properties of hemp-lime concrete, using binders developed from hydrated lime and pozzolans as well as hydraulic and cementicious binders. To assess the acoustic absorption of hemp-lime walls, as they are commonly finished in practical construction, wall sections are rendered and the resulting impact on absorption is evaluated. Hemp-concretes with lime-pozzolan binders display superior acoustic properties relative to more hydraulic binders. These are diminished when rendered, as the open surface porosity is affected, however hemp-lime construction offers the potential to meet standard and guideline targets for spaces requiring acoustic treatment.

Soil Stabilization with Lime Fly Ash, Iowa Highway Research Board Bulletin No. 26, 1961

The sixth in a series, this bulletin further compiles the reports on completed research done for the Iowa State Highway Research Board under its Project HR-1, The loess and glacial till materials of Iowa; an investigation of their physical and chemical properties and techniques for processing them to increase their all-weather stability for road construction. The research, started in 1950, has been conducted by the Iowa Engineering Experiment Station at Iowa State University under its Project 283-S.

Soil Stabilization with Lime, Iowa Highway Research Board Bulletin No. 25, 1961

This is the fifth publication in a series of compilations of the reports on research completed for the Iowa State Highway Commission. This research was done for the Iowa State Highway Research Board Project HR-1, "The Loess and Glacial Till Materials of Iowa; an Investigation of Their Physical and Chemical Properties and Techniques for Processing Them to Increase Their All-Weather Stability for Road Construction." The research, started in 1950, was done by the Iowa Engineering Experiment Station under its project 283-S. The project was supported by funds from the Iowa State Highway Commission. The principal objectives of the project may be summed up as follows: 1. To determine by means of both field and laboratory studies the areal and stratigraphic variation in the physical and chemical properties of the loess and glacial till materials of Iowa. 2. To develop new equipment and methods for evaluating physical and chemical properties of soil where needed. 3. To correlate fundamental soil properties with the performance of soils in the highway structure. 4. To develop a scientific approach to the problem of soil stabilization based on the relationships between the properties of the soils and those of the admixtures. 5. To determine the manner in which the loess and glacial till materials of Iowa can be processed for optimum performance as highway embankments, sub-grades, base courses, and surface courses.

Hydric behavior of earth materials and the effects of their stabilization with cement or lime: study on repair mortars for historical rammed earth structures

Earthen building materials bear interesting environmental advantages and are the most appropriate to conserve historical earth constructions. To improve mechanical properties, these materials are often stabilized with cement or lime, but the impact of the stabilizers on the water transport properties, which are also critical, has been very rarely evaluated. We have tested four earth-based repair mortars applied on three distinct and representative rammed earth surfaces. Three mortars are based on earth collected from rammed earth buildings in south of Portugal and the fourth mortar is based on a commercial clayish earth. The main objective of the work was over the commercial earth mortar, applied stabilized and not stabilized on the three rammed earth surfaces to repair, to assess the influence of the stabilizers. The other three earth mortars (not stabilized) were applied on each type of rammed earth, representing the repair only made with local materials. The four unstabilized earth materials depicted nonlinear dependence on t1/2 during capillary suction. This behaviour was probably due to clay swelling. Stabilization with any of the four tested binders enabled the linear dependence of t1/2 expected from Washburn's equation, probably because the swelling did not take place in this case. However, the stabilizers also increased significantly the capillary suction and the capillary porosity of the materials. This means that, in addition to increasing the carbon footprint, stabilizers like cement and lime have functional disadvantages that discourage its use in repair mortars for raw earth construction.

Chemical resistance of lime-based grouts for masonry strengthening

The stone masonry walls are present in many buildings and historical monuments, with undeniable asset value, but also in old buildings housing both in Portugal and in Europe. Most of these buildings in masonry are in certain cases in a high state of degradation needing urgent intervention. This requires the identification of deficiencies and the application of appropriate intervention techniques. One of the possible techniques for structural consolidation works of stone masonry walls is the injection of fluid mortars currently called grouts. The choice of grouts is very important with regard in particular to their chemical and physical properties. In this study, carried out under the Master of Chemical Engineering, two types of lime-based grouts were used, in order to evaluate and compare their chemical resistance due to the crystallization of soluble salts. One of the grouts is a pre-dosed blend commercially available, Mape-Antique I from company Mapei (CA), and the second grout is a mixture prepared in the laboratory (LB), comprising metakaolin, cement, hydrated lime, water and superplasticizer. With the purpose of evaluating the action of sulphates on these grouts, a series of samples underwent several wetting-drying cycles using two different temperatures, 20 °C and 50 °C. During the experiment it was determined the change of weight and compressive strength in the analyzed grouts, as well as the sulphate ion concentration and pH of the solution in which the samples were dipped. The commercial grout (CA) apparently has a greater chemical resistance to sulphates. However grout LB showed to have positive results in some parameters.

