Linghua LEl，You XlAO，Jinghua TANG

Landscape Architecture College，Huaihua University，Huaihua 418008，China

Study on Engineering Characteristics and Application of Sticky Rice

Linghua LEl*，You XlAO，Jinghua TANG

Landscape Architecture College，Huaihua University，Huaihua 418008，China

Sticky rice is not only a notoriously food，or a kind of important medicinal herb，but also serves as a kind of important engineering materials having rich resources.Sticky rice has excellent toughness，anti-seepage property，bonding property，reinforcing property，high strength and superior engineering performance with superior engineering value，ecological value and landscape value on account of its starch composition mainly composed of amylopectin of which the granules are polyhedron.The development and application of sticky rice has important strategic significance to promotion of sustainable development of ecological landscape construction，alleviation of resource shortage，reduction of environmental pollution，acceleration of constructing environmental friendly society and realization of sustainable development of China.

Sticky rice；Ecological material；Engineering application；Architecture landscape

S ticky rice is a name called in south China，and known as Jiangmi in north China.It is not only a kind of food known by everyone，but also serves as kind of healthprotection medicinal material capable of warming spleen and stomach，alleviating deficiency-cold，reducing urine，stopping spontaneous sweating and curing smallpox.China is rich in cultivars of sticky rice，and it was recorded in“Qiminyaoshu”of the Northern Wei Dynasty that there were 11 cultivars of sticky rice in Huanghuai area，accounting for 45.8%of all 24 cultivars.Local chronicles of Song Dynasty recorded 88 cultivars of sticky rice，accounting for 29.2% of all 301 rice cultivars.“Daopin”written by Huang Shengceng recorded that there were 14 cultivars of sticky rice in Taihu Basin，accounting for 40%of all 35 rice cultivars［1］. Sticky rice is very fond by Chinese people，and the sticky rice cultivars cultivated by Huaihua Dong minority who likes to eat sticky rice reaches more than 33 in number［2］.It is indicated that the cultivars of sticky rice are very abundant in China，and in another word，sticky rice is very important in the life of ancient Chinese people.

Definition

Sticky rice is the kernels obtained by harvesting slightly-round smooth caryopsis of the annual herb Oryzasativa L.var.Glutinosa Matsum of Poaceae in autumn，drying，and removing husks.It is cultivated all over China.

Components and Structure

It was indicated by experiments that 100 g of sticky rice contained proteins 7.30 g，fats 1.00 g，carbohydrates 78.30 g，cellulose 0.80 g，potassium 137.00mg，magnesium 49.00 mg，calcium 26.00 mg，phosphorus 113.00 mg，iron 1.40 mg，zinc 1.54 mg，sodium 1.50 mg，selenium 2.71 μg，nicotinic acid 2.30 mg，riboflavin 0.04 mg，vitamin E 0.80 g，vitamin B10.19 mg，vitamin B20.04 mg，vitamin B61.7 mg，etc［1］.The contents of ordinary nutrients including proteins，fats，ash and VB2and the contents ofmineral elements in sticky rice are higher than ordinary rice，and it is thus clear that sticky rice is rich in nutrients.

Sticky rice starch mainly consists of amylose （Am），intermatial fraction（Im）and amylopectin （Ap），in which amylopectin has a weight-average molecular weight of 8.96×107-7.96× 109g/mol，which changes little according to habitats and cultivars［3］.The starch granules of sticky rice showed a stereo-morphology of polyhedron mostly，and of spherical otherwise，with a grain size of 2-10 μm.

Types of Sticky Rice

Sticky rice could be divided into long sticky rice and round sticky rice. Long sticky rice is Indica sticky rice，the rice grains of which are long and thin，light pink in color，and transparent and have strong viscosity.Indica sticky rice grows in the south.Owing to the climate characteristics of simultaneously heat and rain，high-temperature and rainy summer，and low-temperature winter with less rainfall in the south，double-cropping or three-cropping sticky rice could be cultivated in the south.Multi-cropping rice is softer due to short growth time.Round sticky rice is Japonica sticky rice，which is round and short in shape，white and opaque，and tastes sweet and greasy，with a viscosity lower than long sticky rice.Round sticky rice grows in the north.Owing to cold weather in the north，single-cropping sticky rice is cultivated in the north.Sticky rice can be divided into white sticky rice，red sticky rice，purple sticky rice and black sticky rice［2］，among which，white sticky rice could nourishing lungs，red sticky rice contains more iron as well as a variety of vitamins and amino acids and is capable of enriching the blood，nourishing liver and caring skin，black sticky rice could nourishing kidney，and purple sticky rice is also known as Jiegunuo，capable of curing falling injury and incised wound［1］.

Engineering Characteristics of Sticky Rice

High strength，excellent toughness and superior anti-seepage property

It was shown by experiments that sticky rice paste had obvious regulating effects on size and morphology of calcite crystal:in certain concentration range，greater concentration of sticky rice paste resulted in lower crystallinity of generated calcite，and smaller particles represented denser structure；and meanwhile，sticky rice starch could well bond calcium carbonate particles and fill micropores.These properties lays the micro-foundation forhigh strength，excellent toughness and superior anti-seepage property of sticky rice-lime mortar.On the other hand，the lime surrounded by sticky rice paste which did not reacted completely could inhibit the growth of bacteria，such that the components of sticky rice would not rot in a long period［4］.

It was reported［5］that after adding 3%sticky rice paste into lime，the mixture had a compressive strength improved by 30 times and a surface hardness improved by 2.5 times and could resist soaking by water for more than 68 d due to the regulating effect of the sticky rice paste to carbonation of lime and the synergistic effect between the sticky rice paste and the generated calcium carbonate particles.The stone tower in Baohe Town of Rongchang County in Chongqing with a height of 10 m adopting sticky rice-lime mortar as bonding material still stands after more than 300 years since it was built in Qing Dynasty，though its gradient has reached 45°，indicating that the toughness of sticky rice-lime mortar is better than cement［6］.The results of the tests of uniaxial compression and tensile splitting strength showed that the carrying capacity of tabia containing sticky rice paste was remarkably higher than tabia which was not mixed with sticky rice paste［7］.

Excellent bonding property

Amylopectin as the main component of sticky rice is formed from monosaccharides which are connected into branch shapes and winded mutually.It is insoluble in water，forming stable colloid.Afterheating，amylopectin is gelatinized，resulting in loose chains in molecules and higher viscosity.Because sticky rice is composed of amylopectin substantially，sticky rice paste is very soft and sticky. Sticky rice starch gel has high transparency and good viscoelasiticity.The crystallinities and characteristic viscosities of the starches of different sticky rice varieties are different.

Sticky rice has the protein residual quantity and characteristic viscosity of starch and the relaxation time and high elastic modulus of starch gel affected by habitats.The starch of sticky rice produced in Hanchuan has higher protein residual quantity and lower characteristic viscosity，the starch gel of the sticky rice produced in Yingcheng，Hanquan and Jingshan has higher relaxation time，and the starch gel of the sticky rice produced in Yunmeng has lower plateau modulus［3］.

Good reinforcing property

It was found by experiments that the clear liquid composed of sticky rice paste and whitewash had better reinforcement performance by infiltration and mixing without changing the appearance of the reinforced objects. Sticky rice-lime clear liquid is a kind of transparent solution which is preferred to be saturated with lime （calcium oxide）and has its reinforcing effect obviously influenced by the concentration of sticky rice paste therein.From the measurement results of compressive strength and surface hardness，it was found that when the concentration of sticky rice was 4%，a best reinforcing effect could be achieved.Sticky rice paste could improve the cementing effect and water-soaking tolerance of calcium hydroxide，and the combination of sticky rice paste and calcium hydroxide and the microstructure formed thereby are the main reason for the resistance of mortar to rain wash and moist［4］.

Indica sticky rice cake is usually selected as the engineering cementing material in projects due to the fact that its hardness，glueyness and chewiness are greater than those of red sticky rice cake and Japonica sticky rice cake［5］.The sticky rice mentioned usually in life is ordinary sticky rice，i.e.，Indica sticky rice in the south，which is white and opaque，and soft and sticky in nature.Sticky rice is viscous，fragrant and smooth，and has good reinforcing performance and bonding performance.

Storage of Sticky Rice

Sticky rice starch is usually stored in airtight，cool，dry and ventilative en-vironment，and should be stored at a low temperature hermetically in summer.Sticky rice flour is usually subjected to natural drying treatment to maintain the total raw starch state of starch in the sticky rice flour，so that the αgelatinization of starch in sticky rice flour is sufficient，and its products obtain strong viscidity and good quality. However，the sticky rice flour subjected to natural drying treatment is prone to deterioration and rot caused by fungi and yeast due to its high water content，and its room-temperature storage time might be as short as 1 d，and 3 d by cold storage.

A better storage method for sticky rice starch includes the following steps:sticky rice is soaked in water until the water content reaches 15%-30% ，mixed with saccharides（the weight of sugar alcohol，starch hydrolysates and one or two kinds of saccharides selected from saccharides）at a weight ratio above 4∶1，and subjected to soaking and pulverizing，the obtained powder is filled in dampproof packaging bags or containers without drying treatment.Sticky rice could be stored for a long period by such method.The dampproof packaging bags is made from thermoplastic resin films including dampproof glass paper，polyethylene，polyesterand polyvinylidene chloride and aluminum foil as well as laminated films of above materials.The dampproof containers mainly are pots including aluminum pots and iron pots，bottles and formed containers fabricated with above thermoplastic resin materials［8］.

When selecting ordinary sticky rice，the grains，which are opaque，milky white or wax white，in a shape of prolate ellipse and relatively long with lower hardness，are preferred.

Landscape Application of Sticky rice

Gelatinization bonding agent-sticky rice-lime mortar

Sticky rice-lime mortar is widely used in Chinese ancient coffin chambers，urban construction，engraving，water conservancy project，etc.The footing of wall built with sticky rice-lime mortar is warterproof，dampproof，and as firm as cement.It was recorded that the sticky rice-lime mortar layer coating the periphery of coffins in coffin chambers had the hardness not lower than cement，was waterproof and free of cracking［1］，and could withstand the force of bulldozer sometimes.Dong minority decorates the decorative mascots of drum towers with the mixture of sticky rice，raw soil and juice of Actinidia chinensis Planch vines［2］.Beside sticky rice paste，other plant juices such as Averrhoa carambola L. vine juice，Polygonum leaf juice and Bletilla pulp，as well as egg white and animal blood are applied in building mortar［8］.