Effects of mineral admixtures and lime on disintegration of alkali-activated slag exposed to 50 °c

Alkali-activated slag can totally disintegrate when exposed to 50 C. This paper presents a study of possible solutions to avoid this disintegration by using silica fume (SF) and fly ash (FA) to partially replaceslag. It was found that partial replacement of slag with SF significantly reduces strength loss. A mixture of 50% slag 50% SF (cured at 25 and 60 C) showed no strength loss after the exposure. In comparison, a55% drop of strength was observed in a mixture of 50% slag 50% FA (cured at 25 C) after the same exposure.However, the strength loss of this mixture was reduced by 50% when cured at 60 C. The presence oflime in AAS pastes increases the degree of strength loss after the exposure. The mechanisms for the abovestrength results are discussed in terms of hydration products and microcracking.

Annual crop rotation of tropical pastures with no-till soil as affectedby lime surface application.

Soil acidity and low natural fertility are the main limiting factors for grain production in tropical regionssuch as the Brazilian Cerrado. The application of lime to the surface of no-till soil can improve plant nutrition, dry matter production, crop yields and revenue. The present study, conducted at the Lageado Experimental Farm in Botucatu, State of São Paulo, Brazil, is part of an ongoing research project initi-ated in 2002 to evaluate the long-term effects of the surface application of lime on the soil?s chemical attributes, nutrition and kernel/grain yield of peanut (Arachis hypogaea), white oat (Avena sativa L.) and maize (Zea mays L.) inter cropped with palisade grass (Urochloa brizantha cv. Marandu), as well as the forage dry matter yield of palisade grass in winter/spring, its crude protein concentration, estimated meat production, and revenue in a tropical region with a dry winter during four growing seasons. The experiment was designed in randomized blocks with four replications. The treatments consisted of four rates of lime application (0, 1000, 2000 and 4000 kg ha−1), performed in November 2004. The surface application of limestone to the studied tropical no-till soil was efficient in reducing soil acidity from the surface down to a depth of 0.60 m and resulted in greater availability of P and K at the soil surface. Ca and Mg availability in the soil also increased with the lime application rate, up to a depth of 0.60 m. Nutrient absorption was enhanced with liming, especially regarding the nutrient uptake of K, Ca and Mg by plants.Significant increases in the yield components and kernel/grain yields of peanut, white oat and maize were obtained through the surface application of limestone. The lime rates estimated to achieve the maximum grain yield, especially in white oat and maize, were very close to the rates necessary to increase the base saturation of a soil sample collected at a depth of 0?0.20 m to 70%, indicating that the surface liming of 2000 kg ha−1is effective for the studied tropical no-till soil. This lime rate also increases the forage dry matter yield, crude protein concentration and estimated meat production during winter/spring in the maize-palisade grass inter cropping, provides the highest total and mean net profit during the four growing seasons, and can improve the long-term sustainability of tropical agriculture in the Brazilian Cerrado.

Development of tahiti acid lime [Citrus latifolia (YU. Tanaka) Tanaka] budded trees in combination with different rootstocks.

2016

Growth, mineral composition, fruit yield, and mycorrhizal colonization of feijoa in response to lime and phosphorus application.

2016

Different doses of phosphorous and lime on Paspalum regnellii crop.

2016

Insights to the Clarification of Sugar Cane Juice Expressed from Sugar Cane Stalk and Trash

Processing of juice expressed from green sugar cane containing all the trash (i.e., tops and leaves, the nonstalk component) of the sugar cane plant during sugar manufacture has been reported to lead to poor clarified juice (CJ) quality. Studies of different liming techniques have been conducted to identify which liming technique gives the best clarification performance from juice expressed from green cane containing half of all trash extracted (GE). Results have shown that lime saccharate addition to juice at 76 °C either continuous or batchwise gives satisfactory settling rates of calcium phosphate flocs(50−70 cm/min) and CJ with low turbidity and minimal amounts of mineral constituents. Surprisingly, the addition of phosphoric acid (≤300 mg/kg as P2O5), prior to liming to reduce juice turbidity (≤80%), increased the Mg (≤101%) and Si(≤148%) contents particularly for clarified GE juices. The increase was not proportional with increasing phosphoric acid dose. The nature of the flocs formed, including the zeta potential of the particles by the different liming techniques, has been used to account for the differences in clarification performance. Differences between the qualities of the CJ obtained with GE juice and that of burnt cane juices with all trash extracted (BE) have been discussed to provide further insights into GE processing.