In order to promote the gelatinization performance of sticky ricelime mortar，additives can be added into sticky rice-lime mortar，to improve its strength.It was shown by experiments that the free water stored in the cavities of paper fibers could exert the effect of“internal curing”in the interior of mortar by adding paper strips in sticky rice-lime mortar；and meanwhile，paper fibers were in cross distribution in sticky rice-lime mortar，which enhanced the strength of sticky ricelime mortar and improved its freezethaw resistance，thereby greatly improving the carburization degree of mortar，resulting in densermortar structure，and as a result，the 28 d and 90 d compressive strengths were improved by 354%and 114%compared with the blank，respectively，as well as its freeze-thaw resistance was improved to 10 cycles without damage. Paper strips （3%）and aluminum sulfate（6%）could serve as the additives for sticky rice-lime mortar in the masonry cultural heritage protection projects including ancient building restoration，bridges and water conservancy projects， to enhance its strength.

Seepage-proofing agent

A good anti-seepage effect could be achieved by treating planting containers and wine containers with sticky rice congee cooked on slow fire for three times generally.Treating cucurbit containers for wine not only could prevent seepage，but also could remove the bitter taste of cucurbit.The anti-seepage property of soil bodies obtained by adding tong oil and sticky rice juice at a proper ratio into silt，clay and BS soil（the silt is added with bentonite 15%）could be improved greatly，and the average osmotic coefficients of the improved soil bodies decreases by 1-2 orders of magnitude.It is thus clear that tong oil and sticky rice juice not only could effectively improve the anti-seepage property of a variety of soil，but also could improve the antiseepage property and durability of soil bodies.

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Sticky rice juice could improve a variety of soil，among which clay exhibits an osmotic coefficient decreased by two orders of magnitude after being improved by sticky rice juice，silt shows an osmotic coefficientdecreased by one order of magnitude after being improved by sticky rice juice，and BS soil with extreme-low osmosis has an osmotic coefficient which further decreases after being improved by sticky rice juice.It was shown by experiments thatthe geotechnical properties of the mixed soil improved by tung oil and sticky rice juice were greatly improved［10］.

Discussion

Sticky rice is not only a kind of food，or a kind of important medicinal herb，but also serves as a kind of heath-protection medicinal material as well as a kind of important engineering materials having rich resource，and it is the sole rice variety applied in engineering.The sticky rice-lime mortar taking sticky rice as an important component has the advantages of high bonding strength，excellent toughness and good anti-seepage property.It is shown by literatures and archaeologicalevidences that sticky rice-lime mortaris a masterwork in the history of cementing materials for Chinese or even world ancient architectures，as well as an important ancient invention of China exhibiting the superb wisdom and skill of ancient Chinese.Sticky rice-lime mortar plays an important role in the reservation of Chinese ancient architecture.It is necessary to explore theengineering value of sticky rice-lime mortar from the points of carrying forward Chinese culture，repairing ancient architectures and solving the problems in ecological construction of modern landscape architectures with traditionaltechniques scientifically.

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Responsible editor：Yingzhi GUANG

Responsible proofreader：Xiaoyan WU

糯米的工程特性及應(yīng)用研究

雷凌華*，肖悠，唐京華 （懷化學(xué)院風(fēng)景園林學(xué)院，湖南懷化418008）

糯米不僅是一種眾所周知的糧食，也是一種重要的保健藥材，還是一種重要的工程材料，資源豐富。糯米淀粉主要由枝鏈淀粉組成，淀粉顆粒呈多面體，糯米具有優(yōu)良的韌性、防滲性、黏接性、加固性，強度大，工程性能優(yōu)越，糯米具有卓越的工程價值、生態(tài)價值及景觀價值。糯米的開發(fā)和應(yīng)用對推動可持續(xù)生態(tài)園林建設(shè)、緩解資源緊缺、減少環(huán)境污染、加快建設(shè)環(huán)境友好型社會、實現(xiàn)國家可持續(xù)發(fā)展具有重要的戰(zhàn)略意義。

糯米；生態(tài)材料；工程應(yīng)用；風(fēng)景園林

湖南省科技計劃項目（2011NK3046）；植物學(xué)湖南省十二五重點建設(shè)學(xué)科資助。

雷凌華（1972-），男，湖南衡陽人，博士，副教授，從事風(fēng)景園林規(guī)劃設(shè)計與教學(xué)，E-mail：linghualei@126.com。*通訊作者。

2015-08-03

Supported byScience and TechnologyPlanning ProjectofHunan Province（2011NK3046）；Hunan Leading Academic Discipline Project of Botany during the Twelfth Five-year.

*Corresponding author.E-mail:linghualei@126.com

Received:August 3，2015 Accepted:October 18，2015

修回日期 2015-10-18